# Is clamping box (finger) joints necessary when gluing?



## TopamaxSurvivor (May 2, 2008)

I am wondering if clamping a good tight box joint is really necessary when gluing? If they are tight enough to stay in place when dry fitting, do you need to clamp to have enough pressure to make the glue work? Some adhesives are pressure sensitive and you need to hold pressure for a few seconds to make them stick well. Is that the case with wood glue like Titebond II?


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## tierraverde (Dec 1, 2009)

My guess is with glue in between any joint, it is never quite seated until it is clamped. The glue sitting there is not forced into the porous wood without clamping, causing the joint to be weaker than it would otherwise.
I'm no expert but it's just my thoughts.
You know the old saying "Squeeze it till it Squirts"


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## helluvawreck (Jul 21, 2010)

*Topamax*, I think I would clamp it but I'm no expert either. However, another reason for it to be clamped would be that it makes it less likely that someone or something may come along and bump it or knock it off and disturb the alignment or break the bond while it is sitting there unattended.


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## richgreer (Dec 25, 2009)

If I have a tight fitting box joint (or dovetail joint) I don't bother with clamps. For me, a tight fitting joint is one that requires some persuasion from a mallet to fully seat the joint.

If I have a loose fitting joint, I always clamp.


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## Karson (May 9, 2006)

I've done a lot of glueing that I slide the pieces to get good glue distributation and then let them sit.

When making toys their are a lot of parts that are impossable to glamp easily if they cdan sit for 20 minutes they are usually hold enough for you to stack them higher. Glue takes about 24 hours to cure fully but Titebond is set pretty well in 1/2 hour or so.


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## Cosmicsniper (Oct 2, 2009)

I use large rubber bands to assure that the finger bottoms seat properly. Before I got the Incra LS setup and used a homemade box joint sled, I would purposely leave the finger joints proud so as to use regular parallel clamps to allow for the clamps to dig in.

IME, you should use some form of light clamping pressure though in order to keep things square, seat those finger bottoms, and firmly seat in your floating bottom panels. Sometimes, I cut box bottoms a little too snug and I need that pressure to close the joints.


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## teejk (Jan 19, 2011)

I vote with Rich. If it's tight inside and out (and square), I don't know what the clamps are going to do for you.


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## DLCW (Feb 18, 2011)

You should clamp. Glue will expand and contract as it dries causing your joint to become loose and things not fit right.


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## tierraverde (Dec 1, 2009)

I agree with DLCW
Why not clamp it and risk movement? It only takes a second.

Per Titebond II (right on the bottle)

"Surfaces must be clean and dry. Joints should fit tightly.
Apply a heavy spread of glue to surface and CLAMP for 30 minutes. Do not stress joints for 24 hours. Remove excess glue with clean, damp cloth. Close cap after use.

Game, Set, and match.


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## Bertha (Jan 10, 2011)

I can actually contribute to this! I've done them both ways. I found that without clamping, the joint is a lot more visible (if that matters; heck, it might be desirable). I've clamped them just to wipe up the squeeze-out and let them sit for as little as 20 minutes to a few days. I can't say that there's been any appreciable difference. Once, I let a larger box sit entirely unclamped and it racked itself a bit out of square somehow. I just cranked it back square once dry and kept moving. Fingerjoints are ridiculously strong in my experience. I don't think they need much help at all.


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## SnowyRiver (Nov 14, 2008)

I have done it both ways too, but I find the clamps help to seat the joint even if its for 30 minutes or so. I find though its easier to clean up the joint if there arent any clamps on it.


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## TopamaxSurvivor (May 2, 2008)

Thanks guys. I was just curious. I thought they would be fine without clamps after they were seated with a mall, oops, mallet ;-)) or with clamps. Since I used clamps, I left hem on.


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## Grandpa (Jan 28, 2011)

I would use clamps and something to keep it square if it is that kind of piece. Somehting like a drawer should be squared. I have some home made squares I use. They are 3/4" plywood triangles. I cut the outer ends parallel to the back so I could use clamps out there. I cut the corner off about an inch in case glue squeezed out. I didn't want any extra wood glued inside my drawer. I leave them 30 minutes then they can be unclamped and set aside untill tomorrow if you need the clamps. Just my way I suppose.


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## Bertha (Jan 10, 2011)

Pa, I bought some expensive Bessey 90-degree clamps. They were so fussy that I use your triangles now


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## Grandpa (Jan 28, 2011)

I like the Irwin one hand clamps that most folks don't like. I use them for this purpose and they work well. I can hold the square with one hand and tighten the clamp with the other.


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## Bertha (Jan 10, 2011)

I have about 20 of those Irwins. Those and some bigger Kobalts are my go-to clamps unless I need the pipe. I don't own a single K-body but I want them (for no good reason).


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## Grandpa (Jan 28, 2011)

well, of course, you can never have too many clamps. I got them cheap from Rockler. I went without them for years because I refuse to pay the price they ask. I read an article in an engineering magazine once about tools that we use and the difficulties that they designer had in getting them marketed. This clamp was one. the man needed a clamp that he could work with one hand since like most wood workers he worked by himself. It took 7 years I think to get someone to pick up the design and market it for him. The very next year it was the #1 selling clamp in the country.


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## okwoodshop (Sep 15, 2009)

Don't know about the tightbond but I used gorilla glue and didn't clamp the wedges I was putting in the corners of a picture frame and the swelling of the glue pushed them out. If I have the clamps I use them. Grandpa can you send us a picture of those triangles??


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## roman (Sep 28, 2007)

I think the sole reason for the clamps is that "pressure" is needed to push the glue into the cell structure of the wood, more pressure, deeper penetration……….to a point, too much pressure and the joint is starved of glue

drop the box…………c if it breaks at the joint


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## Grandpa (Jan 28, 2011)

This doesn't appear to be square but it is and has to be square on the back side. I cut these on my miter saw. I used the table saw to cut the pieces on the ends then I used either a chop saw or band saw to cut the piece from the center. I trimmed the corner to keep it from glueing to the drawer if glue squeezes out. !


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## Grandpa (Jan 28, 2011)

Well, I need another lesson in using the photo bucket. This is the clamping part of one of the squares. Sorry.


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## MedicKen (Dec 2, 2008)

I would clamp them. I would also use cauls that are perfectly square to keep the box joints square as well


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## gfadvm (Jan 13, 2011)

I usually use 2 sets of parallel jaw clamps on my box joints. I feel it keeps the boxes from racking/warping while the glue dries. I use the same clamping when I do my pinned[ no glue] box joints. this keeps the drill bit from moving the joint.


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## NBeener (Sep 16, 2009)

My $0.02.

Can't hurt. Might help.

Last ones I did … came out SO perfect and SO tight (an accident, I swear) that I e-mailed the pics to the Wood Doctor, to ask if I should even glue-em-up. He said nah. Don't bother.

But … had I … an hour of clamping time ain't ever a bad thing ;-)


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## TopamaxSurvivor (May 2, 2008)

thanks guys, Wood glue must not require pressure like the peal and stick type adhesives, eh?


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