SoliForum - 3D Printing Community — Limits for gearing on an extruder?

Re: Limits for gearing on an extruder?

null@example.com (accusedmonk) — Fri, 12 Dec 2014 03:22:56 +0000

I was considering the same conclusion, it would be pointless to gain that torque only to lose it in micro steps. I'm going to order a motor tonight then.

Re: Limits for gearing on an extruder?

null@example.com (elmoret) — Fri, 12 Dec 2014 03:04:45 +0000

Yes, that is correct - but with reductions like that (27:1), you shouldn't be micro stepping at all. With a 14:1 reduction I'd do a 2x microstep.

Re: Limits for gearing on an extruder?

null@example.com (accusedmonk) — Fri, 12 Dec 2014 01:20:52 +0000

Did a little digging, it is limited in Marlin by the frequency capabilities of the chip and electronics. Apparently some at megas have a quad step function, anyone know anything about that?

Just so i have the limitations correct in my head, i can't go over what would end up totaling more than the 16k in one second correct?

So say 2500 steps per mm, would limit at 16khz around 6mm/s.

Am i understanding this correctly? Thanks for the help too, i appreciate it greatly!

Re: Limits for gearing on an extruder?

null@example.com (accusedmonk) — Thu, 11 Dec 2014 00:56:44 +0000

Ahh, i forgot about the software side of things, thanks for pointing that out.

I'm going to make up a test bench for this. It's probably already been done somewhere but i could use the hands on.

Is the 15k limit due to a limit in frequency or memory buffer?

Re: Limits for gearing on an extruder?

null@example.com (elmoret) — Thu, 11 Dec 2014 00:08:19 +0000

Two limitations:

1.) Available torque. Stepper torque falls off as a function of speed.
2.) Marlin's step rate. Can't exceed 15k steps/sec.

You're fine in both cases. Go with the lighter/cheaper option.

Limits for gearing on an extruder?

null@example.com (accusedmonk) — Wed, 10 Dec 2014 23:49:21 +0000

I'm going to be ordering a geared stepper motor soon for my bowden. I don't think a higher ratio will affect actual printed extruding in a negative way since its so slow anyway. I'm mainly concerned about the retraction aspect.

At the moment I'm looking at either 27:1 or 14:1 stepper. I can go to 32 microsteps, which if my math is right would give me about 5208 steps per mm for the extruder. Is there a good way to figure out limitations running some numbers they have detailed for the steppers?

Here's the link for one I'm considering :
http://m.omc-stepperonline.com/item_description/41