wedge clamps and dowels - dumb idea?

Hi all,
A while back, a friend of mine and fellow wrecker named Mark from across the pond introduced me to the concept of using wedge clamping to hold together a mitered box during glueup. It worked like a charm and I have used that method since then on a few other small boxes with great success.
However, the setup involved each time has been somewhat of a hassle. The biggest time consumer is making the base each time. I've got to get four chunks of wood, make sure the faces are dead square, then screw them to a base making sure they are all at right angles to each other. Sure, it's not a huge amount of work, but that's a lot of drilling, squaring, and screwing for a one-off jig.
So this morning, I got to thinking there must be a better way. I came up with the idea of drilling a grid of 1" holes (spaced 2 inches apart on center) into a 2X12x18" chunk of pine construction lumber that has been face glued to a ~3/4x12x18" thick piece of slippery countertop material. To change the spacing, I can just move 1" dowels around then keep a handful of various thickness loose blocks around to use as spacers.
I've got all the supplies, and am ready to do the glueup, but I figured I would toss the idea out to the wreck first to see if anybody spotted any critical flaws in my plan or if anybody had suggestions on improvement.
Here is a drawing (top view) to give a better example of what I mean. One thing you can't see from the drawing is that the mitered box, wedges, and blocks will all be about the same height (2"-3"):
http://webpages.charter.net/29Y/woodworking/members/spamola/dowelwedge.gif
Thanks a bunch, -Rick
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Rick Nelson wrote:

I've considered doing the same thing with pegboard that has 1/4" holes because drilling all the 1" holes accurately would be a problem. I figure sticking about 4 sheets together with contact cement would provide enough stiffness.
Then I'd use it to replace the single, warped sheet of pegboard that is the top of my downdraft sanding table. ;-)
I have various dowelled slabs that work well enough for holding something in place for sanding, but I need more table stiffness for gluing.
-- Mark
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[snip]

Great idea. I see a couple of potential gotchas, though:
1) The wedges must be tapered at precisely the same angle to ensure that opposite faces of each pair of wedges are parallel, and hence to ensure that the box is in fact aligned square. This isn't likely to be a problem, if you cut your own wedges all at the same time using a table saw with a taper jig. Just be aware that the bandsawn softwood wedges you can buy at the Borg are not likely to supply the degree of precision you will need.
2) When assembling the jig, you must take care to have the wedge which rests against the pegs rest against *all* of the pegs, again to ensure proper alignment. For example, in your drawing, the bottom pair of wedges is just fine. But the pair on the left isn't. As shown, with the inner wedge bearing against one of the pegs, and the outer wedge bearing against the scrap block, the scrap block could be cocked slightly, with both the direction and magnitude of the deviation dependent upon how far the wedges are driven in.
-- Regards, Doug Miller (alphageek-at-milmac-dot-com)
For a copy of my TrollFilter for NewsProxy/Nfilter, send email to autoresponder at filterinfo-at-milmac-dot-com You must use your REAL email address to get a response.
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Doug Miller wrote:

Not a problem. I don't have a table saw, but I do have a radial arm saw and a taper jig sled that I've used before with good results.

Good eye! I had to look, come back and reread what you wrote, then look again to see what you meant. With the fixed block tables I have used before, I never had spacers and would put the wedges directly between the secured block and the workpiece. When I first drew up the diagram, I did it the same way but figured it would help to avoid marring the workpiece (from the sliding action of the wedges) if I put the spacers next to the workpiece instead of the wedges. I guess it wouldn't be a problem to use it as shown in the drawing, but include a couple of thin flat pieces of wood or aluminum between the wedges and dowels to give the wedges a flat face to push against. Thanks for pointing that out.
-Rick
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Another option might be to use 90 degree corner clamps, such as those found at:
http://www.lowes.com/lkn?action=productDetail&productId!2028-28920-48404
I am not an expert cabinet maker/wood worker, though I have made a few items for the house. The corner clamps have worked quite well for mitered corners. If the pieces are pretty wide, you might want two for each corner. They have holes drilled allowing for mounting them on a work surface. At about $8.00 US each, and the fact they can be re-used indefinitely, they are a good buy.

[snipped]
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box making. They're pretty close to square, but not precise. And they flex under clamping pressure, too.
-- Regards, Doug Miller (alphageek-at-milmac-dot-com)
For a copy of my TrollFilter for NewsProxy/Nfilter, send email to autoresponder at filterinfo-at-milmac-dot-com You must use your REAL email address to get a response.
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The ones I bought at Home Depot are made of aluminum, and don't flex.
wrote:

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How close to square are they?
-- Regards, Doug Miller (alphageek-at-milmac-dot-com)
For a copy of my TrollFilter for NewsProxy/Nfilter, send email to autoresponder at filterinfo-at-milmac-dot-com You must use your REAL email address to get a response.
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close enough...
wrote:

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I have one of those corner clamps. It was my frustration with that pile of...aluminum in the first place that led me to seek out a better way and brought me to wedge clamping.
Aluminum corner clamp: Put it on one board. Put it on the other board. Loosen the first side and push it closer. Loosen the other side and the board slips through your hands into a pile of sawdust on the floor. Quick clean off the glue and reglue. Put it back in. Oops, looks like I smeared a bit of glue on the inside face of the board when I was cleaning up. Too late now. The top looks good - big gap in the bottom Loosen, fidgit, tighten, loosen, fidget, drop, etc... Not working, gonna need another one for the bottom. Clean off all the glue, and go to the hardware store for another clamp. Shell out $56 for 7 of them so I can do the whole box at once. Put glue on all the mitered faces and start over with a new confidence. Realise ends of the box are too short to use two clamps at the same time. Grit teeth and swear under my breath as I watch the glue dry and realize that not only did I just waste a total of $64 on these clamps, but that I'll have to retrim all the miters to get rid of the glue and modify all the other adjoining pieces to fit. And all that is without using thin pieces of scrapwood to keep from marring the finish.
Wedge clamp: Build the base making sure all your stuff is square. Glue up all 8 mitered faces. Put the four panels in place and let the tackiness of the glue hold them for the time being. Push the wedges finger tight. Tap tap nudge nudge everything to a perfect fit. Tap the wedges in firmly. Rejoice.
If anybody is going to spend much time making small boxes, I'd strongly recommend at least giving wedge clamping a try. I tried it and found it so much easier and more accurate than using those cheap corner clamps. Maybe there are nicer, more expensive 90 degree clamps available, but I just haven't had any luck with the $8 borg ones.
-Rick
L. A. Powell wrote:

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Good idea. It seems simple on the surface but as Mark & Doug have already pointed out there are gotchas. Another one not mentioned yet is that the dowels will have a tendency to lean away from the box as pressure is applied. A 1.5" thick baseboard may not be thick enough to keep them sufficiently vertical to provide good clamp force on the top of the box.
One way around this would be to center a lengthwise ridge on your thin scrap boards so that they only contact the dowels in one place. You'd also need to add a similar thin scrap board between the wedges and the dowels (or reverse the wedges and the thick scrap boards). And then again this could give rise to a different unforeseen problem.
Art

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Wood Butcher wrote:

With the countertop face glued to the dimentional lumber, it comes out to 2 1/4" thick. I'm using 1" thick dowels that will have about as much exposed as is buried in the base, so I don't think I will have a problem with flexing, but time will tell. I'm also planning to implement your idea of using thin strips between the dowels and the wedges. Thanks for the suggestion.
-Rick
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Another possible glue-up fixture is http://www.leevalley.com/wood/page.asp?page1162&category=1,43293&ccurrency=2&SIDor http://www.rockler.com/ecom7/product_details.cfm?&User_ID "438963&offerings_id401
Use two for a small box... or make your own...
JeffB
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JeffB wrote:

http://www.rockler.com/ecom7/product_details.cfm?&User_ID "438963&offerings_id401

Ha! That explains the all threaded rods, threaded inserts, and wingnuts I have sitting in my shop. I bought them a year or two ago to make a couple clamps just like the one in the picture, but got sidetracked. Time went by and I never got around to making it. Eventually, I completely forgot why I had bought that stuff in the first place. Thanks for jogging my memory. I definitely plan to give that a shot (unless my memory clutch slips again).
-Rick
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Rick Nelson wrote: It's good to buy the 'Speed Nuts' or 'Quick Release Knobs' pictured - they are available separately - to avoid having to turn a regular wingnut over long lengths of threaded rod.
Make sure to let us know how all the different things you try work out...
JeffB
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I think it's a great idea, and, unless you're required to conform to NASA specs, it should work out just fine.
Kevin
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