Printer strips filament at certain height of model  

Re: Printer strips filament at certain height of model

Hi Anton

Use attachment for pictures.

Re: Printer strips filament at certain height of model

Thanks gert, totally missed the attachment option.
I've got more pictures of the parts and one of the stripped filament, that basically got taken a bite out of. The extruder wasn't jammed, and it took only two attempts of unloading and pulling to get it out, so no real jam. The hobbed wheel also didn't seem to be particularly dirty. I quickly brushed it off before printing and initially, everything seemed fine.

Re: Printer strips filament at certain height of model

from the pictures we can see, that you use an enclosure.
are you sure, that all the 3 cable trunks doesn't interfere with either each other or the boundaries of your enclosure during the print (in every thinkable position) ?

Re: Printer strips filament at certain height of model

Thanks Jeff, good point.
Initially, I did have problems printing the triceratops that came on SD with the printer. I thought they were exacerbated by the enclosure, but I blamed them on high idler tension and suboptimal filament feed through the top of the enclosure (drilled a hole, fed a PVC pipe through, filament got bent in weird angles or friction was too high).
Since then, I've significantly released idler tension and cut a massive hole in the top to ensure filament feed just as if it were without the enclosure.

I'm also reasonably sure that the cables can move freely and will not bend or interfere, but will double check tonight.

I'm not near the printer right now, but I will post pictures later on, of the complete setup. It's basically two IKEA Lack tables, plexi glass sheets to keep the cats out, and a massive hole in the top table for the original filament holder, a relatively heavy stone plate to keep noise and vibrations to a minimum, plus some cheap LED lights.

Re: Printer strips filament at certain height of model

Ok, here are some more pictures of my setup. Please ignore the shitty box construction. The hole on top was my brute force approach to minimising problems in the filament feed.

The blue and orange part took about 35h at .2, no infill, one filament change, and came out fine. I pretty much used a whole spool of Prusa PLA to learn that I shouldn't print this particular model in .1 layers, because the overhangs will curl and it will get torn off, and printing it with infill will pretty much guarantee stripped filament.
I then switched to .2 layers and no infill, and it printed fine. I also assumed that the same settings would carry me through the other parts of the helmet, but they did not.

The large helmet consists of about 12 parts so far, .2 layers, 10-20% infill, 8 to 17h print time each. I was experimenting with settings, but it seemed to be a forgiving model, and I can't remember a failed print.

I also checked the cable movement inside the enclosure, and while the left cables seem to touch slightly, nothing appears blocked.

Re: Printer strips filament at certain height of model

It is possible that the inside of your enclosure is getting too hot for the fan to cool the heat break. If the heat break gets too warm, it will melt the filament and you will get a clog. It will do this many hours into a print as the temp rises. Try keeping the door open.

Re: Printer strips filament at certain height of model

It is possible that the inside of your enclosure is getting too hot for the fan to cool the heat break. If the heat break gets too warm, it will melt the filament and you will get a clog. It will do this many hours into a print as the temp rises. Try keeping the door open.

With the big gaping hole in the top I seriously doubt he is going to run into heat issues. I run my enclosure fully closed most of the time and my temps in the enclosure seldom get above 38C.

My suggestion would be to change to Slic3r. It will allow you to adjust the retraction settings. I believe this is where the problem is.

Re: Printer strips filament at certain height of model

a few more tests:
* printing inside enclosure, no infill, .2 layers, 17mm/s retraction speed => failed earlierat about 10mm height
* printing outside enclosure, well ventilated room, thoroughly cleaned hobbed gear, same gcode file => failed again at about 20mm height, just like the first two tries

I'm running another test print right now with retraction speed at 10mm/s, retraction length .3mm, but I'm running out of ideas.

Re: Printer strips filament at certain height of model

You may want to look for an intermittent connection in your extruder cable bundle, that is triggered at certain bends in the cable (e.g. heights).

I had this, with the thermistor, and it caused the printer to heat up too hot (even though it was measuring low temp) and cause a clog.

Intermittent fan would cause this also, as would a bad stepper.

Can you watch the printer closely around the fail points? Is the extruder cooling fan still running? Is the stepper stepping?

I assume you checked the hob pulley to make sure it is not slipping?

Re: Printer strips filament at certain height of model

Bump your temp up 5-10 degrees.

Re: Printer strips filament at certain height of model

Wow, setting retraction speed to 10mm/s and retraction length to 0.3mm actually worked! The print finished and is looking really nice. No stringing or any artefacts that I would attribute to the modified retraction parameters.

Now, can somebody please explain why the preset default values are so much higher?
Changing these values didn't seem to affect anything apart from the fact that the print actually finished and the filament was not stripped.
Do tolerances between printers really vary that much that you need to tweak the presets so drastically to just finish a print? Was the model so weird? The gcode?

I've been printing for 4 months now and am really just trying to understand the issues here.
Thanks everybody!