Need help extruder jamming

I need some help, my extruder keeps jamming. I have a mini kossel, that can probably be leveled better but it should be close enough. Prints start fine but eventually fail due to the extruder jamming after layer 10(sometime it gets all the way to layer 100), very frustrating.

Things I have tried:
Different filament, some known good some not
Bought a new extruder
Different nozzles
Adjusting the tension on the extruder
Cutting the Bowden tube and stretching the opening
Several fans on the hotend
Moving it inside from the garage due to colder weather, though its in the 60s lately

Nothing seems to help. Anybody have any suggestions?

I will be swapping out power supplies a little later as a last resort, outside of that I am at a loss.

Also, if anybody has a link on how to use repetier's delta leveling stuff without a probe, or can explain it that would be greatly appreciated.

I really don't understand because it was working awesome for a few weeks and now its just jams every time, not one good print.

is it jamming in the extruder, or the hot end? Do you have a fan cooling the heatsink finned part of the hot end? The top part, called the cold end, needs to be cooled so the plastic only melts in the aluminum block at the bottom. If heat is climbing up into the finned part you can get jams like you describe. You said you have several fans, but not what they cool. What material are you printing? What temp? PLA will jam if it gets too hot. For me PLA will jam if I look at it too long Have you tried a cold pull to clean out the nozzel? Overheated PLA won't melt again correctly and can jam things up, too. You need a cooling fan that blows on the part right at the nozzel tip for PLA. ABS can be printed without the lower fan most of the time, unless the part is complicated with lots of bridges, etc. Hmm, how do you clear a jam?

Quote
voi9viper
is it jamming in the extruder, or the hot end? Do you have a fan cooling the heatsink finned part of the hot end? The top part, called the cold end, needs to be cooled so the plastic only melts in the aluminum block at the bottom. If heat is climbing up into the finned part you can get jams like you describe. You said you have several fans, but not what they cool. What material are you printing? What temp? PLA will jam if it gets too hot. For me PLA will jam if I look at it too long Have you tried a cold pull to clean out the nozzel? Overheated PLA won't melt again correctly and can jam things up, too. You need a cooling fan that blows on the part right at the nozzel tip for PLA. ABS can be printed without the lower fan most of the time, unless the part is complicated with lots of bridges, etc. Hmm, how do you clear a jam?

Clearing ABS jam's is easy just dismantle the hot end and soak the affected items in acetone to dissolve the ABS left behind. this just takes a little time (hours/days rather than minutes mind)

If you are printing PLA, check two things (I had the same Problem)
1.) Check if you did buy your Filament at a plastic-welding-company. For Plastic Welding, Filament needs to be much less clean than for 3D-Printing... (i had small metal parts in it...)
1.) Check your PLA printing Temp... (Specification-Sheet) In earlier days PLA was always printed arround 185°C; Nowadays I'm only able to buy PLA which is ment to be printed at about 210-230°C

You need to provide more information, in particular:

1) Picture of entire printer with the extruder visible
2) Closeup picture of the hotend
3) Information about your temperature. If you are using Repetier host you can look at the upper left and select "temperature curve" and then screenshot that. Or just post the numbers here.
4) Information about type of plastic (PLA or ABS)
5) After a jam, can you disconnect the bowden and extrude by hand? Aka, extract what is in the bowden, then disconnect it and use a different piece of plastic and see if you can push the thru?

x) (optional) Take your hot-end completely apart and take a photo of all the parts

Few general tips:

a) Stop replacing parts at random. At worst you just introduce a new problem into the mix
b) If you are the type of person who gets frustrated with your printer, then be careful at this stage. The Delta printers are very fragile if you start using force on them. When handling the extruder and affector (the part that the hotend is mounted on) be very careful only to apply forces on it, in the directions that it is designed to absorb them. If you feel that it is getting too much then take a break. If you don't have a second printer for replacement parts then it can set you back weeks if you break something.
c) The Kossel is a proven design. There is no reason why it as default should not be able to print just fine. Either a part is bad or you are doing something wrong.

I kept having problems with the filament jamming in the heat break of my E3D v6 hotend. It was really frustrating, and it happened over and over again, and I had to disassemble the hot end every time. I had a working fan and everything. The solution, as suggested in several forums online, was to add thermal paste on the heat break top thread (the part between it and the heat sink). Just keep in mind that the thermal paste needs to be the kind that tolerates high temperatures. I first used Arctic Silver, the kind that is commonly used to cool CPUs. That worked initially, but the thermal paste melted and dripped down as a thick brown liquid all over my prints, yikes. I now use a brand called Halnziye, which works flawlessly.

Thanks for all the responses, to broadly respond to everyone:

I will try to get pics up soon, my camera is broken on my phone
Using PLA, temps I have tried range between 190-220, jams always happen on every print with layers > 10ish
The filament is jamming in the hotend, sometimes that forces the extruder to get jammed too, but most of the time when it jams the extruder just starts slipping because the filament can no longer be pushed through the nozzle
The filament cannot be pushed through by hand, the heat must be turned up to 240ish and then I can push the filament in a little and pull it out backwards, after pulling this piece out I can then push some through manually without issue

@LarsK I have no plans of physically abusing my delta , just want to get it working

I don't think I am replacing parts at random, I tried adjusting things when the jams started happening, and when the adjustments did not work I replaced the hotend thinking maybe the thermistor was not reading properly and/or the hotend was a cheap knock off that was not machined well. THe brand new hotend came in and jammed on the first print. My thinking is that I will adjust the current to the extruder on the polulu pot, maybe its too high? Or the power supply isn't providing enough juice to keep things hot.

I will try to get the temp graphs and pictures soon, but last time I checked the temp didn't fluctuate more than +/- 1 degree.

@tomasf The thermal paste sounds like a good idea, and I thought about vegetable oil on the filament too but haven't tried either yet. I tried 3 different fans, and honestly when it was working good I had the fan wired backwards so that it was pulling air from the hotend rather than pushing air onto it. Maybe I should try turning the fan around again.

@Sir_Death I bought the filament from micro center, I know there is mixed reviews on it, but I have a few rolls that are known good in other printers and I have only had trouble with one roll out of about 50 from them(and in that case it was only because for about a quarter of the roll the diameter was uneven)). AFAIK their filament is specifically made for 3d printers and not plastic welding, and IIRC the suggested temp range on it is 190-210. I don't think my problem is filament, but I could be wrong, assuming I am not wrong about the filament I would recommend buying filament from microcenter for ok quality and a great price(1kg for 14.99). I have definitely used better but for their price you can't beat it.

Knock on wood seems turning the pot down has helped, but print isn't done yet so we shall see.

I had a TAZ 5 and never got PLA to print right. ABS was so easy I stuck with it. Now I'm trying it again with my new Kossel. I hope it works this time. I think the upper end cooling is not perfect, and when the extrusion rate slows plastic melts in the cold end , and jams. I have no idea how to fix that.

Quote
voi9viper
I had a TAZ 5 and never got PLA to print right. ABS was so easy I stuck with it. Now I'm trying it again with my new Kossel. I hope it works this time. I think the upper end cooling is not perfect, and when the extrusion rate slows plastic melts in the cold end , and jams. I have no idea how to fix that.

Most hot ends need an always-on fan blowing cool air over the heatsink fins to prevent PLA melting in the cold end. Putting thermal paste between the heat break threads and the heatsink helps too.

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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].

So I think it was a combination of of the driver current being too high and too many steps per mm on the extrude. Though I have no idea how this would have changed from the weeks of good printing it did?

Either way once I turned down the pot on the extruder driver the jams were gone, it did click alot so I turned down the steps per mm to 90.5 from 106.5 and things seem a lot better now. I have another extruder that looks like the same exact model and I always run it at 90.5, but the firmware recommendations I found for this printer kit suggested 106.5.

Anyway, thanks for the quick responses, hopefully somebody else stumbles across this and gets some ideas of things to look at when their extruder is jamming up frequently.

Quote
miked63017
So I think it was a combination of of the driver current being too high and too many steps per mm on the extrude. Though I have no idea how this would have changed from the weeks of good printing it did?

Either way once I turned down the pot on the extruder driver the jams were gone, it did click alot so I turned down the steps per mm to 90.5 from 106.5 and things seem a lot better now. I have another extruder that looks like the same exact model and I always run it at 90.5, but the firmware recommendations I found for this printer kit suggested 106.5.

Anyway, thanks for the quick responses, hopefully somebody else stumbles across this and gets some ideas of things to look at when their extruder is jamming up frequently.

The trick is to have the motor current high enough to push the filament, but low enough so that if the nozzle becomes temporarily obstructed because of over-extrusion, the motor skips steps instead of grinding through the filament.

Regarding extruder steps/mm, you should calibrate this such then when you ask it to feed 100mm of filament, it feeds exactly 100mm. This is easy to do, just remove the Bowden tube from either the hot end or the extruder, make a mark on the filament where it exits, then you can extrude 100mm of filament and measure how far the mark has moved. After you have calibrated the extruder, you can adjust the extrusion factor to suit a particular filament either in the slicer settings, or using the extrusion factor adjustment in your control panel or web interface, or using the M221 command from Pronterface etc.

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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].

Quote
miked63017
So I think it was a combination of of the driver current being too high and too many steps per mm on the extrude. Though I have no idea how this would have changed from the weeks of good printing it did?

Either way once I turned down the pot on the extruder driver the jams were gone, it did click alot so I turned down the steps per mm to 90.5 from 106.5 and things seem a lot better now. I have another extruder that looks like the same exact model and I always run it at 90.5, but the firmware recommendations I found for this printer kit suggested 106.5.

Anyway, thanks for the quick responses, hopefully somebody else stumbles across this and gets some ideas of things to look at when their extruder is jamming up frequently.

I think it is important to, even as harsh as it sounds, make it clear that this is not a solution and if the problem is truly solved, then it is most likely something else. The above approach was not recommended by anybody in this thread.

I note the following:

1) If you cannot push the filament through with your hand, then it is a blocking in the hotend. Not a problem at the extruder. No matter the condition of your extruder, it is possible to have a hotend that will never be blocked no matter how long it is left on, etc.
2) The steps pr mm should never be modified. It needs to reflect how much filament the extruder puts forward and it needs to be very exact to get good prints.

With the very limited information available I give the following diagnostic to this problem:

The hotend has problems with heat-creap into the heat-barrier (the thin stainless steel thing). This softens the filament and it jams. This is the reason why, now that you are putting a constant flow through, it never gets time to settle in and get stuck. If you leave the hotend at a high temperature for some 30 min and try to extrude, then it will probably be jammed again.

If this is true, then the solution is to put thermal paste on the thread between heatbarrier and cooling block (the upper part) and teflon tape between the heating block and the heatbreak (the lower part). The teflon reduces heattransfer into the heatbreak and the heat-paste helps to move the heat from the heatbreak into the cool aluminium. Also proper fans with strong cooling on the cooling block is required.

Alternative the hotend has problems with an open gap between the bronze nozzle and the heat-break (inside the thread on the heat-block, the two parts are not meeting up perfect) - The solution to that, is verify that it is screwed all the way in and/or use emerald paper to create a perfect blank contact surface between the two matting surfaces. If any of the parts threads are "scewed" a little then it will almost for sure never come to work perfect.

I've had extruder failures (mainly with PLA) from:
- breakdown of PTFE linings within the hot end
- too much retraction pulling hot filament too far up the heat break
-filament grinding through at the drive gear/hobbed bolt sometimes from too tight (low) first, layers meaning the filament flow is restricted at the nozzle.
-insufficient hot end temperature for a given filament
-excessive hot end temperature for a given filament
-intermittent heat sink fan or failed fan

I think that whilst really good quality hot ends with beautifully machined and polished filament paths certainly help, it is clear that if we are going to have consistent printing time after time, we need filament to be quality controlled to some sort of standard. It's a bit like using compatible ink cartridges in your 2d printer, sometimes they work, sometimes they break it completely. The problem with 3d printing is there is no "genuine" filament for a reprap, some are better, some worse but no standard exists. Whilst this would add to the cost of 3d printing - how much is your time worth, trying to find and fix the problem?

It's certainly dawning on me that its not the cost of the printers themselves, the filament, the electricity or the spare parts that is the real cost of reprappng it is the value of your time. Thankfully I enjoy tinkering, but if I were doing 3d printing commercially I'd have to think about buying a Stratasys.