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I built a modified QU-BD direct drive bowden extruder similar to Werner's Berrybot with a 5:1 planetary gear and Mk7 drive gear, and I've got a E3d all metal hot end. I've been able to dial in retraction really well using two 20mm single wall cylinders in slic3r. You can barely see that a gap in the wall is starting to develop at 5 and definitely at 6mm retraction, so 3-4mm is probably optimal for this setup in ABS. Now I am left with what appears to be either backlash or delta blues. The arrows show the direction of print motion. Looks like its pretty close to a wall thickness (about .4mm) I slowed the non-print motions down to 20, thinking that might point to delta blues and that didn't make any difference. I've had the rods apart 4 times and now have them swinging freely but didn't feel any particular play within the joints. Any ideas?

Broose wrote:I built a modified QU-BD direct drive bowden extruder similar to Werner's Berrybot with a 5:1 planetary gear and Mk7 drive gear, and I've got a E3d all metal hot end.

Rostock Setup.jpg

I've been able to dial in retraction really well using two 20mm single wall cylinders in slic3r. You can barely see that a gap in the wall is starting to develop at 5 and definitely at 6mm retraction, so 3-4mm is probably optimal for this setup in ABS.

retraction lengths.JPG

Now I am left with what appears to be either backlash or delta blues. The arrows show the direction of print motion. Looks like its pretty close to a wall thickness (about .4mm)

Single Wall Cylinder.JPG

I slowed the non-print motions down to 20, thinking that might point to delta blues and that didn't make any difference. I've had the rods apart 4 times and now have them swinging freely but didn't feel any particular play within the joints. Any ideas?

Is that extruder listed on Thingiverse?

Eaglezsoar wrote: Is that extruder listed on Thingiverse?

Part of it is: http://www.thingiverse.com/thing:38281 I used just the aluminum block from a QU-BD extruder and JB welded the PTF connector into it because the threads didn't match. I made the motor mount and front plate out of aluminum. I had to bore the MK-7 drive gear to 8mm to fit the planetary gear motor which I got here:
http://www.stepperonline.com/gear-51-pl ... p-104.html

If I was better at 3d CAD today I'd print the block to mount the PTF connector. Then the QU-BD extruder is not necessary.

By the way. I love the quick release function. So much easier to switch filaments.

nice work,

for the misalignment have you checked your towers to see if they are sqaure?

cambo3d wrote:nice work,

for the misalignment have you checked your towers to see if they are sqaure?

Thanks. Thats a good idea. I did check them when I first built it, but its been moved a few times since and they probably should be checked again.

Broose wrote:

cambo3d wrote:nice work,

for the misalignment have you checked your towers to see if they are sqaure?

Thanks. Thats a good idea. I did check them when I first built it, but its been moved a few times since and they probably should be checked again.

worth a try, but if you checked it when you built it, most likely its still the same. might be something else.

cambo3d wrote:

Broose wrote:

cambo3d wrote:nice work,

for the misalignment have you checked your towers to see if they are sqaure?

Thanks. Thats a good idea. I did check them when I first built it, but its been moved a few times since and they probably should be checked again.

worth a try, but if you checked it when you built it, most likely its still the same. might be something else.

I checked the towers out and they were a little out of square. Before realigning them, I pushed on one of the towers and it was pretty easy to knock all three of them out of kilter. It must have taken a bump when I had it lying sideways in my car. Anyways, after getting them realigned, it didn't fix the problem, but I'm glad you pointed that out. Next time I move the machine, I'm going to quickly verify squareness once I get to my destination.