Cant decide what to do with some weird joints

[Doug Shepard]

I'm currently working on a mockup from mahogany of this profile that will eventually be done in mesquite. Disregard the dimensions. Those and the thickness of the pieces is somewhat open, but the number of pieces and the angles are fixed.
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It's going to be the top till section of a jewelry box in this shape. Also disregard the small diamond shapes at the corners. Those are just where SU drew them as the intersecting pieces will actually interfere with each other unless cut/trimmed to fit. Also the angle on the 2 front setbacks will be shallower (start a little further in from the corners) than what I have in this version.
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I've got the mockup pieces of the profile cut and am working on a beveled shooting board to nail the angles and edges. I'm having a bit of a quandary on how to make the actual lid shape though - which is why I'm doing the mockup and posting here.

I'm going to approach the mockup in 2 ways:
#1 - Glue up the entire profile and see if I can figure out a way to cut the joinery on the total piece
#2 - Cut the joinery and glue up each tier of the lid then stack and glue them to form the lid

I dont want any splines showing on the outside corners of the lid section and want to go with joinery that isn't visible. I'm thinking that leaves me with a few options:
a) Slot the end of the miters and use splines
b) Blind mitered finger joints or Mr.Buxton's splined version
http://www.sawmillcreek.org/showpost.php?p=190074&postcount=24
c) Possibly just scarf joints on the 2 forward-most angles
d) Other ??

Both assembly methods have some pretty gnarly issues though
#1 - Cutting the joinery might be difficult due to tool access with the whole profile glued up but special jigs, lam trimmers, Dremels, and hand tools are probably called for.
#2 - A whole bunch of compound angle cuts I'd rather not deal with.

Any thoughts?

[Jamie Buxton]

Wow. That is going to be darn tricky. I'm usually full of suggestions for joinery, but this one will take some thought.

[Doug Shepard]

Wow. That is going to be darn tricky. I'm usually full of suggestions for joinery, but this one will take some thought.

Geez I feel like I just won a round of Stump-The-Band:D
Now you know why I was so interested in your blind mitered finger joint thread.

I also forgot to include just using biscuits to do the joinery and I've got the little Ryobi Mini-Biscuit jointer that might work out size-wise. But I'm leaning toward wanting to do something a bit more substantial. Also not too sure I want to include dowels as a possible joinery method.

[Dave Richards]

Doug, first a clarification. The front two corners will have the corners cut off but the back two will be square?

Could you make up a sort of molding in a long enough run or maybe several that have the profile of the top? Then you could cut the needed miters and build it up like a picture frame.

BTW, if you want to send me the SKP, I can show you how to get rid of those little diamonds.

[Doug Shepard]

Doug, first a clarification. The front two corners will have the corners cut off but the back two will be square?


Yeah the back corners are just 45 deg miters.
Dont know the angle on the front corners. It's going to be 2-3" wide and 1-1.5" deep, but "cut off" isn't exactly what I'd use to describe it. I'll have to have a separate cut piece of the profile to make that corner, not just cutting off that angle. In other words, I'll have a 6 piece run to get the shape.



Could you make up a sort of molding in a long enough run or maybe several that have the profile of the top? Then you could cut the needed miters and build it up like a picture frame.

That's pretty much the plan with method #1 for this mockup but connecting them is where I'm a bit stumped.



BTW, if you want to send me the SKP, I can show you how to get rid of those little diamonds.

Thanks - I appreciate the offer, but I actually kind of like them there as a reminder that I've got to deal with the problem of cutting/planing those interfering sections away.

[Zahid Naqvi]

I am not one of the more experienced WW'ers here by any stretch of the imagination, but I'll offer my 2c anyway. And without a decent drawing program it is hard to verbalize.

You can always get a single piece of lumber a little longer than the perimeter of the box and cut the step by step profile on it. Once you get one side profiled according to angles you need you can cut 45 degree mitres and glue them to get you box. The insides will remain straight though. From the drawing it seems all your angles between adjacent sides will be the same, let's assume it is 15 degree. Cut a long wedge of this (15 degree) angle, twice as long as your work piece. Cut this wedge in two equal pieces. Tilt your tablesaw 15 degree away from you work piece. Measure the length of the first two straight blocks (shown as 1.5 and 1.25 inches in your drawing), make a 90+15 degree cut on this line along the length of your work piece. Mark the height/length of the first angular piece on this 105 degree surface. Slide the first wedge against the flat side of your work piece, attaching by double sided tape, such that the thick side of the wedge is towards the saw and your work piece tilts away from the blade. Make your second cut along the line you just marked. Mark you second cut on this new surface. Slide the second wedge against the first wedge to move your work piece another 15 degree away from the blade. Make your last cut.

Excuse the crude drawing (and you can adjust the angles and length/width of each face) but it should illustrate what I am trying to verbalize. Keep in mind you are cutting in from top to bottom, sorta like in reverse order. The numbera indicate the sequence you will cut in. I haven't really done this, just tried to visualize in my head, so in practice the order of the cuts may be reversed. But atleast it may give you some ideas.

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Opps!:o the last image should have been numbered 4

[Doug Shepard]

...
You can always get a single piece of lumber a little longer than the perimeter of the box and cut the step by step profile on it. ...


Zahid - Thanks. I got the jist of what you were getting at right away and started thinking that the larger surfaces might make the joinery less problematic. But then I started thinking about how big a piece of wood I'd need to do it that way. I'd end up needing something like a 2.5" x 6" piece of stock to shape it and the mesquite that I have is only 4/4. If tried gluing something up, I'd end up seeing the glue joint lines when I cut through it to form the 15 deg. facets. Plus it would make the weight of the lid be excessively heavy too.
Making up the profile isn't really what I'm struggling with. That part is fairly straight-forward. Just cant think of an easy way to join up all the corners to form the box.

[Jamie Buxton]

Well, here's a scheme which might could work. It might not be as elegant as you'd like, but....

1) Make up a long piece of molding of your desired cross-section.
2) Cut it into the sections you need.
3) Glue the sections together using the masking-tape trick. In this, you lay the pieces out straight on a bench. Use masking tape to pull the outside faces together. Then turn the taped-together string over and put glue on the glue faces. Stand the string up on edge and pull the string around so that the two ends meet. Add another piece of masking tape, and stand back to wait for the glue to set. If you've cut your pieces at exactly the right angles, this does a surprisingly good job of forming a box or a picture frame. I've never tried it for a piece of molding with as elaborate a profile as you are tackling, but it should work.
4) So far, all I have is end-grain to end-grain glue faces, which isn't good. To fix that, span the joints with glue blocks on the inside. They provide face-grain to face-grain glue faces. They don't really have to be very big -- just span the glue joint. These glue block are going to be visible when the box is open, so you'll want to do a very clean job of building and installing them, unlike the usual glue block. Perhaps you could make the blocks with a contrasting wood -- y'know, turn it into a feature.

[Alan Turner]

Doug,
As I understand the problem, you are making a series of end grain glue ups, and you are concerned about strength, so want to use some sort of a mechanical joint, such as a spline or biscuit, blind.

One possible answer, and keep in mind that I have never worked with mesquite, is a product sold under the trade name "Cool Chem". At a WW show a year or 2 ago, they were present, and were demonstrating an endgain glue up of 3/4" by 3/4" by 4" pine, using an aersol activator to set the glue. Might have been just CA glue with a pretty label; don't know. Anyway, they glued it up in front of our very eyes, and no one is the crowd was strong enough to break the joint by hand. This is not elegant, but glue of this sort might work. You could mock it up and test for strength. This is only a small box, so the stresses would seem to be pretty minimal.

[tod evans]

doug, 3-m jetweld holds pretty well on end grain, a simple blind spline cut with a straight bit in a router is quick and easy for mechanical strength. .02 tod

[Jim Becker]

Stopped splines will add strength without showing in inappropriate places...provided, of course...you put them in the right places! LOL

[Lynn Sonier]

Weird joints?? Smoke em if you got em.

[Chris Giles]

I would miter the front corners the same as the back corners, then chamfer it off as shown in the sketch, either with an edge belt sander or a very sharp chisel. The beveled corner would show as end grain in both directions and should pretty much match in color after finishing. The end grain detail would be a nice accent tone to the face grain front and sides. You might consider doing the back corners the same way as I think it would establish a more confident and cohesive form, but that is perhaps a discussion best left to the design forum. Trying to provide a continuous face grain all around the perimeter may be making the situation more challenging than it really needs to be.

[Doug Shepard]

Weird joints?? Smoke em if you got em.
You didn't think I dreamt this mess up sober did you ?:D


Doug,
As I understand the problem, you are making a series of end grain glue ups, and you are concerned about strength, so want to use some sort of a mechanical joint, such as a spline or biscuit, blind.
...


Yep, that's exactly what I'm trying to do.



Doug,
One possible answer ...is a product sold under the trade name "Cool Chem"....


doug, 3-m jetweld holds pretty well on end grain, a simple blind spline cut with a straight bit in a router is quick and easy for mechanical strength. .02 tod

I think I'm going to investigate both of these. Never heard of either one, but you can never have too many rabbits in your hat - I'll check these out.


...
span the joints with glue blocks on the inside....

That idea actually has some merit. I'd already planned on doing some bracing inside the lid parallel to the grain. Thinking along the lines of guitar bracing but a little thicker so I can rabbet the inside edge to provide a frame to hole a mirror inside the lid. Hadn't thought about putting some bracing inside the corners though. I may do a little of that in addition to some of the other ideas.

I spent some more time today with SU and cut a 45 through the profile to see what came to mind and I think I can come up with a few small jigs that will allow me to put in these spline slots on the complete glued up profile. This is (sort of) what I had in mind with joinery option "a" and I think this is the same idea that a few of you mentioned. This is starting to look a bit more feasible and will let me avoid having to go the other route of gluing up each tier then stacking and gluing those up. Think I'm going to try and get one of the front corners mocked up. If I can get one of those figured out, the back ones will be a piece of cake. I think if I stand the piece up on end like the 3rd pic and use something similar to a jig for putting mortises on the end of a board I could pull this off - with the appropriate angles to the surface of the jig. Doing those 2 small pieces in the front will be a little hairy, but I don't think it's an insurmountable problem.
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Hope I can get some more of this done before it gets too darn cold to work in the shop any more. It was 14 degs before firing up the propane heater and I managed to get it up to a balmy 40-ish. Spent the day building a jig to build a jig. I got a taper jig for small parts almost done. I'll use that to cut the wedges for my beveled shooting board to trim up the beveled pieces of profile. At least I can haul a workmate, and shooting board inside where it's warm and do some planing in the laundry room. I figure once it gets too cold to work, I'll spend some more time learning SketchUp so things don't look quite so crude and don't take me so long.


Thanks for all the good input.