I second the biscuit joints. They are self-aligning. If you want to try them without investing in a biscuit jointer, there are router bits with the right diameter and width. I used my router with bit for a year before I broke down and bought a dedicated biscuit joiner machine. Never regretted the purchase. (And I am CHEAP)
That biscuit jointing is probably the "best". However, as mentioned glue and clamps even with butt joints should be very strong. I use a resin based wood glue, Evo-stick, UK name. In a test with an edge jointed to a top of MDF when pushed to breaking the top layer of MDF pulled away. If for some reason your speakers might be applied to this sort of pressure, dowels could be added on the joints to improve strength.
rinx said:
Becasue i dont have a saw bench and have to use a jigsaw to cut out sections I use 2 by 2 inch bracing on my speaker boxes.
Clearly a jig saw is never gonna get it straight so I then cover in a thin carpet to hide the rough edges.
I usually finish off with a speaker connector plate and cab corners to make it look at least a little professional !As my cabinets are disco sized I always add 5 inch castors to make the more managable.
rinx said:
I respectfully disagree. I find it one of the quickest ways to assemble.
Lots of options.
MJL21193 [/i][B] use cleats (battens) in the corners after the box is assembled [/B][/QUOTE] It is easier if you attach them to one of the pieces beforehand. Then the only piece with exposed fasteners is the back. (brad or finish nails) [QUOTE]Just glue these in place without screws. [/B][/QUOTE] Use a brad nailer. Placing in glue without fastening is not going to strengthen the joint very much. [QUOTE][i]Originally posted by MJL21193 said:
Agreed.
chiily said:
Excellent idea if you are using just glue and clamps.
Cal Weldon said:
Hi Cal,
A nailer is not something everyone has. A compressor to drive it isn't either.
I'm pretty much dead against corner cleats. They are not needed for most boxes, especially small ones. They take up space inside that you need to factor in. They do add a LOT of time to the assembly - buy the material, cut, cut to length, glue, position, nail or screw, check alignment, remove, refasten, so on and so on.
A good compromise, if you lack confidence in the strength of the but joint, is to glue the cleats in after. This will be just as effective as putting them in beforehand. The correct glue is strong enough, don't doubt it.
Aligning just glue and clamps can be a real pain, esp on large, heavy panels. A biscuit joiner is very, very simple to use and fast to master.
Simply, clamp both pieces together flat (easy to get straight as they are both flat); mark both pieces at the centre of the biscuit; apply to each piece the biscuit joiner lining up the marks to the centre of the tool; undo clamp; insert biscuit; construct a flush, perfectly aligned joint; add glue and clamps. Dead simple.
Simply, clamp both pieces together flat (easy to get straight as they are both flat); mark both pieces at the centre of the biscuit; apply to each piece the biscuit joiner lining up the marks to the centre of the tool; undo clamp; insert biscuit; construct a flush, perfectly aligned joint; add glue and clamps. Dead simple.
I use battens, glue and countersunk woodscrews. There are many reasons beyond strength to do so. I use 2"x3/4" poplar boards cut to fit and glued around the inside of the box. As well as strengthening the corners, the front and rear baffles are attached to these battens. T bolts can also be sunk into the battens so that you can remove either the front or back or both to service the driver or crossover. The battens also brace the inside to cut down on resonance. Plus I don't have tons of clamps so I just line up the joint, countersink, glue, screw and its done, heck you can do the whole speaker before the glue dries. I think the extra hour it would take to use battens is worth it.
Toughen your MDF screw holes?
I have a biscuit jointer, I have a nice brad nailer and a nice big compressor, and I have a lock miter bit.
If you're producing quantities of speaker cabinets, the brad nailer is a godsend, it's SOOOO much faster and easier than clamping.
One problem with using the brad nailer: I think the brads would dull router bits fast? The last pair of speakers I put together (for myself) with the brad nailer I later realized I wanted 3/4 roundovers on the front edges. I'm hesitant to route the edges with the brad nails in them...
I thought the lock miter bit would be cool, but, I haven't tried it yet because: I don't want tons of MDF dust. If you are worried about the glue joint showing through the finish (and that does seem to happen in most cases, eventually, from what I've seen others post), then the lock miter joint would be a good option (unless you're going to do roundovers?).
The biscuit joiner ~ hmm, If I was building furniture, I would definitely use it. If I was building PA speakers for road use, I would use it there too. But for home speakers I usually just glue and clamp with yellow wood glue. I prefer to use the white Titebond Molding and Trim glue: http://www.titebond.com/IntroPageTB.ASP?UserType=1&ProdSel=ProductCategoryTB.asp?prodcat=1 because it doesn't drip and it dries fairly quick, the stuff is a real pleasure to work with compared to other messy, drippy wood glues, but, it costs more so I don't use it as much as I'd like to.
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- but -
The point of my post is something entirely different, I was searching for "screw" + "MDF" because I've thought of something potentially very useful for MDF speaker cabinets:
When mounting drivers on MDF baffles it's easy to over-tighten and strip the MDF so the screw just spins. This is particularly true if you are removing and re-mounting the drivers multiple times. I was trying to think of an easy solution (including situations where it's not convenient to use T-nuts) and I think I've got it: I'm going to use a little syringe to put thinned polyurethane into each screw pilot hole and let that harden before putting in the screws. I think that will toughen up the MDF sufficiently?
I'll use 50/50 thinner + poly so that it will soak in readily.
I have a biscuit jointer, I have a nice brad nailer and a nice big compressor, and I have a lock miter bit.
If you're producing quantities of speaker cabinets, the brad nailer is a godsend, it's SOOOO much faster and easier than clamping.
One problem with using the brad nailer: I think the brads would dull router bits fast? The last pair of speakers I put together (for myself) with the brad nailer I later realized I wanted 3/4 roundovers on the front edges. I'm hesitant to route the edges with the brad nails in them...
I thought the lock miter bit would be cool, but, I haven't tried it yet because: I don't want tons of MDF dust. If you are worried about the glue joint showing through the finish (and that does seem to happen in most cases, eventually, from what I've seen others post), then the lock miter joint would be a good option (unless you're going to do roundovers?).
The biscuit joiner ~ hmm, If I was building furniture, I would definitely use it. If I was building PA speakers for road use, I would use it there too. But for home speakers I usually just glue and clamp with yellow wood glue. I prefer to use the white Titebond Molding and Trim glue: http://www.titebond.com/IntroPageTB.ASP?UserType=1&ProdSel=ProductCategoryTB.asp?prodcat=1 because it doesn't drip and it dries fairly quick, the stuff is a real pleasure to work with compared to other messy, drippy wood glues, but, it costs more so I don't use it as much as I'd like to.
********************************************
- but -
The point of my post is something entirely different, I was searching for "screw" + "MDF" because I've thought of something potentially very useful for MDF speaker cabinets:
When mounting drivers on MDF baffles it's easy to over-tighten and strip the MDF so the screw just spins. This is particularly true if you are removing and re-mounting the drivers multiple times. I was trying to think of an easy solution (including situations where it's not convenient to use T-nuts) and I think I've got it: I'm going to use a little syringe to put thinned polyurethane into each screw pilot hole and let that harden before putting in the screws. I think that will toughen up the MDF sufficiently?
I'll use 50/50 thinner + poly so that it will soak in readily.
Just fit threaded inserts, if you find t-nuts too difficult. Have a look at http://www.modelfixings.co.uk/threaded_inserts.htm You can get flanged or non-flanged versions. I would think the non-flanged ones would be just what you need.
As for the original problem of the joints showing and general assembly, I agree with MJL that cleats are just not needed, butt joints with glue are fine. Shock breaking an MDF joint I guarantee you will not happen. If a loosely nailed and PVA glued large MDF box can roll around in the boot of a car whilst crashing and rolling down a carriageway from over 70 MPH and nothing at all happen other than being chewed up and smashed in on the corners then I think that says it's good enough to me.
The only reason to use screws is if you can't use clamps. I'd rather use clamps then I can roundover the edges if I want. And of course I don't have to mess about drilling holes. Screws create yet another different surface that can show lines as well.
The lines appear because of different expansion properties. The whole box inside and out needs to be sealed properly.
As for the original problem of the joints showing and general assembly, I agree with MJL that cleats are just not needed, butt joints with glue are fine. Shock breaking an MDF joint I guarantee you will not happen. If a loosely nailed and PVA glued large MDF box can roll around in the boot of a car whilst crashing and rolling down a carriageway from over 70 MPH and nothing at all happen other than being chewed up and smashed in on the corners then I think that says it's good enough to me.
The only reason to use screws is if you can't use clamps. I'd rather use clamps then I can roundover the edges if I want. And of course I don't have to mess about drilling holes. Screws create yet another different surface that can show lines as well.
The lines appear because of different expansion properties. The whole box inside and out needs to be sealed properly.
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