Mounting screws?

[kware1096]

Hi,
I am new here and was wanting to know what type of screws or hardware would be best for mounting an 18" Dayton U Max subwoofer in a subwoofer enclosure ? I purchased two of these and the mini Marty enclosures and will start the build next week .

 

[NINaudio]

I used course grain wood screws for mine.

 

[kware1096]

What size and how long?
I know that some people use allen or torx head bolts with a grabber nut on the bottom, but from my experience they fall off or do not cut into the wood .

 

[ryanosaur]

Possible solutions:
Install T-Nuts and use the appropriate matching screw/bolt with, perhaps, a little Blue Loctite.
In this case, match the hole size on the driver to the best fitting screw or bolt and associated t-nut.
Wood Screws, if you use them, should not penetrate through the other side... so as to how long... 1.5" thick baffle, use 1.25" screw.
Torx is good because they do resist stripping.
If installing a t nut or threaded insert... use a little epoxy to help lock them in place.

 

[Swerd]

Standard wood screws do work. With large heavy woofers, I'd use #8 wood screws long enough to penetrate at least ¾ of the way through the front baffle.

I prefer to use threaded inserts made for softwood (not hardwood). They come in a variety of lengths and diameters. They also come with flanges (as shown below) or without them. In my hands, these threaded inserts work much better than T-bolts or hurricane nuts. For a large woofer, I'd use ¼" diameter threaded bolts, but less than ¼" can work.

This is a T-nut (below). They can work alright in soft wood like fir, pine or some plywood. With MDF, I avoid them like the plague. Getting the sharp prongs to actually penetrate all the way into MDF is difficult enough to make the effort fail.

If you're mounting a large woofer with 8 bolts, you really need a drill press to make sure all 8 holes are parallel. Without 8 parallel holes, the T-bolts go in ever so slightly crooked, making it impossible to drive all 8 bolts in.

 

[lovinthehd]

I've used 10-24 x 1 allen cap socket screws with both threaded inserts and t-nuts (t-nuts carefully installed and glued in, no problems---so far ).

 

[kware1096]

Standard wood screws do work. With large heavy woofers, I'd use #8 wood screws long enough to penetrate at least ¾ of the way through the front baffle.

I prefer to use threaded inserts made for softwood (not hardwood). They come in a variety of lengths and diameters. They also come with flanges (as shown below) or without them. In my hands, these threaded inserts work much better than T-bolts or hurricane nuts. For a large woofer, I'd use ¼" diameter threaded bolts, but less than ¼" can work.
View attachment 35745

This is a T-nut. They can work alright in soft wood like fir, pine or some plywood. With MDF, I avoid them like the plague. Getting the sharp prongs to actually penetrate all the way into MDF is difficult enough to make the effort fail.

If you're mounting a large woofer with 8 bolts, you really need a drill press to make sure all 8 holes are parallel. Without 8 parallel holes, the T-bolts go in ever so slightly crooked, making it impossible to drive all 8 bolts in.
View attachment 35744

Thank you for the helpful info!
The T-nut is what i have tried in previous builds with MDF and failed . They will not sink the teeth into the MDF.
I will look for the above mentioned threaded inserts and allen head screws for them.

 

[ryanosaur]

Thank you for the helpful info!
The T-nut is what i have tried in previous builds with MDF and failed . They will not sink the teeth into the MDF.
I will look for the above mentioned threaded inserts and allen head screws for them.

You have to tap them in with a mallet and help secure them in place with a little epoxy or other strong glue.
Don’t rely on tightening the screw to pull it securely into place.

 

[Swerd]

The T-nut is what i have tried in previous builds with MDF and failed . They will not sink the teeth into the MDF.

That's exactly the same problem I had. Tapping them with a mallet didn't help, it only caused the teeth to bend.

For what its worth, threaded inserts also require that you drill starting holes for them. But I find them easier to work with than T-nuts. Maybe it was my failed experience with T-nuts that made me drill more carefully when I used threaded inserts. I also practiced in scrap wood before I did it on the speaker cabinets.

One brand of threaded inserts is E-Z Lok. Buy the inserts meant for softwood, not the ones for hardwood.

In my hands, I drill a full length starter hole while carefully holding a hand-held drill as perpendicular as possible. Unlike for T-nuts, these holes don't have to be full diameter, just wide enough to allow the insert's outer teeth to get hold. Next, you drive the insert in by hand, with an Allen wrench. The outer teeth of the inserts are tapered. As you drive it in, it tends to go in perpendicular. I found this worked well with large drivers that had multiple bolt/screw holes, much better than with T-nuts.

I will look for the above mentioned threaded inserts and allen head screws for them.

The threaded inserts work with any bolt with matching threads. The bolt heads can be whatever you prefer. I like the bolts with square drive heads, or the combination Phillips/square drive head. If I use a square drive driver, it doesn't slip out when I drive the bolt. Allen heads work as well.

I never use a Phillips head driver when near a speaker cone. It's too damn easy to slip out and puncture the cone. I know that for certain – don't ask how .

 

[highfigh]

Standard wood screws do work. With large heavy woofers, I'd use #8 wood screws long enough to penetrate at least ¾ of the way through the front baffle.

I prefer to use threaded inserts made for softwood (not hardwood). They come in a variety of lengths and diameters. They also come with flanges (as shown below) or without them. In my hands, these threaded inserts work much better than T-bolts or hurricane nuts. For a large woofer, I'd use ¼" diameter threaded bolts, but less than ¼" can work.
View attachment 35745

This is a T-nut. They can work alright in soft wood like fir, pine or some plywood. With MDF, I avoid them like the plague. Getting the sharp prongs to actually penetrate all the way into MDF is difficult enough to make the effort fail.

If you're mounting a large woofer with 8 bolts, you really need a drill press to make sure all 8 holes are parallel. Without 8 parallel holes, the T-bolts go in ever so slightly crooked, making it impossible to drive all 8 bolts in.
View attachment 35744

T nuts suck unless they can be held in place with a screw. Threaded inserts are the way to go but they need to be set deep enough to avoid pulling through.

 

[lovinthehd]

Thank you for the helpful info!
The T-nut is what i have tried in previous builds with MDF and failed . They will not sink the teeth into the MDF.
I will look for the above mentioned threaded inserts and allen head screws for them.

FWIW I don't use mdf, use birch ply.

 

[kware1096]

I wanted to thank everyone for the info .

 

[truckermaster]

Congratulations on your new purchase and your upcoming build! I'm sure you can do it all, and good luck with it.

 

[TLS Guy]

Thank you for the helpful info!
The T-nut is what i have tried in previous builds with MDF and failed . They will not sink the teeth into the MDF.
I will look for the above mentioned threaded inserts and allen head screws for them.

You have to mount them before you put the enclosure together. Tap them in with a metal drift. I use a brass drift.

 

[highfigh]

You have to mount them before you put the enclosure together. Tap them in with a metal drift. I use a brass drift.

They're steel- you don't need to use brass and they're made to be hammered in but they can be installed after the cabinet has been built. It's not always fun, but it can be done.

If I really wanted to make sure my screws don't loosen, I would probably glue a hardwood rim into the opening and use that, so the holes don't strip but, OTOH, that usually happens after repeated removal.

On boat hulls that use fiberglass over a wooden core, the standard practice is to drill the hole oversized, glue a dowel in and use that to hold the screws, but the edge in the hole is too narrow. If the baffle is made 1" or thicker, the screws should hold just fine but if it's only 3/4", a rim can glued behind the baffle, to add thickness.

Bottom line, drive the screws in with a cordless, but hand-tighten.

 

[nauc]

fwiw, JLs W7 subs come with pan head sheet metal screws...

 

[Swerd]

fwiw, JLs W7 subs come with pan head sheet metal screws...

View attachment 62980

That's useful info, except for one thing. The pan head screws JL supplies are good with one major exception … they're Phillips head. For that reason alone, I would throw them out and replace them with similar screws where the heads are either Square Drive, Hybrid Square/Phillips, Allen Head, or Star Drive. They're widely available, in stores or online.

Throw out those T-nuts too. Use threaded inserts (see post #5 above). You'll thank me later .

Square Drive (Robertson Drive)

Hybrid Drive

Allen Head (Hex Drive)

Star Drive (Torx Drive)

 

[MrBoat]

Start with wood screws and put a drop of epoxy on the screw first and once set, they will be difficult to crack loose again initially and may even have to be heated with a soldering iron to break free. If those give trouble, then resort to threaded inserts. I built a wood boat that sees pretty rough use in salt water and I used screws and ring nails set in epoxy throughout and none have backed out in 18 years of hard use.

Both of my sealed 12" subs have just drywall screws holding the drivers in. I meant to upgrade them but forgot until I saw this thread. I rock this system hard, too. They're just epoxied into MDF for 5 years by now.

I can pretty much repair stripped screw holes in mdf or wood indefinitely with epoxy mixed with sawdust or CA glue and a wood sliver.

Can pre thread the screw holes with the wood screw and then put a couple drops of CA glue in the holes to harden the MDF, too.