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

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Forum topic by distrbd posted 06-14-2016 03:37 PM 2431 views 0 times favorited 27 replies Add to Favorites Watch
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2220 posts in 1865 days

06-14-2016 03:37 PM

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.

-- Ken from Ontario, Canada

27 replies so far

View pintodeluxe's profile


4824 posts in 2232 days

#1 posted 06-14-2016 03:52 PM

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!

-- Willie, Washington "If You Choose Not To Decide, You Still Have Made a Choice" - Rush

View a1Jim's profile


115171 posts in 2996 days

#2 posted 06-14-2016 04:00 PM

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.

-- Custom furniture

View splintergroup's profile


720 posts in 641 days

#3 posted 06-14-2016 04:09 PM

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!

View MadMark's profile


965 posts in 872 days

#4 posted 06-14-2016 04:11 PM

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.


-- Madmark -

View distrbd's profile


2220 posts in 1865 days

#5 posted 06-14-2016 04:34 PM

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.

-- Ken from Ontario, Canada

View TheFridge's profile


5676 posts in 905 days

#6 posted 06-14-2016 04:42 PM

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.

-- Shooting down the walls of heartache. Bang bang. I am. The warrior.

View Rick M.'s profile

Rick M.

7696 posts in 1799 days

#7 posted 06-14-2016 04:45 PM

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.


View a1Jim's profile


115171 posts in 2996 days

#8 posted 06-14-2016 04:52 PM

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.

-- Custom furniture

View JKMDETAIL's profile


162 posts in 1074 days

#9 posted 06-14-2016 05:38 PM

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.

View Jerry's profile


1709 posts in 1067 days

#10 posted 06-14-2016 06:04 PM

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.

-- There are good ships and there are wood ships, the ships that sail the sea, but the best ships are friendships and may they always be.

View distrbd's profile


2220 posts in 1865 days

#11 posted 06-14-2016 08:49 PM

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
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.

-- Ken from Ontario, Canada

View Redoak49's profile


1817 posts in 1407 days

#12 posted 06-14-2016 09:01 PM

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.

View distrbd's profile


2220 posts in 1865 days

#13 posted 06-14-2016 10:05 PM

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.

-- Ken from Ontario, Canada

View clin's profile


485 posts in 415 days

#14 posted 06-14-2016 10:46 PM

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).

-- Clin

View ArtMann's profile


103 posts in 235 days

#15 posted 06-15-2016 01:26 AM

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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