Best joint for frame

I was thinking of making a frame which would fit around a box being glued, and with T-nuts and bolts on each of the four sides, would be used to compress the sides.

So the proposed frame would be subject to forces on each side forcing the sides out, so would need to be strong in all 4 directions. The problem is selecting suitable corner joints for the frame. Through or half blind dovetails would be unsuitable as they are only very strong in one direction. Mitred joints would be far too weak.

Can anyone please suggest a suitable joint for the frame?

So what you're proposing to make is some cauls?

Try eight of these Bessey clamps from Masters. $11.40 each They're brilliant!

https://media1.masters.com.au/media/...9831303748.jpg

Thanks LGS. Sadly, there are 3 Bunnings in Townsville, and it doesn't look like Masters is coming here. I remember having a set of them over 40 years ago, and I used them for holding RHS steel in place while welding :) Still have them somewhere, but can't use them for wood any more

Think I have it. Use a sliding dovetail tenon joint on each corner

Quote:

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Originally Posted by Dengue

Thanks LGS. Sadly, there are 3 Bunnings in Townsville, and it doesn't look like Masters is coming here. I remember having a set of them over 40 years ago, and I used them for holding RHS steel in place while welding :) Still have them somewhere, but can't use them for wood any more

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I'm sure I recall that you can order online at Masters. We don't have one locally either but I was on their website a week or two ago looking at some other clamps.... I didn't end up pursuing them though.



Thx
Jon

Quote:

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Originally Posted by Dengue

I was thinking of making a frame which would fit around a box being glued, and with T-nuts and bolts on each of the four sides, would be used to compress the sides.

Can anyone please suggest a suitable joint for the frame?

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something like this?

http://lumberjocks.com/assets/pictur...40104-438x.jpg

or this

http://nebula.wsimg.com/d874a2d92b0f...&alloworigin=1

I use these.

Attachment 364198

cheers
Arron

Thanks for the pics, guys. The first one is exactly what I had in mind ian, mainly for dovetail joints where I let the pins and tails protrude outside the box sides and then cut them off after gluing. The side of the frame in the foreground would need to be very strongly jointed to the cross member, hence the question. Not so sure the two screws would be adequate when all those bolts are tightened and forcing the long caul in.

I was thinking a sliding dovetail joint or a pinned mortice and tenon joint for those joints

Arron, I find that band clamp great for mitre joints, not so good for my dovetails

Hi Dengy

the base of the frame adds immense strength to the whole jig meaning that the corner joints don't need to be massively strong.
also the clamping pressure exerted on the box doesn't need to be that great. If you need great pressure to bring the box sides together, then there's something wrong with your box's joints and you need to think about re-cutting / trimming them.

Thanks ian, I hadn't noticed the base as it is much the same colour as the bench. Agree with your comments about the tension required for glue ups. I do tend to over-tension the joints :(