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My Problem with T-Nuts

topper

topper

May 22, 2005
1,404
776
Charlottesville, VA
cakefightband.com
#1
So a while back my bass cab developed a nasty buzzing/farty sort of noise. I discovered three of the screws that held the speaker in were stripped. I replaced those three with t-nuts and machine screws and all was well for months.

Until this week. The noise started again. I decided it was time to replace all the screws. I started to take the speaker out and discovered that all three of the t-nuts I had previously replaced had vibrated loose. They were no longer stuck in the wood. They had come loose and were just vibrating their way off the machine screws.

I hammered those suckers in pretty good when I put them in. How did this happen? Do you guys glue in your T-Nuts or something? What am I doing wrong?
 
#5
I have to disagree with using LocTite on speaker mounting screws. I's all well and good putting the stuff on but if you have to get the speakers out again you could be in deep you know what!

Installing T-nuts, all you need to get them in place is a big pair of slip joint pliers. you simply squeeze them into place. Hammering can deform the teeth and prevent them from gripping into the wood. A small spot of glue between the T-nut and the wood will prevent them coming out again as you install the screws. In forty odd years of cab making I've never had a mounting bolt come loose.

Paul
 
#6
BassmanPaul said:
I have to disagree with using LocTite on speaker mounting screws. I's all well and good putting the stuff on but if you have to get the speakers out again you could be in deep you know what!

Installing T-nuts, all you need to get them in place is a big pair of slip joint pliers. you simply squeeze them into place. Hammering can deform the teeth and prevent them from gripping into the wood. A small spot of glue between the T-nut and the wood will prevent them coming out again as you install the screws. In forty odd years of cab making I've never had a mounting bolt come loose.

Paul
Click to expand...


As specified, using blue locktite would allow for future removal of the mountings screws... I used to shake them loose occasionally, until I started using a spot of blue locktite on them - and haven't had one loosen since, but have still been able to remove them, if needed...

The same locktite works well on saddle height adjusting screws on Fender type bridges...



- georgestrings
 
#7
I have had good results with a T-nut alternative called Hurricane nuts. You can pull them into place with a screw & washer instead of hammering or using pliers. Use a split-type lock washer under the head of the screw when you mount the drivers, as this will maintain pressure and prevent it from vibrating loose over time.

Another alternative to the T-nut is a threaded insert, reinforced with a drop or two of glue on the outer threads when you screw it into the wood.

I've never used loc-tite in this sort of application, but the idea makes me nervous.
 
#8
If t-nuts are coming out of the wood locktite isn't directly addessing the problem. It's better seating of the T-nuts that is needed. Since T-nuts are often riding on the edge of the driver cutout and sometimes can't get all teeth into positive grip I use the dab of glue BassmanPaul suggests, though I think Hurricane nuts are better, like Duke.

Another problem is when you attempt to remove a woofer and press down with the screwdriver it sometimes pushes the T-nut out and then you sometimes have a tougher time ; }
 
#9
BassmanPaul said:
I have to disagree with using LocTite on speaker mounting screws. I's all well and good putting the stuff on but if you have to get the speakers out again you could be in deep you know what!

Installing T-nuts, all you need to get them in place is a big pair of slip joint pliers. you simply squeeze them into place. Hammering can deform the teeth and prevent them from gripping into the wood. A small spot of glue between the T-nut and the wood will prevent them coming out again as you install the screws. In forty odd years of cab making I've never had a mounting bolt come loose.

Paul
Click to expand...

Finally, a sane suggestion. T nuts work perfectly fine in plywood as long as they're installed correctly. I've never had any fail and I use them not only in speaker cabinets but also for making shop jigs and fixtures.
 
#11
Maybe I'm wrong, but it sounded like the screws loosened up, and allowed the T-nuts to back themselves out of the wood... If the screws stayed tight - by using the locktite, then the T-nuts really can't back themselves out of the wood, right???



- georgestrings
 
#12
As an alternative i installed a 15" speaker in my cabinet
which had drywal screws,i put 10/32"
bolts with two washers two nuts a dab
of locktite,so far so good, the k3015 is
as solid as can be..
 
#14
Topper, you never said what size T-nuts you used. Maybe that is your problem. There are also different size barbs on the T-nuts. Use one that goes deep enough into your baffle. I drill the hole slightly smaller than the shank on the T-nut, and countersink the head of the nut slightly. I apply a little glue (construction adhesive) and seat the nut by drawing it into the wood with a screw and washer from the other side of the baffle. I mount the T-nut on the opposite side of the baffle that the speaker is on. Some people don't do this. I use a #10-32 screw.

I think that it is better to use a little Loctite (242) to gently but firmly hold things in place than to over tighten the mounting screw and risk warping the speaker frame.
 
#15
I'm using 10-32 bolts and T-Nuts. The T-Nuts have a pretty long barb on them. I think the problem is partly that they aren't seating well to begin with. Then over time they vibrate loose.I've tried using pliers and hammering to seat them. Honestly neither seems particularly effective.

And anytime I have a bolt that requires a little gentle encouragement to go in, the T-nuts have a tendency to pop out creating all sorts of problems.

Hurricane nuts look promising, but I don't think I've ever seen those at Lowes and need my cabinet back in operation ASAP, so I don't think I can wait for delivery.

I think the solution is going to be to glue these suckers in with a dab of construction adhesive.
 
#18
topper said:
I think the problem is partly that they aren't seating well to begin with. Then over time they vibrate loose.I've tried using pliers and hammering to seat them. Honestly neither seems particularly effective.
Click to expand...

I agreed with the whole locktite thing, but I can see how if the T-nuts aren't seated flush with the baffle, it wouldn't really help.

To seat the T-nut flush, you could try mounting them in the baffle first without the speaker with a really big washer on the front side of the baffle and then just crank away until the barbs are completely sunken in to the wood. Then you could remove the bolt/washer and install the speaker.

I'd still use a dab of blue locktite on there just to p*** off the more anal argumentative folks around here, though..:hiding:
 

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