1 Topic by biotour2008 (edited by biotour2008 2022-01-08 23:50:23)

  • biotour2008
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Topic: Filawinder with Filabot

I'm using a filawinder with a filabot, mainly because i dont want to wait a whole day for a spool of filament. I changed the gear ratio so the winder can keep up (https://www.thingiverse.com/thing:2912099) however the filament spooling is quite jerky and as a result the filament diameter is very inconsistent. How can this be accounted for in the firmware? I changed some variables to improve it and it works good when spooling starts, but when spool is full it's much more sensitive and has issues. it seems the motor turns on and off at 1 second intervals . is there a way to have it activating more times per second, polling more frequently for a shorter duration, to keep filament at a more consistent arc/height/diameter? please see below for reference:

https://youtu.be/SlGH_1CvzPc

firmware changes:

The changes are all made to FilaWinder_11.ino:

line 290 changes max motor speed. Default is 1.7, i'm running it at 0.4:
int ScaledOutput = (Output * 0.4); //Scale the Output from 0-150 to 0-255) default is output * 1.7

line 295 is acceleration. It speeds up at 20 units/cycle:
if ( (puller_speed - puller_speed_old) > 20) puller_speed = puller_speed_old + 20; //default is 25

line 296 is Deceleration, -4 units/cycle:
if ( (puller_speed - puller_speed_old) < -4) puller_speed = puller_speed_old - 4; //default is 25


I was thinking it may be beneficial to implement PID auto-tuning of motor speed, has anyone looked into this? I'm not sure if this would be static or if it's going to account for slowing down the wind speed as spool fills up.

2 Reply by elmoret

  • elmoret
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Re: Filawinder with Filabot

I think you're really going to struggle with a setup like that. The reason a typical setup has a U-shaped filament loop is to minimize tension variance as a function of loop height. The closer the filament is to a straight line, the more variance in tension there is as the height changes. Same concept with hammocks, etc.

The Filawinder's DC motor does not have speed/position feedback, so you're going to struggle putting a control loop around it unless you add sensor(s). Changing to a stepper motor would be one option, or making the loop more U shaped.

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