3D Printing Forum

Yeah, the pancake stepper without a form of transmission won't make a reliable extruder IMHO, and personally I'd always go with an adjustable spring-loaded idler. It can be a pain to stuff into a miniature design but I think it's worth it.

I've also been making small extruders in my spare time for quite a while now. Experimented with all sorts of stuff, my current extruder is ridiculously small and light (NEMA8) but it has problems with 3mm filament - I think it would work as is with 1.75 though but I don't have a hotend for that. Currently I'm going with a NEMA14 pancake, just working out the gears for a new prototype. Although the latest one is worm-gear driven I've done successful runs with printed and laser cut gears as well.

Anders Olsson wrote:I have been using that tinkergnome firmware for some time and is certainly has some nice features
The individual motor current is not 100% working though. I haven't had time to sort it out yet though, but one thing I noticed is that the second extruder current setting seems to need power cycling to really update the current.

Ah, i see - the interesting stuff is discussed here now...

The challenge was: There's only one (PWM)-setting for both extruder currents. As far as i understand the schematics, the PWM setting is used as a reference voltage for the stepper driver - and both input lines are connected together.

The main idea is:
1. disable the previous e-stepper
2. set the new current (the PWM output of PL3/pin 46 in this case)
3. enable the next e-stepper

These steps are done on each extruder swap... but not (yet) correctly after changing the preferences...

I assume the latter is the issue you observed?
And if so... it's an easy fix - are you interested...

I think I came to the conclusion that changing the current settings in the motion settings menu only has effect after power cycling.
Of course it would be nice if it immediately updated the current setting, if you have time to look into that

I did not first understand why the setting had no effect, so I ended up changing both current settings every time I changed extruders.
Had an incident earlier on when the pancake stepper was resting next to the printer, before the individual current settings, which made me a bit cautious:

Did not try the "swap extruder" option yet by the way, used G-codes for the second extruder instead, so many things left to test, need more time..

It would be nice with a separate tinkergnome firmware thread by the way, I have a few more things that I would like updated.

Anders Olsson wrote:I think I came to the conclusion that changing the current settings in the motion settings menu only has effect after power cycling.
Of course it would be nice if it immediately updated the current setting, if you have time to look into that

I think, in V16.01 the new value is used after storing (but still not "live" updated)
I want to double check it - any tips how and where to measure the current? (or voltage?)

Anders Olsson wrote: It would be nice with a separate tinkergnome firmware thread by the way, I have a few more things that I would like updated.

You're the one with the ideas - you should start it...
I'm also afflicted with the "need more time" issue - but i'm in!

I can make a forum for TinkerGnome under this Modders Kiosk area if you want? Or...would prefer firmware to fall under the Software & Electronics area?

Either way is fine for me, tinkergnome should decide
I have a few general questions/issues with the Marlin firmware too, so maybe a firmware area would be nice at some point

LePaul wrote:I can make a forum for TinkerGnome under this Modders Kiosk area if you want? Or...would prefer firmware to fall under the Software & Electronics area?

Let's assume, i have just registered and i would like to discuss a firmware topic (very unlikely - i know...) -
...but no matter - i would expect it somewhere under "Software & Electronics".
What do you think?

I can make that happen

Okay I have created a firmware area

I also moved the Ultimaker firmware topic into that area

TinkerGnome wrote:Let's assume, i have just registered and i would like to discuss a firmware topic (very unlikely - i know...) -
...but no matter - i would expect it somewhere under "Software & Electronics".
What do you think?

You actually made me reconsider this Modders Kiosk thing.
Maybe it would make more sense to have my threads under the UM2 category.
Have to think a bit about that.

TinkerGnome wrote:I want to double check it - any tips how and where to measure the current? (or voltage?)

Sorry, I forgot to reply on this one.
I don't have any sophisticated method to measure the current right now, other than using my thermal camera to measure the temperature of the motor

I made a TinkerGnome firmware thread here by the way: viewtopic.php?f=48&t=150

This might be quite interesting to check the force!

Made by the guy that redesigned the feeder spring system on umo

https://ultimaker.com/en/community/1989 ... ent-system

Ups this isn't the place for that post.. Anyone remembers where we where talking about measuring the input force? Maybe on the hard nozzle?

Anders, you have access to a CNC lab. I would recommend you to have a larger knurled wheel CNC'ed.
It will act as a larger contact surface with the filament and should help reducing the skips.
If you can machine something like this, but not in the format of a knurled bolt but as drive gear, I'm sure you'll be able to increase the performance of your stepper: https://thingiverse-production-new.s3.a ... el20mm.PDF

Pro-tip: don't add the 1mm gap in the middle.

Neotko wrote:Ups this isn't the place for that post.. Anyone remembers where we where talking about measuring the input force? Maybe on the hard nozzle?

I saw this discussion somewhere else too, can't remember where though
Interesting way to measure the feeding pressure anyway.

antiklesys wrote:Anders, you have access to a CNC lab. I would recommend you to have a larger knurled wheel CNC'ed.
It will act as a larger contact surface with the filament and should help reducing the skips.
If you can machine something like this, but not in the format of a knurled bolt but as drive gear, I'm sure you'll be able to increase the performance of your stepper: https://thingiverse-production-new.s3.a ... el20mm.PDF

A larger knurled wheel is what I was aiming for too, but it requires a gear because the torque of the stepper is too low at 600 mA to support more than about 4 mm diameter of the knurled wheel.
So a geared version really is the way to go I believe, even thought my prototype was working surprisingly well.

Another thing that I have been thinking about lately is if one should consider a two motor setup, where there is an extra motor that feeds the filament of the spool and into the bowden. If the pancake stepper always had to use about the same force pulling the filament one would have much less slipping issues I believe.