Retraction Issues

[bpopilek]

Ok, I have been fighting this one all day! If I didn't already suffer from baldness, I would have pulled every last strand out!

So what is going on is this. I am using Simplify3D because of it's advanced features. I have tried with retraction off and it strings something horrible. If I enable retraction, I lose the stringing. However, the hotend always seems to lose it's prime with every retraction. So the start of any move, after the retraction occurs, is short on filament. If I set retraction to even a low number like 1mm, it still strings, see the photo below. If I enable it at 2mm or more, the prime is lost. I can't seem to find the sweet spot! This is a big problem for the first layer when there are small areas that occur after the retraction takes place. I end up with small blobs instead of lines on the print surface. I have also tried BuildTak and Glass w/harispray. The glass seems to work a bit better, but not by much. I have attached a couple of screenshots of my current retraction settings and an example of a print made with those same settings. Also, when a retraction occurs, the extruder is very loud when performing the maneuver. Is this normal or should I be checking that our? I can upload a video if that is helpful to hear it. Any help is appreciated!

[bpopilek]

Here is a short video showing what I'm hearing when a retraction takes place. Is this normal?

vimeo.com/196376484

[tkelley]

That's nothing like what mine sounds like. Mine just lightly hums when it's retracting. You could try setting the retraction speeds back down to 25, and double check that the gears of the extruder are clean. I've noticed that sometimes they get gummed up. It might also help to test the extruder's tension. After it retracts like that, you should stop the print, and check the filament and see if it seems ground down. If it is, the extruder is just chewing filament.

Let me know how it goes! Hope it helps.

[bpopilek]

Thanks. It's running a print still right now. Once it completes I had planned on pulling it apart to check it out.

[bpopilek]

I pulled the extruder apart last night and the only thing that I could find was that the gear on the stepper motor was sitting a bit too far forward. I moved it back a bit, and that did help a little bit with the grinding sound, but it is still happening. I tried printing with one one of the cover screws in place and there was no grinding. but as soon as all 4 are back in, it starts back up. The frustrating part is that I cannot see anything that would be rubbing to cause this. The gears are all clean with no filament ground into them. Any other ideas?

[bpopilek]

I think I have this resolved finally. The extruder is much much quieter now, and after adjusting the spring tension, I'm not getting any grinding or retraction problems. Just fine tuning my retraction settings to get rid of the very minute stringing.

[3DprintedLife]

That sounds super funky, definitely something wrong there. Make sure you aren't overtightening any of those bolts and you may want to move the drive gear back a bit further, it should be flush with the large gear. Too far forwards and it may be rubbing on the case, which would explain why it only makes that noise when the cover is on.

Also, retraction is too low! After fixing the extruder noise (or before, idc!) Try this..

Up retraction distance to 3mm
Reduce restart distance to 0mm
Reduce minimum travel for retracting to 0.5mm

Also, this won't help with the retraction issue but adding the z lift during retracts will reduce possible fan duct dragging on prints during fast moves!

[bpopilek]

I ended up using my Dremel and grinding the fan duct down a bit. That fixed the problem for now until you get an updated one designed. 😉

[3DprintedLife]

Dec 22, 2016 3:40:49 GMT bpopilek said:

I ended up using my Dremel and grinding the fan duct down a bit. That fixed the problem for now until you get an updated one designed. 😉

Gotcha sounds good. Yeah I'll be redesigning the bracket and duct so there is first of all clearance of course, but also so the duct is a bit further away and has slightly better clearances to account for slight variations in print tolerances, especially for when other people print these parts on their own different printers!

[m8kerrc]

guys im having a hard time trying to get rid of blobs at the end of perimeters im not having a lot of stringing after i increase my coasting distance but still having blobs. wondering what extruder settings and retraction have work for you.

thanks

[3DprintedLife]

Have your settings somewhere around 3mm retraction, 30-40mm/s retract speed, and temps around 200-210 for pla.

Additionally, make sure your hardware is all properly put together. For the extruder and hot end, you will want to pull up on those black collars which hold in the ptfe tubing while you push the tubing down at the same time. If you don't do this, you will notice some play in the tubing whenever a retract is made. You can use the ball end of one of the smaller allen wrenches to pull up the collar on the hot end, since that is kind of buried below the aluminum bracket and there isn't much clearance!

[bpopilek]

Jan 4, 2017 2:06:46 GMT m8kerrc said:

guys im having a hard time trying to get rid of blobs at the end of perimeters im not having a lot of stringing after i increase my coasting distance but still having blobs. wondering what extruder settings and retraction have work for you.

thanks

What slicer are you using? I am using Simplfy3D and finally got my settings dialed in. I was also having the same issue you're describing. I'll post screen shots of my settings later.

[m8kerrc]

Jan 4, 2017 7:44:11 GMT bpopilek said:

Jan 4, 2017 2:06:46 GMT m8kerrc said:

guys im having a hard time trying to get rid of blobs at the end of perimeters im not having a lot of stringing after i increase my coasting distance but still having blobs. wondering what extruder settings and retraction have work for you.

thanks

What slicer are you using? I am using Simplfy3D and finally got my settings dialed in. I was also having the same issue you're describing. I'll post screen shots of my settings later.

im using S3D as well .  3.50 at 40mm/s  for retraction and 1.60mm coasting distance for have reduced the blobs . but still is not as dialed in as i like .  

[bpopilek]

Here is the full list of settings (via screen shots) that I am currently using on my copy of Simplify3D. I have been able to get rid of almost all stringing and the layer restart zits are gone as well. Hope these help someone else get setup and feel free to share any changes you make.

[rock75]

bpopilek Looks like we are pretty close in our settings. Mine are getting great results as well. The zits and blobs are pretty much non existent and and I am only getting some extremely fine hairs between travel moves across open spaces. The learning curve with retraction has definitely been interesting with the bowden style extruder.

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