random extrusion fail

Hi All,

I am back to being totally frustrated with this printer! I am having to force myself to take a break from it or it's going out the nearest window. It seems randomly my extruder will just stop feeding filament. This can happen 10 mins into a print or 1 hour in, but in general I would say it happens more when the printer is doing fast moves.

Once it's stopped extruding, when I reverse out the filament I see that it's been thinned out into a point at the bottom. Not always but often some of the filament also looks crimped where it recently passed the hobbed bolt. If I trim and push through the filament by hand it flows through easily. When I tighten the latch over the hobbed bolt I can also extrude again fine. I have tried temps from 195 to 210 and it still happens. On the filament feed screws I have tried everything from hand tight to screw driver tight but it does not seem to make any difference. I also do not really hear any slipping and no real shavings on the hobbed bolt. How tight should the latch screws really be?

In repetier I dropped speed from 100mm to 90mm, it's still happening. Is this speed just too high for the robo? What speed is everyone else printing at?

I am trying to print the robo 3d top spool holder as I think feeding from the side is definitely not helping. But the only thing I have managed to print so far since getting this printer is a calibration cube, y-axis holder and a shark!

I have re-checked my z height and bed level, all looks good and the layers are going down flat. In fact until it decides to stop extruding it looks great.

Does anyone have any ideas what I can try to resolve this? Or is it time to give up on the stock hot end and go e3d?

Thanks again everyone
Adam

 

Bit the bullet and just ordered up a new hobbed bolt with grooved bearing and also e3d v5. I can only hope this will fix my extrusion issues because right now the printer is useless.

 

The default settings are closer to 50-60 mm/s, but I have similar issues to you all the way down to 10-20mm/s, so you are better off than I am right now!

 

Where did you get these parts?

 

You might want to disassemble your hot end and check to make sure you don't have a large gap between the liner and the hot end itself.

 

Thanks splk3 - I am also using the default settings in mattercontrol. This evening I am going to try the supplied robo filament just on the off chance the filament I purchased is bad. But it was from a reputable reseller so I am not expecting that to be the issue.....but I guess you never know!

@johnstack - the hobbed bolt and grooved bearing is from this ebay seller:-

http://www.ebay.co.uk/itm/RepRap-Ho...141?pt=LH_DefaultDomain_3&hash=item48638ee3dd

My biggest concern right now is how I am going to print the replacement fan bracket so I can fit the e3d. Right now the only things I can print are very small.

 

Hi Country_3030 - I read your post with interest about this earlier today. But I am just really not very confident at dismantling the hot end. I have had the hot end out etc to remove blockages, but I am not sure how I would check the liner gap?

thanks

 

Since it's PLA, I keep thinking it isn't the hot end. How about some data?

What are you trying to print? Does it have lots of head movement and retraction or is it something like a cube? All / any prints?
Have you printed both ABS and PLA in it?
Is your spool clear and unspooling smoothly?
Before these stoppages, have you printed with something other than PLA?
Some PLA is really bad - in terms of width (some over 1.80 at times) What are you using? Is it mostly consistent with a mic?
If you print from Repetier, are you seeing fairly consistent temperatures?
I like slower prints because it is easier to manage flow real time versus anywhere else. I haven't ran mine at 100 - but if I do, I don't fare well. Sometimes not even at 60 like @Spik3 is suggesting. Try slowing it down and checking.
I don't find the filament tensioners that sensitive. I have them so that the filament is grabbed and forced between the extruder and the bearing.

Just some thoughts...

 

Hi,

Thanks for your reply and thoughts, appreciate it. I will try and answer your questions as best I can, but I am pretty new to this printer (2 weeks). I only have PLA right now, nothing else. I purchased the filament from printme3d.com which is the same reseller I purchased the robo from. The PLA is supposed to be +- 0.1mm in tolerance.

http://www.printme3d.com/pla-filament.html

I can print calibration objects successfully. I also printed 1 z-axis rod stabilizer. But when I am trying to print something larger it seems to always fail. For example I would like to print the following spool holder:-

http://www.thingiverse.com/thing:216117

1st attempt it failed on layer 3, the next attempt it probably got around half way through the print and then stopped extruding. I hit pause, backed out the filament, trimmed off the thing strand and manually extruded a little. I then set it off on it's merry way and it continued for another 3-4 layers. It failed again but this time I didn't catch it in time so the entire print was ruined. Since then I have tried other items such as the dial indicator holder:-

http://www.thingiverse.com/thing:185643

It started to under-extrude by around layer 3, once again the filament had stopped feeding through.

In repetier the temps all stay stable, in fact they are fairly stable with mattercontrol. I am using the recommended default settings in repetier. If I were to try and slow down my prints, do I do this from the manual settings page in repetier and just reduce that from 100mm down to 60mm? Or is it the slicer settings I need to change?

Thanks
Adam

Thanks again

 

You should change the speed in Slic3r - under Print Settings. Be systematic. Try 25 for everything on a smaller print, then bump them up gradually. Your print times will naturally increase; however, failed prints are so much worse than slow prints!!!

With PLA, it's doubtful that you're having so many problems with the printer or the head itself. ABS is another story, typically, it's all about adhesion.

Cheers and Good Luck!

 

thanks! I will try this tomorrow. If I could at least get the spool holder and dial gauge printed even at low speeds, it will mean I can improve my setup / check bed level etc. Can I ask what speed settings do you use in slic3r that give you consistent results?

 

You should see this update as well. Apparently, you might have a gap....by @Country_3030

http://forums.robo3dprinter.com/index.php?threads/filament-not-feeding-through-hot-end-fixed.2348/

 

Yes, it could perhaps be the same problem. Only thing is I am not sure how to check for this gap that is referred in the other thread. I am guessing I need to completely un-assemble my hot end but not sure.

 

does your current hobbed bolt show plastic shavings in the grooves or around it? If so, the current hobbed bolt is slipping/eating away at the filament and probably should be upgraded for a more reliable print.

 

Hi Bob64 - It's really 50/50 - as in sometimes when the extruder stops and I notice it straight away then the bolt will not have shaved the filament. But if I did not catch it then yes the bolt starts shaving the filament, but it's because the the hot end is jamming. I did go ahead and order a recessed hobbed bolt and grooved bearing, which should be better then the stock regardless. I did not get time to do any further testing today, but I am hoping tomorrow if I slow everything down as suggested by JohnStack that perhaps I can get it to at least print my gauge dial holder and go from there. I am going to be gone all next week and then my e3d should be here. I am hoping that will resolve all these issues.

 

When you install them make sure you add a few extra washers to increase the tension on the idler bearing. You need to compensate for both groves. I think I have six washers total on each side.

 

Thanks SteveC I will do that! I tried slowing all settings down to 50/40mm/s in repetier and it's still failing. New glass bed arrives tomorrow so I am going to leave it for today, only so much of this printer I can take in one day

 

I've had this same issue. It's basically the hobbed bolt stripping the filament instead of advancing it. Pulling it out, I can see a nice little round bite taken out of it. I thought it might have been caused by either resistance at the spool or resistance in the hot end. I put together a spool holder that allowed the spool to ride on bearings. Helped a little. I got an E3D hot end. Helped a little more. I've pinned it down to very rapid x-axis movement along with very slow extrusion. I've been trying to successfully print the platform lifters for weeks now.
I have to order more plastic. When I get to the thinner walls (approx. 1/8 inch) that go inside/outside the robo base, it will behave like this when filling in the centers of these thin walls. It shakes like an out-of-balance washing machine. I've slowed the speed down as far as 40% and am able to get further but still have to sit next to it and mark the filament w/ a Sharpie every 30 seconds or so to make sure it's still moving.
It may be something simple in the Repetier Infill or Retraction settings. Maybe I need the shallower hobbed bolt and grooved idler you mentioned earlier. I'm even considering seemecnc's EZ-struder but it would require printing another x carriage. I got so tired of constantly opening and closing the filament holder, chasing springs and washers all over the place, that I designed a replacement that just latches into those two recessed nut holders. No more nuts & screws and just one spring. The problem isn't solved but at least it's a lot easier to remove the stripped section and get back to printing. I'm going to dig into the g-code and see if I can track down the offending lines and see if it's something I can change in the Repetier settings.

 

I just found this... http://slic3r.org/releases/1.1.0 . It's the experimental release but one of the top new features... New algorithm for linear gap fill: no more shaking and adaptive extrusion width! Yay!

 

interesting......let us know if the new slic3r version fixed your issue.