EZstruder "backslip" problem?

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DITAmech01
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EZstruder "backslip" problem?

Post by DITAmech01 »

Rostock Max v2. E3D hot end, EZstruder, Repetier 92.2 firmware, printing PLA at 210 deg C.

Printer was working well the last 6 weeks, until I started a new roll of PLA - brand new, so that shouldn't be the issue.

I don't know what to call this other than "backslip", so that's what I'll call it. EZStruder appears to slip backwards while feeding filament, appears to cause under-extruded filament. If I manually "help" by pushing filament through the EZstruder, seems to work better.

Clip: https://youtu.be/RmhgmmPms5w

Already removed the extruder gear and cleaned it up. Checked hot end for clogs - all OK. Is this an under-temp problem? What's going on here?

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Re: EZstruder "backslip" problem?

Post by geneb »

It's called "skipping". It happens when the filament ins't able to flow through the hot end at the rate the extruder is driving it. The EZR is going to try to push the filament and it builds up compression in the bowden system until enough potential energy is built up that the stepper can no longer push filament - the "spring" (filament/bowden) energy is released and pushes the stepper in reverse for a short distance.

Up your printing temp a bit, or slow the print speed.

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DITAmech01
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Re: EZstruder "backslip" problem?

Post by DITAmech01 »

Thanks for the suggestions. Tried both and seemed to eliminate the skipping, but didn't change the under-extrusion. Thought I found the answer in the discussions on chamfering the end of the Bowden tube. Looked promising, made a couple of calibration pyramids that almost came out OK, but ultimately the same results. Not sure what to try next - my budget for replacing parts, and my patience for further tinkering, have worn thin.

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Re: EZstruder "backslip" problem?

Post by geneb »

You made no mention of under-extrusion in the original post.

I'd be curious to see what the theory is behind chamfering the bowden tube. It kinda sounds like the 3D printer equivalent of wearing copper to fight arthritis. (looks nice, is complete bunk. :D )

If you've already calibrated your extruder, they'll you'll need to tweak the material flow for the new filament. I seriously doubt there's anything wrong with the printer.

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Mac The Knife
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Re: EZstruder "backslip" problem?

Post by Mac The Knife »

This all started with a "new" spool of filament? Under extruding, and skipping,,,, Have you compared the diameter of the filament with the old spool??

If the only thing changed was the spool, and the machine checks out, I'd be looking at that spool.
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DITAmech01
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Re: EZstruder "backslip" problem?

Post by DITAmech01 »

Here's the Bowden tube article: http://forum.seemecnc.com/viewtopic.php?f=37&t=11909&p=104777&hilit=chamfer+bowden+tube#p104777. It sounded like my problem in that I also got a clog a couple of days ago.

Machine seems to work OK otherwise. Manual extrusion from MC controls works fine. Temp checked with thermocouple and all is well.

Will double-check the new filament. When the printer was up and running well (thru most of January), I was using a brand new roll of PLA purchased in November. The problem started with the next brand new roll of filament, purchased in January, both from MatterHackers.

To verify: "Under-extrusion" = lines of printed filament becoming thinner, tiny blobs appearing in those ultra-thin lines, happens without warning, sometimes returns to normal operation, sometimes print fails altogether. Correct?

DITAmech01
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Re: EZstruder "backslip" problem?

Post by DITAmech01 »

:oops:

Filament was waaaaay under spec at 1.47 mm. Recalibrating appears to be the fix. I could've sworn I checked beforehand...

UPDATE: After a test pyramid, made one successful 2-hour print. Next try failed: first layer skirt OK, first layer perimeters OK, first several inside lines OK, then no extrusion at all. Now checking.

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Re: EZstruder "backslip" problem?

Post by geneb »

That's bad enough that I'd contact MatterHackers and see if they'll replace it.

Right before I start using a new spool of material, I'll pull off about 3 meters of it and sample the diameter at at least 10 places and write the average down on the spool's label as well as the date that I opened the packaging. If the spool doesn't have a label on it, make one.

The closer the actual diameter of the material matches what you've told the slicer, the better chance the slicer has of creating gcode that will work well.

3D printers are just like computers - they'll do EXACTLY what you tell them and not ever consider what you MEANT. ;)

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Re: EZstruder "backslip" problem?

Post by DITAmech01 »

After recalibrating for the filament diameter and running a test print, noted that there was melted filament oozing out of the heater block above the nozzle. Shut everything down, disassembled the hot end again, and replaced the no-stick stainless nozzle with a stock 0.4mm brass nozzle.

All is well! Printer now on third day of creating R2-D2 parts.

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Re: EZstruder "backslip" problem?

Post by geneb »

I don't think I've ever seen an E3D v6 leak before. Is there something wrong with the back face of the nozzle?

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Re: EZstruder "backslip" problem?

Post by DITAmech01 »

fullsizeoutput_9ba.jpeg


Doesn't seem to be anything unusual, but I've never looked for this sort of thing before. You can see the melted PLA all over the threads.

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Re: EZstruder "backslip" problem?

Post by geneb »

It may not just not been tightened properly - the E3D v6 requires that you tighten the nozzle at temperature. I don't recall what the temp setting is - it should be listed in the assembly docs for the v6.

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Re: EZstruder "backslip" problem?

Post by adarcher »

The temp use to be around 260 or 270.

You are lucky you got the nozzle out, can you get the heat break out too? I forgot to tighten a nozzle once and had to dremel out the nozzle and heat break from the block.

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Re: EZstruder "backslip" problem?

Post by geneb »

Instead of destroying the heater block next time, try a pair of wrenches. One on the back side of the heater block, another on the nozzle.

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Re: EZstruder "backslip" problem?

Post by DITAmech01 »

I did tighten the nozzle at temp... I think it was around 210 or so. Held the heater block with a wrench while tightening. And that's why I was surprised to see leakage. I actually had no trouble removing the heat break after all had cooled down.

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Re: EZstruder "backslip" problem?

Post by geneb »

That might have been your problem - the tightening temp is listed as 285C. See the last bullet in the "PID Tuning" section here: https://wiki.e3d-online.com/E3D-v6_Assembly

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