So that's why I missed the 20D encoders before - they introduced them *after* my December post! They look like they'll be fantastic for this role, though. Yeah, it won't be 30gm, but the performance will be up there with anything else in common use. I'm going with a slightly different path forward this time. I'm running a Titan extruder on my current printer. Instead of replacing the whole thingby matthock - General
I've been a bit stalled on this - I couldn't get it to both work and meet my speed requirements with the old specs. Taking a new tack. I didn't realize this before, but the next size of Pololu motors, the 20Ds, also have encoders available. Don't know if this is new, or if I just missed it before. Much worse power to weight ratio (40gm vs 10gm for about twice the power), but it's still a lot betby matthock - General
Progress report: 75:1 Pololu motor experiment has thus far failed. Not enough torque - it can run the filament in an aggressive extrude/retract cycle without the hot end for ages without the heat problem with the fan mounted on there, but once you add the hot end, it stalls. Part of it may be the geometry. When I shifted the motors to the inside of the filament paths, I think it made things a bby matthock - General
Most hobby brushless controllers work that way, yeah. It works best when running at high speeds - there's not enough back EMF at lower RPM, so for low RPM operation and startup from idle the controller essentially has to "guess", which severely degrades low end torque. Hence it tends to work quite well for things like quadcopters where you just need to get it started once then it runs pretty muchby matthock - General
The reason the steppers use a current limiting controller is due to their intermittent run cycle. They have extremely low coil resistance to enable them to go from 0 voltage to saturated voltage (and hence full step torque) as quickly as possible, but it enables such high current without a limiter that they'd burn up in minutes (a standard NEMA17 stepper will happily burn 6+ amps at 12v if you doby matthock - General
Heat is the biggest problem I've run into. Unlike steppers, DC motor current is directly related to torque (whereas steppers are constant current and heat is oddly enough mostly inversely proportional to speed), so running it without the hotend attached didn't end up being a good representation - I did exactly that with a length of filament I'd bonded into a loop so that it could run continuouslyby matthock - General
Been doing some more work on the physical side of things. This is for the double drive Chimera-compatible version. PETG, 25% infill, 2 perimeters, 4 top/bottom. Almost everything's there - the second motor's encoder/wiring harness and 3mm to 5mm shaft adapter are the only parts not present. Also possibly a couple of tiny heat sinks (same kind as comes with A4988 modules). Looks like the finalby matthock - General
Yeah, the ideal would really be a brushless motor with encoder, but they're pretty expensive. My overall goal is lightweight dual direct drive with a Chimera, which will make the overall mechanism big enough that I was just going to stick a dedicated 40mm fan on top to cool the motors, at least for the time being. Maybe add one of the little sticky heat sinks for the stepper controllers on eachby matthock - General
The Pololu encoders seem to be a high enough resolution that they work for this, although I do believe they're close to the minimum that would work. Got a video of starting a print: https://youtu.be/RM7vpJJLMw8 (Apologies for shaky camera work, I was just using my cell phone) Ended up having to cancel that run halfway through due to a new problem - heat creep from the motor. I've got a print prby matthock - General
Not sure if OP has dropped this project, but I've been working on something similar and having moderate success. Here's a picture of the current prototype mounted and wired in my VORON CoreXY printer. This is using a 12v 150:1 Pololu micro gearmotor with their 12 count per rev magnetic encoder - since the encoder is before the gearbox, it works out to about 1800 counts/output rev; with a MK8 hby matthock - General
So I had a bit of a surprising event just now. Was going through my normal print cycle, and my printer (a DIY job but roughly analogous to a Wilson) had just finished preheating and had started head movement when it stalled, communication dropped with my computer, and I smelled smoke. I immediately pulled power, let everything cool down for a few minutes, then tried to power things on... no dice,by matthock - RAMPS Electronics