View Full Version : Mdf
12-30-2004, 01:39 AM
i'm planning on using some mdf for a project and wanted to know what's the best way to join it, I know screws will work but do i go with fine or coarse thread?? i am going to predrill the holes first, i know it splits easily.
12-30-2004, 07:06 AM
My limited exposure to MDF has been to use course thread screws with glue.
12-30-2004, 07:40 PM
This is something I know about! I would use connecting screws if you are making cabs or boxes. You can find them at McFeely's.
12-31-2004, 12:08 AM
cool, thanks for the help guys
12-31-2004, 04:35 PM
Vipermanz, How thick is your MDF? If the conecting screws are the same as the ones I'm thinking they are... We call them Knock down Screws, they are 1/4" dia. with a corse thread, and a hex head. Length is 1 3/4" or 2 1/4". They work very well in K3, partical board, and will also work well on MDF...But... should only be used with 3/4" or thicker. Drill holes 1/4" dia, and ensure they are centered and straight. (If not, when the screw is seated, it will bulge out the side) Also Drill holes as deep or slightly deeper than screw length. If it's something that needs to be dis assembled, these screws are great. You can also use dowel pins, or biscuts, or even dado's to help strengten your joints. Depends on what your building. Oh ya, use a counter sink for the screw heads too, this will prevent the top piece from spliting too.
Or..... If your pinning, or dadoing, and no disassemble, use glue too. then you can just use Drywall screws, again, about 2" long, with a drill approxamately the same diameter, and again as deep or deeper than the screw length. The long screw with corase threads, is the secret to holding, not the amount of thread biting into the MDF.
Good luck, and have fun. When cutting MDF, always where a dust mask. That stuff is ugly when you breath it.
01-02-2005, 01:32 AM
Great tips, i am planning on using 3/4 to 1''. it's going to end up as a speaker box and i want it rock solid.
01-02-2005, 10:33 PM
If you're going that thick, I'd biscuit it. Biscuits and glue are BULLETPROOF. I've put a LOT of cabinetry together with plate joinery, and it is unbeatable for strength and appearance.
01-03-2005, 02:11 AM
I would consider wood edging. The sharp corners are easily broken
01-08-2005, 05:56 AM
Thick stuff eh. yup they'll be heavy, and very solid. How big are the boxes? Are you going to cover these boxes with a cloth type material? If so, the glue and screws will work, since the cloth will hide the screws. If they are just going to be painted, then the biscut way "Hides" the joinery, more or less. It looks cleaner. Another thing about MDF I forgot to mention too. If you don't use the wood edge trim Idea. Chamfer all the edges with a 45 degree router bit. This helps to stop the edges from chipping out. If you plan to cover with cloth, use a round over bit. then when you apply the cloth it fits around the corners, nicely and again less chance of breakage, if dropped or banged. Another suggestion to, is if you plan to move them around a lot. OSB 7/8" thick makes nice speaker boxes too. And it will stand up to a little more abuse too.
Just a thought.
01-08-2005, 04:22 PM
Thanks again, I haven't made a final choice on the speakers yet so the actual size is still in the air. I had planned on covering it with automotive carpet like most all the rest of them have.
01-08-2005, 08:40 PM
I always use "partical board" screws that I buy at Home Depot. They are a coarser screw but you still must pre-drill. Use carpenters wood glue or you could use urethane glue. I built a "kids kitchen for my daughters out of MDF. If you decide to paint it, sand everything down to at least 120 grit and prime with KILZ primer. It is an oil-based high build and easy sanding primer.
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