fixing an inaccurate hole ??

[picclock]

Hi

I seem to have made an error and drilled a 6.25mm hole 0.8mm out of alignment in a 10mm steel plate. It has to be a lot closer than that as it has a 2mm oring seal in an 11mmx1.3mm recess on the top and screws into a third party component. The question is how to fix it. If I just correct the offset there is a good chance the oring will leak. If I plug it using steel fixed with epoxy and re-drill the piece left would be very small.  I could make the hole bigger and fit it with say an M10 threaded piece which could then be drilled in the correctly, but I don't think I have enough room. Alternately, I could put the hole in the correct place leaving an oval hole, but then counterbore the hole to say 3.3mm depth with an 11mm mill and epoxy fit a 2mm thick insert for the oring to seal against.   

Any better ideas much appreciated.

Best Regards

picclock

[awemawson]

Carefully measure your off set. Overbore your hole and loctite in an eccentric bush

[Jonny]

Think I know what it is.

A few choices, scrap it or realign a larger hole central to O ring.

My choice would be to realign hole where it should be and go larger diameter (min 7.05mm) for the bolt. If O ring is then too small a bore  could use a larger 2mm cross section.

Other alternative is keep hole where it is just realign and cut the O ring to the hole by going larger diameter and subsequently a BS numbered 2.62mm cross section O ring to 1.8mm deep.

That brazed washer, is it machined after?
If not you will have problems even with 0.7mm compression of o ring.

[Joules]

I would loctite in a tapered plug, then surface and re drill it. Assuming you can get the plate on the lathe. Top slide only needs setting once to bore hole and make tapered  plug.

[sparky961]

I hope I didn't miss something that would rule it out, but what about building it back up with MIG or TIG?  I've done this with countless holes that jumped over 1/2 inch thick when my back was turned.

[picclock]

Hi All
Thanks for the ideas. I've gone with oversizing the hole and fitting a sleeve with J-B weld.
@ Jonny
It was intended to get oversize headed bolts and not use a washer at all, but the threads are UNC american 1/4" standard and thats tricky in the UK. Other option is to epoxy washer to bolt head, or try to get some UNC studding and make up a bolt with a flanged nut. Brazing the washer and clening up by machining seems the best option. Recutting the threads to metric is not an option.

Many thanks for your help

Best Regards

picclock