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Using T-nuts to mount speakers

Discussion in 'Amps and Cabs [BG]' started by Soulfinger, May 2, 2005.


  1. Soulfinger

    Soulfinger

    Sep 20, 2004
    Houston, TX
    Need a bit of advice here--

    I'm going to mount a speaker in a cab using T-nuts instead of just screwing it into the wood.

    Do I want the type of t-nut with the prongs that dig into the wood on the opposite side, or that kind the mount flush and are just held on by tension? My thought was to go with the prongs, but I was wondering if I might be missing something.
     
  2. BillyB_from_LZ

    BillyB_from_LZ Supporting Member

    Sep 7, 2000
    Chicago
    Prongs!!!

    And maybe some glue too if you won't be able to get to the back of the T nut if you happen to push the screw in too far before engaging the threads and punch a T nut out.

    Murphy's law dictates that it will be the last one and you'll have to remove all the other screws to take the speaker out and reinstall the displaced T nut... :D
     
  3. I agree with Billy.

    Also probably worth remembering that you can often take off a handle to get access to the inside of the box... if you have an 'incident' with the last speaker screw. A lot easier than taking the speaker out again (especially if you have an electric screwdriver)
     
  4. Yes, use the pronged type. I prefer the ones with 3 prongs over the 4 prongers. Why? Because the speaker screw holes are usually very close to the cutout hole's edge, and using the 4 pronged type usually means that one or more of the prongs will be very close to the edge. Using the 3 prong, you can position them where all the prongs have plenty of wood to bite into.

    Most T-nuts have dull prongs. They don't often bite into tough wood like ply very well. What I do is to take a small file and give the prongs a sharper point. I know it's tedious, but they dig in so much better. The further they go into the wood, the less chance that one is gonna push out.

    Use some glue. If not, you'll probably have one fall out the back like mentioned.
    Only put a small amount on the flange part (with the prongs) not on the shaft. This way you won't accidently get the glue into the threads.

    Don't hammer them in, or try to press them in with a C-clamp. This will distort the barrel and mess the threads up. I know. I ruined 4 like this.
    The best way is to get a bolt with the same threads as the t-nuts, and use a large washer between that and the t-nut. Postion the t-nut, and use the bolt to draw the nut up good and tight. I keep one hand on the t-nut when tightening, until I'm sure the prongs are biting into the wood properly.
    The washer keeps the bolt from digging a hole in your baffle board face.

    And last but not least. If you haven't drilled the holes for the t-nuts yet, make sure you drill the hole the size of the t-nut barrel, not the bolt you're using. If possible, try to use a scap piece of board on the back of the baffle to keep the bit from splintering the wood when it drills through the back. Since the holes usually aren't extremely large, I try to drill them the correct size the first time. It's ok to use a small pilot hole at first if you want but Once you drill a hole in the board, it's difficult to redrill to a slightly larger size without the drill bit chewing up the wood and splintering it so close to the cutout hole's edge... Even though it usually still works, it leaves you wishing you could have done a better job..

    Mag...
     
  5. tplyons

    tplyons

    Apr 6, 2003
    Madison, NJ
    Definately use T-nuts. Don't want to strip your new-speaker-in-your-kinda-customized-cabinet-holes now do we?
     
  6. Soulfinger

    Soulfinger

    Sep 20, 2004
    Houston, TX
    Thanks y'all.

    I'm on it.
     
  7. Petebass

    Petebass

    Dec 22, 2002
    QLD Australia
    You must have different T-nuts to the ones we get in Austr. Ours are designed to be hammered in. There's no other way to do it because the prongs face straight down. Yours sound better.

    If you're worried about diging holes into your baffle board face, do what I do and put the T-nuts on the back of the front baffle.
     
  8. I prefer using L-brackets with T-Nuts. This lets me mount the T-Nut farther away from the baffle board cutout, plus use much larger diameter T-nuts. I use 5/16" and Blue loctite.
     
  9. I don't think they are different. Standard t-nuts with a barrel (internal threads), having a round, flat flange area with prongs that face the same direction as the barrel. They go in from the backside, the prongs bite into the back of the baffle board to keep the t-nut from turning when you tighten..
    The problem is that when you hit them with a hammer, if that flat area you're hitting gets even slightly bent, the thread hole is already damaged. This actually happens quite easily, even more so if you use a C-clamp to try to press-start them. Everything looks just fine, but when you try to screw the bolt in, the threads are warped..
    If one was going to hammer them in, it would be a good idea to screw the bolt into the threads to keep the barrel/threads from being damaged.

    Using the bolt/washer technique, the t-nut starts properly aligned, and you tighten the bolt to draw the t-nut up tighly. The glue keeps them in there, and one won't push out the first time you remove the speaker and try to remount it.

    On my last project, I used some threaded inserts that worked surprisingly well. They screw into the hole from the back side using a hex wrench, the flange on the back is smaller (less chance of any overhang), and they don't slip. They only require a slightly larger drill hole to install.
    Another excellent alternative is the "hurricane" nuts I've seen at PartsExpress.com . These have barbs on the barrel instead of the flange. You tap these in with a hammer, and those barbs bite INSIDE the screw hole. They would probably be my next choice for a new project.

    Mag...
     
  10. Petebass

    Petebass

    Dec 22, 2002
    QLD Australia
    OK gotch now. Sorry I misinterpreted your first description. I'll definitely try this next time.
     
  11. 4Mal

    4Mal Supporting Member

    Jun 2, 2002
    Columbia River Gorge
    What Bruce said ... $4.00 a set from Brownell Sound in Portland is where I get mine ...
     
  12. Soulfinger

    Soulfinger

    Sep 20, 2004
    Houston, TX
    I'm having trouble picturing the L-bracket thing---hmmm....I wish I could expound on that more, but I guess all I can say is that I totally don't get it.
     
  13. 4Mal

    4Mal Supporting Member

    Jun 2, 2002
    Columbia River Gorge
    The "L" brackets ship 4 to a pack. You locate the Tee nuts 3/4 to and inch off the hole cut for the driver. Place driver in hole, place the short leg of the 'L' on the driver frame, bolt through the slot in the 'L' and tighten. Repeat three more times. Basically, the L is a small clamp after you tighten the bolts down. They work great and have the buge advantage of moving the bolt hole away from the edge of the driver cutout. The clamps in this pic are a little more deluxe and sort of 'Z' shaped. The other's I get a really L shaped and work just as well.

    [​IMG]
     
  14. Bud Bolf

    Bud Bolf

    Apr 17, 2005
    Howdy,
    I agree with Magneeto on the installation of the T-nuts useing a heavy washer and pulling the T-nuts into the wood! Then too make sure that the screws screw in nicely, first make sure that the screws turn in and out easily before placing the Speaker on. This way you know that the barrell of the T-nut did go in smoothly and not warp. If you have any screw's that go in roughly and heat's up, stop and back it out, put in a new T-nut and try again with a new screw (throw that screw out because it's probably stripped) make sure that it screws in ok. I've had this happen and had to hacksaw a screw to get it out!
    When you place the Speaker on the baffle for mounting, do it with the Cab laying flat on it's back, this removes tension from the Speaker. Now start all the screws and make sure that they still screw in as nicely as when there wasn't a speaker there!. If one or two screws are now tight, try a slight turn of the speaker and the holes may line up better.
    Lightly screw them all flush to the speaker then I snug up screws on a Speaker like installing a Spare tire on a car, snug up one, then go accross and so on and so on.
    Take your time.
    When removing speakers, push onto the Screws and turn to loosen, but once loose no further forward force should be applied to the screw, except to keep the screw driver on the screw. Too much forward force and you could push out the T-nut. Once loose you really should be able to un screw them with your fingers.
    Good Luck,
    Bud