Cold-end clogs every print. No changes.

First pic: Clog is always here in the end of the inserted part of the cold-end
Second pic: this is after i clean it, before it clogs again on the next print

I have no idea whats going on but I have a very frustrating problem. As of 2 days ago the cold end part of my extruder keeps clogging. Im using red makerbot filament on my Prusa I3. I have used a needle to clean out the nozzle end and I have used metal rods with heat/drill bit to clean out the cold end threaded part where the clog seems to always be. It's also worth noting I am not printing anything with retraction. Its a simple cube test.

Print test cube
clog half way through
clean thoroughly
Print test cube
clog half way through

200 degrees C
1.75mm pla
red makerbot filament
Prusa I3
First time having this problem after months of printing.

Any tips are appreciated.

Edited 6 time(s). Last edit at 01/23/2016 09:22AM by davidbananas999.

Just with the new filament or with other filament as well?
Sometimes the culprit is just a bad batch of plastic....

This is a newer spool of filament however i printed for a solid 24 hours with it with no problems and now it still persists every print. However i am going to go back a spool just to be sure.



edit: same problem with different spools

Edited 2 time(s). Last edit at 01/22/2016 10:36PM by davidbananas999.

ok so my printer will clog with 3 colors of filament from 3 different brands, 2 of which I have used plenty of times. It doesnt seem to be right away, as if it builds up slowly inside the cold-end. I have tried printing a couple different objects and it seems like the clog happens around the same time of each print too. There is no common link between when it happens on each print though, no retraction or anything etc.

Edited 1 time(s). Last edit at 01/23/2016 08:46AM by davidbananas999.

What's your cold end cooling setup?

Also, you said you are using 1.75mm filament, but I don't see a ptfe liner in your cold end. Is that a 2mm bore specifically for an all metal 1.75mm hotend? With pla you will have better luck with a 4mm bore and a ptfe liner.

Edited 1 time(s). Last edit at 01/23/2016 06:33PM by JamesK.

This is my printer


there is no liner, and i wondered if there should be.

OK, the cooling should be fine (as long as the cold end fan is connected to 12v full time). Yes, I think the ptfe liners help with pla. If your existing heatbreak/throat isn't designed to take a liner you can get a replacement fairly easily on ebay. The only issue is the different lengths - standard is 30mm. Some printers come with a longer 38mm throat. If your existing throat has a 4mm bore then you can just buy some ptfe tube and slide a piece in. Make sure to cut it off square to the bottom of the throat.

unfortunately i snapped my cold-end in half from over tightening it today. All of the cleaning probably weakened it. I have ordered new ones with sleves inside. thanks! 2 day shipping for the win

Hi David,

FWIW, I have 3 Chinese knockoff E3DV6 hot ends, all different. I couldn't get it to work with the one without a PTFE liner. You also need to turn down the retract distance in your slicer to < 1mm.

I did still get jams for a while from other causes -- clearing them sometimes wrecked the liner. So I suggest getting some spare liner from AliExpress or wherever. You can buy 6 feet of tube for the same price as 3 or 4 pre-cut liners.

I broke a heat break too... they're not strong. The proper way to tighten a hot-end is:

1. Heat to operating temp
2. Screw nozzle in all the way
3. Back out the nozzle 1/4 to 1/2 a turn
4. Screw the heat break into the heater block, finger tight
5. Tighten the nozzle against the heater block with a spanner.

This ensures that the nozzle is hard against the heat break, inside the heater block. This is important in preventing jams.

Quote

5. Tighten the nozzle against the heater block with a spanner.

A small addition, use two spanners, one on the heatblock, the other on the nozzle.That way you're not torquing the heat break. You can do 1 through 5 at room temp to make life easier, then heat to working temp and give it one more quick tighten with the spanners. No need to go nuts on the torque as long as the mating surfaces are in good shape, and if they aren't use fine grit sand paper on a flat surface to bring them back to flat and level.

Edited 2 time(s). Last edit at 01/24/2016 07:55AM by JamesK.

thanks for the tips guys. There was a REALLY bad clog that started it all, and the thermistor slipped out of my heat block one day, so maybe when the thermistor slipped, my block shot up to over 360 degrees because the heater wasnt told to shut off, and melted the pfte enough to clog, and when i cleaned it I didnt realize what it was, and didnt know there was supposed to be something in there to begin with. Its a stretch but maybe?

Im going to use all of your installation tips for the new heat break when it comes

Edited 1 time(s). Last edit at 01/24/2016 06:15PM by davidbananas999.

If possible try not to use a teflon liner in cold end.
Instead take some time and polish it properly same for the heat break.
I tried the stuff with liners and as long as you only print PLA they are really great, obove those temps the teflon causes more trouble than good IMHO.
I mostly print in Nylon now, but sometimes also in PLA or some ABS parts and can't really remember when I cleaned out my hotend the last time...

i ordered this extruder along with a couple other cheap parts to fix my original. This new one is a 1.75 all-metal extruder as far as I can tell. I am having trouble finding info about how to properly polish it though. I have searched on google etc. Does anyone have any tips or links? Thanks! Oh It is worth mentioning I cant use that new extruder until I fix my orignal and print the carriage for it.

Easiest was I found is to use something like a piece from a bike spoke, add a drop of glue and wrap fine sandpaper around it.
Insert and let it sping until clogged.
Remove clogger bit of paper and continue until the marks and grooves inside are gone.
Then polish with metal polish, you can use the same clogged sandpaper for this step.
Obviously it makes sense to first use coars sandpaper and then go finer.
With coarse in this matter I mean 400 grid or finer - don't start with anythin like 200 grid or you will have a long polishing session ahead of you.
It is also easier to sand / polish with just the nozzle removed - this way you also remove all bur or possible mismatch drill holes.

Hi,


The jam you have is in your hot end, not your cold end.
First of all, make sure you're hot end fan isn't blowing at the bottom of your heatbreak.
But if i were you I would replace the heatbreak, i had exactly the same problem for days and now i placed a new heatbreak and the problem is fixed.
I think it's of using pliers to much on these things.

Good luck