FIlament jam/grind at height.

[midnitmike]

Good morning... So im working with a client and every time i get to a certain (+ or - an inch) on this part it fails. It stops extruding, jams and grinds on the filament.
I dont know if it stops feeding because it buckled or if buckled because it stopped feeding.
here is a pic of the filament


Ive tried to loosen the extruder screws to put less pressure on the filament. ive also tried to tighten it to put more pressure on it.
its failed 3 times... these prints are 25 hours each... it fails about 15-18 hours each time.

.2mm layers
75mm/s
215c temps (at high speeds i need the temps up there, and the bond is good and strong)


Would love to get a discussion going on why this is happening and how to perhaps remedy it.
thanks

I'd like to see a picture of the part you're printing, especially around the area where the filament jammed and at the bed directly below. My reasoning is that your jam might be caused by the part warping up off the bed causing the slight gap between the extruder and part to close up. I've had this happen innumerable times on large prints and the only cure I've found is to ensure that my part stays perfectly bonded to the bed. Tell tale signs of this happening would be any movement of the part (warpage) , as well as grooves in the upper layers caused by the extruder dragging through the plastic.

As far as remedies go it depends on the part. In some cases I've had success simply by using more hairspray for better adhesion, or raising the bed temp to compensate for the heat loss due to the increased surface area. Recently I've gone to larger and larger brim settings to help hold my parts in place, or even adding more layers to the brim to make them stronger. As always a perfectly calibrated machine and a clean nozzle are required before setting up a large print job.

Mike

[dunginhawk]

I'd like to see a picture of the part you're printing, especially around the area where the filament jammed and at the bed directly below. My reasoning is that your jam might be caused by the part warping up off the bed causing the slight gap between the extruder and part to close up. I've had this happen innumerable times on large prints and the only cure I've found is to ensure that my part stays perfectly bonded to the bed. Tell tale signs of this happening would be any movement of the part (warpage) , as well as grooves in the upper layers caused by the extruder dragging through the plastic.

As far as remedies go it depends on the part. In some cases I've had success simply by using more hairspray for better adhesion, or raising the bed temp to compensate for the heat loss due to the increased surface area. Recently I've gone to larger and larger brim settings to help hold my parts in place, or even adding more layers to the brim to make them stronger. As always a perfectly calibrated machine and a clean nozzle are required before setting up a large print job.

Mike

So its basically about 7 inches across at the bottom and it tapers at the top, its a cone essentially. it fails about 6 inches up. its failed at lik4 -6inches up.
Well, it just failed on a short print too, so something is going on. It is NOT the bed.. I can guarantee that.. the PEI surface im using is VERY good and i have to peel these things up with a putty knife. they are wicked sticky

I may clean out the nozzle and run some cleaning filament through it, or heat it up to 270 and just flush some cleaning filament through it. other than a partially clogged nozzle, i dont know what else it could be at this point. Unless this filament is bad (2 spools in a row) perhaps its diamter is bad but i dont think that is as likely.

[midnitmike]

So its basically about 7 inches across at the bottom and it tapers at the top, its a cone essentially. it fails about 6 inches up. its failed at lik4 -6inches up.
Well, it just failed on a short print too, so something is going on. It is NOT the bed.. I can guarantee that.. the PEI surface im using is VERY good and i have to peel these things up with a putty knife. they are wicked sticky

I may clean out the nozzle and run some cleaning filament through it, or heat it up to 270 and just flush some cleaning filament through it. other than a partially clogged nozzle, i dont know what else it could be at this point. Unless this filament is bad (2 spools in a row) perhaps its diamter is bad but i dont think that is as likely.

I can't tell you how many times I ran into this problem in the first two months of printing...hundreds would be my guess. In the end I traced my fundimental problem down to a dirty nozzle. That doesn't mean I didn't address other issues along the way like the hob-bolt and extruder block being designed for 3mm and not 1.75. I redesigned both, printed a new extruder block with the right size hole and made a new hob-bolt to fit the smaller filament. One day while I was cleaning the extruder I found a small hang-up between the nozzle and filament guide right where they meet in the heater block, chamfering the leading edge of the nozzle fixed that one.

But like I said I eventually tracked down the real culprit and that was a few very small bits of PLA that I had used on my initial test run before switching to ABS. The higher heats needed for ABS carmelized (for lack of a better word) that PLA against the inside of the nozzle causing the majority of my air prints. It took a lot of soaking and cleaning to remove those little bits of burnt plastic, but I was rewarded with weeks and months of flawless printing afterwards. Now I periodically test my nozzle by pushing a piece of filament through by hand...anything other then a smooth easy extrusion means it's time to clean. Oh and I'll never run PLA and ABS through the same nozzle again!

Mike