Self tapping screws into well worn holes?

[Ian_Edwards]

How do you repair screw holes, where the self tappers have been taken in and out too many times, so that the holes in the timber are oversized and the slf tappers no longer grip properly. This has happened on the self tappers that hold some of the floor board down on Eynhallow.

I could use a bit of PVA adhesive and some scraps of wood pushed into the holes, but is there a better method which would give a more permanent fix?

 

[Concerto]

My normal method is to use some matchsticks. Fill the hole with them and then screw in. If still loose, then repeat. Works a treat.

 

[dylanwinter]

Matchsticks are excellent

maybe matchsticks and a dobble from a hot glue gun in extreme cases

D

 

[Spyro]

Wooden coffee stirrers that you get in Costa/Subway McDonalds etc. Poke them in the hole and break off level with the top of the hole. Always grab a handful. Great for mixing epoxy as well.

 

[Minchsailor]

You can drill out, then plug with a bit of dowel glued in with epoxy.

 

[ghostlymoron]

If they're into wood, you don't really need self tappers but there's no reason why not. The best way to make as good as new is to drill them larger and glue in a dowel as already suggested.
You can't do this with self tappers into metal, the only way is to use a larger screw.

 

[VicS]

You can drill out, then plug with a bit of dowel glued in with epoxy.

the trouble then is that you are screwing into end grain.

 

[Ravi]

Just use a bigger screw. When that is loose, use a bigger screw. And again, and again.

You only problem is that you need a big boat ....

 

[Duster]

You could read 'how to do it' on a pack of Plastic Padding Leak Stop.

 

[LadyInBed]

View attachment 54174

That pic gave me a thought - Stud wall fixing
http://www.screwfix.com/p/fischer-self-drill-plasterboard-fixings-metal-35mm-pack-of-100/47347

 

[ghostlymoron]

the trouble then is that you are screwing into end grain.

If you use hardwood dowels, they grip pretty well.

 

[Ravi]

That pic gave me a thought - Stud wall fixing
http://www.screwfix.com/p/fischer-self-drill-plasterboard-fixings-metal-35mm-pack-of-100/47347

Wow. You must have big plasterboard.

 

[Woodlouse]

It depends on what the screw is holding together. If it's a non vital component like a bracket for a towel rail, or anything with little load then I usually get some epoxy putty, roll it into a sausage then stick it in the hole and screw into that. The putty then goes hard and hopefully bonds to the timber to some degree in the hole.

For more important applications, such as planking the only way is to drill and plug the hole then start from scratch. You can get deep plug cutters that are better than using dowel since it avoids the end grain issue as mentioned above.

 

[Poignard]

For something that's going to be load-bearing I'd follow the techniques recommended here :

http://www.westsystem.com/ss/bonding-hardware/

but for less demanding applications I'd follow Minchsailor's advice and insert a dowel, but instead of epoxy I'd use polyurethane glue, eg Gorilla glue because it's so easy to use (and cheap).

In theory, screwing into a dowel endways shouldn't work but in practice it does; probably because the dowel is tightly constrained in the hole. On the other hand, driving a screw into a cross-grain pellet is the technique generally used when you want to remove it.

 

[PetiteFleur]

Try the next size larger screw - certainly the easiest way.

 

[PCUK]

Rawlplug?

 

[prof pat pending]

How about something like this, available in other sizes and decent materials.
http://www.ebay.co.uk/itm/4-x-D-NUT...id=100338&rk=1&rkt=5&mehot=pp&sd=111321340398
Using threaded screws should hold up better

Edit...better example http://www.ebay.co.uk/itm/M4-x-15mm...-Inserts-For-Wood-10-Pcs-100654-/281143614738

 

[LadyInBed]

How about something like this, available in other sizes and decent materials.
http://www.ebay.co.uk/itm/4-x-D-NUT...id=100338&rk=1&rkt=5&mehot=pp&sd=111321340398
Using threaded screws should hold up better

Edit...better example http://www.ebay.co.uk/itm/M4-x-15mm...-Inserts-For-Wood-10-Pcs-100654-/281143614738

That's a damn good idea :encouragement:

 

[Ian_Edwards]

Thanks everyone for the input. I think the gluing in dowel, matchsticks or scraps of wood, would work, but isn’t a long term solution.

Just using epoxy to glue the self-tapper in would secure the boards, but I don’t think I’d ever get them up again!

I’m attracted to the idea of applying release agent to the self-tapper and then using epoxy, that would give a “thread” which could be reused, but I’d be concerned that the self-tappers won’t release.

The best idea seem to be a treaded insert, and replacing the self-tappers with set screws. That would give a good long term solution to floor boards which have to come up periodically to access stuff for maintenance.

I might try drilling out the holes and then gluing in rivet nuts with epoxy. I wouldn’t try and expand the rivet nuts, they would just be a simple way of getting a threaded insert. I’ve not had much luck with the screw in type as posted by prof pat pending and usually seem to make a mess of them and finish up with an even bigger hole to fill.

 

[prof pat pending]

The trick to using them is in drilling the hole out big enough before you try to install them. Even slightly too small and it's easy to make a pigs ear of it.