# Is there an easy way to glue box/finger joints?



## distrbd (Sep 14, 2011)

The project I'm working on is a kitchen (coffee, sugar, tea) jar set.the wood is 1/2" Cherry.

Glue up process in general is my least favorite part of any project but I really dread gluing up finger joints, it has to be done though.
Do you have any tips or trick you can share? 
I made the fingers a little undersized so the joints are a little loose hopefully the glue can creep right in between them,other than that, I think if I add a couple of drops of water to thin the (TB III) glue it will help,that's all I have done in the past,I just don't want to use a rubber mallet to force the joints in.


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## pintodeluxe (Sep 12, 2010)

Like through dovetails, the hard part with gluing up finger joints is where to position the clamp for the best results. I usually use two small clamping cauls along each face of the joint. Get the caul blocks as close to the joint as you can. Unlike through dovetails, finger joints require you to clamp from both directions so it helps to have some clamps with a long throat to reach over the first layer of clamps.

Alternately you could use band clamps with plastic cauls. I haven't tried those yet.

If all else fails, use through dovetails!


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## a1Jim (Aug 9, 2008)

Hi Ken
I think watering down your TB is not necessary and perhaps weakens the glue joint. .I always just use an acid brush and apply a little glue to both sides of the joint . I can only guess that you don't like the gluing process is that you end up with a mess after gluing projects up ,all I can say about that is you are putting to much glue on,all you need is to cover each side with a light amount of glue and wipe off any excess with a lightly dampened sponge . If your problem is cleaning the inside corners take a 1/4" x1/4' stick and sharpen it like a long chisel ( 1" or 2") then let your glue dry to a rubbery state and then use the sharpened stick to clean the inside corners,works very well. If you are pre-finishing your work (which I think can be a good idea White glue works best because it dry's clear.


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## splintergroup (Jan 20, 2015)

I feel your dread 8^)

As Jim says, an acid brush (with the bristles trimmed) works well for getting the glue into all the right places. My problem is getting all the glue in place and the box assembled before the darn stuff starts to set. A real stressor!

My solution to lessen the panic is to use slow set (60 minute) epoxy. This gives me plenty of time to apply the epoxy and consider careful assembly technique to minimize the epoxy from getting scraped off and/or smearing over the finish surface. Some Waxlit or careful taping can help immensely with any squeeze out.

Willie has great advice for the second harrowing part of box joint glue ups, the freaking clamping!


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## MadMark (Jun 3, 2014)

Water does not weaken tbiii or elmers, it simply extends the work time (setting occurs as the water is pulled into the wood by capillary action).

Think about how the fingers mesh, you only need glue on one face. Glue one side of the finger and the bottom of notch on one piece only. Have your clamps preset & ready to go on - ditto for cauls & clean up rag.

I use the cheap tin handle 'acid' brushes as a glue brush. Puddle some glue and wet the brush, mix well and apply quickly.









M


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## distrbd (Sep 14, 2011)

Few great suggestions , I like the strap/band clamp & cauls idea, got a couple of those, also have a few acid brushes, cutting the bristles to half the length was a good tip.
Also like the suggestion to use small amount of glue and only to one side, I'll try that today.

60 minute epoxy? never thought of that, it is a good alternative if TB doesn't quite work out.
I'm now calm and quiet ,on my way to my shop , will let you know what happens.

Thank you ,Great responses so far, the more the better.


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## TheFridge (May 1, 2014)

Mathias Wandel cuts a set of fingers with the same distance finger to finger but with skinnier fingers. I've found it helps a bunch the few times I tried.


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## wormil (Nov 19, 2011)

I watched a How It's Made on fingerjoint boxes and they laid the pieces end to end with fingers interlaced and applied glue only the face of the fingers.


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## a1Jim (Aug 9, 2008)

From Titebond website

Can Titebond Wood Glues be thinned?
Most of our water-based wood glues can be thinned with water up to 5% by weight or by volume. Adding more than 5% water to our glues will decrease the bond strength. Titebond Liquid Hide Glue is thinned by gently heating the bottle in a pan of warm water. Titebond Polyurethane Glue may only be thinned by placing the bottle into a pan of warm water.


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## JKMDETAIL (Nov 13, 2013)

As far as cleaning the inside, I saw this somewhere and do not recall where. Take a drinking straw and pinch it together. Run it down the inside, glue runs into the straw for cleanup. And don't use more than you have to.


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## Sigung (Nov 20, 2013)

http://t.harborfreight.com/1-inch-x-15-ft-ratcheting-band-clamp-66220.html

http://www.rockler.com/box-joint-cauls-box-joint-jig-cauls-sold-separately

glue one side together at a time, square each corner up with an engineer's square as soon as you put them together, only apply glue to one side of the fingers on one piece, and the opposite fingers on the mate. once you have them assembled, tighten the band clamp and square one final time. This method will give you ample time before the glue sets up. Plan ahead! Get your whole glue up operation ready before you apply the glue, IE, clamps ready, wet sponge ready, squeezeout removal tool ready, work area ready. I've experienced the glue up panic many times, and I've found that preparation is the key to being able to get the clamps on and the box squared up before the glue sets up.


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## distrbd (Sep 14, 2011)

I just came back from my shop,finished gluing up the 3 canisters,Followed every advice that made sense to me which means every one of your posts were helpful.
first I adjusted the shop made box joint jig again so it would cut the fingers 10 thou narrower than before, this helped immensely because when dry fitting the pieces, all four sides went in without force .

I guess what I learned today is not to make the fingers to fit too perfectly, a small gap of 10 to 15 thou is still not visible but makes the glue up go a lot faster .
Used a short bristle brush, glue was thinned down within Titebond spec(less than 5%) but it wasn't really necessary since the gaps between fingers could have allowed full strength glue. 
Used a combination of strap clamps, and F clamps.(didn't have enough strap clamps, should buy more clamps.lol).
the squeeze out was minimal so I quickly wiped the little bit that came out.

The only drawback to narrower fingers is, the assembled box tends to get out of square easily so a small 2" try square is a must to have around as mentioned .

Now it's time to route the lids for the canisters, just ordered the proper dish carving router bit ,will post pictures soon.
Thank you all sincerely for your comments ,this is a perfect example why LJ rocks.


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## Redoak49 (Dec 15, 2012)

I use blue masking tape on the inside of the box just at the bottom of the fingers. You pull the tape off after gluing to get rid o f excess glue.

Also. Using less glue is better along with the acid brushes.


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## distrbd (Sep 14, 2011)

Redoak, I saw it on youtube someone using the blue masking tape you're talking about ,meant to use it but forgot,it is a good insurance against spreading and smearing the glue inside the box. next time maybe.


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## clin (Sep 3, 2015)

> I watched a How It s Made on fingerjoint boxes and they laid the pieces end to end with fingers interlaced and applied glue only the face of the fingers.
> 
> - Rick M.


Man, I like this idea. No doubt it's weaker by not using all that available glue surface, but you still have glue surfaces that are at 90 deg to each other. So if one is in tension, the other face would be in shear (the strong direction for a glue joint).


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## ArtMann (Mar 1, 2016)

Loose joints are weak joints. PVA glues have almost zero crack filling ability. The trial fitting needs to be snug and include some resistance to assembly. My opinion is that 0.010" (thickness of two sheets of paper) is too much gap and will weaken the project significantly. The crack will be obvious too. I hate to be blunt but you need to know this.


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## TheFridge (May 1, 2014)

Ehh. I've seen some tests to the contrary. That it's slightly stronger as long as the gap is filled with glue.


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## gfadvm (Jan 13, 2011)

I have done a lot of box joints by pinning them from the top and bottom with 1/8" dowels. The only glue is in the holes drilled for the dowels. You don't need to drill very deep to get a very secure joint.


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## distrbd (Sep 14, 2011)

Doc,that's not a bad idea at all(to use dowel pins),I should give it a try, it eliminates all the aggravation of the glue up process. 
Artmann,thank you for your comment,I never liked loose finger joints myself,have done a few project using this type of joinery in the past and always with snug fit,this was the first time I went with the youtube 's William Ng's suggestion and made the fingers about 10 thou narrower.(~7.10 mark)




The glue up went well, boxes look good and solid to me but we'll see whether the loose fingers will cause the joints to fail, I will let you and the rest of the gan know if it ever will .

Fridge, thanks,sounds reasonable.


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## daddywoofdawg (Feb 1, 2014)

When you dry fit, before you take it apart,put blue/green painters tape as close to the joints on the inside and outside faces,and leave them there.then after glue-up,and the glue is dry,remove the tape with most if not all the glue squeeze out on the tape.


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## unbob (Mar 10, 2013)

I have built musical instrument speaker boxes using 1/4" box joints on 12 to 14" sides. The best way to do those was using slow dry expoxy. Otherwise, it was too risky seizing them up halfway together. Box joints sure look nice when all goes well.


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## JohnDon (Mar 14, 2015)

"I watched a How It's Made on fingerjoint boxes and they laid the pieces end to end with fingers interlaced and applied glue only the face of the fingers."

I, for one, am confused. If I visualize this correctly, when the joint is assembled, the only glued joints will be a side grain (the finger face) against an end grain- which is a notoriously weak glue joint. While easy, you're throwing away the real strength advantage of box joints- the tremendous side grain gluing surfaces of the interlocking fingers. All you're ending up with, from a glue standpoint is a butt joint!


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## a1Jim (Aug 9, 2008)

John 
Sorry but I have a different opinion about the finger joint gluing and their strength . Even if you only glue one side of the Finger joint it is far far stronger than a butt joint,why? because a big part of any joints strength is how much glue surface it has and finger joints has lots of glue surface all most the same amount as dovetails,in addition to that, finger joints are not gluing end grain. like butt joint do.


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## TheFridge (May 1, 2014)

well, if it was on how it's made then it's probably a mass produced piece so they probably do what's easier for the process.


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## wormil (Nov 19, 2011)

> While easy, you re throwing away the real strength advantage of box joints- the tremendous side grain gluing surfaces of the interlocking fingers. All you re ending up with, from a glue standpoint is a butt joint!
> 
> - JohnDon


It's not my argument to have, just passing it along, but I will say that we can become obsessed with making things as strong as possible instead of as strong as they need to be. A box is very strong by its nature and glue alone is very strong.


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## Mahdeew (Jul 24, 2013)

I have found that glue hardly sticks to lacquer. In most of my projects, the finish goes on first before assembly. In this case all I can think of is to glue up all the joints, lay them flat on the table, assemble the six ends, wipe the glue, assemble.


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## Wondermutt (Jan 21, 2016)

Heres what I do:
Make sure Dado stack is square or 90 degrees. I have found if it's off by a few degrees, it will fit odd and hard to assemble

Set tb3 in the sun to help it thin out a bit

Dry fit box, disassemble and line the stock end to end

Glue both joints and press sides down to the piece that is flat on the table top

Take the last piece and press down, and box is now assembled.

Tape or clamp and have a beer.

For me, I make the joint gap according to the wood type. Plywood gets a 6 thou joint where hardwoods get between 4 and 5 thou for a gap. All of my joints are min of 3/8 to 1/2". Normally I get little to no squeeze out.

Stricky my opinion here. If you cannot see the grain of the wood through the joint on a box joint, you have to much glue.

Hope that helps

WM


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## BLarge (Aug 29, 2011)

Epotek epoxy- all you need is a tiny, super thin spread on the mating surfaces, dries in 24 hours, tons of time to get is cauled and clamped.


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