Help needed on repairing a chair leg

[A.Clews]

I need to remount a leg on a wooden chair. The chair's legs are fixed to the chair with mounting plates which carry a threaded stub which screws into the leg. The problem is that the screwhole in one leg is worn out and the threaded stub no longer holds fast. The following photos show the component parts and the problem:

I'd appreciate suggestions on how best to repair it. Basically I'm looking for a way of re-threading the stub into the leg. I'm not sure if fixing the stub into the leg with strong adhesive is the way to go; I'd like to be able to unscrew the stub.

Thanks in advance for any help!

[Bob Minchin]

Insert an appropriate number of matchsticks( no heads!) into the hole until the screw bites again. Too few and it will pull out - too many and there is perhaps a risk of splitting the leg.

Bob

[Peter Crosland]

There are devices called Helicoils to repair damaged threads in engineering components. I am not sure how wide a range of threads and sizes they are available in.

Peter Crosland

[Tabby]

It might work if you wrap a thin layer of cloth round it. If the screw thread were perfectly round, you could wrap it in clingflim, insert resin into the leg and screw it home. But any out of roundness and youre in trouble, and I'd expect it to be moulded, thus out of round. Another possibility is to bore a hoel in a block of wood to receive the leg, and mount this to the tabel top, then your leg just lifts out.

NT

[The Natural Philosopher]

Look the stud does not need to ever come out of that leg again.

Fill the leg-hole with car body filler and screw the stud in finger tight. Wipe off excess with acetone or cellulose thinners or white spirit.

Once set. re-assemble as normal.

[dfrog]

It might work if you wrap a thin layer of cloth round it. If the screw thread were perfectly round, you could wrap it in clingflim, insert resin into the leg and screw it home. But any out of roundness and youre in trouble, and I'd expect it to be moulded, thus out of round. Another possibility is to bore a hoel in a block of wood to receive the leg, and mount this to the tabel top, then your leg just lifts out.

NT

"Machine Thread to Wood Thread Dowel Screw" is what you have and what to look for. You need the same 'machine thread' bit, but a fatter 'wood thread' bit - I'm not sure of the availability of such, but it's worth looking for - you can't be the first one in the UK to ever need one.

:-)

dfrog

Machine Thread to Wood Thread Dowel Screw is what you have

[Roger Mills]

Bore out the end of the leg, glue in a short length of dowel, and screw the fitting into the dowel once the glue has cured.

[Roger Mills]

The bit which goes into the leg is a *woodscrew*. The other end of the fitting has a machine thread - but I can't see what that's for[1] because it appears to go into a plain hole in the table top - with the actual fixing being by means of 3 screws through the flange.

[1] Maybe you put lock-nuts on that as a means of screwing the other end into the leg?

[dfrog]

OR - if you can't find a 'same machine thread with fatter wood thread', what about a 'same machine thread with a LONGER "same" wood thread' ? Drill the leg hole deeper for the longer screw :-) To get this, you may find yourself with a Dowel screw with a 'too long' machine thread. It then becomes a hacksaw job. dfrog

[John Rumm]

I would drill out the hole in the leg and then fill it with something that can be re-drilled at an appropriate diameter for the thread on the mounting plate.

Either gluing a section of dowl into the hole, or perhaps car body filler / fibreglass paste.

[John Rumm]

I suspect the plate and the threaded bit are two separate components. The mounting hole in the centre of the plate being threaded to accept the machine screw on the stud. The hole in the wood of the chair base just being for clearance of the end of the machine screw. Hence you fix the plate to the chair, drive the stud into the end of the leg, and then screw the leg plus stud into the plate.

[Roger Mills]

Yes, that makes sense now you've pointed it out. I guess I was a bit confused by the fact that the two were screwed together in the photo.

Anyway, we both suggested drilling out the leg and gluing a dowel in, and then screwing into that. Still sounds like the best option to me.

[A.Clews]

Yes, John is correct. Sorry, I should have pointed that out in the first place. The stud has two different threads; one to screw onto the mounting plate (the excess, projecting thread fitting into the central recess in the mounting area of the chair - see eralier pics) and the other to screw into the leg. The mounting plate has to be fixed to the chair first (via the four screws shown) because the four screw holes are mostly hidden if you screw the leg to the plate first (see pics).

That's the approach I'm likely to use.

Thank you all for your helpful suggestions!

[A.Clews]

Thus spake The Natural Philosopher ( [e-mail]) unto the assembled multitudes:

I did indeed consider that approach, but then thought of the possibility of the chair leg one day needing replacing, for example if it broke, unlikely though that is: I don't get too many bar brawls and thrown chairs in the Clews household but you never know :-)

[fred]

In article , [e-mail] writes

I'd be worried about the remaining wood outside the dowel splitting in use as the leg appears to be on the limit of strength vs thickness. If it fails at that stage the chair will be stuffed.

Bonding in the coarse screw may be a safer option, either plain epoxy or glass reinforced stuff such as isopon P40 or the current no-name equivalent at half the price.

[A.Clews]

Thus spake fred ( [e-mail]) unto the assembled multitudes:

I ended up adopting a simpler version of the dowel approach: I drilled out the hole a little in the leg, and inserted a pretty substantial plastic screw plug which was quite a tight fit. Then I drilled the plug out a bit to accomodate the mounting stub, because it would otherwise have been too tight and any attempt to screw the stub in would probably have split the leg open. Then I fixed the mounting plate with stub to the chair body and threaded the leg onto it. Feels secure, and there is no sign of distress or splitting to the leg.

[fred]

In article , [e-mail] writes

Result!

The risk is that the semi compliant plastic plug will work its way out through repeated stress and release cycles but if you are aware of the need to keep an eye on it then you can act if that happens and still you have a raft of other solutions to try.

[A.Clews]

Thus spake fred ( [e-mail]) unto the assembled multitudes:

Indeed yes. It does feel pretty secure, though. The plastic plug certainly didn't feel like it was going to loosen up any time soon.