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Help with threaded insert repair in wood products

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Forum topic by groland posted 11-10-2016 05:09 PM 1052 views 0 times favorited 8 replies Add to Favorites Watch
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groland

181 posts in 3251 days


11-10-2016 05:09 PM

Topic tags/keywords: threaded inserts repair

Hello,

I have a pair of loudspeakers into the bottom of which I want to install some stands with a threaded machine bolt (M8) supplied by the stand maker.

In the bottom of each speaker enclosure are four holes that are supposed to have threaded inserts to receive these bolts. My problem is that in five of these holes, the threaded inserts are missing. The material into which they were inserted looks like a very light colored MDF. The holes seem smooth sided and intact. It looks as though the original inserts were pulled out without damaging the holes—there is no evidence of tear-out.

I have ordered some threaded inserts from Global that are M8 thread and look as though they have a similar hole size (11mm or ca. 1/2 inch) to the holes in my cabinets. So far, so good.

My question is about how best to install these threaded inserts. If the holes are a little too large, I could glue some pieces of wood (perhaps veneer) into the holes to tighten up the fit. I could also use some sort of glue to glue the inserts and any wood fillers into these holes to ensure a tight, secure fit.

If anyone has any experience with this kind of repair, I would love to hear what you did and how it worked. Ought I to use epoxy, Gorilla glue or what?

Many thanks,

George


8 replies so far

View bondogaposis's profile

bondogaposis

4482 posts in 2191 days


#1 posted 11-10-2016 05:27 PM

Glue dowels to fill the holes and then drill new ones of the correct size.

-- Bondo Gaposis

View MrRon's profile

MrRon

4497 posts in 3083 days


#2 posted 11-10-2016 08:12 PM

Yes you can fill the holes with dowels, but don’t use the same size dowel as the existing hole. Drill a hole for a larger dowel. A small dowel will not provide enough material to hold a threaded insert. You will just end up with torn out threads. I would recommend inserting 3/4” dowels with epoxy.

View JoeinGa's profile

JoeinGa

7727 posts in 1847 days


#3 posted 11-10-2016 10:59 PM

Any chance they used something like this? If so, they may have been pushed back up inside the speaker box. You can try shaking the speaker and listen for any rattling, or take one of the speakers out of the cabinet and look in the bottom.
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-- Perform A Random Act Of Kindness Today ... Pay It Forward

View groland's profile

groland

181 posts in 3251 days


#4 posted 11-11-2016 02:31 PM

JoeinGa,
No, they did not use these T-bolts. I am familiar with these and am certain they were not used. Some other kind of threaded insert was used.
Thanks for your input.

Bondogaposis,
Thanks…good tip!

MrRon,
This is a good tip as well, and I will consider it when I get my replacement inserts.

Thanks to all,

George

View JoeinGa's profile

JoeinGa

7727 posts in 1847 days


#5 posted 11-11-2016 08:31 PM

Perhaps this type was in the holes?
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-- Perform A Random Act Of Kindness Today ... Pay It Forward

View robscastle's profile

robscastle

4540 posts in 2044 days


#6 posted 02-22-2017 09:20 PM

George,

Give the fellow LJs attempting to help you a hand, add a few photos of the situation.

-- Regards Robert

View William Shelley's profile

William Shelley

479 posts in 1309 days


#7 posted 02-22-2017 11:23 PM

If you added a 3/4” to 1” thick piece of really dense hardwood to the bottoms, or replaced the existing bottom, you could tap threads directly into the wood. M8-1.0 should be coarse enough to get good holding power.

I made a small 19” equipment rack to hold computer networking hardware (ethernet switches), the “standard” is M6-1.0 for fastening the ears. I just used two pieces of hardwood for the rails, printed a template out and used it to line up the holes, then just drilled and tapped with my 18v drill. Works perfectly.

If screws are going to be added/removed frequently, you can thin some epoxy and spread it in the hole. Once it dries, run the tap back through the hole again to clean up the threads.

-- Woodworking from an engineer's perspective

View rwe2156's profile

rwe2156

2716 posts in 1320 days


#8 posted 02-23-2017 04:01 PM

If its MDF, I would drill out a 1” hole, fill with dowel.

You could also open the back and glue a piece of wood over each hole and use a longer bolt.

Bottom line, those inserts will rip out of MDF if the ever fall or get bumped hard enough. That’s probably why they’re missing in the first place.

-- Everything is a prototype thats why its one of a kind!!

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