Home made mitre jig for picture frames

I have been making my first picture frame from kwila. The frame is about 1000 x 500, with the sides 40 x 20 mm.

With the weight of the frame, glass and matboard and foamcore backing, plus the fact that kwila is oily therefore weakening the glue joint on the mitre faces, I decided to re-inforce the frame with floating tenons. That meant making the mortices on the mitred faces of each corner joint using my 1/4" spiral upcut router bit, and making the floating tenons on my router table.

The frames are already cut to size, rebated for the glass and matboard, and the front face is molded, and the lot coated with Wattyl Scandinavian Teak Oil , prior to applying Traditional Wax.

The jig is made of 16mm MDF, and comprises of a top plate where the router runs in a channel to cut a slot in the frame fixed under the top plate. There is a flexible stop piece to set the length of the slot. It must be done for both ends of the top plate, the way the mitres are formed. I used a 6mm 50 x 50 Aluminium channel to keep the top piece at right angles to the support board which is held in the vice.

Guide pieces are screwed to the support board so that the frame pieces sit in them at exactly 45 degrees to the top piece. The frame pieces fit into the guide channel, and are clamped in position, wit the mitered face flush against the underside of the top plate.

The guides screwed at 45 degrees to the support piece are positioned so that the mortice commenced 2 mm past the rebate edge of the frame.

In today's e-letter from Popular Woodworking, it states :

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A jig is, by definition, a problem-solving device. As such, it shouldn't take more time to make the jig than it would to perform the operation without it.

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It certainly took a lot of time designing and testing every step of the way. I can tell you, if I had the hand skills I could have cut thousands of the mortices in the time it took to do this jig- but the results are worthwhile, and suitable for any 40mm wide mitered frame with an 8mm rebate. The results are re-producable


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Pics 1 to 5 above show the top plate with edge runners for the router



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Pics 6 to 9 show the vertical support piece with 45 degree guides screwed to it, the frame piece clamped in position


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Pic 10 shows the end result, with the 25mm wide 1/4" floating tenons
which sit in the 10mm deep mortices. Made from pine with 1/8" roundover bit

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ALL OF WHICH COULD BE DONE BY A $1500 FESTOOL DOMINO TOOL
IN A COUPLE OF MINUTES :p

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Nice job Jill.

I can appreciate the thinking and time that has gone into the jig and the obvious skills involved in the execution of the build.

It should give you a great feeling of satisfaction everytime you complete a frame.

Let's face it - anyone can buy a Domino and possibly use it well - more people would if they weren't so obscenely expensive [my opinion], however, you have come up with a viable, repeatable, inexpensive solution which I think is great.

Many thanks for your kind words, Bob38S. It has been a good learning experience for me, lots of thinking involved:)

Next step would be to make the sliding guides under the tip plate adjustable to take any width of frame timber. The 8mm wide rebate for the glass and backing would have to be cut first, however, as the slots in the mitre face commence 2 mm in from the inner edge of the rebate ( hope that makes sense).

Mind you, I wouldn't mind a Domino, all said and done, but would probably end up making a jig to hold it and the workpieces so every slot is exactly positioned :)

Well done Jill
Though I would have made it smaller and used a 40mm guide.
The way you have produced the slot is how I would have done it some 25 years ago before I was aware of the number of other guides that were available.
The method you have shown uses the base of the router as a template guide.
As a matter of interest when cutting the Mitres on the drop saw the saw has to be checked for accuracy before proceeding and may have to be adjusted. With a little more alteration to the jig the mitres could also be cut with the router set up in that position. One of the processes I had set up on my Super Jig.
Tom

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I would have made it smaller and used a 40mm guide.

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I agree with this, Tom, in hindsight it would have been far easier to use rather than using the router base as a guide. That way I would not have to worry about getting the flat edge of the router base in the wrong position. But I was still going to need stop blocks are one end of each slot, against the router base, to set the slot length. The slot length will vary depending on the width of the frame pieces.

The problem was, at the time I was in a bit of a hurry as always, and trying to cut two exactly aligned 40mm wide slots with 20mm radius rounded ends with precise start and finish positions - quicker to nail a few bits of straight timber to the surface.