PLA Grinding solution (?)

Ok, so I’ve managed to print what I previously was not able to due to grinding by disabling retraction and setting the fan speed to 50%. It’s much better, but still 2 to 3 grinds on a 1 hour print. However, I’m still having to watch it so that whenever it starts to clog up again (starts grinding) I hit pause and do a little dance of lowering temp to 1/2 and taking out filament, cutting it off, and putting it back in. Then resume… This is pretty annoying so going to try a 40mm fan + duct on heat block next. Hope that works, or PLA is going to be unusable.

Here is an idea: why not have an opto wheel (like old mice wheels) or similar to read if filament being pulled in matches up with requested extrusion… if it is far enough off, then this could be a ‘grind detector’ that can then pause printing for user intervention. This would be very handy on longer prints with experimental or finicky materials.

Most likely, your small squirrel cage fan is starting to fail. Moving to a larger fan is the best option.

I am currently running this one on my Mini. I Have tried a 40mm 5V Noctua for this setup. It does not move enough air to be useful. I am currently running a 12 volt fan from a wall wart.

Thanks for the reply! I was about to print that very design when the case fan (over rambo board) failed last night :unamused: I have some 40mm fans but they are 12v. I wonder if they’ll move enough air to be of use at 5v? Or is there a good 12v source somewhere in that wiring harness? How could I tell if fan is providing sufficient cooling?

I do not know if there is an open 12 volt header on the Mini Rambo. I would not think the fan would perform if you ran it from the 5 volt connection on the Mini. I just connected mine to a wall wart.

If the fan is not providing enough airflow, you will continue to have jamming and filament stripping.

Just as an update in case anyone else is having a problem, putting a duct and fan on the hot end heat sink cured all my jamming issues. Long prints are no problem now. The little blower fan is really a POS… it has no real airflow. The 40mm I have on there now may be overkill, but it’s definitely working. Ended up soldering a little 12V 3A regulator to the power supply’s 24V output. Now this 12V supply feeds the fan on the hot end, the fan on my X-axis (it was burning hot otherwise) and a strip of LEDS hidden into the top of the printer for watching prints at night :slight_smile:

I also had annoying grinding issues with PLA on longer prints. My solution was to print a filament filter and put a piece of foam moistened with vegetable oil inside. Haven’t had any grinding afterwards, even on 9 hr .1mm prints.

I’ll try the fan thing too because the micro blower seems like a liability… Do you know the CFM rating of the 40mm fan you are using now?