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Folgertech 2020 Bowden Conversion

Posted by guitarheromatt 
Folgertech 2020 Bowden Conversion
December 04, 2015 01:32AM
Recently I've attempted to convert a FolgerTech 2020 Prusa i3 printer to a bowden extrusion setup, basically I took the direct drive extruder, made it feed into a bowden tube and fed the other end into my e3d lite6. After the conversion I've been getting prints like the second attachment, and cannot figure out why. Basically there are gaps where the ABS didn't attach correctly to itself so it curls up. I measured the extrusion and configured the steps correctly, i believe. And when I lift the print head the ABS seems to extrude correctly. I am somewhat of a noob though so if someone wants to give me pointers anything would be appreciated.

After some scouring the forums I've found a few things; a more powerful stepper motor and a better drive gear, would these solutions help?

Edited 2 time(s). Last edit at 12/04/2015 01:45AM by guitarheromatt.
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Re: Folgertech 2020 Bowden Conversion
December 05, 2015 12:57AM
Well figured out why the prints were lifting, turned off the stupid cooling fan that I left on for some reason. Anyway now I'm facing the grinding and clicking of the extruder not pushing filament out well. So should I try a new drive gear or a new stepper motor first? Any thoughts?

edit. My local store has a q3d mk7 drive gear and a q3d raptor drive gear. Mostly print with ABS so leaning towards the raptor, but open to suggestions.

Edited 1 time(s). Last edit at 12/05/2015 01:00AM by guitarheromatt.
Re: Folgertech 2020 Bowden Conversion
December 05, 2015 01:14AM
Let me know after the update if you now get the big C chewed into your filament winking smiley
Re: Folgertech 2020 Bowden Conversion
December 06, 2015 01:38AM
I was getting a little of that earlier. Installed a MK7 drive gear into the extruder and have a lot less grinding, and no slippage of the filament. However now I'm running into issues with the extruder clicking, so I was thinking of picking up a stronger stepper motor in order to give the extruder a little more strength to push the filament through the tube and hot end. Unless there is another possible solution?

Edit. Also I took apart my e3d and cleaned it. found out that jamming is/was never an issue

Edited 1 time(s). Last edit at 12/06/2015 01:39AM by guitarheromatt.
Re: Folgertech 2020 Bowden Conversion
December 06, 2015 12:11PM
How about printing a geared extruder so that you can continue to use your existing stepper but still get more force to overcome the friction of the bowden?
Re: Folgertech 2020 Bowden Conversion
December 06, 2015 02:15PM
I thought about doing that but the printer isn't extruding enough to make a solid, good print. So I can't print anything that I'll be able to use, unfortunately
Re: Folgertech 2020 Bowden Conversion
December 06, 2015 04:24PM
If the extruder struggles to extrude there are really only two causes:
1. Not enough current for the motor.
2. Too much force required to extrude.

I am using 3mm filament and even the crappy original extruder managed to work with it.
If in doubt print really slow and with slightly higher heat.
If that still does not help check if can push the filament through extruder and hotend by hand - not working or you need tools means there is far too much force required.

Too many people try to mask other problems by using Nema23 motors, bigger drive gears and so on, whil in 99% of case a simple Nema17 with a proper hotend will just work fine winking smiley
Re: Folgertech 2020 Bowden Conversion
December 06, 2015 04:36PM
Thank you for your reply. Do you have a good link to help explain how to adjust the stepper current to my motor? Ive tried watching some videos on YouTube and searched around a little but im still not sure about how to go about it. I'm using a policy stepper driver and a 2.4 NEMA 17 stepper motor. I've found that I can push the filament through the extruder, and it prints fine, but can't do it on its own. Will give printing slower a try
Re: Folgertech 2020 Bowden Conversion
December 07, 2015 05:42AM
As you often need a oscilloscope and a shunt to properly measure the motor current I use a good ear and temperature as a guide.
When you enable the motors or pause a print you can hear the motors as they get the impulses to different coils so they can hold everything in place.
If the motors are screaming it means the current is quite high and could be on the limit of both the motor and the driver.
And if the motor gets hot (not warm to touch but so that it is hot) during a longer print the current is either too high or the motor need too much force to push the filament.
Since you said you can push it by hand just fine you can use temp as a good indicator too.

Keep in mind that this is nowhere accurate and that you should try to keep the motor current as low as possible.
As a rule of thumb for axis and extruder I use a simple print and print with the highest speed I require and with the thickest layer height possible.
During the print I reduce the current for axis until they loose a step or two then go up by agout 10° on the potentiometer.
Similar for the extruder only that here I mainly use the temp as an indicator after I made sure bridging with 100% extrusion and speed does not cause the extruder to click or jump.
Yes I use bridging for that as here I don't have to include the back pressure from other layers.
If you prefer to do the check with normal use a 100% infill at the thickest layer height and highest speed you use as an idicator.
Re: Folgertech 2020 Bowden Conversion
December 08, 2015 12:43AM
Thank you for your detailed reply. Explained it very well, am I correct in saying that counter clockwise on the driver will make the motor cooler by lowering the current? And the opposite for clockwise? Haven't had much time to work on the printer due to finals coming up but will try when I have a chance XD
Re: Folgertech 2020 Bowden Conversion
December 11, 2015 01:33PM
Much thanks to all for your help. Adjusted the stepper motors and installed a higher torque 5.5kg stepper for the extruder and it now works beautifully
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