Easily removable rafts
Hi - I am experimenting with rafts using PLA and I am having problems with removing them cleanly. The bulk of the material strips away nicely, but leaves a layer attached to the part. The remnants will come off with a bit of a scrape, but with the potential of damaging the print. I'm just doing small 30x30x3 mm test pieces at the moment. Would anyone be able to post a proven list of settings for easy raft removal?
Many thanks
Simon
RE: Easily removable rafts
Just to add to the above post, here is the .3mf file. It's a simple test patch but maybe of use to determine the settings etc.
Many thanks
Simon
RE: Easily removable rafts
I must admit, I never use rafts. The only time I would find a need for them is when printing a tall, narrow piece that risks falling over. In that case, I find that a brim is sufficient and risks less damage to the bottom layer. What is it about your print (the real one, not this patch) that needs a raft? I'm curious what they're used for.
RE: Easily removable rafts
Hi - The box is shown in section and there is a difference in section thickness which is causing lifting in the corners as the print cools. In metal casting, this is to be avoided as the thicker sections cool and contract slower than the thinner sections and the result is stress in the form of the lifting corners.
On the printer, I have tried a brim which works fine when printing, but on cooling, the above happens. I was thinking of using a raft as it perhaps doesn't constrain the part as much. I have proved this, but removing the raft potentially will damage the print. The face the raft is attached to must be level with no drop off in the corners and must have a good finish. The section view shows the print orientation. I could print the other way up, but the amount of support structure needed would be extensive. I cannot change the interior design of the box, so I am stuck with the difference in section dimension. I hope this makes sense.
RE: Easily removable rafts
On the printer, I have tried a brim which works fine when printing, but on cooling, the above happens. I was thinking of using a raft as it perhaps doesn't constrain the part as much. I have proved this, but removing the raft potentially will damage the print.
Don't claim to be an expert in this area but I don't think a raft will help. If the part is warping after is is detached from the bed than it seems likely that the design is at fault. Try to ensure that substantial changes in wall thickness are gradual.
RE: Easily removable rafts
Hi Towlerg - I agree with you there, it's a mechanical issue with the part design, which most likely cannot be resolved within the printer settings etc. There is scope to scallop out the interior surfaces to reduce the abrupt changes in section thickness. Fillets in the corners would help distribute and reduce the stresses at the intersection of the unequal sections. There is a solution, I just need to find it. Thanks for your help.