What are the tolerances generally used for a one hand opening folding knife?

[BloodyDonnie]

I designed a flipper folder, and I wanted to know what are the tolerances between the pivot width and the hole on the blade and scales, and the inside of a washer or ball bearing. Because it is a flipper, so it needs to be smooth but not loose.

Also, what is the ideal thickness of washers to use?

And lastly, how much should the liner lock overlap with the lock face of the blade?

 

[Daniel Carraher]

I’m far from an expert but I’d say my goal pivot tolerance is .0002”. I drill slightly undersized and ream after heat treat and surface grinding. I use bearings most often and start with .015 of clearance on each side and that becomes around .012 or so after titanium work hardens. On frame locks I occasionally use hardened washers and then set clearance at .012.

For me, I target around .04 or about half the thickness of the liner and then over time it’ll move over a bit.

 

[HSC ///]

.0005 max