Going out of my mind with Jams

Hello all!

So I am relatively new to the 3d printing world, and so naturally, I gots some problems... :p

I just finished assembly of my new makerfarm pegasus 12 a few days ago and have finally started working with it and figuring out how to get the bed leveled and how different parts of the system works. I have been able to make a few prints without problems, but recently when I try some larger printers (about 6 hrs) the filament jams somewhere around the halfway mark (give or take a few hours). Naturally this is annoying as hell, and I have lost about 4 attempts to this.

My attempted fixes so far are:
re-leveled the bed. re adjusted the endstops (if anything it may be a bit too high now just to keep the end from mashing)
Rebuild the extruder (had to clean the hobbed gear of all the nice shavings)
tightened the springs holding the filament against the hobbed gear
rebuild and checked the hot end

I am using E6b hot ends with a .35 nossel. The filament that I am using is Esun 1.75mm green abs filament. The temps I am running are 230c for the hot end and 110c for the bed.

When the jam happens, the stepper keeps on going and eats a hole into the side of the filament, this naturally means every time I get to take apart the extruder to clean the hobbed gear before I get to try again. However, if I push on the filament slightly it begins to feed properly again. It does seem to feed straight out of the hot end and is not deflected by anything on the end of the hot end.

Any ideas I would greatly appreciate,
Thanks!

Check your fans and check your filament feed.

So far as I can tell, the filament is feeding as smooth as I can make it. Also, cooling fans for the hot zone radiator seem to be working as best I can tell.

recommended temp for that filament is 220-260, try increasing your print temp to 240,

Out of curiosity, does this happen after a series of retraction moves? I've run into this where too many retractions on 1 area of the filament will cause it not to feed anymore because its cut so many teeth marks into one area that it can't grab anything to feed. In my case, the tension on the filament was way too high and the retraction distance was too long. Reducing the tension to the point it will push the filament but not deform it solved my problems that was similar to what you've described.

As best I can tell the timing is random. It's just as likely to fail on a long straight as it is to fail when doing lots of small moves

When you clean out the filament after a jam like this, is the filament flat with teeth or is it still round with the tiny teeth indentations? If its flat, it could be binding in the PTFE tube being too wide to slide through.

It's common for the nozzle to be temporarily obstructed, for example by curl up in the print or the nozzle being too low. When this happens, you want the extruder stepper motor to skip steps. Otherwise it will create a gouge in the filament and there will be no traction when the obstruction is removed, which is what you observe. So reduce your extruder motor current.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

And/or tighten your idler bearing.

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Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions

Also you might just be trying to print too fast. A 0.35 nozzle is pretty small and if you try to print fast the back-pressure could be enough to cause the extruder to chew through the filament like that. ABS is a bit softer than PLA so more likely to get chewed. A perfectly set up extruder would skip steps before it chewed the filament so you could lower current to the extruder stepper a bit to limit the torque to something the filament can take. You could try lowering your print layer height (thus extruding less filament per layer), or just slowing down the print. Also maybe try some experimentation to determine the fastest reliable extrusion and set that in firmware as your max extrusion speed.

You could also check for high friction stages in the filament feed system. Pull the hot end off and just run filament through by hand to get a feel for how much no-load friction there is in the extruder.

Another thing to check is for potential filament feed snags. If the filament gets tangled or snagged it can pull on the extruder and cause the filament to stall and get chewed.

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bryanandaimee
Also you might just be trying to print too fast. A 0.35 nozzle is pretty small and if you try to print fast the back-pressure could be enough to cause the extruder to chew through the filament like that. ABS is a bit softer than PLA so more likely to get chewed. A perfectly set up extruder would skip steps before it chewed the filament so you could lower current to the extruder stepper a bit to limit the torque to something the filament can take. You could try lowering your print layer height (thus extruding less filament per layer), or just slowing down the print. Also maybe try some experimentation to determine the fastest reliable extrusion and set that in firmware as your max extrusion speed.

You could also check for high friction stages in the filament feed system. Pull the hot end off and just run filament through by hand to get a feel for how much no-load friction there is in the extruder.

Another thing to check is for potential filament feed snags. If the filament gets tangled or snagged it can pull on the extruder and cause the filament to stall and get chewed.

Im using layer height of .2mm and first layer of .35mm seem too fast?

Edited 1 time(s). Last edit at 12/09/2016 07:46PM by cobrasvt1999.

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cobrasvt1999

Im using layer height of .2mm and first layer of .35mm seem too fast?

Try printing at about 25 mm/s to start with, and if that doesn't jam, then increase the speed until it starts jamming. Then you know the upper limit of your system. You can also increase the temperature to help increase the upper speed limit.


On one of my printers I hit the limit at 0.6mm extrusion width, 0.3mm layer heights, and around 60 mm/s. The nozzle just can't melt any more plastic than that.
That speed is very dependant on the setup of your hotend though.

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nebbian

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cobrasvt1999

Im using layer height of .2mm and first layer of .35mm seem too fast?

Try printing at about 25 mm/s to start with, and if that doesn't jam, then increase the speed until it starts jamming. Then you know the upper limit of your system. You can also increase the temperature to help increase the upper speed limit.


On one of my printers I hit the limit at 0.6mm extrusion width, 0.3mm layer heights, and around 60 mm/s. The nozzle just can't melt any more plastic than that.
That speed is very dependant on the setup of your hotend though.

Just ran a print at half speed. no joy, it still jams about 30 min into the print...

Hmm well it's something else then.

Are you sure that your hotend fan is turning the correct way? Is your extruder motor getting quite hot?

In my experience, when jamming is time-based, it's a heating/cooling issue. It takes a while for heat to spread through the hot-end, and then filament softens where it shouldn't be soft and a jam happens. One way to check is to print until it jams, then immediately start the same print again. If it doesn't jam until 30 minutes later, its something to do with motion and position. If it jams soon afterwards, it's heating/cooling.

230C seems high for ABS... 210C would be what I'd use for ABS. Whilst eSun might be recommend temps up to 260, it doesn't mean that your hot-end can handle that. So I'd try running at a *lower* temperature (say 220C since that's the bottom of what you say eSun recommends) to see if that changes anything. Also check your cooling fan is running all the time, and clipped to the bottom of the cooling fins.

I run ONLY ABS and I run most of mine around 240c FYI...

So im going to pick up some PLA today and see if it jams for me...

Do you have some information about this "E6b" hotend ? (nothing shows up under that name on Google)
What kind of extruder are you using ?

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kr_
Do you have some information about this "E6b" hotend ? (nothing shows up under that name on Google)
What kind of extruder are you using ?

My bad. I must have been tired and slipped with another item in my head (aviation). What I meant to say was I have the E3D-V6 hot ends

I'm using an E3D-V6 clone. There are a few things to do to reduce friction that would be true as well for the original one :
- Use little retractation, 1 to 3 mm should be fine. The soft hot plastic expends up to the same diameter than the heat break's inside. Pulling the filament back to the cold side of the heatbreak generates high friction.
- Push a PTFE tube as far as possible through the heatsink, into the top side of the heatbreak to guide the pastic. If some melted plastic can come up and stick into any gap it can generate high friction.
- Make sure there's no gap between the nozzle and the heatbreak. To do that, heat up, untighten the nozzle, tighten the heatbreak into the heater block and tighten the nozzle against the heatbreak (there should be a little gap remaining between the nozzle and the heater block when tight, so you're sure it's against the heatbreak).
- Use dust free plastic. I clip a piece of fabric around the filament before the extruder, to wipe it off.
- Adjust your extruder's steps/mm to send the right amount of plastic through it. You can verify it by printing a single layer width wall and measure its thickness. Sending too much plastic through the extruder generates high pressure (and thicker walls).
- Always have your extruder's fan on. It has to be connected to the 12V power source directly.

For the clone E6D, check that the little PTFE tube in the heatbreak isn't damaged and comes right to the edge when pushed all the way in.
There are a few other things unrelated to your problem I had to do to make it work properly :
- Make the nozzle watertight with Teflon tape (PTFE). There was burned plastic leaking out otherwise.
- Insulate the heated block with self adhesive silicone tape. The radiating heat can mess up small prints...

You might want to use a better extruder that can push harder. The drive gear shouldn't slip and chew the plastic like you described. A good drive gear, like the MK8, can push the filament without slipping until the stepper misses steps.

OK, so you are using a direct drive and a V6.

What is the retraction you are using? Should be around 1 mm, maybe 2.
What is the fan on the hot end doing? Is it full speed? Are you sure?
Is it blowing or sucking?
Have you installed the hot end as per E3D instructions? Heat up the heat block before tightening the nozzle, etc?

How did the PLA work?
Lykle