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Necessary to loosen bondtech tension before cold pulls?  

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bobstro
(@bobstro)
Illustrious Member
Necessary to loosen bondtech tension before cold pulls?

I've read up on doing cold pulls, but most of the guides seem to be for other printers with quick-release filament feeding setups. How critical is it to loosen the tensioner screws for the bondtech feeder (I hope that's the right terminology) before doing a cold-pull? I assume manually pulling filament out against the tensioned gears is not recommended, but I haven't found anything that mentions this specifically. Should I loosen the tensioner screws before doing a pull?

My notes and disclaimers on 3D printing

and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan

Posted : 14/06/2018 2:19 am
motocoder
(@motocoder)
Trusted Member
Re: Necessary to loosen bondtech tension before cold pulls?

I usually completely loosen the screws and open the idler door. The reason for this is that when you pull the filament, it can come out suddenly and turn the stepper motor fairly violently. Moving the stepper like that can generate some significant back EMF. Given the poor electronics design of the MK3 (watch the LCD backlight flicker when you move the build plate), I am worried this will damage something in the electronics. Also, because of the heat break issue, I almost always get a blob on there that requires me to open the door anyway.

Posted : 14/06/2018 4:54 pm
Tiago
(@tiago)
Reputable Member
Re: Necessary to loosen bondtech tension before cold pulls?

Yes you need, it won't pass the gears because the diamenter will be thicker than regular filament. If you don't do some you risk break the filament and it drop inside something

Posted : 14/06/2018 6:45 pm
CybrSage
(@cybrsage)
Honorable Member
Re: Necessary to loosen bondtech tension before cold pulls?

Excellent info, thanks!

As an aside, every 3D Printer I have owned has created power by moving the motors. DC Motors turn into generators when you apply mechanical rotation to them.

Posted : 14/06/2018 8:03 pm
dimprov
(@dimprov)
Noble Member
Re: Necessary to loosen bondtech tension before cold pulls?


Yes you need, it won't pass the gears because the diamenter will be thicker than regular filament. If you don't do some you risk break the filament and it drop inside something

Wouldn't the springs allow for it? When you take those into account, there seems to be plenty of headroom.

Posted : 15/06/2018 6:10 pm
motocoder
(@motocoder)
Trusted Member
Re: Necessary to loosen bondtech tension before cold pulls?


Excellent info, thanks!

As an aside, every 3D Printer I have owned has created power by moving the motors. DC Motors turn into generators when you apply mechanical rotation to them.

Yes, I'm well aware of this, being an Electrical Engineer. My point is that it's possible with careful design, to prevent this back EMF from spilling into other electronics, like the LCD board.

Posted : 15/06/2018 10:01 pm
Tiago
(@tiago)
Reputable Member
Re: Necessary to loosen bondtech tension before cold pulls?

About EMF you can protect printers using this: https://www.aliexpress.com/item/Trianglelab-4-pieces-pack-TL-smoother-PLUS-addon-module-for-3D-pinter-motor-drivers-motor-Driver/32841473812.html Also will improve movement and noise, but i don't know the side effects it can have with mk3 drivers

Posted : 16/06/2018 5:11 pm
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