Powder bed design

Hello

I have built my first SLS prototype and are using sand as powder. However I ran in to problems with sand jamming the moving powder bed preventing a smooth motion. The friction from the powder stuck between the moving bed and the side walls makes small layer heights impossible since sometimes the bed does not even move and after some layers it suddenly jumps. Is the solution to make the gap (currently 0.1-0.2mm) even smaller? Making it lager could also maybe solve the issue but a lot of powder would fall down in between to the bottom of the printer. I also consider some type of seal but I am not sure how that could be implemented and wear would be a problem. The bed and side walls are made of 3mm aluminium and I do not know if some other material is better? If someone has had similar issues or know of a good working design I would really appreciate some advise.

Thank you!

/Henrik

... better make it bigger and add a brim on the bed perimeter, so it would hold/contain the inner volume ...

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Viktor
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Consider using vinyl sheeting as a seal - cut it with a border 0.5mm larger than your piston chamber, and adhere it to your piston, or sandwich it between the piston and a plate on top.

Thank you, I like the sandwitch idea, that is definately someting I could try. If the melting temperature becomes a problem I am sure I can find some other suitable material.