Motor delays

Armed with a diode, more croc-wires, and a Ritter Sport marzipan, I'm going to get that motor sorted out once and for all.

First test that the LED does what I want it to, by running it across the Y motor. Ok, so that wasn't a multi-color LED as I hoped, but I can at least see it change intensity when the motor starts and stops.

Wiring:

Black-Red: Lights up a bit, but doesn't change when "extruding".
Green-Red: Lights up a bit, but doesn't change when "extruding".
Black-Blue: Nothing.

After carefully marking the wires the wrong way (RGBK instead of RBGK), I put the extruder wires into the Z axis jack. The light lights up more now when I run the Z motor. Wiring the motor back up, I get - no movement whatsoever.

Finally took some better wires and wired directly from the Z jack to the motor, carefully matching the colors. Motor moves not the least bit, even though the heater is at full. I can only conclude that this motor is no more. It is an ex-motor. It has ceased to be.

Curious: I set the LED back on the extruder wires, but didn't actually wire the extruder. When I do the first extrude after the power cycle, I still hear a "chunk" sound. That can't be the extruder, then, like I thought. Some kind of cross-wiring? It appears the X axis will sometimes move a bit when starting to extrude, to get away from homing. So does Y and Z. But that doesn't give that "chunk" sound.

Powercycled again and looked carefully. The "chunk" is indeed the X-axis moving a tiny bit the first time. So the actual extruder was dead the whole time.

FabLab has no spare compatible stepper motors, nor do I. So I can't get that much further.

Tried wiring up the extruder wires to an incompatible stepper motor. Didn't get any reaction out of it with any combination of wires, but then I don't know if it works or if I'm giving it enough power to work or anything, so that doesn't prove much.

In conclusion, I have an extruder stepper motor that is almost certainly dead, wiring for it that is possibly faulty, and still no prints. *sigh*

Ramping up slowly. Very slowly

With the fighting season winding down, printing season starts up. Last, I was stuck at the extruder motor being unwilling to move, even at proper temperature. +Tim Hatch gave some ideas for fixing that in the last post:

Check motor current - checked black wire first, it shows about 10-20 mA whether running or not. Green and blue show nothing.
Can the extruder move without any filament - heated up and pulled out filament all the way. Still doesn't move.
Compare with a spare motor - don't have any here.
Swap drivers with X - tried swapping pins in pins.h, but that didn't take, oddly.

Noticably, the motor gave a brief "clank" when first set to move. That could be problems inside the motor, or maybe that one of the connections is faulty, so the motor moves a quarter rotation, then stops. This is repeatable after the power has been off.

Enough for tonight (got out here rather late and poorly prepared). Next time, bring extra motor and extra clippy cables - everything has moved here in FabLab. They also got a huge laser cutter, that'll be fun once it's up and running!

A Dance of Filaments

Next step is getting the extruder tuned. I grabbed a piece of filament from the scrap box, and went "What is this, actually?" Some googling found several methods of testing, most of which weren't practical: Burning a bit and sniffing it - no open fire in FabLab. Dunk in acetone - don't have any. Test in the extruder - not good when the extruder isn't tested yet. Break it quickly - it whitens a bit and breaks, but I wouldn't call it "snapping". Rubbing it against clothing and smelling it - no noticable smell (hints at PLA). Heating with a properly controlled soldering iron - seems to not melt a lot @200. Dipping in warm water does make it bend easily, that strongly indicates PLA.

From the last test I'm going with it being PLA. And indeed, some properly marked rolls of PLA behave the same way.

With the glass plate one, Z level is 1.6 and it's perfectly flat. Turns out I'd missed the bit about clipping on the glass plate. I have the clips, and they just barely fit in the opening, if I place them just right. Adjusting the firmware to have a Z home of 201,7. Then re-measured and subtracted another 0,2 mm to allow for expansion, and set the Z screw pointers.

Annoying thing about the clips is that one is right where the extruder comes down if I just home and then down.

Strange hiccup while heating up the extruder, the temp reading stayed the same for a while then jumped. That's potentially dangerous, but it did end up at the right temperature.

Alas, actual extrusion failed. A small amount of the previous black filament drippled out, but I was unable to force the new orange on in by hand, and the extruder motor refused to turn in either direction more than a brief second at the start.

Took out the hobbed bolt to see if it was ok, looks fine to me. Loosened the idler on the side, fastened it, no difference.

Took out the idler and looked inside. Aha! A stump of old filament from mid-bolt down. Heating up the hot-end, I was able to pull this out. Didn't help on getting more in.

On a lark, I looked at what happeend when the idler was in but the hobbed bolt was out. Turns out my filament wasn't even making it through to the hobbed bolt. When in doubt, more violence! Pressing harder moved the idler aside. Knowing now how much to press I was able to do this with the hobbed bolt in, and have it grab. I then hand-cranked until I started feeling resistance, then turned on the heater and handcranked out black goo till it turned white.

Still no luck running the extruder motor, though. Tried measuring the inputs, but that's not so easy with a stepper motor's varying input. Looked like the right-hand input was at least different than the others when measuring alternating current across them, so maybe there's something up with that one.

Enough for tonight, alas. Tomorrow a more physical battle awaits (if anybody but me are crazy enough to go fight in this heat:)

Little lost connection

Got a new D-Sub connector to replace the suspect one, finally. Got two, actually, just in case, and indeed I broke one during installation. New one is on and seems to work.

Took the opportunity to cut some 1mm plastic for holding up the ribbon. Much better, but I'm only attaching it on the X-axis so far (which was the worst) since the other ones would require major disassembly.

Putting the D-Sub back on didn't make the hotend work. After some futile debugging of the connector (the firmware aborts when the thermistor is disconnected), I finally did the simple thing and measured across the male D-Sub and the wires. Voila, no connection on pins 3, 10, and 11. That would explain it.

Turns out one of the pins one the circuit board wasn't soldered well enough. Fixing that helped, now there's hole all the way through and it heats nicely, all the way to 230 degrees.

Calibrating the bed. Put in extra washers on the right side, which, once I re-read the instructions, turned out to be the wrong way to calibrate those. Front-back is fine, but the middle sags a little.

Re-adjusted the Z-height, but still want to do it like the instructions say. Not tonight, though. Also need to calibrate the extruder.

Picking up where I left off - or what?

Moving has taken almost all my time this year, but the dust is now starting to settle (figuratively and literally - I should call that cleaning service) and I can get back to my printer and get on with calibration and testing. 

After a moment's confusion about negative temperature warnings, I remembered to switch the firmware back to a standard 100K thermistor setting.

Following the testing part of the manual meticulously now. I have 250K baud rather than 115200, not entirely sure why. Limit switches work. Added some oil to the Z lead screws, but I don't see any lithium grease for the extruder gears. Motors move nicely, and oh so much faster and reliably than on the old machine.

Even with the cardboard under it, the bed still sags somewhat in the middle, even though the corners are within a washer's height from each other. I may have to stick with smaller pieces at first and calibrate for the middle.

I'm slightly concerned about how the ribbon cables sag and get tangled occasionally. I should get some stiffer plastic to hold up the ribbons instead.

Bed heats nicely, but the extruder heater does nothing. Measuring on the applicable screws, the HOTEND+ does not connect. Or HOTEND-. I'm getting inconsistent readings. Getting too late. Maybe the mount in the D-connector is off. It looks a little funny:

TODO

• Get lithium grease (Lithiumseife) or acceptable alternative.
• Get better cable strip

Little fix, 10x resistance

Amidst the moving chaos that has prevented me from doing much with my printer the last few months, I did get the time to pull out the old 10kOhm thermistor (thought I'd have to drill it out, but even JB Weld doesn't hold on that well) and add a 100kOhm instead. It should now be able to measure the interesting temperature range appropriately.

I also added some insulating cardboard under the hotbed, which may also help with the slight sagging I noticed earlier.

With this done, I can't think of anything in the way of actually printing. Except the lack of time...

The Strange Case of Mister Thermistor and the High Temperature

I went in today to do some measurements on my thermistor. After trying with an infrared meter (which didn't work at all) and with an ohmmeter (which didn't work while connected to the Melzi, so was hard to control), I realized I had gotten not a B57861S0104F040, but a B57861S010_3_F040, which is a 10K rather than 100K thermistor. I should have double-checked when only one value was available at Conrad, but I thought that was because I had given sufficiently precise search terms.

Bother.

There is a setting for a 10K thermistor, but with the comment "!! do not use it for a hotend. It gives bad resolution at high temp. !!". That doesn't sound good. I would definitely not be able to do ABS with that, not sure if it would be good enough for PLA even. But it'll be as easy to swap out then as now, so I'll do some first experiments, knowing this is a potential issue, and see how it goes.

Change the setting and uploaded new firmware. Tried setting to 185º (PLA), but for some reason Pronterface thought 476º was much more exciting and kept switching to that as limit. The heating went fast, and while I tried resetting to lower and lower temperatures, it kept switching back up. WTF? Looks like the limit is confused by the 10K setting - it also starts out at -35º. I guess it's going to be tricky at best to get it to work anywhere close to reliably. Bother again.

I can get a new one for €2,50, but with €5 shipping. I might as well grab a few extra then, for leaner times.