# How Tight Should Box Joints Be?



## chessnut2 (Sep 15, 2011)

Hey folks. I wasn't sure this is the right category or not. I just tried out a new homemade box joint jig today. The joints are extremely tight. I can press them together by hand, but with a lot of effort.

I measured the tongues and slots, and they are all equal, tongues the same and slots the same. There isn't a steady increase in spacing as you measure across the tongues either.

Here's what bothers me: The tongues are right on 3/8" but the slots are a hair under. Around 11/32" or maybe 23/64". I had to buy a new Whiteside 3/8" straight bit (couldn't find a spiral in stock around here) that is 2 and 1/2" long to get enough cutting height above the jig. Has anyone ever had a problem with a bit being slightly undersized? I double checked the package to make sure I hadn't picked up a plywood bit.

I meant to take a picture of the alignment and comparison of the 2 mating pieces but forgot before I locked up for the night I've heard that if you can get the joint together by hand you're OK. But the joint is tight enough that I worry about swelling and splitting when I glue it. Any ideas and suggestions will be greatly appreciated. Thanks. Jim


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## Mike (Nov 22, 2004)

It sounds like your joint is too tight Jim. You have to have some room for the glue in the joint. If your jig is based on the Router Workshop design slightly tapping the jig end closest to you to the right will tighten the joint. A small tap to the left will loosen the fit. Just like with jar lids: "Righty tighty, lefty loosey."


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## jw2170 (Jan 24, 2008)

You will need a "fine adjusting tool". VBG.

As Mike said, a slight tap should be enough.


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## Daikusan (Apr 12, 2013)

Here is a thought, borrowed from George Nakashima out of his book _The Soul of a Tree_. George would super dry his dowels and tenons with a heat lamp in a box - removing the moisture and shrinking them. He would then glue and the dowels/tenons would return to normal size forming a tight joint. He did not refer to any splitting. If the joint can fit without hard forcing then I would think super drying them, gluing, and assembling them you would be fine. The glue would set before they had a chance to return to normal size.


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## harrysin (Jan 15, 2007)

As Mike has described has always worked for me.


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## chessnut2 (Sep 15, 2011)

Mike said:


> It sounds like your joint is too tight Jim. You have to have some room for the glue in the joint. If your jig is based on the Router Workshop design slightly tapping the jig end closest to you to the right will tighten the joint. A small tap to the left will loosen the fit. Just like with jar lids: "Righty tighty, lefty loosey."


Thanks, Mike. It did what you said it would. I was surprised at how much I had to move it over, but I think I'm good now. The joint goes together easily, but holds together until you pick it up.

I've been looking through the threads for advice for buying a good router, and I saw the post you put up with 2 photos showing tables full of routers. My son saw it and said that in itself says a lot for Bosch.

Like I said, I've been shopping around for routers and I'm really liking the info on the Bosch 1617EVSPK. A couple of the home stores around here have them for around 200. Thanks again for everything. Jim


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## chessnut2 (Sep 15, 2011)

Hey James. My son borrowed my 8 pound F.A.T. to break up a concrete floor. I'll tell him I need it back.


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## Mike (Nov 22, 2004)

Jim, notice what shade of blue my name is?


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## chessnut2 (Sep 15, 2011)

Now I do. Bosch blue..........nice touch.


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## chessnut2 (Sep 15, 2011)

Steve...........thanks for the idea. I'm being pulled in too many directions to take on something new right now, but I'll keep it in mind for the future. Jim


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## Daikusan (Apr 12, 2013)

chessnut2 said:


> Steve...........thanks for the idea. I'm being pulled in too many directions to take on something new right now, but I'll keep it in mind for the future. Jim


It was just a thought more than a suggestion. It is an interesting book though. He was the master of the masters with hand tools.


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