Problems with filament jambs

[clough42]

but the .1 shift on the y axis I do not understand.

As others have pointed out, this is difficult to diagnose. It's possible that it's s software problem, but that's not where I would start. It's usually skipped steps on the motor or a skipping belt.

If you can precisely measure the amount of the shift with calipers, see if it's a multiple of *exactly* 2mm. If so, it may be a belt skip. If it's not exactly a multiple of 2mm, it's not the belt. Friction or inertia (or an outside force) probably overcame the motor's holding torque and it skipped some steps. By "outside force" I mean things like bumping the printer or getting your finger caught between the bed and the Y idler while trying to feel the belt tension. Not that I would know anything about that.

If it only happened once, ignore it. If it keeps happening, you can try making sure your mechanics are moving freely and try slowing down.

[CalifDan]

I printed the same part again, twice. I also printed some other parts and no recurrence. The shift was an even .1 inches. Just that once....and I did not have my finger in it. That is my story and I'm sticking to it.

CalifDan

[CalifDan]

I am resurrecting this thread. My respite from the filament jambs was short lived. I made some adjustments, but I think that I now know what the problem is.

Let's start by saying that I am changing from 1.75mm filament to 3mm. This was suggested by Colin as likely to be more reliable. I realized in ordering the necessary parts that it only requires a change of the hot end and new filament. I figured that the feed bolt and even the whole extruder mount might need to change, but not so.

Which means that the 1.75 filament is traveling between the bolt and the hot end entrance in a space designed for much larger filament. This is a space which allows flexing of the filament and that is exactly where my jambs occur. I think that the feed bolt, pushing on the filament against the back pressure of the hot end finally allows enough bend to cause the filament to kink. There may be some heat associated help with a longer print (where I usually get the jamb). That said, it makes sense that the thinner filament would need more, not less, support as it travels between the feed bolt and the extruder.

It the 3mm provides me a significant improvement in reliability, I am going to look into a modification of the extruder printed section to accommodate 1.75mm filament and test same. That might take awhile, but I will report back.

Any thoughts appreciated.

[printbus]

This just isn't making sense. Going back through the thread, you have a hex hot end with fan and shroud. The fan is wired to constant 12V so that it is on all the time, and not wired to the RAMPS D9 fan output, right? Is the fan one that MakerFarm provided? Does it seem to move air pretty good and make at least some noise (ie, does it work)? When you're printing, how warm does the aluminum plate under the extruder feel? Does the hobbed bolt chew into the filament when it stops extruding?

Just how "soft" is the filament cold? Does it bend a lot easier than the other PLA you have? We never did understand how you were getting those knots or folds in the filament above the extruder. Seems to me the filament is unusually flexible or you have some significant temperature issues going on.

[CalifDan]

Printbus,

The fan is wired correctly and runs constant. I do not notice any temperature issues up high, but frankly, the 1.75 is off the machine now and I can't test it. I used 1.75 filament from Makerfarm and Ultimachine. There were three rolls involved and all jammed.

I have installed the 3.0 filament hex head with .4 orifice. No jamming problems, however I am getting some pretty awful looking prints. Photo attached.

3mm_Print_Issue.jpg

I thought that this photo might show the crappy perimeters from over-extrusion, but it appears that may not be the case. I set up a hollow cube to print for testing and I varied the feed rate and temperature until I got something that looked much better.

I came up with a feed rate at about 118% and a temperature of 198. This is for PLA. This is significantly off Colin's proposed settings. In fact, I forwarded the g-code to him and using an identical setup, his print looks fine. He wanted me to season the hot end with Canola oil. I did and that really made no difference until I varied the feed rate and temperature. I just want to get reliable and reasonably good prints.

I have another part printing right now. I changed the extruder multiplier to 1.18 and the temp to 198. We shall see how it turns out. Meanwhile, I am curious if extrusion multipliers should be that extreme?

OK, I need to edit this. It turns out that I loaded Slicer with a .5 mm head rather than a .4. I am not sure where in my tests that occurred. Anyway, now trying a print at 1.05 multiplier and lowered temps to 186. I was getting too much stringing at 196. Also, trying a Cura slice as Slicer (even though I selected avoid perimeters) was depositing a problematic amount of ooze in one particular spot.

I also seem to be unable to get retract to work in Slicer or Cura. I am not sure what I am missing as I had it working when I was using 1.75 filament.

[clough42]

What retract rate and length are you using?

[CalifDan]

4mm retract, 10mm sec rate

[clough42]

That sounds good. I haven't had much trouble with stringing with similar settings. I wonder how much difference there is from one brand and color of PLA to another.