Joint for different thicknesses along the grain

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Forum topic by Zach117 posted 10-30-2010 04:54 PM 1857 views 0 times favorited 10 replies Add to Favorites Watch
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19 posts in 3669 days

10-30-2010 04:54 PM

What joint would you use if you are joining two boards of the same species of different thicknesses along the same grain. Im joining a 4/4 vertical stile to a 8/4 vertical leg. My first thought was a butt joint since there is no cross grain problems. Since they are different thicknesses wont they move at different rates?

10 replies so far

View GaryL's profile


1099 posts in 3439 days

#1 posted 10-30-2010 05:04 PM

At risk of ridicule I will suggest bisquits, or better yet, if available, Festool dominoes, or even better yet, a 1/4” spline, or cut a groove in the 8/4 for the 4/4 to sit in…....Or what I would do would be to just edge glue them without worry since the grains are parallel. The expansion rate at the joint will be the same.

-- Gary; Marysville, MI...Involve your children in your projects as much as possible, the return is priceless.

View canadianchips's profile


2632 posts in 3606 days

#2 posted 10-30-2010 05:33 PM

Tongue and groove.. Cut the groove in the 8/4 half inch thick. Cut the tongue (1/2”) on 4/4 stock to fit into groove. This gives you more area for glue joint to bond to ! The secret to GOOD wood joinery is to have as much wood contact as possible. (In this case you wood have 1/4” + 1/2” + 1/2” + 1/2” + 1/4 = 2”glue joint
A regular butt joint would be 1” glue joint.)

-- "My mission in life - make everyone smile !"

View Walnut_Weasel's profile


360 posts in 3831 days

#3 posted 10-30-2010 05:51 PM

I am by no means an expert. If I understand you correctly the grain in both pieces of the joint are running in the same direction. If that is the case I would just butt joint and glue it. Modern glues are stronger than the wood itself. Just make sure to take your time to get the joint nice and flat along it’s length.

-- James -

View a1Jim's profile


117909 posts in 4186 days

#4 posted 10-30-2010 06:03 PM

A butt joint is the weakest joint . It sounds like your making a table were a apron meets a leg, if this is the case mortice and tenon is what I would suggest.


View levan's profile


472 posts in 3588 days

#5 posted 10-31-2010 10:02 PM

Zach not knowing what you have for tools, Gary L and canadianchips both have great ideas. I think James idea is ok also, I just prefer to have some kind of mechanical means to help align things.and more glue surface is a plus. good luck

-- "If you think you can do a thing or think you can't do a thing, you're right". Henry Ford

View Ken Reed's profile

Ken Reed

156 posts in 3793 days

#6 posted 11-03-2010 02:58 AM

The strongest joint, believe it or not, is without any machining other than making sure that the boards meet along their length tightly. There was a big discussion in WoodenBoat a few years back and after much debate aan lot of joints being destruction tested, this flat to flat proved to be the strongest!

If you need to line them up, then, yes, Dominoes or whatever can be quite helpful, as can a T&G. While what CanadianChips says seems to make sense, the tests don’t bear this out, largely because it’s next to impossible to get that tight of joint along the entire length of a joint on all those different surfaces.

On the other hand DON”T attach a table top to an apron with glue! The planks in the top need room to move with the seasons and if you glue to the table apron you’ll have problems when the humidity changes.

View Zach117's profile


19 posts in 3669 days

#7 posted 11-03-2010 05:45 AM

How about an actual WW post right now. Not sure if some you understand my question or I am not explaining it clearly.

This is for a desk. The stile to the leg.

View tbone's profile


288 posts in 4293 days

#8 posted 11-03-2010 06:27 PM

No one has suggested a sliding dovetail yet. That would work fine. Canadianchips is right on with his tongue and groove suggestion also. They’re the same principle—maximizing your glue surface.

Dowels, biscuits, and dominoes would all work nicely, but they require a butt-joint that MAY open up on you in the future.

Wood movement should not be a concern EXCEPT on the panel in the middle. That’s where you should make allowances for wood movement.

-- Kinky Friedman: "The first thing I'll do if I'm elected is demand a recount."

View levan's profile


472 posts in 3588 days

#9 posted 11-04-2010 12:27 AM

Zach hope this top view helps. The only places you have to be concerned about wood movement is at the rail to stile joint and any solid wood panel insert. I have indicated a mortise and tenon joint at that point. Of coarse location of the groove is dependent on your preferences. As far as gluing the stile to leg you can use most any of suggestion movement at this joint should not be any problem. I just indicate tongue and groove because thats what I prefer. I would just stop the groove in the leg before it would be visable. Once glued up into a unit, it will all move as a unit. Do not glue to the top. Any fastening system to top should allow for movement. You should allow for movement in the panel by letting it float. have fun Lynn

-- "If you think you can do a thing or think you can't do a thing, you're right". Henry Ford

View eruby's profile


79 posts in 3383 days

#10 posted 11-04-2010 10:52 PM

May be showing my ignorance here but why do you need the extra styles? (unless its integral to your design???) Why not just use mortise and tenon joinery between the rails and legs?

-- Eric - Baltimore MD

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