How to change E microstepping to 1/8 from default 1/16th??

[Artesian]

I've peeked into the firmware and it's clearly quite easy to change microstepping for XYZ axes... but that's not what I want to do.

I am going to attempt to mount one of Mutley's custom "Flexstruders" with a flexible drive shaft to the effector platform. This will enable "Direct drive" printing on the Rostock. Pretty cool right?

Only problem is that his mod requires 1/8th microstepping on the E axis... and as far as I can tell there is no way to do that in firmware. Anyone know how to do this?


Thanks.

[mhackney]

Yes, the easy way is to just divide the steps/mm for the extruder by 2 in the EEPROM. The micro steps settings you see in Configuration.h are used to calculate the steps/mm so you can just bypass that and set it directly.

There us a downside though. You really want to keep the steps/mm for your extruder up around 400 mm/s for optimal results.

[Artesian]

Wow that sounds like it's amazingly easy! Thank you...

A few things: there are lots of commented warnings inside the firmware that say "DO NOT increase the speed your motors run at." Does that mean going to 1/32 stepping? Or is that referring to what I want to do with 1/8th? Is 1/8th faster than 1/16th? I'm really skilled with hardware, but these firmware and motor changes are totally alien to me and I want to triple check any changes I make here.

Why do I need to keep steps/mm up around 400? What's going on that makes this a necessity? They're currently at 440.

[mhackney]

I haven't looked at repeater firmware for awhile and I don't recall seeing those comments. You shouldn't have any problems.

Well, the ezStruder is around something like 84 steps/mm with 16 micro steps. You can actually see the pulses from the extruder if you print very viscous materials like carbon fiber filled PLA. This is really at the low end of the range. 400 mm/s will give a much smoother extrusion. That's why geared steppers are a great upgrade for an ezstruder. A 5.18 to 1 geared stepper results in about 400 steps/mm.

[bot]

I don't think you can just divide the steps/mm by 2. You have to change the microstepping for the motor driver in firmware. I believe there is a line in repetier that has the microstepping factors set in an array (16 16 16 16 16) I would assume it goes (X Y Z E0 E1) But I'm not positive.

[mhackney]

Yes, you are correct bot. Too much wine tonight! The 4th value is the extruder 0 (which is the first extruder since you can't have 0 extruder son and print!) micro steps.

[Artesian]

Changed the fourth value in the array to 8. Nothing happened. Printed well, no change apparent.

Changed the value to 4. Now everything is badly overextruded and the motor is making HORRIBLE noises.

[bot]

If you had previously halved the steps/mm, then it would print well with 8 set. Each time you change the microstepping, you need reduce (or increase) the steps/mm.

[mhackney]

There are a LOT of things going on here.

If you have EEPROM enabled, simply changing that value in the config file WILL NOT overwrite the EEPROM settings on the RAMBo UNLESS you also change the value of #define EEPROM_MODE to ANY OTHER value than it is set at (or 0 which turns off EEPROM usage). Here is the comment above that line:

IMPORTANT: With mode <>0 some changes in Configuration.h are not set any more, as they are taken from the EEPROM.

So unless you are absolutely sure you did that, I would go back and try again from the start.

Once you go back to where you were originally, open the EEPROM window and write down the value of the extruder steps/mm. Then change microsteps to 8, change EEPROM_MODE and compile and upload and check it again. It should decrease by 2. If not, then you should set it in EEPROM directly - assuming the stepper is actually running in 8 microscope mode.

This is why I liked the Azteeg X3 Pro board, not only did it support 32 microsteps, but you set those with physical jumpers so there was no question about what the MS were set to.