Comment on How to design a print with better tolerances – Slant 3D (12:34)
j4k3@lemmy.world 4 days ago
It is an interesting approach to use feather fingers to hold a lid. That one has never occurred to me in design, but I loath thick useless walls like this.
He kinda touches on the way sharp corners are an issue because of the overlap in the extrusion diameter at the direction change. The overlap in circles is ignored in the slicer so there is always some amount of over extrusion in corners without a built in radius matched to the tessellation resolution and step accuracy of the machine.
Personally, I prefer to make a slightly larger clearance for such an interface. Then I use a small round dimple between the parts in the center of the long wall. Any long wall will have some flexible compliance at the center. I use a small 2-4mm diameter dimple that is padded/pocketed 0.5-1.0mm with a similar tolerance to the part. The subtlety of this feature is far less likely to disturb the outer part perimeter wall smoothness. The trick is to design the positive dimple pad with a closer tolerance to one side so that contact pressure is held to prevent looseness.
TheButtonJustSpins@infosec.pub 4 days ago
I’m still trying to get the hang of that sort of fit. I saw it in a video about crush ribs but it didn’t work when I tried it. Will keep at it until I figure it out, though.
MysteriousSophon21@lemmy.world 4 hours ago
Try starting with a 0.2-0.3mm interference for crush ribs and print a small test piece first - I’ve found the key is getting the right wall thickness so they flex just enogh without breaking.
j4k3@lemmy.world 4 days ago
Just do small test prints first. For a table saw feather board in PLA this worked but it is length and material dependant.
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Calipers are consistent for the 2.6mm but too dead of a battery to charge the capacitive sensor past around 50mm so the scale shows ~63mm long. I think the optimum angle is around 30° but don’t quote me. I just imported an image of another feather board and used it to get basic working dimensions. You only need to know 1 measurement in a flat image in CAD to calibrate the size for use in the background to draw your sketches on top of. With a table saw feather board, you know the slot dimensions. You could easily screenshot the video’s sketch of the feather pattern here, import that and make a copy at any scale in FreeCAD. Mango Jelly has YT vids about this if you need them.