It missed, make sure you do not HAVE to home Z first…so close.
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It’s still neat to use the list as a reminder of what to rule out!
That is mind blowingly amazing. I mean, it could do another scrape about that info and catch my post and next time the question is asked it will be that much better. Think about all the recent articles with people making fun of the things it got wrong. That is just like learning at school, except it doesn’t forget. So each correction or article very well could train it to do it correctly the next time around.
Insane, scary, awesome. All at the same time.
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The plotter is finally alive! It’s been quite a ride, with many bumps in the road. Now remains encasing the card, fixing up the wires and tuning the speeds. Thanks a lot for a nice machine, @SupraGuy !
How do I embed a video directly? I’ve seen others do it.
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I think I have only seen videos loaded to YT or google photos and people post the link. The link gets embedded.
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And now with a z stepper instead!
Found a pancake stepper from a salvaged printer. Perfect size, but it gets quite hot! If I turn down the voltage, the torque slips. How hot is too hot?
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The rule of thumb for PLA is about 50C. Above that, the PLA creeps faster and you deformation of the mount.
That tiny stepper probably can’t handle much current.
The mounts for the stepper is plywood, so it could handle plenty more than 50C. But alas, today it just stopped working while stress testing! Not sure if it stopped because a wire shorting or from heat and stress. The torque needed to lift the pen must be neglible, but still. I guess I’ll try a bigger one:
Wow, somehow I missed this entire topic, this is an awesome one!!!
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Man when you have your machine in a HOT (and i really mean hot) environment. Your steppers and pla pieces works against you -and running AC all day long isnt cost effective. 
SHOOOT. I was trying to remove the metal spur gear from the stepper - and I RUINED it. It was quite fitting for this application. Now I only have bigger (uncommon) printer stepper motors, that are even bigger and only runs on 24V.
Edit: I guess I can try my luck with the 28BYJ-48, 5V, again. I didn’t figure out how to run it on the MKS DLC32, with TMC2209 drivers and fluidNC. Well well - the rabbit hole goes on and on!
Edit 2: I did try to convert to unipolar 28BYJ-48 to bipolar, to use it directly with the control board. But now it only hums when running it, with no movement.
Edit 3: OOOH - this one is nice!! https://www.aliexpress.com/item/1005005101736266.html I wonder if it has enough torque. But I sort of defeats the whole idea of building the plotter as a re-purposing of old parts.
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I saw someone used a Cheap peltier to push their electronics. May work here.
These little 28BYJ-48 steppers are geared way down and you need drive them with a lot of steps to move any distance at all. Put in a pretty large steps/mm number (1000?) and try moving a convenient distance (10mm)… hopefully it perceptibly moves. If it does, measure the actual vs commanded movement and compute the scale factor (commanded/actual) to multiply the current steps/mm by…
They actually can be driven with our little stepstick drivers. You just need to set in a very small Vref that keeps the current low enough to keep the generated heat manageable… they’re drawing current even when holding position. Unfortunately I don’t remember the numbers I used way back when…
Eventually the Z-axis morphed to this…
and then ultimately became beltless in favor of a printed leadscrew.
Here’s the portion of my long thread where I played with this little motor. IIRC I think I ditched these belt-driven Z-axis designs because because I kept losing my focus distance every time I powered down and the motor ran hotter than a firecracker… 
– David
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I often refer to my journey into the reprap world as tumbling down a deep rabbit hole, leading into caves of both knowledge and confusion.
And here you are David, along with all the other friendly souls - showing up in your tunnel boring machines! I’m so thankful for all your knowledge and patience you share! At times I feel like a frantic rabbit, while you guys have dwarven fortresses full of treasures.
Well. I did try increasing steps/mm a lot and tweaking vref. But the only movement I got was random jumps. Nothing predictable to work from. I feel like moving the whole plotter down to the basement, to tidy up the mess in the living room. I’m tempted to order the nema 14 mentioned earlier. Do you think it’ll be up to the task?
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More like a cluttered mess that continually frustrates the heck out of me when I can’t find stuff… possibly a “dwarven fortress full of treasures” only because I keep ordering stuff I already have just because I can’t find anything.
I’m sure a Nema14 would be the better choice. I never could really get Vref dialed down enough to keep the 28byj-48 motor from running hot, while just holding the laser in focus position. Plus I don’t think it was really all that accurate at positioning anything… probably due to the gearing.
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For completeness sake, I happened to run across this video… if you’re still interested in playing with the 28BYJ-48 steppers. He’s modified them for bipolar operation, of course, and determined the coil pairs… orange/pink and yellow/blue. He also had to rearrange the wires to directly plug into the shield.
It also appears he sets up the A4988 drivers with no jumpers so he’s using single-stepping IIRC. Later, and after he demonstrates movement, he shows that he’s using 250 steps/mm… which he later changes to 500 steps/mm for some reason. He never mentions his Vref settings that I could see… but it will be quite low, maybe 0.1V?
Could be fun if you like to tinker… and I did play with them enough to convince myself that they do work and, in some use cases, could be useful.
– David
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Thanks for new insights from your dwarven fortress! I did try the bipolar mod, but to no avail. Still only shaking and jittering. The plotter has been exiled to the basement, and I’ll bring it back up when the Nema 14 has arrived and I’m ready to start my new career as a plotting artist.
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David, i want to come over and learn!!! Wish u were in michigan!!!
Finally! The Nema 14 is installed and works like charm. Was a little annoying to find a balanced vref. It quickly got too hot, so I had to try many times while adjust from lowest setting.
The sides are from left over bathroom wall plates, small parts from disassembled printers, and long rails + hardware bought online and locally.
It’s silent, runs quickly and quite precise and has a decent work area. I can run it in the livingroom while my wife plays Zelda - and she doesn’t complain! 
(and btw - I finally figured a simple way to embed videos! I upload them to my website and paste the file location here. Easy peasy) (one more edit: and yes - I’m a little proud of modelling my first ever moving mechanism… The pen lifter not be very good looking, but it works - and I drew it!)
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Looks like that works great!
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