How do you get flush external edges when joining 2 frames?

[Fellows Framing]

Hi all,

Can any give me some advise on the following please:

I often made deep shadow box frames. They are deeper then the deepest moulding you can buy so I make then out of length of wood approx 2cms wide by whatever depth needed and router a section out of the back face for backing board. I then place a nice moulding on the top with the external sides flush.

BUT I always end up with the bottom deep frame and the top thin frame not quite matching so there is a few mms under and overlap at several points around the frame. I spend ages getting the mitres tight and true (or so I think) and the top frame lengths are measured of the bottom frame lengths but I can never get the frames to match (yes I am a perfectionist!). I end up having to sand the edges to make flusher. This is very time consuming. I have just done one with seasoned dry oak and it has happened, I thought it may be because the soft timber used before is abit green.

Any idea how to get both frames the same please? What am I doing wrong?

And if the over/under laps are unavoidable what's the best to sand them flush? I use a small belt sander and it's painfully slow progress even on soft wood.

Thanks
Sarah

[Roboframer]

It's not easy, especially if it's not two identical frames/boxes.

This is two identical boxes - from a flat frame moulding actually - mitred on its side and fixed together with pocket hole screws - I managed to get it almost, but not perfectly flush - had to sand it before finishing to match the top moulding.

But the top (capping) frame sits INSIDE the section formed by mitring the moulding on its side - so that might solve your problem, especially if you are hand finishing - just route out a section both sides, one for the backing and one for the capping frame to sit in.

[prospero]

This is one of those weird things. You can cut the deep box part and facing part using the same settings - put it together and in theory it should be a perfect fit. In practice there is always a bit gone astray. Even if you use Robo's elegant solution, you can dry fit the facing rails and they will be perfect, but pin them and there is a fair chance that one or more sides will need nibbling. I have various theories about how this comes about, which I won't go into here.

I have never made a box frame as you describe, but have often had to extend mouldings backwards. To level the two surfaces I've found that a scrap of glass makes a good plane. Slice a small piece and place it perpendicular to the frame side. Grasp it each side and tilt it a little toward you. Draw it down the side and it will shave off the high points. On a square piece of glass there are 8 cutting edges so when one dulls, just switch. A working framer should have an almost inexhaustible supply of little bits of glass.
This is much less effort than sanding and gives a better result. Cabinet makers use this technique for a really fine finish.

Don't press too hard or you'll snap the glass.

[Fellows Framing]

Thanks Roboframer - that's looks an elegant frame and I have noted the technique for future deep boxes saving the over/under lap issue.

Thanks Prospero - I have used the glass shaving method today to get rid of the overlaps and it work a treat. So much quicker than sanding. So obvious once you know about it.

From to after your advice - cheers

[IFGL]

great suggestion Peter, that is now stored in my arsenal of awesome ideas.