Hey guys ran into another problem again. I have a couple of items that seem undersized after measuring the finished product. Holes that are suppose to be 3mm are @2.8mm and 3.5mm are @3.3mm. I am using 1.6mm bit and surface finish seems good (still need to play with feed and speed). I have a pretty good calibrated machine on X, Y as I measured almost perfectly. The holes on the finished piece doesn’t look to be perfect as well. I’m cutting G10 3/32". My settings were 10ipm, 9in plunge, and 0.01 DOC. This is getting FUN!
Inside or outside you can fudge the size of your bit to get the perfectly sized holes @PhilJohnson has a bit size calculator to help you figure it out. Or it’s simple math. outside cut you add the amount your off to your bits size inside you subtract the amount your off. Obviously test first so you don’t ruin your materials
Thanks guys! I will experiment now! Yes I think those eBay china bit sets may be off!
UPDATE So I changed the bit to from the calculator spreadsheet from 1.6mm to 1.4mm and everything lined up pretty GOOD! But the drilled holes still aren’t perfect. Probably 80-90% round. Any ideas? Do you think it’s my belt tension or should i change another bit. I have some better quality ones that I have no idea if it’s even suited for this G10 material. Here are the bits I want to try. I have limited G10 sheet at the moment.
Which way are they out of round and by how much? Is it off by the same amount and direction every time ?
it’s more than likely belt tension or v wheel adjustment. I ran into a dust build up on my rails caused a tight spot and gave me a out of round issue as well. I wipe down my rails every time and good dust collector. You can get yourself a digital fishing scale on Amazon pretty cheap and search belt tension on here lots of good info on it. Do you have arduino or x controller?
Adam, thanks for the reply! Appreciate it! I found out (I’m pretty sure) that it was the carpet tape that the tip was cutting and wrapping around it. So I think the endmill is not bare and does not make a perfect hole. I tried just drilling the first small hole then a bigger one and it’s very good. My part(s) after the first 1-2 holes, it cuts some long edges so it rubs some of the junk out and resets itself until the next holes, etc. I’m trying to cut just enough to NOT hit the carpet tape but every time it hits it by 1 or 2 rounds before going into the wasteboard. I thought I had set thickness perfectly at .093 for the material which I did in fact measure with digital calipers. I even sent the cut to .092 to no avail. Perhaps my next cut will be .090? I also have never calibrated the Z-Axis. Only the X & Y.
Definitely calibrate you z axis. You may wanna look into the masking tape and superglue hold down method works amazingly well. I use it a lot for smaller parts.