IR comms considerations (for penlift for the Drawbot)


I was planning to hold this to be part of a much larger writeup of the Drawbot, but while it started as part of that project, it sort of took on a life of its own as an IR comms optimizing exercise.  I blew a huge amount of time on this, sticking my head in the sand and ignoring other things I really should have been working on.  I kept thinking “just one more test” – but that wasn’t how it worked.

The first version of the pen lift for the Drawbot included a nice servo mechanism driven by a Tiny85, but time forced the major ugliness of a light pair of wires from the main Arduino to carry control info to the gondola.  It worked fine, but those wires were never supposed to be there.  IR communication was the plan.

Finally, using a (20 year?) old 3 pin 38KHz IR receiver still in its Radio Shack bubble pack, I made up a PCB with a Tiny85 listening to the receiver module, driving the servo to lift the gondola and red and green status LEDs (for pen down/up).  I defined a simple pulse position protocol (in DrawbotStuff/DrawbotTinyServo4_IR.ino) on top of the required 38KHz pulses to deliver the 1 bit (up/down) messages, made up a test sender with an Arduino and an IR LED sending alternate state messages every half second and got it working.

A little aluminum bracket glued to the back of the PCB clips it to the gondola.  Servo and power wires were both perfect length to go to the board.  Sometimes we just get lucky. 🙂

Unfortunately, I wondered whether a useful improvement in range could be made by increasing LED current, along with a corresponding decrease in pulse width.  Now, the plan is to use 3 IR LEDs spread across the width of the Drawbot base, shining up at the gondola so even when it’s at the bottom corners of its movement, it will still have a transmitter LED more or less under it.  And with 50% duty cycle and 20mA – completely with the LED’s specs – I can get range much greater than to the top of the Drawbot.  So it really doesn’t need any range improvement.  But I just had to go and ask the question.  Bad decision.

Rick S suggested a 50% duty cycle would contain the most energy at the fundamental, thus providing max signal after the receiver’s bandpass filter.  Sounded like a reasonable argument against a range increase.  I tested at the space with 5.5 mA/50% DC pulses and got range (go/no go, with the actual receiver and protocol) of 50″.  Dropping to 25% DC but still 5.5mA, range dropped to 40″.  I can believe that.  Keeping 25% and increasing current to 11mA range went up to 167″!  WTH?

Christine suggested maybe the LED output was nonlinear and at the lower current wasn’t putting out as much as expected.  I tested with a very small 8 cell Si solar panel directly into my bench meter in current mode (~100 ohms), which I think is a good way to test for light energy in.  (I crudely covered the panel to keep out ambient light.)  Results of output current v LED drive current were VERY linear, 1-30 mA.  So I think doubling the current does indeed double the light output.

(A vaguely possible explanation for the wild range increase  (sorry for no pics 🙁 ):  The test was done with the LED near the end of one of the gray tables at the space, maybe 5″ above its surface, and aimed horizontally.  *Maybe* – energy off axis, which should never have come into play, hit the table top and reflected/diffused off toward the 167″ away receiver over another table.  That effect could be eliminated by mounting the LED out in space, not over a possibly reflective surface.  A subsequent test with similar currents but without the problem table did not show the wild range increase.)

Of course while testing using the actual intended receiver and message protocol provides great “real world” chops, it violates my “No boolean failure indications!” rule.  I should really structure a better test indicator.  Hmm – if I can’t get inside the receiver module to get an analog indication of how close we are to max range threshold, what if I can control the stimulus – LED current – and use that to sneak up on the indicator?  (Interesting idea, cost me lots of time digging into how to get an analog handle on LED current with a bench supply, but never got used.  All I did was suffer along with the go/no go indications of the IR receivers. 🙁 )

A good next test would be another doubling (or more) of LED current (with corresponding decrease in duty cycle to keep from blowing the LED) and testing range.  Maybe simplify the pulse train to eliminate any funnies created by my protocol, and maybe use a newer (and just different) IR receiver module.

Range test approach

Ugh.  The first tests (at W88) were with 2 known resistors that measured a factor of 2 difference in LED current: 5.5mA and 11 mA.  I kept the current low so the range would be manageable.  But the results were just unreasonable.

For the next round, I wanted to compare the range with a known LED current at 50% duty cycle (of the 38KHz pulses) with the range with a considerably higher current and correspondingly lower duty cycle (to not smoke the LED) – for nominally the same energy per pulse.  How hard can that be?

The lowest duty cycle I could easily arrange on the Arduino at 38KHz was 20%:


That gave me a 2.5:1 change from the 50% D.C. I took as reference.  That should be enough to see whatever effects there are by increasing LED current by a factor of 2.5.

To provide known current pulses, I set the IR LED up with a fixed resistor and an adjustable bench power supply.  Pulse current was gated by a logic level MOSFET driven by an Arduino (or sometimes a bench pulse generator).  I mounted the FDS6670 MOSFET (in its odd SOIC 8 package) with power, logic in, and load connections so it might be reused some time.

By measuring the voltage pulses across the known resistor (with my nice new scope), I made a table of supply voltage v LED current so I could easily produce any desired LED current.  That approach was chosen so changes in the forward voltage of the LED would not affect the results.  The first 2 columns below show the results.

I, mA   Vsupply   Vsup, computed
  2       1.55     1.53
  5       2.16     2.26
 10       3.27     3.36
 20       5.57     5.56
 40      10.6      9.88
 50      11.6     11.9
 80      18.5     18.6
100      22.8     23.0

(In hindsight, the limited accuracy of reading the pulse amplitude on the scope introduced more error than the LED.  Better would have been to measure the LED’s forward voltage at a couple of currents, measure whatever drop there was across the MOSFET (if any), interpolate the LED voltage and compute the supply voltage.  Working backwards and subtracting the drop across the resistor at each current from the required supply voltage in the table above, I computed LED voltages from 0.6-1.17V, with no particular correlation with current – awful.  Still close enough to be useful – just not very ideal.  Measured DC LED Vf=1.19V @10mA.  Later I computed the Vsupply based on known Vf (third column above); that’s what I used for subsequent tests.)

Knowing I’d need a long straight shot, I mounted the LED (with Arduino dangling) on a stick hanging out in space so it could see past various obstructions, “up” a small staircase, and along the floor on the next level.  At 50% duty cycle and 50 mA, it worked for the full 44′ shot.  (11′ down the computer bench, 6′ to the stairs, 7 ft “up” the stairs, and 20′ across the kitchen.  View from the LED is on the left.)

Unfortunately, I never got very crisp results.  The go/no go indication of the pen lift receiver was too capricious.  Once again, I could see some decrease at constant current going from 50% to 20% duty cycle.  But when I tried to change current, results were unclear.  (Note that the observation of range decrease going from 50% to 20% DC has no relevance to the tradeoff we’re investigating.  But it’s a very easy test, and can at least give some warm fuzzies when it behaves as expected.)

Trying to get better results, I made up another simpler receiver, using a different IR module and just an LED.  After verifying that this one was indeed open collector (the RS one wasn’t), and getting past some dumb mistake, I second guessed myself and made it and remade it so the LED would be on, then off, then on when pulses were sensed to make the most usable tool.  (Is it easier to see it stutter off or on at the ragged edge of range?)

But it’s not that simple.  In reading the datasheet for the common Vishay TSOP devices, I found you can’t just send continuous 38KHz pulses – something about AGC.  It’s designed only for messages, and messages have a maximum length, and dead time is required between messages.  That meant I would have to rewrite my test sender, honoring the gaps, but still giving a ‘mostly continuous’ indication on the receiver.  Yeah, it’s just datasheets and code and design decisions, and yes, I can do it all, but boo.  So I did it.  Boo.

Trying to decrease the range (to make measurement easier) while staying pretty linear, I made a little diffuser/attenuator out of a bit of plastic tube that (when split) fits over the (5mm) IR LED and has a Kleenex cover taped over the emitting end as the diffuser.  I can’t imagine its effects could be brightness dependent.  It might, however, act as much more of a point source, changing the parts of the range behavior related to the narrow beam divergence created by the LED’s lens.  Ugh.

Real test results (finally!)

Using the new supply voltage values, new code on the penlift board, new code on the test driver Arduino, the 3d version of the independent receiver, and clamping the LED on the edge of the bench looking out so  there wouldn’t be any possibility of unintended reflections, I did some tests.  Finally.  To keep from frying the LED’s resistor (oops), I quit the 50% DC tests early.

The new sensor (with new “as continuous as I dared” pulse stream) worked, but not great.  Its LED was constant brightness (and blinking at ~10Hz), but gently started to dim as it reached max range.  Then it went out.  I tried to gauge where it just started to dim (what a terrible indication!) and moved just a little closer for the official range.  Uncertainty was a couple of inches.  Ugh.

The penlift receiver exhibited some kind of hysteresis.  I’d move away until it stopped responding, then go closer again so it restarted.  But then if I went away very slowly, I could get an extra inch or five.  This was over the course of several seconds.  Parts of the AGC seem to be very slow.  Again, I moved a little closer than the very furthest I could finesse for the official measurement.  For both the penlift and the alternate receiver, I moved around in space to make sure I was fairly centered on the beam.

The new receiver, tested with the diffuser shows the expected (and unimportant) behavior of somewhat shorter range (~72%) when DC is reduced from 50% to 20%.  For the payoff test of decreasing DC and increasing current by like ratios:  Using the 20mA->50mA points nets a 15% range gain.  Using 10mA->(interpolated) 25mA gives a 32% gain.  That’s probably statistically significant, though hardly a “Hallelujah!”.

Data from the penlift – including its protocols – with the diffuser provides similar range decrease (66%) in the irrelevant dropping DC test.  The payoff tests – two pairs of direct data and one interpolated – gives an average range gain of 8%.  Big whoop.

The penlift with naked, lensed LED – the configuration I had expected to use all along – again gives similar range drop (70%) with reduced DC.  But the payoff tests – real data for 2->5mA and extrapolated for 5->12.5mA (ran out of room to go any farther!) average 62% gain.  But there’s a partial explanation:  Graphs of both data sets covering several points (the ones with diffuser) show a clear curve – with greater slope at low currents.  Since the scant data points we have are at the bottom, steepest part of the curve, one could argue that current increases have more effect there.  But (in a fit of sensibility!) I haven’t done any curve fitting to see if that’s justified.

The bottom line

Results were mixed, but it does look like increasing current and decreasing duty cycle, here both by a factor of 2.5, increased range by 10% – 30%, possibly more in some cases.  Interesting.

But putting my adult hat on for a moment, this was all unnecessary for the case at hand:  At just 5mA and 50% DC, the penlift worked out to 16 feet.  The farthest the gondola can ever get from the LEDs is a little over 3 feet.  But once some dumb question insinuates itself into my head, rational behavior is out the window.  Ugh.

 Notes on IR receiver modules

For at least my future reference, here are some random bits I learned diving down the IR receiver rabbit hole:

  • The receiver modules are cheap and wonderfully effective.  Just use one!
  • They come with center frequencies from 30-56KHz.  It doesn’t matter which you use, but do be sure your transmitter matches it.
  • There are several quite well documented control protocols used by commercial remotes.  The IR receiver docs often include nice info on them.
  • These things are expressly designed for delivering small (a few bytes max) asynchronous messages, and REQUIRE gaps between them.  They’re NOT designed as general purpose comms links.
  • They will (usually?) detect the beginning of a pulse stream in well under a millisecond.  But their AGC/other internal timing is very much not designed for DC carrier.  Don’t try to use them for a (normally on) beam break application!
  • There are multiple versions of modules tuned for different use cases.  I ran across families supporting “AGC 2” and “AGC 4”.  Presumably there are at least two others AGC classes.  There are versions for “short” and “long” data packets, and something called “continuous”, though it might need gaps as well.  I’d guess they would all work for simple hobby applications.
  • If you can’t get a datasheet for a junkbox/surplus IR receiver and don’t know the pinout, the following is alleged to have worked well and never fried any parts:  With a 1K resistor between the power supply and the device (for safety), just try all the possible pinouts of power/ground/signal out while shining a TV remote at it until you find the one that works.
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Chinese nail blocks not a fraud

Well, that was informative.  As Ziggy taught me to say back at Reuters, “The test is the test.”

cheapieblock4703When Scott told me about keeping a nail buffer block on the bench to provide 4 grits of sandpaper in one convenient, easily replaced tool, I thought I’d try it.  But after the 4-for-a-dollar Chinese cheapies arrived, they didn’t seem to do anything!  Even the coarse side didn’t begin to do what even the fine side of an emery board did.  I was convinced they’d just glued 4 colored pieces of paper to a nice foam block.  OK, I could glue some real sandpaper to the nice block, but that’s not what I was trying to buy.

But just because my fingers couldn’t feel any grit (at all!) didn’t mean the blocks were a fraud.  How could I test it?  How about “sanding” a piece of polished acrylic with them?  What about controls?  Name-brand commercial products exist – and surely those aren’t frauds.

The test

products4675Armed with products from Revlon and Trim for comparison, I set up the test.  Knowing I was going in with a strong bias, I tried to basictestsetup4664make it as objective as I could.  I put a 22 oz anvil on the pad (with a bit of sticky waffle rubber between to reduce slipping), and tried hard to not apply any force normal to the plastic as I scrubbed.  I revlonsetup4665arbitrarily chose 16 strokes back and forth for each sample as a nice round number.  Of course while the anvil provided constant force, it certainly didn’t provide the presumably more important constant pressure on the various sandpapertapedtoblock4667width and stiffness blocks.  Oh, well.  (Oops.)

I included some 1200 and some 2000 wet/dry sandpaper as well.  I just taped some bits of those around a block for a comparable test.


depthgauge0827To take closeup pics of the scratches, I mounted some little short FL positive lens in a bottle cap that just lightly press fit over the lens on my usual camera.  A bit of wire made a distance jig.  A black background and camerasetup0832side lighting seemed to give about the best results.  Unfortunately, auto-exposure can’t be turned off, so that tends to normalize the appearance of the pictures.

Being chinzy with the plastic cost a bit:  Some of the Revlon scratches impinged on some of the foam block tests.  Fortunately, they went a different direction, so when I took pictures I could try to exclude them.


Short answer:  I was completely wrong.  The 4 sides of the cheapie blocks clearly scratched the plastic, and in 4 graded ways.  And within the eyeball-quality results, their gradations were about the same as the 4 sides of the comparable Trim product.  The Revlon board included a side (black) that actually felt like an emery board (plus another medium grit white side), so those were in a different league from the Chinese (and Trim) “polishing” blocks.  In all cases, the #1 side was most coarse, #4 smoothest.

testacrylic4697Here’s the whole piece of plastic after the tests, marked for the blocks/sides used.  Overall fairly successful, though in hindsight I could have reduced the number of scrubs to 10 or 8.

Hmm – there’s a strong and repeatable artifact that grits 1 and 3 scratch more than 2 and 4, for both the Chinese and the Trim blocks.  Both 1s/3s are on the narrower sides of the blocks.  I’d have to guess we were seeing an effect of higher force/unit area on those smaller sides.  The Revlon block is more square in cross section, and doesn’t show that effect.  Interesting.  Yeah, I could retest and mask the surfaces to fix that – but I got the results I was after, so I’m done.
Here are the closeups, including a steel ruler for scale.  Identical contrast post processing was done to each.  Top to bottom, we have the cheapie, the Trim block, the 4 numbered sides of the Revlon board, and finally the white and black surfaces of the Revlon along with 1200 and 2000 actual sandpaper.

chineseblocktrimblocksrevlonblocksrevlonsandpaperThe closeups aren’t as definitive as I’d hoped.  But the result that the cheapie does in fact have 4 different (if fine!) abrasives is clear.

The test is the test.

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Hot melt strain reliefs – next phase

old4657I’ve used hot melt glue for strain reliefs on connectors – typically 0.1″ headers abused as connectors – for a long time.  Insulation is a secondary plus, but the primary goal was physical strengthening/protection of the quite small (and therefore weak) solder joints.    Yeah, the technique is good – no cold joints – but they’re still pretty small.  Cheap, works great.

I’m happy with a new, slightly more sophisticated application.  I’ve been soldering ribbon cable to cheap USB-TTL adapters for a long time.  They’re fine for the first couple of years, but after having to repair several broken wires, I’ve started taking a longer view.

The common failure mode is due to solder wicking into the stranded wire.  With a nicely soldered joint, there’s reasonable mechanical strength right where the wire goes thru the hole.  The next millimeter of wire is strengthened by the wicked-in solder, so all of that is OK.  But then comes the junction of the stiff, solder impregnated wire and the plain wire (typically slightly inside the insulation).  That’s where the flexing happens, and that’s where the fatigue failure occurs.

newtop4658The new application of hot melt strain relief is to go far enough up the wire that the solder/no solder junction is protected.  Yeah, there’s still additional flex at the very end of the hot melt, but I think that’s better than flexing at the junction.  I’ll bet these don’t fail the way the unrelieved ones do.

Maybe I’ll remember to come back here in a couple of years and report back. 🙂

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Prius footrest

On road trips in the (new, 2015) blue Prius, my left foot is frequently unhappy.  It would like a comfy  place to rest – the way IT wants to sit.  While there is a nice left foot rest, it’s not what my foot wants.  I’ve finally hacked in at least a first pass at what my foot has wanted for a long time.

footwell4358The existing foot rest assumes the drivers left foot wants to rest pointing straight forward.  Mine doesn’t – it wants to point to the left by maybe 30 degrees.  And the foot rest assumes the bottom of the foot wants to be flat (though toes raised).  Mine doesn’t – it rolls outward (is that supination?).  Making a new rest with angular correction in 2 dimensions was “interesting”.

I considered a sock full of quick set concrete, smushed into place then with its top shaped by resting my foot on it.  That might have worked.

A physical prototype/strawman usually helps me visualize what I have to make. I put a thin flat piece of wood maybe 3″x6″ on the foot rest and rotated it CCW about how my foot wanted.  OK – I’ll need to trim the bottom at an angle to meet the floor nicely.  Good start.  Now for the wedginess.

makingwedges4367I tried to block it up on the right side ’til it felt good, but couldn’t find a trivial way to do it.  So I rocked my foot back and forth (flat-supinated) to get a very seat of the pants idea what angle it wanted.  I guessed about 20 degrees, and sliced a slightly narrowed piece of 2×4 at that angle on the table saw.  While I was right there I hacked freehand the angle on the bottom, and plopped it on the rest to see how if felt.

thewedge4375Oops – that 20 degrees was too much.  Back to the saw.  After turning the wood lots of ways and scratching my head some, I used the nice blade angle scale to slice 7 degrees off, for about 13 degrees of wedge.  Felt good!  Let’s attach it – at least as version 0.1.

I was going to drill it and put a couple of self tapping screws thru whatever the original footrest was made of, but got spooked at the thought of wires (or brake lines or worse) being routed right behind it.  Very unlikely, but inposition4383high stakes.  Bummer.  Let’s just go with Liquid Nails.  It’ll be a mess if I ever have to take it off, but c’mon – it’s on the floor.

The tube of Liquid Nails has been sitting in the caulk gun for a liquidnailstipsealer4391couple of years now (though to my surprise, I hadn’t put a date on it).  I keep a 1/4-20 bolt “screwed” into the tip to try to keep it from drying out.  Pulled the bolt, squirted some out and sure enough – it was still good!

A lead block on a piece of wood to gluedup4388hold it down and some scrap to keep the bottom of the new footrest up so the floor mats will still slide out, and it’s done for now.

clamped4390It’s cold out – low in the 30s tonight, highs only in the 40s.  Recommended application temp range is 40-100, so it’s a little out of spec.  The good news is that the wood and carpet are both porous, so that should help.  (Well, except for the rubber tread on the original.)  I left the car door open (and clamped the light switch “off”) hoping it won’t smell too bad tomorrow.  We’ll see.

Foot is very anxious to try it out.

Update 1/8/17:

fail4417Well, fail.  Probably due to not letting the glue set up long enough, the wedge fell off the next morning.  Bummer.  And a mess.

itsfoam4418Second try:  I peeled the carpet back to see what I had to work with underneath.  Wow – a big block of nice closed cell foam!  Guess the worrying about puncturing brake lines was unnecessary.  (Well, no.  It was appropriately erring on the side of caution.  Just turned out to be wrong.  No regrets.)  I should be able to hack that foam into submission.

reshaping4422It was a challenge to hold the odd-shaped piece of foam to work on, and a sort of seat of the pants guess for the angle, but I chopped a big piece off.  I removed the most in the mainchunkremoved4427lower left corner to accommodate my heel.  But the upper right needed to be raised a bit more.

gluingonshim4438I cut a shim out of the cut off piece, and glued it on.  There are NO parallel sides or right angles on this sucker.  But I got it stuck on, probably with Gorilla Glue.

foaminplace4482It went back in pretty easily.  You can see some of the glue outline of the upper right shim.  The carpet went back on fine, and I got all the clips and other bits in.  The carpet didn’t seem fazed by upper right shim, but I had to wedge a block of something in below the side molding to hold it down into the heel depression.

cleanedupwell4483Now I had to face the dumb Liquid Nails.  It had had several days to cure by now.  But with a little scraping, it came off very well – even from the carpet.  Yay!  (Hmm – did the glue in the sealed, but aged tube lose some of its sticking power?)

done4494The final result is hard to tell from stock.  You can see the bit of dark stuff I wedged in to push the carpet into the heel hole.

I’ve been driving with it for a month now.  It’s definitely better than it used to be, but not perfect.  I think I was too conservative when I cut out the heel hole.  And in order to gain the maximum outward roll comfort, my heel needs to be way over to the deepest place on the left.  Unfortunately, that compromises the toe’s desire to point out to the left.  I’m not likely to go back and do it again, but my foot appreciates the improvement, tradeoffs and all.

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Mantis tiller

Mantis+Toys3976After many years of dithering, I finally decided to get a Mantis.  I found a used one for $80? $100? on Craigslist and bought it.  It’s great!  I found edger and dethatcher parts for it and it’s ready to rock and roll.  This note will hold some details about it and its history.

Last summer (2015) I edged all the sidewalks with it and tilled up the big mess where the tree in the inside front lawn was removed and the stump ground out.  Despite its size, the thing is a beast!  I drained the tank and ran out what fuel was left in the carb and put it away for the winter.

When I tried it this spring, it wouldn’t start.  Not even a pop.  Yeah, the fuel was a little old (whatever was in the snowblower/lawnmower can – of course with Stabil, which is great), mixed fresh with oil to 50:1, but I doubted that that fuel was an issue.  I choked it and pulled a lot, but when I pulled the plug, it was completely dry.  Looks like a carb issue.  C’mon – I even ran it dry, which is a lot more than I ever do for any of my other small engines!  I drained the tank and put it away for a couple of weeks.

When I got back to it I’d decided to disassemble and clean the carb.  I had a tuneup kit (almost the right one) with fuel lines, plug, and air filters on the shelf, but no rebuild kit.  If I got in trouble, I figured I could probably find a kit at some local lawnmower place.  And I’d watched a couple of rebuild videos on YouTube.  That’s a pretty amazing resource.

The carb came apart easily, and looked pretty clean inside.  I sprayed carb cleaner kind of randomly thru holes, but didn’t know where it should come out.  The first glitch was when I went to reassemble the machine.  Since I had new fuel lines (and fuel filter and check valve and tank grommet), I figured I’d install them.  But the hoses PartsIboughtMyFuelFittingswere way longer than the originals, and the 3-hole grommet was too big for the hole in the tank.  The parts in the kit I got are on the left, but the originals look like the pic on the right.  The old grommet was still OK, so I cut the other hoses down and put it together.

You’re supposed to pump the primer bulb on top until you see gas in the return (clear) line.  I’d replaced the quite dark (but still flexible) bulb with a new clear one, but it didn’t seem to do much.  I did finally see some fuel in the clear line (a red herring:  it was coming from the tank, not the carb!), but the bulb wouldn’t flex back to normal after pressing on it.  Grumble, cheap chinese parts, grumble, put old bulb back.  Same behavior.  Choked it and pulled a lot – but still not even a pop and the plug was still dry.  Rats.

I took the carb off and apart again, sprayed some more carb cleaner at it, and pondered the primer bulb and its plastic environment.  Sucking and blowing on the (top) fuel return nipple, there was very little flow, but it seemed like a check valve (flowing out of the carb).  The brass insert apparently at the other end of the return fuel passage could be there to hold a check valve in.  But I could barely suck any air thru it.  I worked a bit of wire insulation into the hole and could hear/feel what could be a sticky flap valve.

After working it a bit more, I blew carb cleaner in to the brass fitting and it sprayed out the return nipple!  I’d done that before, but nothing came out.  (A tech doc I found later confirmed that the primer bulb blows fuel/air out the return line thru the check valve, and then sucks fuel thru the carb passages, thru an inbound check valve and into the primer bulb.)

Encouraged, I put it back together again and pumped the (new, clear) bulb.  It filled with fuel!  So that’s how it’s supposed to work!  Some normal steps later, it started and ran.  A couple of tweaks to the low and high speed needles, and it was running well.  I tilled the little flower plot next to the garage (just in time for Lauren to plant the flats of impatiens she’d just bought) and the little Mantis did a terrific job.  I should be able to do the edging the next nice day.  Oh yeah – this was all with the same old fuel I’d tried in the beginning.  Stabil is great stuff.

Label3981Handles-Age3979For the record, here are some pics.  Looks like it’s pretty old, based in part on the white handle grips, and in part on the C1U-K17 carb.  I’m guessing the newer tanks take the larger 3 hole grommet.  The air filters in the tune up kit were the right shape, but a little too large – SerialNum3985presumably another later update.  I was able to poke them into place with a screwdriver.  The SV-4B engine ID is old, too.

The machine ran fine when I got it, and this carb cleanout is the only work I’ve done on it (so far).  I really should check the gear case grease, and I sort of think there’s something about the muffler that should be checked.  I haven’t done anything to the plug since I got it (except pulling it to look for gas).

The used dethatcher I found on Ebay seems to be in good shape, but doesn’t have the sheet metal cowling.  I found a video of a guy (Jim Barry) doing dethatching with a Mantis.  He pulled the cowling off briefly as a demo.  It threw the thatch everywhere without it.  Thanks, Jim!  I should be able to make something pretty functional from the 22 ga sheet steel from the animal cages Ed S tore out.


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Laser etched rubber stamp

AdafruitPassportEver since Mitch Altman presented the idea, I’ve thought hackerspace passports were pretty cool, if geeky.  (Thanks to Adafruit for the pic.)  I’ve also felt that Workshop 88 should be able to participate with a good stamp.  Of course we couldn’t just buy a stamp – we had to make it.  Thanks to the laser cutter, we can now do that.

GreenFlameA block of rubber stamp rubber from Carlson Art in Glen Ellyn failed the Beilstein test, the green flame showing it contained the dreaded Chlorine.  I then ordered some sheets of 0.09″ by A4 “laser engravable” gray rubber stamp material from China, poised to give negative feedback if that failed Beilstein.  But it didn’t (yay!), so I did some calibration raster etches.  The stuff etched beautifully.  I ended up at 250 DPI 100% power, 2% speed, and did a second etch at 6% speed just for a little extra depth.  It looks like it’s about 0.025″ deep.  I StampF+B3787also etched a non-mirrored (and non-inverted) copy of almost exactly the same artwork fairly deep into a little block of scrap wood to serve as a mount/handle.

Epoxy now holds the roughed up back side of the rubber to the block.  It seems to give quite nice impressions.  One improvement:  There’s a line at the bottom for a date/signature/whatever that’s too thin.  That line should have been considerably bolder.  But it mostly worksPageWstamp3788.

As I got ready to post about it on the W88 blog, excited that we could now produce rubber stamps, I realized that rubber stamps are a thing of those quaint old paper-based days.  Aside from this one, I doubt if any W88 folks will ever have need for a rubber stamp.  But it was an interesting project…

Update 4/1/16: Raster engraving speed depends on the base resolution in Retina Engrave.  It takes twice as long at 500 DPI as at 250 DPI.  For most applications, 250 DPI is fine; many of the raster data entries in the settings Dropbox Paper doc are at 250, including for the rubber stamp.

250v500DPI3801I was  slightly curious about whether etching the rubber at 500 DPI would make a visible improvement, but was even more interested in seeing whether the engraved depth would change.  At higher DPI values, more laser energy is deposited per unit area, so it should engrave more aggressively.  Sure enough, with the same raster power and speed, it etched noticeably deeper at 500 DPI.  I think it looks very slightly smoother and better detailed, but I might be seeing things.  The deeper engraving, however, is completely clear, and needs to be part of our understanding of the raster engraving process.

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W88 Laser Exhaust Fan Replacement

When we first got the W88 laser cutter up and running, we scavenged the ancient circulation blower from the old, gutted in-wall furnace, took advantage of the 8″ flue/fresh air hole in the wall, and hacked a mounting to provide the exhaust for the laser.  That (admittedly overkill) blower died around 3/14/16, about 6 months after we put it in.  After an urgent discussion on Slack Fan3224about flow rates (FSE recommended 60-100 CFM), pressure drop, 8″ and 6″ duct booster fans, a marine ventilation blower, a big honker 110VAC muffin fan from American Science & Surplus, and other possibilities we decided on the sciplus fan.  Daniil picked it up on the 15th, and we hacked it in that night.  (Some upgrades are visible since the original picture:  The vent pipe now runs thru the side of the furnace shell, the water cooling tank has moved inside the furnace, and there’s a power switch up where you can reach it!)

That fan (spec’d at 198 CFM, presumably in free air) (after removing a plastic mount for the electrical connection) fit inside the 8″ pipe perfectly.  There’s maybe 1/8″ clearance around the edge.  By installing it inside the pipe, we gained clearance for the 4″ flex pipe to bend to horizontal.  In the original installation, it fed vertically into the blower. Tom M suggests that mounting the blower with its shaft vertical probably speeded its demise.  It died of a bearing failure, and the bearings weren’t designed for that load.  But it served us well getting the laser running – and it was free!

Fan+MountPlate0237We reused the 4″ flange Daniil had hacked together as the inlet at the bottom of the old blower, screwing it to a plywood plate to mount it and to cover the hole to the 8″ pipe.  We’d planned to mount the muffin fan directly to the back of that same plate, but the motor hub almost completely obscured the air flow from the 4″ inlet.  We found some 1/4-20 threaded rod and tapped holes in the fan for it.  (Thanks for bringing in the tap set, Daniil!)  Setting the fan deep in the pipe provided what seemed like reasonable air path.  A standard IEC power cord lost its C13 end and provided the power connection.  The green wire is even connected to a threaded hole in the fan body!

BeingInserted0238Here’s Daniil about to put it in place.  We left the original wood plate that fit the 8″ pipe.  The new plate mounts over it (with the foam gasket from the old blower still there) with the same long screws ReadyToConnect0239into anchors in the concrete block wall.  It’s all quite solid, and we think it should serve for quite a while.

The only remaining work is to plug/cover up the holes resulting from the flats on the top and bottom of the fan.  Expanding foam is a possibility, as is removing the fan, laser cutting a circular plate and screwing it to the exit surface of the fan.

Done0242With it all buttoned up, the only clue that there’s actually a fan there is the power cord going into the plywood plate.  It also runs MUCH more quietly than the old blower.  While your can hear the whine of the fan spinning up if you listen, the reduced noise is an excellent reason to continue with plans to put an air vane flow sensor in the exhaust port of the laser cabinet.

All in all, it was a fun emergency repair project/hack, and very satisfying to get the laser back up within hours of deciding what parts to use!

FanRing0246Update 3/18/16: Daniil and I stayed late after the meeting Thursday and made a ring to reduce the backflow/leakage around those two non-round areas of the fan.  We pulled the fan, measured, did some quick artwork in inkscape, put the fan back in temporarily, and cut the ring from 3mm plywood without incident.  Well – one incident:  My artwork, on the laser PC, looked perfect in inkscape, but didn’t export as vector to RE.  The design showed up – reversed B/W – in the raster view, but not in vector.  Daniil did the same thing on his laptop and it worked fine.  Troubling.

We feared that drilling the ring for screws would weaken it a lot, as half the width of the skinny ring material would be lost to the holes.  He was for some mysterious and unvoiced reason uncomfortable with using zip ties to hold it on, so we decided to glue it on with some HF 5 minute epoxy.  RingWeightedDown0247We found a very appropriately shaped weight to hold it while the epoxy cured.  It’s all back in place now, looking from the outside exactly like it did before.  But we know we picked up maybe 5% better airflow from the patched up leakage path.

Unrelated to the fan ring, I worked a lot that Thursday putting in NewOutletsA0249better AC power wiring for the whole laser setup.  I scrounged some of the Greenfield apparently ripped out of the media room initial electrical rough in, and put 2 duplex NewOutletsB0254outlets outside and one inside the furnace shell, all powered from the original BX-connected box.  I cut a hole in the side of the shell at a comfortable height NewSwitch0258and put a in switch that controls all 6 outlets.  It’s a little close to the edge for a normal switch plate, so I made a narrow one from fluorescent acrylic.  The possibility of some UV LEDs has not been ruled out.  The sign above it was vector engraved, as the artwork I made up in inkscape for that one imported as vector but not as raster.  That remains troubling.  But I’m delighted and relieved to have much more civilized power control for the laser.  That was one of the last big punch list items to get the laser “production ready”.  Maybe now I can go back and do some work on the Shapeoko 2!

InkscapeOpacityUpdate 4/29/16: I discovered the problem that caused my inkscape prints to Retina Engrave to work wrong:  I had the “Opacity” set to less than 100%.  Apparently RE doesn’t like that.  It had become a default value, and all docs created since that happened were so corrupted.  Changing the opacity back to 100% (and making sure it stuck as the default!) completely fixed the problem.  Who knew?

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Observations on laser cutter kerfs

I wanted to have the laser cut center holes in 3mm acrylic gears that would provide just enough clearance to use 4-40 screws as pivots while allowing the gears to spin freely.  I didn’t know exactly how much clearance that was or what the laser kerf in that plastic was, but since the kerf is significantly wider at the top GearHolesurface than the back surface of the cut, an experimental approach seemed suitable.

The nylon 4-40s I was using were about 0.105″ OD.  After a couple of tries, I found that a  0.090″ hole in the svg produced a (conical) hole 0.115″ at the top and 0.107″ at the bottom.  (180 LPM, 10% S, 100% P, 100% VC)  I don’t think Retina Engrave tries to make up for the kerf like CAM for a milling machine (or EASEL) does.  But whatever it does, those were the FilingHole3439results.  Those holes were sloppy for the screw at the top, and too tight for it at the bottom.  (Yeah, should have fit.  I don’t know.)  This approach did let me do the final fitting with a round jeweler’s file for just the clearance feel I wanted.  If I had to do a whole bunch I’d want a perfect drill bit, but for hand made onesy-twosies, this worked out very well.

So to produce that hole, I needed to provide a circle in the svg about 0.017″ smaller diameter than what I wanted.  Another set of measurements showed needing 15 mils smaller.  I think that represents the (whole) kerf (at the bottom surface).

As for the conical nature of the holes, these ended up about 80 mils smaller at the bottom.  Other notes during the same set of experiments showed 60, but making those measurements was difficult, and probably not very accurate.

KerfIn2mmAcrylic3436In another note in the kerf tests done for the gear hole, I noted that the kerf in acrylic was about .030″ (presumably at the top surface).  In a separate cut for a finger joint box in 2mm acrylic, I measured the kerf using a graticule at about 0.5mm, or 20 mils at the top surface.

Searching for “kerf” in the FSE laser product forum provides some more points of reference.

RaisedEdges3428RaisedEdge3435In addition to the actual kerf and the difference between the kerf at the top surface and bottom surface, there’s usually a small raised lip of presumably melted plastic above the top surface at cut lines.  (Not much on the bottom.)  On a straight line cut it seems to be about 0.4mm wide.  There was a comment in the FSE forum about covering acrylic with a wet paper towel to reduce some effects like this.

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AT&T Uverse failures


The damn NVG589 modem on my ATT Uverse internet/phone service failed again today 12/5/15.  This post will be a place to keep details of this and subsequent failures.  There have been many in the past; I’m sure there will be more.

I put router reset stuff into the home automation system years ago (4/11) to protect against router/modem lockups making the home monitoring system unavailable when we were out of town.  The local server pings our ISP’s first router, and if those pings fail for a while, it tried to reset the modem and router (then separate devices) by cycling AC power to them.  It took a couple of rounds of rewrites before timing issues causing infinite reset loops were ironed out (oops), but it finally got pretty robust, and automagically kept our internet connection up when we didn’t even know there was a problem.  Reset events are posted on the main HA page.

When we switched to Uverse VOIP (when? a year or so ago?), AT&T swapped our old modem for an NVG589 (and started charging us $7/month for it!).  That device has internal battery backup (most appropriately for a phone connection), so my dear old power cycling would no longer work, and so I disabled it.  The modem runs off my local UPS, so removing the battery wouldn’t be a show stopper (and would let power cycling work again!), but somehow I haven’t been quite willing to do that.  I investigated rebooting the modem programmatically, but at least partly due to a password dialog, I gave up.  Now I no longer have automated reboot capabilities.  I’ve considered a solenoid striker strapped to the back of the 589 to hit the reset button, but have done no work to implement it.  (A servo might be a practical, lower power solution.)  After the latest failure, just removing the battery is looking better and better.

The 589 was replaced a few months after we started with Uverse, basically for the same kind of failure, and I think a guy came out one time since then for similar failures, but didn’t replace it again.  There was also a very unpleasant incident with AT&T support where they remotely did a factory reset of the modem when they said they were going to reboot it.  That wiped out all my network customizations, Wi-fi SSID and passwords, etc, made me a very unhappy customer, and caused a lot of extra work to get my network back up as it was.  I had them put a note in the account file to NEVER do that without expressly asking me.  I’d like to back up the config, but several investigations have all pointed to the fact that there is no way to back the config up except looking at the screens and writing everything down!  (OK, could take screen captures.)  That really sucks, Motorola/Arris.

It looks like rebooting the modem also wipes the logs.  I learned that after the reset button reboot today when I tried to go into the logs to see when it first detected a problem.  I hope I remember to grab the logs before I reboot it next time.

Current status

(last updated 7/2/16, 7/27/16)  We’re on about the 5th modem now, a Pace 5268.  My ping/power cycle stuff is back in place and seems to be working.  Had a bad case 7/27/16 of a reset loop which might have been my fault.  Increased time between resets to 700 sec, but have no info if that’s appropriate.

Failure event details

(first) Event: 12/5/15  As has happened 3 or 4 times previously, both Internet and phone were out, with the modem showing green on both Broadband lines, green on Service (!) and off for phone line 1.  My watchdog noted old file on the host at ~7:30 AM.  We noticed internet out about 10 AM.  The ping stats display on the home page showed ~1000 missed pings.  I showed Laur how to reset the modem, but since it’s hard to get to, that wasn’t pleasant.  I need to add bookmarks to browsers on all the devices to check modem status.

I called AT&T service (after it was back up) and complained that the modem knew at least that the phone was out, but didn’t fix itself.  The rep (Cara) seemed puzzled that both broadband lights had been green as well as the service light, but internet had been out.  She did a remote reboot, and after the usual 15 or 20 minutes it came back up and internet and phone were good (again).  She scheduled a service call for Monday AM.  She also told me that the My ATT phone app would allow remote rebooting.  Cool.  I just set that up on Laur’s phone as well as mine.  Actually, that reduces the pressure for an auto-restart facility driven by fearing failures while we’re out of town.  Of course we’d still like it to fix itself even when we are at home.  (Doesn’t actually work:  see update 1/18/16.)

While I was still on the phone with her, the modem spontaneously restarted.  She offered to wait ’til it was up again, but I said I was pretty confident it would be OK, and I’d call again if it wasn’t.  Sure enough, maybe 20 minutes later all was working, and seems to have been OK since.  My watchdog noticed the second outage, and again said the datafile on the hosting server was > 1260 seconds old.  I wonder if I can get that watchdog to send me a text on failures.

Update 12/6/17: AT&T guy came as scheduled.  Did several tests inside and outside with a tester that plugged into my bonded VDSL pairs, saw it sync WAY faster them my modem ever did.  He replaced a couple of connectors and the last cable to the modem, but his tester sync’d in less than a minute at the end of the same cable that my 589 took many minutes to sync on.  While the modem does usually take a little longer than the tester, the difference was more than he would accept.

He replaced the 589 with a brand new one – same slow sync behavior.  Then he replaced that with a new NVG599.  That’s bigger, faster, supports high end service.  That sync’d up quicker, and that’s what he left in place.  Of course I had to reconfigure it with my local network and wifi details, but at least I’d cleverly gotten screen snaps of those bits of config before he came. 🙂  Unfortunately, just like the 589, the 599 has no way to save config info to a file.

Interestingly, my all-but-static IP address changed with the new modem.  The little wget-based screen scraper that runs in a cron job to read the gateway’s /cgi-bin/dslstatistics.ha page and emails me if the IP address changes no longer looked for the right hard-coded strings, so I had to touch that up.  While the main PC has a fixed address allocated by the DHCP server, and stayed on my non-standard subnet, the nice red laptop in the kitchen runs a normal DHCP client, and so by pulling and replugging its network cable could see the gateway on its default address and let me do the initial config without having to drag a laptop down to the basement and wrassle cables.  Much more civilized.

I continue to consider pulling the battery on the 599, but continue to hold off.  The home monitor page reports occasional “router resets” – presumably meaning it missed more than 20 consecutive pings (pings every 5 sec).  But the ping stats graph doesn’t show any missed pings.  I should look into that.  But especially with those not consistent, it’s hard to pull that battery.

(a few hours later)  OK, there’s one bogus reset reported 12/8/15 06:47.  I can’t find any evidence of missed pings near that time.  There are a whole bunch of resets mid 12/7, but there’s a big bunch of missed pings at that time as well, so those match up.

Ohhhh…  When I was trying to figure out how the reset stuff had been turned off, I’m medium sure I touched a file (presumably “resetFlag”)  to see if it got picked up by the main poll program.  (It did.) writes its ping info (including the critical “got reponse after N…” entries) to pingstats.csv, from which the ping stats graph is made (by graphs.php).  But completely separately, when it thinks there should be a reset (power cycle) it touches resetFlag.  The main poll program – which of course is the only thing that can talk to the 485 modules – like the power cycle controller – looks for that flag file to know when to send a reset message.  The resets reported on the main monitor page come from the main poll program’s datafile.csv – essentially independent of the actual ping stats, linked only by the reliability of  I broke that reliability by experimentally touching the flag file.  So that bogus reset report was truly bogus, created by me trying to figure out how stuff worked.  So it can safely be ignored.

That removes the concern about flaky false positive reset requests – yay!  I’m still not going to run right over and pull the battery out of the 599, but at least I have confidence (once again) in the reset detection stuff.  And I recorded it all here so maybe I won’t break stuff the next time I need to know how it works. 🙂

Update 1/18/16: Discovered that Internet and phone were out again this morning.  The good news is that the NVG599 knew about it and was working on it.  Unlike the 589, the status page showed broadband and phone down, and from the lights on the front it was clearly trying to resync.  The bad news is that after 15 minutes or so, it was still failing.

I thought it would be a great opportunity to test out the remote restart capability the rep told me about in the My AT&T app on my phone.  Found the app, logged in, found the U-verse restart screen.  There were 2 choices: Automatic and Manual.  Since I wanted to test doing it when we’re on vacation, I chose Automatic.  Click, whirr – and an error message came up to the effect that this service is not available at this time.  Apparently you can only restart the services when they’re already working.  That’s dumb, AT&T.

Went downstairs and hit the reset button.  In a few minutes, we were back on the air.

Ping stats showed about 350 missed pings (in 2 or 3 batches), for about 29 minutes of outage.  The reset algorithm logged 10 tries to restart between 10:38 and 11:14AM.  Of course that doesn’t actually do anything right now, but re-enabling it and pulling the 599’s battery is looking better and better.

Update 4/5/16:   Service went out again last night.  Phone and internet were out suddenly.  From router web interface tried to restart phone line, got something like “verification error”.  Tried to restart broadband, somehow failed.  Restarted device (still from web interface).  Eventually got both broadband lights green, service red.  Waited a few minutes, gave up and hit red button on back.  It rebooted, came back to both broadband LEDs green, service red.  Waited more minutes – no change.  Called AT&T (from cell).  They said they were going to run some tests.  Service came back while on the phone – don’t know if it was something they did.  Also don’t know if it just took a long time and would have eventually come back after the web interface restart.

Rep (Andrew) said it looked like cabling from NID to modem, and they would send someone out.  HA showed ~120 lost pings, 9 “resets” over 38 minutes.

Colin came out today (Tues 4/5) (again tried to go to Villa Park instead of Elmhurst).  We talked, but apparently miscommunicated, and he reset modem to Factory, fucking my whole network!  He said something about multiple IP addresses but wasn’t clear.  I said I thought I was clear to do whatever I wanted on my side of the modem.  He replied something like “Well, mostly.”  Couldn’t pin him down on what I couldn’t do.  What I eventually got out of him was that anything non-stock (changing wi-fi, local subnet, DHCP allocations, etc) increased the risk of something going wrong, for example when an update came down.  He said the problems seemed to start Apr 1.  I asked if an update had been sent down and he replied quickly that he couldn’t tell anything like that.  Nice.

His resets showed up as another 120 missed pings, for 37 minutes of 10 “resets”.

I asked about the MyAtt app only being able to restart service if it was already working.  He said if at least some broadband lights were green – like flashing trying to sync – they could talk to the modem enough to restart it.  Don’t know if I believe that.

Took advantage of the factory reset to refine my notes on what needs to be done to get back after such a reset.  Again used red Gateway to get into modem on default 192.168.1 net.  Had to pull the cable to get new IP.  Did ipconfig/renew on main PC to refresh its IP.  It got its same IP back, and then I was able to tell the modem’s DHCP to always give that IP.  Added details on enabling outside access to the Pogo.  All details are in My Documents PcSetup/RouterConfig.txt.

Also couldn’t talk to the new TP-Link access point.  Lights showed a problem.  Power cycled it and it seems to be back on the network.  Seems like I couldn’t connect to that AP (Jims G Router) for quite some time.  Wonder if it’s been down for months.

I still need to call AT&T: change service addr Villa Park->Elmhurst, and ask for specific answers to when MyAtt app can restart modem.

Update 5/13/16: Got home and found internet and phone down again.  Logged into modem; it said broadband was down (as well as phone).  At least that was right.  Tried to restart broadband, but didn’t help.  Hit the red button on the back, and it was back up in a couple of minutes.  Why should I have to do that?  Ping stats showed 1100 missed pings.  At 5 sec/ping, that’s about an hour and a half.

Called AT&T.  Rep “Dawn” was friendly and responsive, but couldn’t see anything wrong.  Right – it’s all working fine after I hit the reset button.  I asked if she could confirm the 90 minute outage my ping stats showed, and she said they couldn’t tell anything like that (in the past).  She offered to send someone out, but it didn’t seem worthwhile.  She offered to monitor the line for a week, and I said to go ahead with that.  My estimate was 95% probability that there would be no problems.

It looks like the problem is that the modem gets stupid and can’t recover.  I don’t know how often the modem notices a problem and does reset itself.  I suppose that might (better!) be shown in the logs.  I think I tried to get the logs sent to the PC, but it probably didn’t work or isn’t working any more.

Hmm – I wonder if the connection between the battery and the modem is accessible.  Maybe I could add another relay to the reset node and have it both power cycle and temporarily disconnect the battery.  If I just pulled the battery, they might notice it and want to send someone out to fix it.  Maybe that solenoid on the reset button isn’t such a bad idea.  If it were AC powered, normally retracted (reset button not pushed) and spring loaded normally “pushed”, it would require no additional software changes.

Maybe I should have the reset stuff email me when it kicks in.

Update 6/19/16: Damn modem locked up again – this time while we were away on vacation.  According to the 106 “router reset attempts” it was out for about 7 hours.  Hit red button when we got home and it all came up promptly – just like every other time.  Called AT&T, spoke with “Sherry”.  She says there’s  a problem with signal to the modem and that’s why it fails.  They say that most every time, but I don’t believe it.  (I can believe the signal isn’t perfect, but I have trouble believing that’s why the modem locks up and can’t restart itself.)  Tech will come out tomorrow morning.

Oops – the time slot I agreed to with the rep on the phone won’t work.  My fault.  I logged into My AT&T phone app and was able to change the appointment time with no problem.  Gold star for AT&T for providing a simple, effective tool for at least that application.  Too bad it can’t restart my hung modem, but they do get credit for what does work.

That outage was the straw that broke the camel’s back:  I’m going to re-implement my router reset stuff.  Found a schematic for the resettable power outlet, and it looks like the PIC node puts out 5V to operate a relay.  I should be able to use that to hit the reset button.  Looking around for a solenoid I can bolt to the back of the 599 to hit the red button…

Update next day 6/20:  Service guy came (to Elmhurst instead of Villa Park – progress!) and swapped the NVG599 out for a Pace 5268AC.  Took quite a while to sync, download an update (power LED blinking yellow), install, restart.  He said the 5268 was a more stable modem.  We’ll see.  Reconfigured the new gateway with my network stuff, updated Jim/Documents/PC Setup/RouterConfig.txt.  Got new IP address.  The user interface on the new modem is completely different, so in addition to slowing me down in setting up the config, it breaks the monthly ‘warm fuzzy IP check’ script (perl/  I made a quick first try at patching it, but failed.  Just need a little more time.  Update: Fixed.

Set up a syslog 1.2.3 server from Sourceforge on the (now Win10) machine to capture the logs.  Seems to function, but won’t log much.  Status bar shows messages coming in, but nothing sticks.  Still noob playing with it.

We’ll see whether the new modem locks up the same way the 599 did.  This one didn’t come with a battery (though there’s a place for one).  Guess instead of mechanically pushing the reset button I’ll just hack the timeouts in the existing ping test stuff and enable it so it actually power cycles the new modem.

Update 6/21/16:  Touched up to 30 consecutive missed (5 sec) pings to declare time to restart modem, and dead time between restarts to 500 sec to give the gateway a good chance to resync.  Restarted  Ensured only modem was plugged into controlled outlet, and reconnected the outlet control line to the reset PIC node.  I’d cleverly put a well-labelled dummy connector on the same pins and in the same orientation as the wire to the controlled outlet, so reconnecting was trivial.  I think it’s all in place and armed.  I think.

Update next day 6/22/16:  Touched resetFlag, and sure enough it power cycled the modem!  Broadband lights came on (red) after about 4:30; Service went solid green after about 6:40, with phone up several seconds later.  Since I triggered the reset artificially, the dead time between resets wasn’t in force yet, so I think it detected ping loss while the modem was restarting, and power cycled it again.  Main HA page showed 2 resets – again because of touching resetFlag plus one normal ping loss detect plus power cycle.  Hooray for having written up how that works above!  All is good.

Update 7/1/16: The new 5268 apparently failed today.  The good news is that the restart stuff kicked in, power cycled it, and it all came back up automagically.  I was on the computer when it went down, and was inconvenienced for a little while, but other than going downstairs and noticing the lights on the 5268 were in a restart pattern and picking up the phone during and after the reset to check, I did nothing to help the process along.  I haven’t decided whether to call AT&T about it.

The syslog server seems to work, but doesn’t start or save the filtered log data automatically, so I don’t have the logs from the most recent reboot.

The main HA page showed one reset (07/01 20:34:02) and about 160 missed pings.  So as near as I can tell, everything (except log capture) worked perfectly.  Yay!

Update 7/7/16: Another fully automatic reset.  Didn’t even know about it – it just worked.  Main HA page showed about 130 missed pings.  At 5 sec/ping and a count of 30, I’d expect more like 150.  But the missed ping spike was still completely clear, and I’m confident the reset was justified.  I suppose the question of whether the modem might have taken care of it by itself remains.  Guess I need to get the logging stable to see if I can infer anything from that.

Update 7/27/16: Another auto reset yesterday 7/26.  I sort of quit even logging them here because it just works!  Well, not quite.  Log on home page currently looks like this:
0   07/26 15:21:43
1   07/27 09:09:24
2   07/27 12:03:30
3   07/27 12:11:54
4   07/27 12:20:18
5   07/27 12:28:42
6   07/27 12:37:05
7   07/27 12:46:32
8   07/27 13:08:34
9   07/27 13:10:40
10   07/27 13:18:01
11   07/27 13:19:05
12   07/27 13:27:28
13   07/27 13:28:32
14   07/27 13:35:53
15   07/27 13:37:59

I noticed the phone said “No Line” today 7/27/16; RG was in the process of resetting.  Fine.  Checked back in a few minutes – still down.  Started poking around on the Pogo, and it looked like it might be in a pingstat-initiated reboot loop.  Unfortunately, all the “Resetting router” timestamps in pingstatstdout were the same – from the very first instance.

I moved the global timestamp code in to a new function and called appropriately so resets would show correct time.

But it was still looping.  So I kicked the $resetTimeout minimum dead time between resets from 500 to 600 sec, waited until it resynced to restart  But then the reset loop restarted!

Pingstatstdout showed continuous ping fails to ISP.  Ooooohhh – did they change me to another router (so my pings will fail forever?)  The IP of the AT&T router I ping is hard coded.  Killed  <waits…>  Nope – same IPs for the RG ( and its first router (  Manual pings work fine.  Restarted  Seems to have gotten a ping response.  So I don’t know whether my $resetTimeout was too small and caused the loop or their stuff was screwed up for a long time.

WTH?  I’ll post more if it fails again.  Kicked dead time from 600 to 700 sec several hours later to be even more conservative, though no new resets before that.

But how do I protect against the case where they change me to another AT&T router?  Shouldn’t happen often, but I’ll stay down (or at least in a reset loop) until I fix it manually.  I guess just killing pingstat process should stop the looping, though that would be almost impossible remotely when it’s in a reset loop.  I suppose if I wanted to be really anal I could scrape the router IP from the router broadband page (, looking for the first (IPV4) instance of
 <td>Default Gateway</td>
Of course I’d have to code around sometimes not being able to reach the page, and when not connected getting some kind of <none> value (or look for the much more complex Internet – Connected table entries before it).  And I’d have to catch that new value during the narrow window of a reset loop after the RG is running but before I reset it again.

I suppose I could add a state to and when pings fail (and after my powercycle!), scrape Internet Connected status from the RG.  Then if not connected, I could forego pings ’til it came back up.  And if I have that much, I guess I could scrape the AT&T router IP as well.  Yeah, but getting a ping reply is even more absolute indication of success.  Ugh.

Update 7/28/16: One more automatic reset I didn’t even know about until I saw it on the HA page, no drama, just as designed. 🙂   07/28 10:23:58.

Update 8/14/16: Another automatic reset I didn’t know about.  Yay!    08/14 10:23:29  I sort of think there was another a week or so ago, but I didn’t think to log it.

Update 10/9/16: Wow.  After an email from a watchdog timer saying the HA web site wasn’t being updated, I checked and found the router reset robot had fired 4 times while we were out:
0   10/09 16:40:22
1   10/09 16:52:58
2   10/09 17:04:30
3   10/09 17:16:03

Everything was running fine again when I checked it at around 7 PM.  I don’t know what to do.  I could call AT&T, but all they’d do is come out – interrupting my day – find that it was working fine, do some tests, maybe swap out the modem again.  And it would still be running fine when they left, except I’d have to reconfigure my network back to the way it was.  How does that help anything?  Thankfully, it only happens once a month or so.  Nuisance.

Update 10/21/16:  This one wasn’t AT&T’s fault!  My 9 year old D-Link 1108 8 port 10/100 switch died.  First symptom was no internet, so despite a working in-progress phone call (sorry, Lauren and Cathy!) and the unusual indication from the main PC that the network cable was unplugged on and off, I power cycled the router.  (Manually, of course – since I couldn’t even log into the Pogo to have it do it via the sendusr1 interface to  Ordered a new switch from Frys.

Update 10/26/16: More failures cheerfully and invisibly fixed by the auto power cycler.

0routerresets10-26-16   10/21 20:22:21
1   10/22 12:49:14
2   10/22 13:00:47
3   10/26 10:23:18
4   10/26 10:34:50
5   10/26 10:46:23

The first one was from the post above – not their fault.  Presumably the other 5 were legit fixes.  The ping stats show the traditional signature of the outages today and 4 days ago.  All I can say is that AT&T ought to be paying me for the service calls I’m saving them!  I should call and ask/force them to make notes in my account record of the failures.

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Shapelock lesson with zipper pull repair

Bag+BrokenZipper3337The bits of hardware that attach the zipper pull to the slide broke off on the orange mesh bag that holds adapters in my black recording bag.

Candidates3339As a replacement, I made a loop out of 17 ga baling wire with extra wire to provide surface area about matching the slide for gluing.  The first one I made (without looking at the slide) was silly too small.  Oops.  I cleaned and roughed up the surfaces and stuck the loop on with 5 minute HF epoxy.

Pull3348Done3352For a pull, mildly inspired by a zipper pull replacement Andrew made out of a paper clip and Suguru, I formed a bit of paper clip wire so it wouldn’t slip out and folded and squished a rectangle of Shapelock around it.  It’s completely functional.

I tried to make a fairly uniform sheet of the plastic by shaping it into a rough rectangle, pressing it against a smooth flat surface, flipping it over and pressing it again.  That worked pretty well for thickness, but because the overall outline wasn’t a neat rectangle, the finished pull looks fairly sloppy.  Next time, by paying attention to both the thickness (by flattening as above) and making a neat squared-off outline (maybe cutting it hot with scissors?) I bet you could make quite a neat looking whatever.  It’s interesting to watch the progression from the initial ‘aha’ that you can actually make stuff with Shapelock to polishing and refining the techniques.

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