How to clamp compound miter joints?

[Painter]

I am new to framing and am building my first compound miter frame (not sure if it is called something different in the UK). I successfully made it through the labrynth of calculating a bevel at 25 degrees, and a miter of 38.4 degrees. But now I have four sides of a frame that remain a mystery of how to successfully glue them together. I normally use a strap clamp for a flat miter as I glue the sides together. However, these compound miters will not fit in any of the clamps I have. I wonder what the right solution is. I have gotten by holding pieces together for thirty minutes, but my wrists get fatigued and I feel kind of silly!

[JFeig]

Might I assume that your strap clamp has "corners" that are threaded on the strap. If I am correct, take them off and proceed to tighten the strap around the frame after gluing. The proper procedure for a multi-sided frame is to dry fit the complete frame prior to any gluing, just for safety. Safety = measure twice, cut once.

[The Crofter]

Any chance of a picture ?

My take is that you have a frame that looks a bit like a shadow box with sloping sides. Putting the strap on the widest part of the profile will cause another part to try to open and the strap will not stay on any other part of the frame. I think I would look at manufacturing my own clamping system using alloy channel, t nuts and some custom timber profiles/clamps to support and hold it together. Another approach would be to invert the frame and place weights against the outside to hold the pieces together.

This site may help http://incra.com/product_jfc_t-track_reg.htm

ps Never tried this myself....

happy new year

[prospero]

Hi and Welcome Painter.

I think I know where you are coming from.....

I have had this dilema sometimes when trying to strap-clamp a reverse moulding. I got around it by putting in a couple of small nails on the edge of the moulding to stop the strap slipping off. I should mention that this was on an unfinshed moulding, so any nail holes could be made good prior to final finishing. But there is no reason that this could not be done on a finished moulding if you are handy with the filler.

Once upon a time there was a tool which all framers seemed to use. It was like a pair of pliers that came with a set of springy C-shaped thingys with pointed ends. The pliers part opened the 'C' thingys so that they could be placed on the corners to clamp the mitres together. I haven't seen them advertised for years, so I doubt they are still available, but I can't help thinking they would be ideal for stuations like this.

[JFeig]

Here they are Prospero ---- at the bottom of the page


http://www.fine-tools.com/rahm.htm

[calvin the framer]

The answer is Ulmia clamps as used by frame restorers. Purchase from Bohle in Germany. Mind your fingers the buggers are sharp and very powerful. You buy the kit hich includes clamps of varying sizes and the reverse pliers to open the clamps.

[Not your average framer]

The answer is Ulmia clamps as used by frame restorers. Purchase from Bohle in Germany. Mind your fingers the buggers are sharp and very powerful. You buy the kit hich includes clamps of varying sizes and the reverse pliers to open the clamps.

There are similar clamps available in the UK from Tilgear. They are based to the north of London in a place called Cuffey (I hope I've got the spelling right).

I always said I would get some from Tilgear and one day I'll probably do so, but I manage just fine so far, as when I need to join "cove" type mouldings, I have the advantage of owning an original Stanley framers vice, (which is worth it's weight in gold when doing such jobs). Proper cove mouldings are machined so the bottom fits into the frames vice and all you need then is the glue and pins to join the corners. You still need to put each un-clamped front edge together with your fingers before pinning them in place. Handy wrap is also good for pulling things together while gluing, especially if like me you like making frames with stacked mouldings and want to pull the mouldings together along the lengths between the corners.

[prospero]

Handy stuff Handywrap. I use it exactly the same way for stacked frames.