Corner joint

Quick question how do I clamp this joint ?

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The best way that I know is pressure at 90 degree to the gluing faces as usual .
The outer angles and also shaped surface with polish has to be got around though .Attachment 451828

This leg break below had similar issues.

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I taped it first and scuffed the shinny surface with steel wool . Cut a block and roughly shaped its inside to match the leg surface. Then fixed the block to the tape with BOG to make up the differences and get the perfect fit . I use Sellys Plastibond. Its a high quality filler. Builders Bog is cheaper and should work for this.
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I didn't take any more pictures . It worked very well . I think I just had the inside of the clamp on a block with a cut out that sat on the inside corner. After it dries peel it off and wash the surface with turps to get tape residue off .

Something like that both sides of your job should work and give you the important 90 degree off the glue face angle .

Rob

Can you do it using three clamps, as in the attached figure.

Clamps A and B are clamped to each segment of the joint.
Clamp C clamps to A and B and draws them together, taking the joint with them.

Obviously A and B must be tight enough to not slide, but in truth a dowel joint doesn't benefit from great pressure. Generally, I like lots of pressure for the sake of the old 'drive the air out and the glue in' philosophy, but it wont work with dowels because after snugging the shoulders up tight there is no value in extra pressure as the dowel glueing surfaces are perpendicular to the direction of the pressure. Further, the surfaces of the workpieces are endgrain so they contribute little to the hold.

cheers
Arron


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Thanks for that auscab. Trying to get my head around it. I wonder if I could fix one side in some sort of a jig using the taper on the piece then I only have to square up one side.

Thanks arron that looks interesting perhaps securing a couple of angled pieces with the black clamps to give the red clamp some thing to work of

Quote:

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Originally Posted by goldie1

Thanks for that auscab. Trying to get my head around it. I wonder if I could fix one side in some sort of a jig using the taper on the piece then I only have to square up one side.

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The other way is you make up long wooden or steel jigs that have the same clamping face direction.
The other end has a block or some means of hooking the end of your pieces so it stops the two jigs from sliding along the work when the pressure gets applied . You can cut them out of flat ply or chipboard . I made steel ones with a wooden block screwed to it for a type of table I used to make a lot of.

This is a steel version . It hooks over the foot. I'm sure I made two for this job, didn't photograph them though . One each side clamped two legs on at a time. The wooden block gave the 90 degree to the glue face pressure. And the bit that slips over the foot stops it slipping. This same way can be cut out of wood instead of the steel. its a bit more bulky and can have weak spots.

You need two things for it to go well . The 90 degree thing and no way of it slipping . The sticky tape way can slip with enough pressure . So you have to have a larger area covered to stop that . If you do the two things mentioned and give it a dry run you will understand how well it works and why .


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Arron's way above is another good way . I would add protective blocks as well with the angles for clamping . And I fold sand paper three times and have that in between the blocks and the work . that helps stop slipping .

Rob

Great thanks Rob I'm getting the idea. I will make something up in wood. I'm no metal worker. This is a T H Brown bar stool. Its from a set of 4 but fortunately only one needs doing at the moment. I think I will try Arrons idea first with a couple of angle blocks and that sandpaper trick.
I will post a pic when I get something that works.

Cheers Ray

Ok all good. It was fairly simple in the end. Went with the three clamps idea. Made up some blocks cut on the diagonal sanded to the same profile as the work pieces
Then two clamps. I didn't have to worry about them slipping as the pieces were tapered and the last clamp was working against the taper.

Then the third clamp and Bobs your mothers brother


Thanks Arron and Rob. I wonder how they do them in the factory ?