After Print Best Practices Help

Hey guys,

I must have missed this in the volumes of data out there on printing.

Basically, once I've printed something on my Prusa I3 Rework, with PLA and Bowden extruder, what's the best practice to prevent clogs?

What I do now is bring the temp down to 80, and then retract 20mm. I've tried other variants, including not doing anything, and every time my hot end gets jammed. Tried different hotend, etc.

Recommendations would be greatly appreciated. Would like to be able to print more then one print in a day!

Thanks,

Chris

After a print I retract 1mm and let it cool down to room temp.
This is with ABS but ive done the same with PLA before.
Retracting 20mm is probably whats screwing you up and making jams.

Edited 1 time(s). Last edit at 01/09/2017 01:13PM by Floyd.

I just let it cool off. If you're having"clogging" problems it may be that your extruder needs some adjustment. Specifically, the pinch roller that pushes the filament against the drive gear must push hard so the drive gear teeth bite deeply. If the thing ever carves a divot into the filament, the pinch roller is not pressing hard enough. The motor should skip instead of the thing chewing into the filament.

Direct drive extruders without great reduction are operating at about the limit of torque. If things get a little sticky in the hot end, many don't have enough torque to push the filament through. Extruders with gear reduction/torque multiplication don't seem to have such problems.

If you're looking for a recommendation, my BulldogXL and e3d v6 combo has experienced exactly one jam in 2+ years of daily printing. Of course, the pair costs as much as many people pay for their entire printer, but sometimes you get what you pay for.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

Trick is to not let it sit at high temps for any length of time, if its at extruding temp and not printing keep purging filament, or cool it down quick with extra fan, and start over.

I found that there was a space between the PTFE and the heatbreak. After letting it cool off a bit, it created a really nice wedge that prevented retraction, and extrusion, i guess because it was too far away from the heat source that it wouldn't melt and allow movement.

There's a picture attached if you're interested. I tried reinserting it and hope its a better fit. The ambient temperature in the room I do printing is about 17.5 degrees, so its a little on the chilly side. But I'm Canadian.

Thanks,

Chris

Well found, and a classic photograph to illustrate the problem. PTFE liners that don't go all the way to the nozzle junction are a real pain and very prone to exactly the problem you had. You really want at least two hotends, one just for pla with the PTFE to the nozzle, and another for everything else without a liner.

Quote
JamesK
Well found, and a classic photograph to illustrate the problem. PTFE liners that don't go all the way to the nozzle junction are a real pain and very prone to exactly the problem you had. You really want at least two hotends, one just for pla with the PTFE to the nozzle, and another for everything else without a liner.

I'd have to disagree with that to a degree. If you buy a cheap clone, sure you might need a PLA only hotend with the PTFE liner, but if you use the geniune E3D V6 hotends you should be able run anything through it. I use the E3D V6 (all metal version, not the lite6) with PLA and don't have any issues with it. The only thing I've ever had to change was the nozzle when I wanted to play with a 0.3 nozzle, and I've run PLA, ABS, Ninjaflex, PETG all through the same hotend. I've also got a roll of wood filament and nylon to monkey with too when I get some time to play with it again.

I guess we agree in parts. I build my own hotends and have well polished all metal ones that will run PLA fine, so, yes I agree it's possible. I also think that for PLA temps and given the amount of trouble people have with PLA, using a PTFE liner is a good way to improve reliability. My hotends are quick-change, so I have PTFE lined ones that I use for 1.75mm PLA, but since I can't fit a liner for 3mm through the heatbreak I use an all metal for 3mm filaments including PLA.

(edited for clarity)

Edited 1 time(s). Last edit at 01/11/2017 02:26PM by JamesK.