Hello all , i have a question for anyone who has built or is familiar with the fla 100 plans from cnc router parts. In the pdf drawings it shows all of the holes in the frame are .28125 or 9/32 however all the bolts being used are 5/16. Should the holes drilled in the frame not also be 5/16?
Thanks for any help, i am finally ready to start this thing.
Krieg Kuts thanks for the help. It makes perfect sense.
Daryl thanks for the tip. I will definitely keep that in mind.
On my machine (I built 2 so far), I drilled the top row 5/16" and the bottom 3/8" to allow some room in case I drilled slightly off. Now that Ahren has the drill guides, it should work just fine I would think.
Freecnc thanks for the reply, i will have to look @ Ahren site again. Hopefully im going to get my aluminum ordered in a week or two.
I would drill all holes for 5/16 bolts at 3/8.
If you can drill them accurately, then 5/16 works fine: the carriage bolts have enough slop to align the rail.
Of course if you can't drill them accurately, then you need more slop in the holes to get the carriage bolts to go into the T slots and still allow some alignment.
Because you have more adjustability with 3/8" holes. There is no significant strength advantage with smaller 5/16" or 11/32" holes because the cold rolled steel is held against the extrusion by the bearing surfaces of the carriage bolt and lock nut. Sure, the bearing surface of the nut is slightly smaller when the holes are bigger. However, if you want to have a larger bearing surface, you can buy "extra-wide" lock nuts from McMaster-Carr. Since I had to buy lock-nuts anyway, I bought the wider nuts but I doubt that significantly added to the strength of my build.
Thanks for all the replies. I have all my rails (pre drilled ) from fine line automation. So the only holes i should need to drill are the holes in the aluminum frame. That being said should i make the access holes in the frame larger then the the planed 9/32?
Would making these access hole 3/8 help in aligning the frame as well ?
Thanks again everyone
I think as long as you position them accurately, there is no need to machine them larger. 3/8 is a big jump from 9/32. If you go to assemble and have troubles, you can always enlarge a smaller hole.