I am building a sealed sub box with dimensions of 20" H X 30"L X 30"W. I am using 1" MDF all round and a 2" MDF baffle and 1" MDF bracing with cutouts. I using the glue a screw method as I don't have clamps.
I started on the bracing today even though the holes are pre drilled I am getting very little cracks in the MDF after I have screwed the screws in. It is only on the bracing that this is occurring.
I was wondering if this is going to affect the integrity of the box? They are also glued, so I was thinking that it won't make a difference, but I thought I should ask the experts anyway.
Cheers
Dave
Edit: I am using a single 18" TC sounds LMS Ultra driver
I started on the bracing today even though the holes are pre drilled I am getting very little cracks in the MDF after I have screwed the screws in. It is only on the bracing that this is occurring.
I was wondering if this is going to affect the integrity of the box? They are also glued, so I was thinking that it won't make a difference, but I thought I should ask the experts anyway.
Cheers
Dave
Edit: I am using a single 18" TC sounds LMS Ultra driver
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The cracked material may buzz at high power.
Since the cabinet is sealed, the buzzing may not be audible, but the cracks may get worse under hard use, and become audible.
If the material is cracking, the pilot hole is not large enough.
Injecting glue or caulk into the cracked areas would be a fix.
Printer cartridge refill syringes work well for that type of fix, drill a hole the size of the syringe "needle" and inject until the crack cavity is filled.
The other reason that it is cracking is that you are screwing into the "end grain" of the board. MDF doesn't actually have a grain, but the ends do split more easily. A couple pipe clamps would only set you back about 30 bucks or less, and would be the best thing to do. And lots of glue! (wipe off the squeeze out) Jim.
I should have also mentioned the proper screw to use for MDF is a "Confirmat" screw. There is a special drill bit that corresponds with the the size screw you are using. Available from woodworking stores like Rockler, or Woodcraft. If you needed them in bulk, then someone like Mcfeeley's online is a well respected supplier. Hope this helps. Jim.
I am in Japan, so I don't have those stores you are talking about. But , I am sure I can get some somewhere.
Looks like I am going to start from scratch.
The braces are not that good anyway.
Can anyone tell me how much wood needs to be taken out of a brace to allow good air flow of a sealed box? Eg, in a piece of MDF that is 30"H X 20"W. This would work out to a surface area of 600 Sq Inches, does the surface area of the brace need to be say under 300 Sq inches?
@Cal Weldon , I am already getting slippage when screwing, as the screw stops biting and does not seem to grab anymore. Maybe I am using the wrong screws?
Looks like I am going to start from scratch.
The braces are not that good anyway.
Can anyone tell me how much wood needs to be taken out of a brace to allow good air flow of a sealed box? Eg, in a piece of MDF that is 30"H X 20"W. This would work out to a surface area of 600 Sq Inches, does the surface area of the brace need to be say under 300 Sq inches?
@Cal Weldon , I am already getting slippage when screwing, as the screw stops biting and does not seem to grab anymore. Maybe I am using the wrong screws?
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MDF is strange stuff. I use a lot of it for tables in the shop that I want to stay flat. But I always make a torsion box with it, cover the top and sides in plastic laminate, and seal the bottom with polyurethane to seal it up. I have used screws, but it doesn't hold hold them well. They are just there to hold it until the glue cures. I general use 1 5/8" brads with an air nailer. But even they will split the MDF on the edges at times. The sub box I made for 2 15" Cerwin Vega subs for my van have held up very well with just Ozite carpet on the exterior.
JapanDave, I heard from my friend today, said he's never used them, so hasn't really looked for them. He will poke around his suppliers and see what he can find. Jim.
JapanDave, I heard from my friend today, said he's never used them, so hasn't really looked for them. He will poke around his suppliers and see what he can find. Jim.
Yeah, I thought so too. The sides and bottom did not split ,just the braces.
Never mind, I just ordered 16 X 3/4" pipe clamps from Rockler. Can you believe that Japan does not sell pipe clamps, only really expensive bar clamps. Picked up 16 clamps about $250 + shipping and got some pipe locally for an extra $70. Going with the bar would have cost me close to $1,500!!!
So I am going to start over just use glue.
I know this is probably the most asked question and from the research I have done I am pretty sure I know the answer, but,
Will butt joints be ok or should I use another method?
Butt joints are not the strongest. Do you have a way of cutting a dado slot? That would add some strength. You can make the dado with either a table saw, or a router. If not, then just do the butt joint and make sure there is plenty of glue. I'll let you know what Stu finds. Adding some type of fastener would add some strength. Jim.
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Anticipating the fact that the butt joints would no suffice, last weekend I went ahead and bought myself a $2,500 table saw and $900 router table, so I should be able to do dado joints with those two tables on hand. (I have been putting off getting these tables for years, so I thought now is the time)
I have plenty of scrap wood that I can take to practice from the cracked box, so as I don't screw up the actual box.
And I would love to hear what Stu has to see about anything over here.
will something like this below be ok,
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Or something like this?
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I will look into it. I have been looking at air compressors for a while now too, so this also mabey a good to to take the plunge!Yes, either one will work great. Man, you don't play around do you?
Hi JapanDave,
The pictures in this thread: Danley DTS-10 "Super Spud" DIY kit - AVS Forum may be of help.
With MDF you want to capture both edges of the material in the groove (if you are going to the trouble to dado) whenever possible.
Regards,
The pictures in this thread: Danley DTS-10 "Super Spud" DIY kit - AVS Forum may be of help.
With MDF you want to capture both edges of the material in the groove (if you are going to the trouble to dado) whenever possible.
Regards,
Do it, you won't regret it.
Butt joints are fine if you use full length cleats. It's really fast too with a nailer. You do all but one panel with blind fasteners. Use your clamps to hold while you nail, release and go onto the next panel.
For what you spent on clamps I got this little Porter Cable combo set with 3 nailers.
Thanks for the advise Coolmeadow & Cal.
I needed the clamps for the vener anyway.
I am a Makita man myself, and I am going to see what they have over here. No doubt they(Makita) are expensive. But those tools last forever.
Another Q, on a 1" thick piece of MDF, how deep should the dado's be cut?
Cheers
I needed the clamps for the vener anyway.
I am a Makita man myself, and I am going to see what they have over here. No doubt they(Makita) are expensive. But those tools last forever.
Another Q, on a 1" thick piece of MDF, how deep should the dado's be cut?
Cheers
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