Box joint by degrees

[chopnhack]

Today after building a box joint jig I got started on a special request. I won't get into what it is or entertain speculation until after its built, but I have questions about box joints and angled box joints that I pose to the collective.

Have you ever used a box joint on an angled piece? Should there be an adjustment made before assembly to compensate for the other pieces that will be affected by the angled piece?

Below is just a dry fit, but I notice that I will have some handplaning to do to get the piece to sit flat as well as on top to be flush. The angle was only 5 degrees and I am sure if it was much more the piece probably would not have come together.

[Bill in Buena Park]

I think your joints look fine, I think its just a matter of planning for extra material on the top and bottom of the side pieces.

Regardless of the degrees, you are cutting your box joints perpendicular to the edge planes of the trapezoidal end pieces, to which your side pieces will mate, and the side pieces are jointed perpendicular to the plane of the end-grain edge - this should always be a fit.

Its the top and bottom long-grain edges where you would leave a little extra un-box-jointed material (i.e., start out with stock that's slightly wider than the cut edge of the end pieces), so when you dry fit you could mark a bevel line on the end grain of sides (top and bottom) for bevel cuts at the table saw.

[cabinetman]

For a simple answer, the joints following the angle of the ends are registered off the ends. They are perpendicular to the edge. If the joints were machined at an angle, there would be a step differential looking at the end, instead of them following the angle of the end and lining up.

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[toolguy1000]

couldn't the edges of the sides of the box be jointed 5* (top and bottom) and the bottom of the 2 ends trimmed to flush up with the jointed bottom pins of the sides?

[chopnhack]

Thanks guys, I had layed this out in sketchup so I thought it should work. I did a test cut anyway. Thanks Bill, your right, I should have left more material on the top, I could have used the ts to finish it out instead of hand planing.

I think the tops of the long pieces can be planed after glue up, the bottom probably easier on ts.

Would you guys plane or rip faced with this situation?

[LCHIEN]

Looks like you should do a 5 °bevel cut on the top and bottom edges of the side piece. which will make them the edges parallel with the top and bottom when installed.
You them have to start the end fingers so the side of the finger facing the end board is full width of the finger and the outside is narrower (bottom) and vice versa for the top.

In your test looks, like the bottom finger slot of the ends is wider than the other fingers. Camera illusion or real?

[greenacres2]

Also will need to account for the 5 deg on the bottom. In other words, if you're grooving for a 1/4" bottom, the groove will need to be cut at 5 deg so they don't point up.

I think.

earl

[Bill in Buena Park]

...In your test looks, like the bottom finger slot of the ends is wider than the other fingers. Camera illusion or real?

I see this too - my guess would be that you started cutting your fingers from the top edges of the pieces shown, and the bottom edges were not trimmed to leave 1/4in finger/socket interface. The advantage to this at the moment is that you could trim a little off the bottom of the end piece, and then bevel the bottoms of the side pieces to be flush.

As Loring said, I'd try the 5deg bevel rip top & bottom of the sides on the TS; you could leave 1/32 over and plane if you're concerned about ripping off too much.

[Black wallnut]

I think it matters what jig or method you are using to cut the box joints as to if you should bevel rip the sides first. If you are using a spacer fence attached to your router table then I would not bevel rip but plane after assembly. That said it looks great as a start and I think your final project will turn out just fine.

[chopnhack]

Thanks all, I ended up taking the block plane to bevel and it worked out just fine.

Loring, I think I get what your saying, the ideal method to account for this variation in the future is to bevel the finger, is that something that can be accomplished with the box joint jig and the t.s. set at a bevel?
The end (small pieces) were tapered by 5 degrees, so the mating long boards would have been the pieces that would need the tapering.

Being that the wood is only 5/8" thick and soft pine, I opted to put the dado for the bottom higher up from the bottom of the piece. I still need to make plugs since I didn't take the time to do a stopped dado.

As woodworkers, I am sure you can appreciate the cathedral grain running around the corner ;-)

[IMG][/IMG]

[Bill in Buena Park]

Looks great C&H. What kind of finish are you planning to use, if any?

[chopnhack]

That depends on the rest of the project... stay tuned!