Fastening to MDF

Jun 22, 2014 14 Replies

I have some hifi speakers, where the speaker units are surface mounted to MDF, and a couple of the crews no longer grip. I know I could twist the unit a few degrees and use fresh wood, but I'd like to use a bolt and captive nut type arrangement that I've seen eleswhere.



Thing is, I don't know what they're called, or the best type for this application. The MDF is 18mm, the screw threaded bit diameter about 3mm. Ideally I'd like a hex.


Insert nuts. There's no problem with the 18mm depth. The only ones I've come across take M6 screws, which you'd need to cut to length in this instance and you screw them into a 7mm hole. And yes with a hex key.

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michael adams

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In article , RJH scribeth thus

Should be plenty of witches around at the moment for one of they;)

As to the speaker fixings. I know the one you mean but I'm bu^^ered if I can remember what its called now or where you'd get a few from. You could try phoning the makers of the speakers if there're British build or give Spendor audio in Sussex a call there're usually very helpful.

Or drill the holes out a bit bigger fill with something like body filler drill out then tap the holes to the right size. Failing that glue a lump of wood behind and use longer screws to reach the new bit of wood....

Any good?

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In article , RJH scribeth thus

Ignore last waffle, there they are:)...

T-nuts ..

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Nuts and bolts.

The bolt it the threaded bit that goes through the board and the nut is the threaded bit that anchors it. Drill a countersink hole under the board that is slightly smaller than the nut and it will pull into the surface.

You can have whatever head on the bolt you like if you can find it.

I use pronged T nuts for this - they fit the back of the MDF. Not sure about M3 - but I've got some in M4, which is a more common size for speaker fixing.

Since they go close to the edge of the MDF, it might be better to drill small pilot holes for the prongs to avoid splitting it. Again if the holes are very close to the edge, you may have to file or grind the fixing down slightly (if it overlaps the edge) after fitting.

+1. repaired may kitchen cabinets this way when the chipboard fell to pieces round the hinges

JAAMOI you can et repair plates for that job;

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We're obviously the only ones who've built speakers. ;-)

Something which goes in from the face side may not be ideal as you need a perfect air tight seal between speaker and baffle.

In article , Dave Plowman (News) scribeth thus

Yes!, and modified them too;)...

See there're no 5/8's at the TV centre sell off, only the 9's;(...

Insert nuts can go in from either side of the MDF, and they're available without a flange and can sit below the surface if required. As to an air tight fit, if they're screwed into a 7mm hole(that's from memory it may be 8mm) using a hex key they really bite into the MDF and make a very solid connection using M6 screws. i.e it would be virtually impossible to separate two panels etc joined together in this way without first breaking the wood\mdf\chip. Not that I've ever tried.

michael adams

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Even they were old hat for the TV boys. ;-)

If not too demanding and the damage only to the actual hole/thread, I have drilled out such holes and hammered in a yellow or red plug, and sliced off whatever is left sticking out. Then simply screwed the thing back in. If something suitable has been to hand, might smear a bit of polyurethane or other glue on the plug before hammering it in.

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