canvas stretcher frame joint

[Woodmonkey]

Has anyone made these before or know the easiest way of doing it? The idea is that the wedges can be knocked into the joint to stretch the canvas so it doesn't sag once the paint goes on.

 

[Brentingby]

Looks like that one was made on the tablesaw. Steve Maskery's Ultimate Tablesaw Tenon Jig would be an excellent tool for this.

 

[Sgian Dubh]

Looks like that one was made on the tablesaw. Steve Maskery's Ultimate Tablesaw Tenon Jig would be an excellent tool for this.

A year or two back we did some research on working these joints and discovered there are machines dedicated solely to cutting them, intended no doubt for workshops that had enough stretcher bar work to make buying a machine viable. Here's a link to one machine manufacturer: http://www.stegherr.net/en/picture-fram ... e-brf.html

The alternative we came up with was to use a dedicated sawblade and moulder blocks all on the spindle moulder, but it would have involved four set ups which is time consuming.

I think for a one off, if that's what woodmonkey's asking about, the most likely approach I'd take would be with the spindle moulder, much as described above. It would have to be that or go with a largely hand worked approach that might include routers and jigs. Lastly, these stretcher bars are pretty economical to buy, even at a custom size from artists suppliers, and that might be a reasonable way to go, which would save a lot of time faffing about until the methodology is worked out. Slainte.

 

[AndyT]

Once you open up the joint with the wedges, to stretch the canvas, the mitre isn't doing anything.

You could get the same effect with a plain tenon and slot mortice joint, with slender wedges working against the side of the tenon in one direction and the shoulders in the other direction.

Alternatively, there is a variant in which the two grooves are run straight through, and the ends cut off with a simple mitre through the whole thickness of the wood. Tapered wedges fit into the slots across two pieces, holding the corners together in the plane of the picture while wedging it apart in the other directions.

These just need through grooves (table saw, router or plough plane, whichever you prefer) with a little bit of angle cutting at the ends, which could easily be done with a narrow chisel or a wide saw.

A diagram makes it clearer!

(From William Fairham's book on Woodwork Joints, available here and elsewhere.

 

[Woodmonkey]

Thanks fellas. I was asked by an artist friend if I could price up making a few for him, he was complaining of the cost to buy them (typically skint artist I guess). Sounds like i would struggle to make them for less than a supplier with a dedicated machine. I don't have a spindle moulder.

 

[glynster]

They're made on a shaper using cutters that work a bit like a cope and stick bit - I worked for company where we used thousands of stretcher bars a year and we looked into making them but it was too much cost to be worth it as they can be made in China for beans

 

[Sgian Dubh]

Sounds like i would struggle to make them for less than a supplier with a dedicated machine.

You almost certainly wouldn't get close to matching the price of mass produced standard size stretchers unless you're willing to work for peanuts and, as I said earlier, even custom size stretcher bars aren't overpriced, or at least that how it seems to me. Slainte.

 

[Steve Maskery]

Whilst I am very grateful for Brentingby's endorsement of the UTTJ, even I would acknowledge that it would be quite a job to build it just for this task. Sure, it could be used for it, and the results would be excellent, you would just need to do the mitres, but it's probably only worth building the jig if you plan to use your TS for tenon work generally.

S

 

[woodchip]

I pay around £4 for a pair of bars (so £8 a frame), including wedges, so I really don't think it's worth trying to make them yourself. Leave it to the mass producers.