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Filament harder to unload after bondtech upgrade  

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Polsaker
(@polsaker)
New Member
Filament harder to unload after bondtech upgrade

After I installed the Bondtech extruder upgrade, filament got harder to unload, since there's now a thicker part at the end and I have to apply a little force to get it out (see the picture). Is there any way to solve this? I want to get the MMU2S upgrade in the future and I feel this would make filament changes more complicated... there's also a really thin line of filament that comes after the little ball at the end of the filament that I didn't have before the bondtech upgrade

Posted : 09/09/2019 3:24 am
Bunny Science
(@bunny-science)
Noble Member
RE: Filament harder to unload after bondtech upgrade

Bondtech MK3S extruder upgrade has a tight filament path molded into the extruder body both above and below the Bondtech drive gears. It is 2.0 mm diameter in their CAD diagrams. This is great for flex filament, but can be an issue for MMU2S big tips. If you are in single filament only, should only be problem with big filament tips created by standard unload. I take care of that in my firmware with with a mini-ram movement during unload.

Once you go to MMU2S, the tight Bondtech filament path can be an issue, but is solvable by Cybersage's report...

I widened the hole a little. Already ran into that issue.  Chamfered the top to help the filament enter easier too.

There are also some filament move distance and speed changes for loading and unloading that should be done for the Bondtech.

Bondtech support can supply you those patches.

Alternatively use my 0.9 motor firmware, with the following changes in Configuration_prusa.h

comment out the default 0.9 degree motor defines like...

//#define X_AXIS_MOTOR_09 //kuo exper X axis
//#define Y_AXIS_MOTOR_09 //kuo exper Y axis

uncomment the geared extruder definitions to select Bondtech MK3S extruder upgrade like...

#define BONDTECH_PRUSA_UPGRADE_MK3S //Kuo Uncomment for Bondtech MK3S extruder upgrade. (Note the S!!!!) 3:1 extruder. This also sets Z_MAX_POS 205.

That should be all you need to modify. My firmware will set up distances, speeds and Z height for you. By default my firmware does a mini-ram move during filament unload to shrink the filament tip.

You should do the commands for micro-steps and e-steps via a terminal 

M350 E16
M92 E415
M500

NB: M350 must be BEFORE M92. Otherwise, M350 may alter existing the e-steps value

verify your work with

M503 //read current settings so you can verify the extruder motor microsteps and e-steps are 16 and 415

 

 

Compilation direction are on my firmware github https://github.com/guykuo/Prusa-Firmware/tree/0.9-Degree-Stepper-Support

Posted : 09/09/2019 8:05 am
Polsaker
(@polsaker)
New Member
Topic starter answered:
RE: Filament harder to unload after bondtech upgrade

Wow thanks! It seems I had forgotten to update the microsteps/esteps settings! Now the filament tip comes out almost as neatly as before! I'll give your firmware a try, since I'm already using some modified firmware for LA1.5

Posted : 09/09/2019 4:08 pm
Bunny Science
(@bunny-science)
Noble Member
RE: Filament harder to unload after bondtech upgrade

Glad you got your printer working better after microsteps and esteps were set. 

Please do give my firmware a spin. It supports what I think are the most desirable add ons.

Posted : 10/09/2019 12:16 am
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