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SH Shoulder Bolt Diameter confusion

Cannonmn

Stainless
Joined
Jun 25, 2016
I was putting away some mixed SH shoulder bolts, checked diameters, and found this group were all about 1% under the common fractional diameters. I thought I'd easily find a convention that spelled out the industry standard so I'd drill and ream right-size holes and select right bolts, but the several bolt-vendor webpages I found all showed even fractional diameters for such bolts, 1/4, 5/15, 3/8, 1/2, 5/8,,etc. Just one example: How to measure socket head shoulder screws | Fasteners, bolts, screws and more from Atlantic Fasteners

So, do I have a special-order batch of shoulder bolts, or is everyone just supposed to know that when a vendor sells a "1/2-inch" diameter bolt, it is really 0.495" like mine?
 
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All the shoulder bolts (or stripper bolts for the tool and die guys) that I ever measured were a few thou undersize.
I always figures it was so you could ream to a standard size and they would fit.
I dunno.
 
Shoulder- stripper bols have allways been under nominal size. Mcmaster- carr says -.002-.004.Stipper bolts used to be found only in tool and die work and were pretty well made.Nowdays they are found on lawn mowers and other equipment and the tolerance might be wider,but they are ALLWAYS SMALLER THAN THE NOMINAL SIZE. EDWIN DIRNBECK
 
Stripper bolts in metal stamping dies

In metal stamping dies ,4 or more stripper bolts are used on a spring loaded stripper plate to stip the sheet metal off of the punches.Even well made stipper bolts are not that good. Often when you tighten the bolt ,you find that the shoulder is not square and the bolt tilts to one side. You then try another bolt or enlarge the clearance hole or recut the seating surface on the stripper bolt.Most times people try to make the clearance hole too small.Edwin Dirnbeck
 
McMaster Carr lists two classes of fit... the STANDARD seem to follow ANSI B18.3, with a -.002/-.004" tolerance on the shank. These are the common stripper bolts, the shanks are intended to have clearance in nominal size holes.

I can't find a standard for what MCM calls PRECISE, but they are spec'd with a +000/-.001" tolerance on the shank. These are the ones to use as pivots, where you are going to fit them to a reamed hole.

Dennis
 
McMaster

I can't find a standard for what MCM calls PRECISE, but they are spec'd with a +000/-.001" tolerance on the shank. These are the ones to use as pivots, where you are going to fit them to a reamed hole.

Dennis
Or as we used to use them; for combination clamping and locating a part. Had fixtures with a bushed hole and threads in the bottom.
Dan
 








 
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