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Discussion Starter #1
First time making a joint with curved wood. FWW recently had an article that showed how to make a sliding dovetail joint on a curved drawer. But that curve wasn't nearly as pronounced as the one I'm working on.



I'll be trimming the bow flush with the sides so I'm thinking the sliding dovetail, if I can do it, might not have enough stock left on the outside of the cut. The smallest dovetail bit I have is 1/4" @ 80. The bow and sides are 1/2" thick. Unless I favored one side, that would only leave me with 1/8" stock on the outer edge. Would that be enough? BTW, the panel will be slid into the frame once the sides are secured to the bow. The panel is 30" wide so the joints would have to be strong enough to handle the possibility of slight racking while the panel is being inserted.

Thru dovetails have been voted out. I can't see dowels working. Only what you see in the pic will be exposed. So I was thinking of corner blocks on the inside as a last resort. I was hoping to make a more professional joint though.
 

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I recently had the same dilemma, and in this thread, I can show you how I solved it for my current project. I did use a sliding DT.

I started to show the process for them at around post # 26 I think. the side drawers were more of a challenge , because of the steep angle that I had to deal with....

I hope this helps.
 

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I can think of a few. Multiple small mortise and tenons struck me as a good way but wood movement might defeat it over not too much time. Ergo I think I agree with Fabian from a purist's perspective.

Alternately you could screw it from the face of the curved piece and plug that hole with a plug from that material and orient the grain to hide it.

Another is to cover the screws with a glued on veneer strip as the final installment of the bent lamination. This might work very nicely since making the curved piece lends itself to using a bent and glued lamination process.

Screws, while not appealing to the purist in me, would be stiffer and stronger over time than any all wood method. I'd embed them in exoxy or maybe JB weld as do a lot of Maloof style chair makers for their leg joints.


When using screws in a blind application one must be careful about using too much or too little torque driving them. Crushing the wood too much will cause the screw to be sloppy loose from the destroyed fibers moving under it and leaving it with too little torque will produce the same result because the fibers under the screw will become damaged by small movements.
Epoxy bedding helps with this because it serves to impregnate the wood a little under the screw thus assisting in providing a firm-er base for the screw to seat.
 

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Discussion Starter #5
Fabian, I saw your thread yesterday when I Googled bow front drawer joints and read the whole thing. It showed me a sliding dovetail wasn't a Herculean feat. The problem is the bowed front will be cut flush with the sides, leaving little stock for strength. I should have posted the sketch I drew to explain the application.



I've done some more looking into wood movement of the panel. Here's what I've come up with:

The panel is sapele. This is the first time I've worked with it. The sides are jatoba. According to the Wood Handbook (which I did not refer to until now):
Sapele - Shrinkage from green to oven dry moisture content
Radial - 4%
Tangential - 7.4%
Volumetric - 14%


Mahogany's numbers are 3%, 4.1% and 7.8%. Sapele's numbers are comparable to Elm, Maple and Red Oak. The Wood Handbook doesn't have Jatoba listed but tells you to refer to Courbaril. That species' numbers are 4.5%. 8.5% and 12.7%. But the Jatoba length is longitudinal so that's not an issue.

I have an Excel spreadsheet that calculates wood movement for a number of commonly used woods. It doesn't do Sapele but it does do commercial Red Oak. Tangential changes from 7% to 11% MC for 30" wide boards is 5/16". It's pretty much the same for Elm and Maple. I have no idea what kind of MC changes I'll see in our kitchen or if heartwood (which the panel consists of) shrinks & swells less, but tangential changes increase 1/16" for every additional degree of MC over 11%.

More and more it's looking like I'll have to make some modifications to the frame, probably by adding some strips of jatoba on the inside. I'm considering making it so the panel is removable. That will make it easier to wire the lights and maintain them later down the road.

If I do that, the joint at the bowed front will only have to carry the load of that piece alone. The sides will be anchored to the wall cabinets and the back to the studs in the wall. And wood movement won't be an issue anymore.
 

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Wow, Julie, that is a wealth of info that I didn't know was available out there. Is that wood handbook online, or an actual printed edition, that I would have to purchase at a store/online.

In thinking about your situation, I remembered that my first inclination was to try to do sort of blind DT on my drawers, but couldn't figure out a way to do it with to overlay..... Since you are going to be cutting the curve flush with the sides, I think that would be a very nice way to do it. The blind DT is a very strong joint, and I highly doubt any expansion/contraction would affect it. Of course, if you have never done one, then I would suggest you practice it a few times first before using the real deal.

Here is a link to how to cut the blind DTs. Of course, you would need to square up your front for the DT to fit squarely into the face piece.
 

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Discussion Starter #7

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Thank you for all the info. That will be quite useful in the future, for sure.

Please keep us posted as to what you end up doing. As you know... We love pics!
 

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Discussion Starter #10
If you have the jig, maybe pocket screws from the inside? As long as you can clamp the parts securely together.
I thought about that but I think the stock is too thin (1/2"). I've never used pocket holes for anything thinner than 3/4".
 

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here's a thought...

a locking rabbet ... well almost. :blink:
By making a curved "bar" that is glued to the horizontal surface, you can capture it with a curved rabbet on the mating piece. Either glue it down for a permanent solution or screw it in place for a temporary one. It would have a clean look on the inside, if that matters?

Another solution is to use rare earth magnets, epoxied in one of the pieces and metal plates on the other, or more earth magnets. Even the small ones are stronger than you'd think. If the pieces mate well, and I'm sure they would knowing your fine work, that would be an easy way to hold the face in place. :smile:
 
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My suggestion would be to make a grid with a formed front to apply the curve. In this thread, the curves were done with a hollow interior. You will need that airspace for your electrical fixtures and a method for accessing to install or service.

You could use veneer, bent lams, kerfed stock, or make the front coopered. If you are interested in a structurally sound method for configuring curves, I'll go into details.





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