Pivot pin tolerances for folders

flatgrinder

flatgrinder

Joined
Dec 20, 2005
Messages
2,045
Hi,

I was wondering what kind of "space" would you use for the hole in the blade tang to the pivot pin? 0.002"? Any machinists out there with ideas?

eg. if the pivot pin were 0.257" wide, what size (in thousandths) would you drill the hole in the tang to?

Thanks! :thumbup:
 
It's more like .0002" if you want a nice, tight fit.
0.002 is petty loose.
Take a caliper and piece of drill rod. Measure it, then add .002 and see how much it wobbles. It might not seem like much, but over the 3 or 4 inches of a blade length, it translates into serious movement.
The pivot hole isn't a drill-to-finish operation. You'll need to get used to reamers to do this right.
 
I just looked it up on my Starrett reference chart and depending on the app. the allowance should be either 0.0005" (class y) or 0.001" (class x) -I think I'm going to shoot for 0.001" (as my drill press is one of those cheapie Harbor Freight ones and I don't think it's that accurate).

Thanks for the info on the reamers. :thumbup:
 
The cause of many sloppy folder blades is drilling on an inaccurate press.The spindle can be out or round by .01 or more.That is a big problem when shooting for .0005 to .001 tolerances.Drill the hole undersized and ream up to a nearly press fit.
Stacy
 
Thanks for all the advice!

Anyone know where a guy can get a good set of reamers at a decent price?
 
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