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Old 18th June 2008, 08:17 PM   #21
Decker is offline Decker  United States
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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)
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Old 18th June 2008, 08:18 PM   #22
Dr_EM is offline Dr_EM  United Kingdom
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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.
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Old 19th June 2008, 09:33 PM   #23
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Default Re: MDF edges and screws

Quote:
Originally posted by rinx
Hei please tell me some ideas:

-how big should be screws diameter (I am doing box 20cm x 45cm x 150cm box. And how often should I use screws.

Why I am asking, is that my last speakerbox I used screws diameter about 3mm and they arent long. I put MDF pieces together and used autospackel to cover connection places, but even when I spackled twice between one week, after waiting a week I felt under fingers that the line where two pieces of MDF were together has some stage. I was wondering , maybe the MDF is playing on this connection line and pieces are removing eachother?! Any ideas?!

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.
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Old 19th June 2008, 10:57 PM   #24
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Quote:
Originally posted by rinx
I understand to use corner batten <snip>
1) it takes too much time for every speaker (its faster without it)
I respectfully disagree. I find it one of the quickest ways to assemble.

Quote:
2) still I believe some other option.[/B]
Lots of options.

Quote:
Originally posted by MJL21193
use cleats (battens) in the corners after the box is assembled
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]
Use a brad nailer. Placing in glue without fastening is not going to strengthen the joint very much.

Quote:
Originally posted by MJL21193
For 99% of the things you would build, yellow wood glue is the easiest and best choice.
Agreed.

Quote:
Originally posted by chiily
You could always try a biscuit joiner.
Excellent idea if you are using just glue and clamps.
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Old 19th June 2008, 11:33 PM   #25
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Quote:
Originally posted by Cal Weldon


Use a brad nailer. Placing in glue without fastening is not going to strengthen the joint very much.
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.
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Old 20th June 2008, 12:18 AM   #26
DJMAC is offline DJMAC  United Kingdom
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In my experience, Glue and clamped well is very strong, the thicker the MDF will also make it stronger since there is more surface area.
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Old 20th June 2008, 12:22 AM   #27
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Quote:
Originally posted by DJMAC
In my experience, Glue and clamped well is very strong, the thicker the MDF will also make it stronger since there is more surface area.

I have read quite a few articles on speaker cabinets and I am told a good glue joint will have the wood break first before the glue gives !
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Old 20th June 2008, 12:41 AM   #28
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Quote:
Originally posted by nigelwright7557



I have read quite a few articles on speaker cabinets and I am told a good glue joint will have the wood break first before the glue gives !

Absolutely true, for a good tight joint, using the correct glue. Clamp it up tight (it's nearly impossible to put too much clamp pressure) and leave it to set overnight.
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Old 20th June 2008, 02:42 AM   #29
chiily is offline chiily  United Kingdom
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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.
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Old 20th June 2008, 07:19 AM   #30
athos56 is offline athos56  United States
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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.
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