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Old 19th November 2006, 03:45 AM   #11
vax9000 is offline vax9000  United States
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Aren't those called dovetails?
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Old 19th November 2006, 04:51 AM   #12
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I build many guitar cabinets, I was doing dovetails exclusively for the last few years using a typical craftsman dovetail jig. It's ok but about 6 months ago I built this jig.

http://www.plansnow.com/boxjoint.html

LOVE IT!!! The ajustability allows me to not have to worry aboutmy dado stack to be of precise dimensions and I can add and remove my jig from my mitre slide and re-add it later without having to worry about loosing registration.

Highly recommend it...

I've made at least 8 cabinets with it now and they work out super...

If you are planning to round over your edges and tolex the cabinet, you cant effectively use screws or nails... a well glued proper joint would require complete destruction of the cabinet before it fails... Do it right and you'll be happy for years. Plus you'll have a nifty jig for all of those other projects. I've made drawers, boxes, a small chest etc... since I made my jig in addition to the guitar cabinet and I keep thinking of new stuff just so that I can use it.
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Old 19th November 2006, 12:47 PM   #13
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If your looking for strenth only and not appearance of "craftmanship" then screws and glue are actually stronger than finger or dovetail joints. There are many modern construction adhesives like gorrilla glue and liquid nails that are stronger than the wood intself according to many tests in the construction trade mags. Finger and dovetail joints allow the wood to expand and contract etc so you don't end up with cracked furniture or drawerfronts etc. If you going to cover your amp case then go with screws and glue (and biscuits if you plan to jump on top of your amp while you play).
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Old 19th November 2006, 01:29 PM   #14
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Old 19th November 2006, 01:30 PM   #15
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A stronger alternative to glue-and-screw is to use a biscuit joiner. These are almost foolproof and the joint produced has been proven to be extremely strong. In the past decade or so the biscuit joiner (aka plate joiner) has become a standard woodshop tool. If your only use is chassis-making, it may be prohibitively expensive. I think I paid less than $200 for mine several years ago.
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Old 19th November 2006, 01:35 PM   #16
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The challenge is getting good gluing surfaces. First of all, the end grain (end of a board) will NOT make a strong glue joint no matter what kind of glue you use. Even screws driven in to the end of a board will not hold very well. You need to glue to the sides or edges of the board.

As already said, finger joints provide those gluing surfaces, but the joints must be tight for the glue to work. Also already mentioned, if you're not set up to make finger joints then you can provide appropriate gluing surfaces with a stringer on the inside corner of a simple butt joint. Screws are completely unnecessary if the glue joint is good. Use enough clamps and 'clamping blocks' to distribute the pressure.

The gluing surfaces must be clean, flat and mate nearly perfectly for a good glue joint. If there are gaps filled with glue then the joint will not be as strong as it could be.

Even white glue (Elmer's) can make a joint that is "stronger than the wood itself" provided the glue joint is tight. Yellow wood glue is a little stronger, has a faster set, and is more water resistant. Polyurethane glue (Gorilla) is completely waterproof. All three require good tight joints with adequate clamping pressure to work well.

If you don't have much experience, then white glue like Elmer's might be a good choice because it gives you the most time to play around before the glue sets up.

If the glue joint is good, then biscuits add no strength. They serve only to help align the pieces when assembling.

When glue is used, screws serve only as a replacement for clamps while the glue is drying. Personally, I would not use any in a project like this.

-- Dave, a professional cabinet maker long ago.
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Old 19th November 2006, 03:11 PM   #17
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Dave,

I agree that the use of screws is not the most eye pleasing method for " fine cabinetry", but this sounds like the guy wants a strong cabinet with reasonable looks. Simply gluing end grain without something to strengthen this type of joint (biscuits would do nothing to make this type of joint stronger) would be a recipe for failure.

Screws will increase the strength of this joint though. The only way to join end grain ro long grain and have it be reasonably strong is with a dovetail joint. Screws in this application will add to the strength of an otherwise weak type of joinery. Not appealling to the eye as much, but stronger than just a glue joint of this type.

If I were building firniture, then definitely dovetail all endgrain to long grain joints. For a less skilled craftsperson that has to go with end grained joints, at the least use an inside glue block the length of the joint, if you forgo screwing this type of joint together.
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Old 19th November 2006, 03:47 PM   #18
Sherman is offline Sherman  United States
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Quote:
Originally posted by PRNDL
I have a vintage craftsman table saw (it weighs a ton) that came with a dado blade (an off-center one)...

I made the jig out of two pieces of 1x8 nailed together.
...

I'm more confident after making all those mistakes and might try making the box joints tomorrow.

Older Craftsman branded tools were outstanding. Even the new stuff is pretty good (my table saw is a Craftsman folding saw since my workshop is too small for a cabinet saw).

I prefer a stacked dado set rather than a wobble dado blade. A stack gives a flatter cut to the bottom of the dado. However if you already have the wobble dado I say use it. An inexpensive new stack would run you $100.

1x8 is good. It should provide good support for holding taller pieces on edge. I agree the 2x4 may not be a big deal but it is hard to have too much support!

Hey, that's what mistakes are for, learning! I'll be once you get two pieces cut and fitting properly you'll love making box jointed corners! They do look cool.
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Old 19th November 2006, 04:02 PM   #19
AndrewT is online now AndrewT  Scotland
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Hi,
I agree with Kak and his suggestion to use biscuits.

BTW,
finger joints are a quick & easy way to avoid the much better dovetail joint.
I wouldn't bother with either.

A lapped joint with strengthening batten on the inside corner is an even easier alternative.
The batten (20mm square) can be either glued in or glued and screwed. If you want a tidier looking batten then triangular fillets provide just as strong a connection.

Another alternative is the grooved and tongued joint.
A router does this preparation fairly easily when you know how to set it up, but it needs more equipment.
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Old 19th November 2006, 04:33 PM   #20
Nordic is offline Nordic  South Africa
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Mittred corners at 45 degrees glues well, especialy on grain ends..

a few panel nails sunk and filled with putty and bob's your uncle...
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