Jamming of Trinity Labs Metal Magma Hotend

I recently received my Trinity Labs metal magma hot end in the mail and it has a .4mm nozzle. I have been trying to get it to work for and I am having issues with it jamming, several times I have started a print and by halfway through the first layer the temperature has dropped of between 10-15 degrees causing it to stop extruding. I tried wrapping the heat barrel in kapton, but that did not help. Also it seems to be jamming other times to when filament will not extrude even though the temperature is at the right level, I have noticed the heat sink barrel and the mounting plate have gotten very warm even though I am using a fan, but I am unsure if that is the cause of these jams. I am using PLA at 190 degrees. Any ideas are much appreciated.

The heat transfer characteristics of all metal hot ends are different than a J Head type hot end. You will likely need to tune the temp parameters specifically for that hot end. Search around on the forum. There are posts from others in similar situations.

What exactly do I have to change? I couldn't find anything else on the forum for what settings to change.

User jollygrimreaper is core dev for the Magma style hot end though IIRC his uses a liner. He may chime in. His blog is at [thejollygrimreaper.blogspot.com]

Recalibrate your extrusion temp for this hot end.

Edited 2 time(s). Last edit at 05/26/2013 09:22PM by vegasloki.

I was able to get it to print by increasing the temperature of the hotend and by increasing the speed of the print a little. The test cube I made came out okay, but does anyone know of any good guides to calibrate and or where I should start.

I would also recommend re-tuning the PID parameters. I had issues at one point with my nozzle's temp swinging wildly, and adjusting the PID parameters made it much steadier. The exact command depends on your firmware, but for Marlin, you'd want M303 C4 S190 (That would do 4 heat up/cool down cycles centered about 190 C). After that you can set the PID parameters through GCode or you can change your config file and re-flash your firmware.

Please excuse my ignorance I am pretty new to this whole thing, but what would the command be for Sprinter? Also where would you change that in the firmware?

I have not used Sprinter personally, but it looks like it should accept M303 S. Since you usually use 190, send M303 S190 and wait a bit. Eventually it will give you three numbers, P, I, and D. (If you're interested in the control theory, the Wikipedia page is a pretty good explanation of how PID control works.) Once you have those numbers, you can set them in Configuration.h. I'm looking at Sprinter's github page, and it looks like there are values for them: PID_PGAIN, PID_IGAIN, and PID_DGAIN. I'm skimming the code, and it looks like when it completes a run, it will spit a bunch of info at you. You should see something like this:

Classic PID
CFG Kp: XXX
CFG Ki: XXX
CFG Kd: XXX


Some Overshoot
CFG Kp: XXX
CFG Ki: XXX
CFG Kd: XXX

Those should be the numbers you plug into your Configuration.h file for PID_PGAIN, PID_IGAIN, and PID_DGAIN (not sure if you have to convert them to whatever funky format Configuration.h wants; hopefully they're just ready to copy and paste). The first three (classic PID) will get you up to temp in (theoretically) optimum time without any overshoot or oscillation. The second trio will get you up to temp faster, but you'll overshoot a few degrees before you settle on the target temp. For this sort of system, it doesn't really matter what you go with.

Now, of course, if you're using an older version of Sprinter, you may not even have PID control, in which case I'd urge you to update your firmware to the newest version, and then do all the above.

PS. I'd recommend doing the autotune with the fan on whatever level you usually use. I tuned mine initially without the fan, and then when I turned the fan on, the temperature became less steady.