Dominik MeffertI did a test with steel powder + sand. It turned out that purging in the ooze shield or a purge block is not the best way for changing the material. So instead of that I performed a 10mm Z hop at toolchange (which is a feature of the marlin firmware) to unload the rest of the old material in the nozzle before starting with the new material. If the feedrate is right there should be almost no material left. If the feedrate is too high, the amount of excess material is a good indicator which helps finding the right feedrate.
Actually it worked quite good besides of that the steel powder I used tend to clump together and get stuck after a short time...
I ordered finer steel powder and will test to move the inlet from 45° to 90° on the toolhead for a better material flow.
Update:
Tested the material inlet on the top. Sand works still good, but steel is still clumping together.
The new finer (<100 micron) steel powder got delivered today and it works way better, it also seems to be higher quality powder because there is no dust while handling it.
Discussions
Become a Hackaday.io Member
Create an account to leave a comment. Already have an account? Log In.
Hmm, maybe your steel is slightly magnetised or just a little too moist, finer powder may clump more. You could try some fine silica powder (from flower store), add up to 5%, but DON'T inhale.
Are you sure? yes | no
Sorry for writing back so late - must have overlooked the notification :)
Ok, I could use the powder, but actually I want to keep the sand + steel powder print free from other substances to prevent it from unwanted reactions while heating in the furnace.
Do you think silica gel pads would work, too?
I could add some of these to the steel powder container.
Are you sure? yes | no
Yeah, they should work, but dry them first and you may need several. I'm now more worried about magnetic clumping, but I don't have enough experience with steel powders to propose any more solutions for now.
Are you sure? yes | no
Got the new powder and it works way better. I will look how it behaves over time and if it will be affected by moisture or electrostatic magnetism. Maybe grounding could help, but if the metal powder itself gets magnetized... Just hope this doesn't happen :)
Are you sure? yes | no