Recommended bolt/thread sizes?

Discussion about Tooling and Fixtures. End Mills, Router Bits, Hold Downs, Fixtures, Etc.
Post Reply
Posts: 8
Joined: Fri Aug 26, 2016 2:56 pm

Recommended bolt/thread sizes?

Post by loneboat » Fri Aug 26, 2016 3:34 pm

I just set up my Shapeoko 3, and would like to put some threaded inserts in the board on the bottom. Are there any best-practices for choosing a bolt and thread size? I suppose any size would work, but I was wondering if it would be wise to choose one over another in case I want to buy some additional clamps in the future. Are any sizes "more standard" than others?

Posts: 8629
Joined: Mon Apr 09, 2012 6:11 pm
Location: Pennsylvania --- south of the Turnpike, East of US-15

Re: Recommended bolt/thread sizes?

Post by WillAdams » Fri Aug 26, 2016 3:49 pm

There's a bit of discussion here:

#10-24 is popular here in the U.S., M5 in Europe and elsewhere which uses metric.

I've been thinking that using something smaller would be preferable --- I've oft' regretted the area I've had to leave aside to make the larger fasteners work.

If I could've gotten M3 inserts affordably here in the States in reasonable quantities w/o jumping through hoops, I might've tried them, but couldn't bring myself to open up a new account and haul out plastic (trying hard to lead a cash-only existence). Considered #8-32 which is about the same size, but even those were more expensive than I wanted to deal w/.

Finally broke down and got T-track for #10-24 hardware. ... Wasteboard
Shapeoko 3XL #0006 w/ Carbide Compact Router w/0.125″ and ¼″ Carbide 3D precision collets

Posts: 164
Joined: Sat Mar 21, 2015 1:33 am
Location: WA, USA

Re: Recommended bolt/thread sizes?

Post by madhatter » Fri Aug 26, 2016 4:05 pm

For my SO3, I went with flanged inserts that are internally threaded 1/4-20 and I use 18-8 stainless steel socket head cap screws (because they are cheaper than 316SS) with a 3/16" Cushion Grip T-Handle Key, all from McMaster-Carr. I did a bit of overkill on the threaded inserts and had them in a diamond pattern with each one only 2" apart from its neighbor, but I do a lot of small work with very thin edge clamping surface available, so having the extra locations is great for me.

For me, I went with the stainless because no real reason. I like them better than the black oxide coated ones, and since I will never need the strength of the black oxide coated steel fasteners, what I got. I bought a set of 10 of each of the screws in 1/4" increments so I can clamp whatever I want and not worry about the screw being too long or too short. I bought screws in lengths from 3/4" up to 3-1/2" in 1/4" increments, and then it goes up to 4-1/2" in 1/2" increments.

If you're not in the US, Then I'm sure you could get the same setup in metric and it'll work just as well. Some people buy T-slot track and use that, and some just screw directly into their wasteboard (ANIMALS!) :-). I am planning on splurging and buying some 8/20 T-Slot for my XXL that has been patiently sitting in it's box in my entry way for the last couple of months while I build my new shed.
SO3 #0054
DWP611 - SuperPID
Prusa i3 MkII
SolidWorks 2015

Post Reply