T-Nuts + Bolts

VR3

I'm gonna keep racking your folks brains - this project is gonna be done RIGHT buddy...

T-Nuts...

Type 1)
http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=081-1075

Type 2)
http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=081-1082

Type 3)
http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=081-1094

Type of bolt I plan to use...
http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=260-846

How wide are these T-Nuts? I am going to be doing a 1/2" route (width) to recess the driver... so they will have to be fitted in the correct position without marring the higher level of wood on the front baffle...

Ill attach a pic of the driver so you can get an idea of where the holes are located...

Thanks for your help!

jcaut

I like the "type 2" hurricane nut a lot better than the regular T-nut. Especially for MDF: The T-nuts are almost impossible to get seated without splitting the MDF, if you're working near an edge.

How wide are they? I don't have any of them handy, and I'm not sure if I know which dimension you're talking about. The big end is close to 3/4" diameter. Small end is sized to "bite" into a 1/4" hole, so it's probably in the neighborhood of 5/16", maybe 11/32". They're about 1/2" long, overall. They press into the hole from the back side, so as long as your recess is less than 1/4" deep (assuming a 3/4" baffle) they won't interfere. You can pull them into place with the screw and a washer, unlike a T-nut where you have to hammer.

Obviously you have to be very accurate when locating your holes. That's the main reason that I just use the Phillips head wood screws. The socket head screws look nice though.

Jason

VR3

What is the likely hood of stripping screws in MDF?

And what precautions - measures would be required to prevent it?

Only reason I want to use the T-Nuts and Bolts is to prevent stripping

Thanks for your detailed response (as usual)

Dennis Gardner

T-nuts and MDF are a bad idea......................Use OSB (strand board) or plywood behind the mdf to allow the t-nut ot take hold. If you strip out the mdf, the t-nut may just spin and be near impossible to get out.

Just my experience from dozens of DIY mdf projects.

VR3

How about taking my trusty .5" router bit (to put a .5" recessed lip) and spin it down about 3/4" (I have a 1" front and back baffle) and take a piece of 3/4" plywood... then cut it with the jasper jig to the size I need... then glue that into place....

Thoughts?

Thanks Dennis!

Dennis Gardner

Vr3MxStyler2k3 wrote:

How about taking my trusty .5" router bit (to put a .5" recessed lip) and spin it down about 3/4" (I have a 1" front and back baffle) and take a piece of 3/4" plywood... then cut it with the jasper jig to the size I need... then glue that into place....

Thoughts?

Thanks Dennis!

That would work great!! I just didn't want to see all the nice work ruined by a spinout. I've done it way too often, during my CA days.

tryrrthg

I agree on the t-nuts into MDF = bad idea. they will work themselves loose. I've used the hurricane nuts once on some speaker spikes. they were pretty nice, but I've never used them to mount a driver.

I just went through this over the past few days on my Atlas 15 sub project. I used 3/4" plywood, cut to the dimensions of the INSIDE of my enclosure. I then glued that to 3/4" MDF that is the size of the OUTSIDE of the enclosure. so my baffle is 1.5" thick. Having the plywood cut to the size of the inside of the enclosure gives me a barrier to help align all the walls of the enclosure. It works out pretty well. I took pics last night but they're at home.

EDIT: oh and if you want to see some T-nuts before you purchase them from Parts Express go to Ace hardware they have a pretty large selection of t-nuts and hurricane nuts.

jcaut

Vr3MxStyler2k3 wrote:

What is the likely hood of stripping screws in MDF?

And what precautions - measures would be required to prevent it?

Only reason I want to use the T-Nuts and Bolts is to prevent stripping

Thanks for your detailed response (as usual)

If you use something like THIS, into pre-drilled holes, and tighten them down by hand, you're not likely to strip them. If you use an electric drill-type screwdriver you can strip them. I use drywall screws sometimes when I'm assembling a cabinet. The threaded part is about the same (deep, coarse thread), and I run them in with a cordless drill. I've actually had more problems with snapping the heads off of them before they'll strip. They don't strip easily. Especially for driver mounting, I don't think you'd ever have to worry about stripping them out. And even if you did strip one, a little wood glue and a match stick or wooden dowel will get you right back in business.

What you're proposing with the plywood behind the MDF: That would work fine for using the T-nuts. Shouldn't be necessary with the hurricane nuts. I would use T-nuts or hurricane nuts on something like speaker spikes, but I've decided it's more trouble than it's worth for driver mounting.

Jason

tryrrthg

jcaut wrote:

What you're proposing with the plywood behind the MDF: That would work fine for using the T-nuts. Shouldn't be necessary with the hurricane nuts. I would use T-nuts or hurricane nuts on something like speaker spikes, but I've decided it's more trouble than it's worth for driver mounting.

Jason

I'm starting to agree. getting all the bolts to line up through the driver, then through the holes, and into t-nuts is one big pain in the ****! I spent at leat 2 hours the other night trying to get everything lined up.

If you want some extra "meat" for mounting a driver with screws you could still use the ring of plywood, that way it shouldn't strip out as easy as the MDF alone.

VR3

Tryrrthg,
I do the side panels under the front and back for one reason only...

And that is to get more accurate internal volume... the enclosure requires 10.25" - and I cut the side panels to 10.25" + 2 : 1" baffles = 12.25"

The bracing in the center and in the bottom keeps everything pretty square...

Thanks for all the responses folks, huge help...

I think I will try the plywood circle idea... after trying it out a few times...

Thanks again!

scottnbnj

tryrrthg wrote:

I'm starting to agree. getting all the bolts to line up through the driver, then through the holes, and into t-nuts is one big pain in the ****! I spent at leat 2 hours the other night trying to get everything lined up.

maybe i'm misreading or something. does a self centering bit like this help?

http://www.rockler.com/product.cfm?page=5911

tryrrthg

scottnbnj wrote:

maybe i'm misreading or something. does a self centering bit like this help?

http://www.rockler.com/product.cfm?page=5911

it might. That looks like a handy little tool.

Here is what I did. I put my 1/4" drill bit through the 1/4" holes in the driver and then tapped it with a hammer so the point of the bit should be in the center of the driver hole. I then used a drill press attachment to my drill to drill straight up and down, but apparently that didn't even help. it all worked out in the end, although not perfect...