Wondering if anyone here has tried using geared extruder motors for a delta or in general? Haven’t used one yet, but after doing some research there seems to be a lot of options/brands out there. Any feedback on what you’ve found works best? Brand name, gear ratio?
For 1.75mm filament, it will just give you too many steps/mm and limit your maximum printing speed. The ideal gear ratio is about 1.5:1, which isn’t large enough to justify the mass or complexity of adding a gearbox.
For 3mm filament, the extra torque and resolution are needed. A 5:1 gearbox is just about ideal.
@Shai_Schechter I used a phidgits 1:5.18 gearhead with the extruder body @Johann_Rocholl designed for the Kossel Mini.
@John_Driggers What’s the estimated maximum speeds you were able to reach?
Extruder speeds are tricky to quantify because in modern firmwares, they’re calculated on the fly based on feedrates. If you’re printing thin layers from a fine nozzle, you can use more gearing, but if you want to be able to print fast, thick layers, you’ll hit the maximum step rate and your whole print will slow down.
Honestly, if they just offered something like a 3:1 gearhead somewhere cheaply, it would offer a good mix of speed and power for both 1.75 and 3mm filaments. I’ve found that the sweet spot for direct drive operation is just too small for my liking.
A friend of mine still prints 1.75 with a wades (which IIRC is at least a 4:1) and has no problem with speeds capping out prints. He doesn’t print crazy fast, but certainly around 80mm/s @ 5000mm/s/s accel
@ThantiK With those numbers, I would definitely expect to see slow-downs if you use 1/32 microstepping and about .3mm layers or thicker. The Deezmaker machines use 3mm extruders with 14:1 gearing, and I saw significant slowdowns when we first started testing DRV8825 drivers, and ended up switching all the extruders to 1/8 step to get the step rate back into the sweet spot.
I don’t let anyone I know use 1/32nd microstepping on extruder motors. Always 1/8 or 1/16…even with DRV8825
@Whosa_whatsis is this just because deltas can run so fast? I’ve been kinda shocked at how fast my 5:1’s can spin the filament. It’s around 520 step/mm. As for weight, it’s on a bowden delta so weight is a non-issue.
http://www.omc-stepperonline.com/gear-ratio-51-planetary-gearbox-with-nema-17-stepper-motor-17hs130404spg5-p-140.html I’ve been using these for a while.
Biggest drawback is they get INSANELY hot, and that can melt filament if paused long enough.
Setting the microstepping too low will increase noise. The audible noise the steppers make is most closely tied to the pules rate, so turning faster, using more steps/mm (due to gearing or using 400-step motors) or using a higher microstepping ratio will all reduce noise. This, along with extruder resolution, defines the lower end of the sweet spot.
@Mike_Kelly_Mike_Make That’s a good step rate for 3mm, but pretty high for 1.75.
Also, sounds like you have the current set too high.
Yeah though if I turn the current down anymore it torque stalls. Only way to fix it is to have active or possibly passive cooling.
Exploring new territory often has unintended consequences.
Basically the reason of my interest in geared motors was to increase printing speed significantly without compromise. Price is not an issue here. Very helpful info @Whosa_whatsis ! I guess I have to do some more digging to see what works best. Considering using 1.75mm since I would think that works best for fast extrusion. This would also be for a bowden setup.
Like I said. There’s been a few times my motor during a retraction shot filament out at a seemingly crazy fast speed. I haven’t really seen how fast filament moves in a delta but my intuition says that a 5:1 could be fast enough. Seems like you need the torque to drive filament at that rate anyways.
Give it a try and let us know
What retract speed and length you use with 5.18:1 gearboxes?