MPCNC Assembly Drilling the holes question

I’m looking at the drawing. The drilled holes have 5-8mm. What size hole should be drilled? 5 mm or 8mm? and do they go all the way through? Thanks

The holes must not go all the way through because the opposite side will be rolling on a bearing, so a hole would be bad.

The holes must be large enough to accommodate the #6 machine screws, which are less than 4mm in diameter but if you make the holes barely big enough, then you must locate them perfectly. And even if you do locate them perfectly, you will probably have a hell of a time lining it up for assembly.

On the inside of the tube will be the nut trap, so there is some leeway on having a larger hole. The nut trap won’t be pulled through the hole, but if the hole is too large it is just sloppy and maybe weakens the Z axis.

Bottom line, use whatever drill bit you have handy between 5 and 8 mm.


I appreciate that. One-sided, bigger than 4mm but not so that it’s weakened.

Now the 5 to 8mm makes sense. Thanks so much.