pin for misaligned holes
pin for misaligned holes
(OP)
Having two steel plates 0.5" thickness with 3 holes each and misaligned within the tolearnce 0.046", which kind of pin should I use for them? There is a torsinal moment between the plates.





RE: pin for misaligned holes
(where people's lives are at stake) ...
i'd suggest opening up the holes to the next standard size.
if your bolt diameter is fixed (by something you're bolting onto the plates), then bush the holes
no more "risky" approach would be to install clearance bolts (the largest bolt to fit into the misplaced holes). this is riskier because you're relying on friction (to an extent), and because the plates "could" move relative to one another. (the first solution virtually prevents any relative movement between the plates because there are no clearances.)
this'll be smaller than your BP fastener, and you should be confident that it is ok.
when you say the plates are loaded by torsion, do you mean that the bolts react with in-plane shear, or are the bolts loaded in tension ? (this tension load would actually carried by the joint compression forces due to the bolt preload ... what sort of preload were you planning ?)
RE: pin for misaligned holes
Regards
Dave
www.wsec1.com
RE: pin for misaligned holes
On a production car there are virtually no bolted structural joints that would maintain integrity in the absence of friction, so I'd have no qualms that a properly designed bolted joint would cope.
The dowel pin is there as nicety, it could be a bolt as well.
Cheers
Greg Locock
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.
RE: pin for misaligned holes
Inevitably I will have offset between the matching holes.
Maybe offset dowel pin is a solution. I don't know how to install them, and I don't know a supplier for offset dowel (metric). Are offset dowels sold in sets? I suppose that during the instalation the necessarily pin is selected depend on the offset between the holes.
RE: pin for misaligned holes
can you enlarge the holes to encompass the offset holes + some, install a plug (suggest shrink fit), then drill out at the correct location ? possibly you can't because of edge distance issues.
i don't think you count on friction between the plates for carrying much load, count on the torsion being reacted by the bolts in shear, so you need a good fit (between the bolts and the holes).
it sounds like you have one plate drilled off, and are planning what to do if (when) you get a mismatch witht he 2nd plate on ass'y. this off, this should have been considered by the original designer, as the holes are not match crilled there will always be some tolerance for mis-match; so what does the drawing say ?
the two plates are oriented to each other somehow in the ass'y. can you align the plates in the ass'y, clamp them together, then drill out on the bench ? if you can do this, next time (if there is a next time) only drill a pilot hole in the first plate, this way you'll get match drilled holes (when you open them up later).
RE: pin for misaligned holes
Cheers
Greg Locock
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.
RE: pin for misaligned holes
RE: pin for misaligned holes
Used for repositioning things like camshafts to change the cam timing and bellhousings to center transmissions.
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You'd have to separate the plates to install them. And would probably need to add some more holes to bolt the plates together ?
As far handling torque with friction, flywheels bolted to crankshafts seem to be the modern day standard.
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RE: pin for misaligned holes
RE: pin for misaligned holes
I think you could use one of the dowel
pin holes on each part as the reference
datum hole and taper ream the other two
holes with the plates bolted together.