Pellets from feeder are stalling the auger.

I received your email as well, but I'll reply here instead of attempting to keep multiple parallel conversations going.

1.) Did you first extrude the ABS as recommended? How did that go?
2.) 190C is too hot for PLA, 150-160C is more reasonable.
3.) What PLA are you using?
4.) How have you dried it?
5.) Have you tried increasing the current limit to 1.8A?
6.) Have you checked that there is 1-2mm of axial play at the hex socket? In other words are you certain there is no thrust load on the gearbox?

The auger photo is normal, it should slice through any pellets that get wedged in there, if everything else is OK.

1.) It is OK if the pellets are not clean, the inside of the barrel is also not clean during the initial purging. It is not complicated switching from high to low temperature material, just run until empty and then run some low temperature material at high temperature, and perhaps remove the nozzle and pull out any high temperature material with needle nose pliers. I'm not saying it is necessary to do this in your case, but sometimes it is a good "check" to ensure that things are operating normally using a well understood polymer.
2.) Increasing the temperature lengthens the melt zone, the amount of viscous polymer the motor has to churn.
3.) This is OK, there are several examples of successful 4043D extrusion on the forum.
4.) Good
5.) The gear motor can handle more than 1.6A. Above 2A there is risk of permanently deforming the barrel. I would try 1.8A, maybe even 2A. In one case a user needed close to 3A with PLA. I suspect his stall protection board was mis-calibrated or the motor was operating inefficiently for some reason, but am not sure.

Those pellets in the video are ABS, not PLA. They are a different shape and behave differently.

Is the thermocouple installed in the hole in the side of the nozzle? Sometimes people incorrectly install it under the heater.

I tried the lower temperatures – but this makes the problem even worse.
Also removed the melt filter completely, but with no change (using 1.75 nozzle).
I Checked again, that all the thrust is going through the ball bearing, not the motor.

Changing the current to 2A will make the motor not completely stalling, but once in 5-10 seconds it is slowing very down to nearly standstill but make it to rotate again, what result in very uneven extrusion rates…
I also checked that the “slow down points” are not always on the same rotation spot, what maybe could be a bend auger.

I still think, the problem is the feeding zone, because when the hopper is empty, the Auger speed and extrusion is perfect. Maybe someone could post a in detail photo of his feeding zone?
Any further ideas?

Just thinking out loud...

Have you tried blocking off the area that has the pellets pinching against the body of the extruder and the screw. A bit of Teflon tape or K-tape could be enough to keep the pellets loaded in the screw from coming out, and pellets being fed from the top from falling into that area.

I have had great success with Teflon tape to hold my hopper in place. A couple of wraps and once the hopper is clamped down it won't go anywhere. Plus the Teflon tape won't get hot enough to melt (that's how I hold my temp sensor in place on the head)...

...Or modify the current hopper and print one with a closer tolerance 'inside' the body of the shaft so that they won't get pinched.

Just throwing some spaghetti at the wall.

Question for you Elmoret.
I have read, you changed the auger in the newer machines to have less gap.

What was the diameter before?
What is now the diameter?

Theory:
PLA get slushy (hope the right word) already at about 90-100°C and may glue the gap between auger and pipe. Possible that a bigger gap here might be helpful?

We have been having the same issue using 3D850 PLA pellets.  We were able to produce ABS adequately.  Still learning, but finally got a short run within tolerance.  Switched over to PLA and stall after stall.  Discovered the filament cooling fan was cooling the nozzle down too much which caused it to get stall more often.  Once we adjusted the fan to cool the filament well after it came out, the temperature remained much more consistent, but we still got the inconsistent speed.  Our amperage was fluctuating between 1.6 - 2.4A.  At 2.5ish it would stall.  You would see the light on the stall controller light up. We also noticed that when it first stalled it torqued our pipe moving the opening over a to one side a bit, and it made it so tight, i have not been able to back it off and make it vertical again.  We are unsure how to proceed at this point for producing PLA.  We plan to test out ABS again to ensure we can still produce that after the stall/torque issue.

Sorry my description was probably bad.  The barrel twisted (more threads used) but about 15 degrees.  So i think its still well within tolerance but we have not run it since it happened.  I started taking it apart to clean up what was still in there.  The Amps never stayed that high, just when it was getting ready to stall.  I'll need to revisit how to reprogram that.  We are using it as it came out of the box.  I didn't see a section telling me I needed to do otherwise, but that is very likely my fault. 

We ran the PLA at ABS temps for the first 2 oz of PLA material to help "clean out" the ABS and color we added to it.  And you are very correct, the ABS temps were way too hot for the PLA once the ABS was cleared out.  We backed it down about 45 degrees to a much more reasonable temp (225 -> 180).  After our initial complications with the fan, I think I could easily bring that done more since the nozzle is staying at temp better.  I'll take apart the machine to make sure everything is properly aligned again and properly setup the stall protection board and see how it goes.  If that doesn't work, I'll reach out about the other version of the auger.  I believe we can get this one working, just need to get it dialed in. 

The 3D850 was attractive to me as it was a newer blend PLA that had a lot of advantages.

http://www.natureworksllc.com/~/media/T … .pdf?la=en

Hi Raven,

Out of curiosity:
"- use a laser micrometer and a puller to get it to diameter."
Is there a device I can buy to do the same, and how were you able to set it up? I am trying to figure out if I can somehow automate the consistency of the filament diameter.

Thanks!