Just checking about sizes for the screws for attaching the lid onto the 3D printed case, and also the screws for attaching the PCB. From the hole size in the model it feels like they should be ST2.2 self tappers - is that right? And what length should they be so as not to go beyond the depth of the holes and risk cracking the print or coming out through the bottom?
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Initially I used m2x8 philips head bolt stainless steel, they are not self tapping, the screws will thread themselves into the 3d material using a slight downward initial pressure, the bolt will take hold and it is easy from there - just do not overtighten, I am currently using m2x12 which gives a little more strength (but again if you overtighten it will strip the plastic real quick).
From memory I think the holes were 12mm deep, so allowing for the lid thickness of 4mm, gives a maximum safe depth of < 15mm
If you do happen to strip the thread - when you have the unit fully functional and ready to use, remove the screw and lid, drop a small drop of super glue down the thread hole, then put the lid and screws back in place. Works well with PLA, not so good on ABS. PETG is strong and takes a bot more effort to strip a thread
Just checking about sizes for the screws for attaching the lid onto the 3D printed case, and also the screws for attaching the PCB. From the hole size in the model it feels like they should be ST2.2 self tappers - is that right? And what length should they be so as not to go beyond the depth of the holes and risk cracking the print or coming out through the bottom?
Initially I used m2x8 philips head bolt stainless steel, they are not self tapping, the screws will thread themselves into the 3d material using a slight downward initial pressure, the bolt will take hold and it is easy from there - just do not overtighten, I am currently using m2x12 which gives a little more strength (but again if you overtighten it will strip the plastic real quick).
https://www.ebay.com/itm/383058130035?hash=item59300b3473:g:c~AAAOSwzsNcxqkP
From memory I think the holes were 12mm deep, so allowing for the lid thickness of 4mm, gives a maximum safe depth of < 15mm
If you do happen to strip the thread - when you have the unit fully functional and ready to use, remove the screw and lid, drop a small drop of super glue down the thread hole, then put the lid and screws back in place. Works well with PLA, not so good on ABS. PETG is strong and takes a bot more effort to strip a thread
For the pcb, I used m2x3mm flat head philips bolt
https://www.ebay.com/itm/152251098764?hash=item2372df668c:g:QM4AAOSwrfRcJxkO
Again finger tight only
regards
Robert
Thanks. I had it printed in PETG so hopefully strength should be ok.
It does hold up very well, even PLA, if one is careful enough. PETG though is a good choice,