Thread: Question on a picture frame

I start with a piece of the wood frame material and mark out a 45º mitre at one end with a 45º marking square.
Then measure 8.5" along from there (on the correct side of the mitre) and mark out the other 45º with the 45º making square. Just make sure the mitre is the right way and you're cutting on the outside of the lines
Repeat, and the then repeat twice using the 11" measurement.

I do mine direct on the mitre saw with two pieces of wood held together by tape, then they are both cut to the exact same length. Repeat for the other side.
For framing purposes it doesn't usually matter if the sides come out at 1/32" over or under as long as they are the same length so they form a tightly closed rectangle.

If you draw a triangle with two 45° angles, you will see that two sides are the same length, since a 45° triangle is just a square cut diagonally. Imagine that triangle at the end of your board…you will see that each mitred end adds exactly the width of the board. So, if you want an 11” inside dimension piece you add twice your thickness to get the overall length.

Originally Posted by Jayhawk714

The frame will be 8.5" x 11" on the 4 short sides. What I need to know is how do I figure what the length be of the long sides? I am using 1 1/4" wide pine.
Hope you can figure out what I am trying to say!!

Thanks!!

The four short sides . That took me three goes to work out what you meant Lol.

I don't get all fancy with numbers and angles doing this sort of thing .

First easiest way is just draw it out on something flat with a stick for straight edge and pencil and measure the outside lengths you
get based on your internal sizes.

Second way is cut a sheet of scrap anything to the yellow or black lines I drew to get internal size wanted so its true rectangle with square corners and lay your oversize made up stick swith their rebates on the back around that to get lengths. Your either working off the Black internal size ( your view of the piece framed).
Or the yellow size (Your picture that fits into the rebate).
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This rectangle piece you make up can also help out with fitting of miters and assembly glue up of the frame .

Another way.
If I was working out a 2436 mm x 3124 mm internal frame then I'd just draw up a corner of the frame and measure the difference of length . Green arrow. Then add it twice to the internal known lengths.

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Originally Posted by Jayhawk714

What I need to know is how do I figure what the length be of the long sides? I am using 1 1/4" wide pine.

Long side of frame member = Short Side of frame member + (2 x width).

In your case, the two calculate to be 8.5" + (2 x 1.25") = 11" for the short (top and bottom) sides, and 11" x (2 x 1.25) = 13.5" for the long (left and right) sides.

Mark those measurements on your material, and check to make sure it's 45 degrees

Originally Posted by Midnight Man

check to make sure it's 45 degrees

Further to this, cut a full square out of scrap to get your angle set properly (all 4 sides, just as you would with the frame). Most saws aren't exactly 45 degrees at the 45 degree stop and the error compounds with each cut (not each piece), so you'll end up with 8x the error at the end and it's REALLY noticeable.

Thank you for your reply!