Desk pedestal joinery choices...

I'm designing a new desk for myself, with modular units for the "pedestals". Each side of the desk will have one or more of these of various widths. Each is a separate box (sides, back, bottom) made from 1/2in plywood with hardwood fronts (face frame, drawer front, whatever, not shown in photo). I'm wondering... what would be the best joinery to use to assemble the plywood box part - rabbet+glue? biscuits? lock miter? pocket screws? something else? a combination of the above?
Photo, details, and sketchup file: http://www.delorie.com/wood/desk/module.html
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I'm thinking of doing something like that, as well. My thoughts were a rabbet joint. I've found rabbet joints to be quite strong as long as the rabbet is reasonably tight (no glue gaps), though I generally use 3/4" ply. For a top I was going to either use a solid core door or for about twice the price Ikea sells Birch, Oak, or Beech butcher block slabs. I bought a small one over the weekend to replace my saw's extension table. We'll see how that goes.
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Me too, but in this case there will be two layers of 1/2 ply between each module - one from each module. Using 3/4 would have resulted in a 1 1/2 inch wall between modules, which I thought was too much.
Here's the full-desk plan so far: http://www.delorie.com/wood/desk /

I'm doing a solid oak top. My current desk sags a *lot* so it's something I'm particularly keen on avoiding.
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I think I'd build the pedestals as single units, possibly with the end book case separate. Not sure about that book case corner hanging in air, either. Plywood warps pretty easily.

If you're looking to buy the top, as I mentioned earlier, look at Ikea. I haven't seen anything close to their prices for butcher block. If you're building it yourself, never mind.
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Those will be solid wood, with a turned post brace. I just haven't added it to the design yet.

Nope, build. 5/4 rough lumber, planed to 1" thick.
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DJ Delorie wrote:

I used rabbeted sides+glue for something similar a few years back:
http://www.e-woodshop.net/images/StackedTansu15.JPG
http://www.e-woodshop.net/Projects8.htm
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"Swingman" wrote

myself. In fact my office is full of modular cubes. But yours look much nicer than mine. :(
The kitty looks very comfortable.
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"DJ Delorie" wrote:

http://www.delorie.com/wood/desk/module.html
Rabbet and/or dado as req'd.
Why make life difficult?<G>
Lew
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How deep though? Or is it non-critical?
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"DJ Delorie" wrote:

I'd consider it non critical.
Both joints are in shear so depth of cut isn't critical.
Rabbets are "shared" joints so 50% from each member.
3/16"-1/4" deep dado cuts for 3/4" wide dado cuts seems to work for Norm, so what the heck, it has worked for me, especially if you have flat bottom cuts.
Have fun.
BTW, might want to consider a sandwich top consisting of 1/4" ply skins and 1" foam core.
Light weight and stiff as a bull in fly time.<G>
Lew
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Just noticed you are using 1/2" ply.
For 1/2" ply I'd use 1/8"-3/16" deep dado cuts and 1/4" rabbet cuts.
HTH
Lew -------------------------------------------------------

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Yeah, shallow rabbets and dados just to keep things aligned. Keep in mind 1/2" is pretty thin. 3/4" would be bullet proof but 1/2" "might" bow, etc. Plus I suppose you will glue and either nail or screw from the outside and again, 3/4 would be better. Pocket screws won't work in 1/2 material, they are designed for 3/4 + but if you went 3/4 you could use them on the front interior to hold the face frames from inside. This is especially OK if it is drawers where they won't ever be seen.
The other option to stiffen up the joints if you do go 1/2" would be glue blocks in the interior. Maybe rip some 1x1 into a like a triangular molding and glue and nail in to the seams inside.

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DJ Delorie wrote:

I've had great success building milk crate sized storage boxes from 1/2" plywood using nothing but lock miter joints cut on the router table. The better quality the plywood the better the results (baltic birch, for instance), but most of the boxes I've built were standard construction quality 1/2" ply and they've held up famously. I've even had to build some for friends after they saw the results. :-) Another plus is that the joint is virtually invisible once it's all locked together. Glue-up is very easy because the lock miter joint is self-aligning; just slather yellow glue in the slots, fit it all together and clamp. You should try building some small boxes with this technique just for grins to see what I mean.
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You are a better man than I. I love the concept of lock miters but have just had a few huge failures that have made them scary to me.
1. Every time I use them I have to look up on the web for a description of how to make the adjustments during setup. Thers is a great document, I think from Amana that shows various misalignment scenarious and describes if you need to move the fence in or the bit up or down. It still takes for ever to get them setup. Yeah, setup blocks help but always still need a tune up.
2. Because the alignment is so critical and on two axis, you can't really do multiple succesivly deeper passes. You have to cut all the material at once. This can be a lot of material. I have ripped a partial bevel in the edge before to help minimize but you need to be carefule to not take too much material so there is enough left for the tounge.
I was building a stickly repro bed for a client. It had 4" posts, over 4' tall. The plan was miter locked boxes with some infill where I had huge 1" x 4" through tenons. I had beautiful figured QS white oak and trashed all 16 pieces because the few times the bit would catch and jump while hogging out the WO it was actually pulling it out of the collet so the setup changed but I was too dumb to recheck and none of them matched up well. I've since gone to a shaper for such ops so things are better but I am still very afraid of this joint type.

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SonomaProducts.com wrote:

I can understand your apprehension towards using lock miters; I had similar problems when I first started fiddling with them, but eventually the light bulb went on above my head and now I can set them up from memory without the assistance of documents or instructions. And you can absolutely make multiple passes without affecting the setup; you just need a fence that can return to a "home" position. I have a Jointech fence which makes this easy, but you should be able to achieve this with any fence using simple stop blocks clamped to the table.
To get the setup correct, you just need to follow some simple rules (all of which assume both workpieces are of the same thickness; let's not even think about the case where that's not true!):
1. Set the height of the bit first, according to the thickness of the stock; once you've done this, the setting never changes.
2. Set the "home" position of the fence, also according to the thickness of the stock, to take a full cut. Install stop blocks against the back side of the fence, or "zero out" the indexing feature of your fence so that you can always return to this position. For the initial cuts you start by moving the fence furthest away from the home position (forwards, towards you) until it's taking very little bite, then gradually back the fence towards the home position with each successive cut. That's all there is to it!
Ok, so I've left out a few details, and I don't have any diagrams handy, but I can try to clarify:
1. All lock miter bits have a vertical "center" position (along the Y-axis). For a bit that has a rectangular tongue, this is the point where the underside of the tongue intersects with the face of the tongue; for bits whose underside of the tongue is angled (upwards), the center point is the midpoint along the angled cutting edge. The height of the bit must be adjusted so that this center point is exactly half the thickness of the stock. When you think you're close, lay a couple of pieces of stock on the table and "nick" their edges against the bit (this works better if the bit is spinning, and you don't really need the fence for this - if you're careful!). Turn one piece over and compare the cuts, tweaking the height of the bit until you've found home center. Done!
2. Setting the home position of the fence is easy. Get a good thick straight edge with crisp edges (I use the 12" slide from my combination square). Place two scrap blocks of stock against the fence, on either side of the bit, then place the straight edge flat on the table against the blocks. Keeping this assembly snug, adjust the fence until the cutting surface of the bit is "kissing" the straight edge at the intersection of the bit and the table. Lock the fence down and set your memory device - you now have your "home" position.
That's it! The rest is left as an exercise for the reader. :-)
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Looking over some of the projects on your web page.. nice work there. Question: on the Lego cabinet, it appears that you have drawer runners on the insides of the doors to allow for full extension of the drawers. How do you prevent the doors from opening beyond 90 degrees and dropping the drawers?
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I don't ;-)
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