Where can I get hold of self-tapping bolts?

Body shops, roofing places, probably b and q. Screwfix definitely, I got some from them last year.

Mrcheerful

"MrCheerful" wrote in news:giXDh.8691$ snipped-for-privacy@fe1.news.blueyonder.co.uk:

You mean coach screws? Local engineers merchants. The price saving compared to B&Q will probably be quite dramatic, cos they tend to sell stuff like that in small price coded plastic packs. You end up paying about £2 for 2 screws!

The one local to me is a fraction of the size of a B&Q, yet you seem to be able to buy just about anything over the counter!

Stu

Unlikely, I think. A coach screw to me is a square or sometimes hex head large woodscrew - typically 1/4" or 6mm minimum diameter.

I'm not sure about a conventional self-tapper or roofing screw, either. I'd be surprised if an exhaust bracket was held to the "undercarriage" (what? is this an aircraft?) by anything less than 6mm diameter, and that's quite big for a self-tapper. I suggest the OP drills out the old thread to the tapping size for the next screw up - perhaps even going to an imperial size if that makes it easier - and re-taps it. That assumes there's no way of using a nut above the defective thread, and that using a new screw, perhaps with a drop of Loctite, doesn't work either.

He might be after some techscrews (blurb says " light section self drilling screws with self tapping thread") the ones I use for fixing panels will drill through 3mm mild steel. They're timco from any builders merchant.

AJH

Cheers. Is "self-tapping bolts" the right name for these? Coach bolts such as those used for bolting satellite dishes to walls might do the trick.

you don't want coachscrews. look on the screwfix site for item no:12714, this is a 6 mm self drilling bolt with an 8 mm head, I often use them for similar jobs. they are 7.50 for

Mrcheerful

Aren't these also called...... "speed bolts"?

Stephen.

Just a manner of speaking. There are also the usual two rubber rings holding the back of the rear silencer to the chassis.

It's actually two 10mm, bolts.

I'm hoping I can just force the next size up in without any drilling/retapping. And yes, there is no access above the defective thread.

If you can force the next size up in then you could retap it more easily.

If the makers thought it needed two 10mm bolts, don't you think it's a bit optimistic to expect a couple of self-tappers to do the same job?

But I suspect you mean 6mm bolts, which are 10mm across the flats of the hex.

Tek screws, as suggested elsewhere, are also usually between 5 and 6.3mm nominal diameter, depending on whether they're supposed to be for biting into timber, thin metal, or thick metal. The Screwfix ones intended to cut a thread in steel thicker than a millimetre or so are only 5.5mm diameter, so they wouldn't have much bite in a worn hole previously tapped M6.

Unless you can find some 1/4" bolts to try, the next size up is 8mm, which won't even look at a 6mm hole.

"When all else fails, use damn great nails"

That might be a little small. The existing bolts have 10mm heads so I assume the thread is commensurately larger. But thanks anyway, now I know what to look for.

I think the steel is only a few mm thick.

The original bolts were self-tappers. One still holds reasonably well, the other not at all.

Yes indeed. Thanks.

OK, so maybe some drilling will be required, but given the thickness of the metal retapping doesn't seem necessary.

It should still be fine. Wear goggles, drill it, & then tap it with a really well greased tap. Cordless drills make really good tap wrenches.

If oit's that thin then a big blob of milliput/chemicxal metal might be easier.

No. 10mm head is usually used with a 6mm thread size. 8mm head in this case is also on a 6mm thread. So the bolt size is very likely to be the same.

Mrcheerful