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Wondered if anyone has a good suggestion before I take the 'bodge it' approach...
I want to fit 10 drawer type knobs to a piece of 18mm plywood, which is permanently fixed and doesn't have much of a void behind it. I only realised there was no access to the back after I bought the knobs and started to measure up where they needed to go!
So I've been hunting for a fixing to either take an M4 threaded rod, or to provide an M4 stud, so I can screw these knobs on.
Everything I can find is either a toggle style fixing or expanding wedge which needs a void. I have some kitchen unit style nuts but they are bigger than M4. One other option would be a bolt with an M4 thread on one end, and a self tapper on the other end, so it can screw into the wood and then take the M4 knob. I know you can get double ended self tappers but not seen a combined machine thread with a self tapper.
My bodge it approach is to chop the heads off the M4 bolts, drill some holes, and epoxy them into place. Just seems a shame to make the fixings permanent if I ever decide to remove them!
I also considered putting some M4 rivnuts into the timber but thats even more 'bodgy' and would be even harder to remove than epoxied M4 studs!
An M4 threaded insert will do it. Widely available, a few different styles. These threaded ones are easy to fit: https://www.orbitalfasteners.co.uk/products/m4-x-10mm-type-d-flanged-timber-insert-nut-4mm-key-steel-zinc-yellow-plated
And when you know what to search for, its as easy as that 🙂 Thanks! Although I'm thinking, I could epoxy them in to start with, if they let go I can drill them out for the M4 inserts later on 🙂
One other option would be a bolt with an M4 thread on one end, and a self tapper on the other end, so it can screw into the wood and then take the M4 knob. I know you can get double ended self tappers but not seen a combined machine thread with a self tapper.
Dual thread screw is what you're after.
Ebay
Epoxy. There is some great stuff out there real cheap. I have just used some for exterior balustrade mounting. I was dubious about the strength of drilling 14mm holes and filling with the resin before dropping in 12mm bolts but the stuff is amazingly strong.
You might only need a smaller weaker amount.
thanks guys 🙂
T-nuts might be worth a look too? Use them in guitar cabinet building
I've get a huge bag of M4 T-nuts I used for a job which I only needed a handful for but a big bag was dirt cheap. If you want some give me a shout and I'll happily send you some. this style:-
T nuts are great but you'll need access from the back. If you put them in from the front they'll pull out easily
All done... Didn't even need epoxy (yet) as a 2.5mm drill and then M4 tap seems to hold pretty well in plywood!
This has been a long time in the planning... I've now got a cab curtain that can blackout the van, help give the heating/air con a chance, no flimsy/stubborn curtain tracks, I can layer up the curtains to keep them out the way, or take them off completely rather than having a bulky curtain taking up space in the day :). And because I can fold them and layer the excess, they are long enough to hang off the cab shelf and enclose the whole cab when the front seats are swivelled 🙂
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Good job. I was going to suggest similar but thought it might be too bodgy for you. Tapping works well in MDF. Done it a few times. Drill a hole, fill it with super glue, let it soak in, then tap it. Not tried it in plywood.