Tricky spinning nut on bolt....

Yeah, sorry about the art quality... No one will mistake me for Rembrandt. I do think it's the easiest and least prone to disaster plan. Cheap too, presuming you own a drill and some bits all you will need extra is the tap and a matching bolt with a good lock washer or a drop of Loctite.

 

This is great. 6 pages and over 100 posts for one 10mm nut. Gotta love it. I will admit I have had issues with bolts or nuts before but I don't recall having this much issue with one so small. I would have cut the whole thing off by now.

Dremel with one of these and a cut-off wheel. Done. But it's easy to say sitting here behind my desk. 225-01 Flex Shaft Attachment / Model: 225-01

Or clamp on a set of vise grips and snap the whole thing off.

 

It (Paul's) is an elegant solution.

Using a final drill size slightly larger than the major diameter of the original bolt thread would also be a nice way to completely remove the damaged threaded portion all together, leaving just a hex shaped blank (the remaining head only of the original bolt) which would have plenty of material left to drill and tap to the correct size creating a new "captive nut" in the chassis in place of the original "captive bolt".

This assumes, however, that the bolt is a standard hex head cap type ---- what if it is a button, carriage, or flat head type (often used for such applications, btw ) ? Well, then you would be screwed ! It would be worth verifying this bolt has a proper head on it first before committing down this path ---- even if you had to drill an adjacent inspection hole in the panel to see the bolt head directly for positive identification .

Then, the only further caution would be to be very careful when drilling / tapping so as not to accidentally break loose the bolt head's attachment (whether it be caged or tack welded in place) ---- if that happens, you would be in a real world of **** .

Make sure it is not one of these first !
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I think even if it was one of those, as long as one is not over zealous drilling the bolt initially to get rid of the spinning nut, there should be enough material left when the hole is then drilled and tapped into the head of the old bolt to get enough turns of threads to allow good purchase of the new bolt. But of course the only sure thing is death and taxes...

 

When you get the nut-off you may want to replace it with a coupling nut which is like a standard 6mm nut except it is about 14mm tall instead of the standard 3-4mm height of a standard nut.
It sounds like you are going to try to split the nut either with a Dremel or a nut splitter. After you get the splits on both sides of the nut it would probably work well to put a right angle screw driver in the slot and twist it to open-it-up and pop it off of the stud.
Good luck and keep us posted.. you may end up being the author of the longest thread of the month

 

I would try the die first. If you don't get threads on the entire bolt, you might at least get some on the outer section of the bolt. It doesn't look like there's anything to lose by trying, but that is one beat to **** bolt.

Failing that, you still might get enough new thread to catch the end with a nut. You can use a couple of the same nuts instead of washers, then put the ant-vibration nut on the end of the bolt.

 

Washers, new nut, on to the next problem.

 

lotsa washers, eh?

Maybe chase the end of the bolt to clean up the threads?

D
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Bugger up a couple of trash bolts and practice first. Mike

 

I'll be surprised if you can get any / enough usable threads, of the original diameter, on that thing --- looks pretty pared down --- also, even if you can get some workable threads near end, you likely will not have enough length to get the locking element of a Nyloc nut to engage anything, so you can substitute some lock washers underneath it I suppose. But, it won't hurt to try.... other than wasted time when it doesn't work.

Personally, I'd go straight to cutting new threads one size down. If that does not work ---- proceed right to Paul's idea (chopping the bolt shank, and tapping the remaining head into a nut). Incidentally, looks like you have a perfect built-in inspection hole right there to visualize exactly what sort of bolt head you are dealing with .
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Well done.