Formula for measuring picture frames - Woodworking Talk - Woodworkers Forum
Old 09-03-2018, 06:33 AM Thread Starter
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Formula for measuring picture frames

There was a discussion on the formula to measure correctly for picture frames back in 2011. I can't seem to find it here.

My question is how the measure the stock correctly for a picture frame with mitre joint and rabbet.

My picture size is 182mm x 182mm. Frame width 44mm and rabbet 6mm.

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Old 09-03-2018, 07:14 AM
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I fail to understand the question. I assume that you are discussing a new picture frame that is to be built. The first thing I would do is to DECIDE on what size I want it. That size would be based on picture size plus matt. You would then measure the wood to be used so that the outside (pointy end of miter) is the desired measurement.] Unless it is a very small frame I would probably use a 1/4" rabbet.

George
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Old 09-03-2018, 07:50 AM
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Quote:
Originally Posted by Chris Vermeulen View Post
There was a discussion on the formula to measure correctly for picture frames back in 2011. I can't seem to find it here.

My question is how the measure the stock correctly for a picture frame with mitre joint and rabbet.

My picture size is 182mm x 182mm. Frame width 44mm and rabbet 6mm.

You would ignore the frame width. If the rabbet is 6mm on a 45 degree angle the inside edge of the miter would be 6mm smaller than the long side of the rabbet on each end. Since the rabbet is 6mm you would make the inside corner of the miter 12mm smaller than 182mm to be skin tight. I think I would allow for at least 3mm shack with the picture so subtract 9mm from the 182 and make the inside of the frame 173mm x 173mm.
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Old 09-03-2018, 10:33 AM
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I'd use a "no measure" technique ...

I would make a stick 3/8" x 1" X 184 mm which fits inside the mitered frame rabbet, leaving the other miter uncut or long. Make a mark where the end of the stick touches the rabbett and that's where you make your other miter. the stick is 2 mm longeer to allow for a small gap inside the rabbet for the picture. The reason for the stick is it's light weight and easier to work with than the actual picture.

Any time you work with math or formulas, it's easy to make an error.

The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)

Last edited by woodnthings; 09-03-2018 at 11:45 AM.
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Old 09-03-2018, 01:30 PM
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No formula required, measure the photo or mask and transfer it to the frame:

Wise men speak because they have something to say; fools because they have to say something -Plato

FrankC
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Old 09-03-2018, 03:59 PM
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This is not complicated. The easiest way is as follows:

1 ~ Measure the picture L & W
2 ~ Measure the width of the frame. This is F
3 ~ Add two times F to L. This is the outside length of the frame. You can easily hook your tape on the frame to measure.
4 ~ Add two times F to W. This is the outside length of the frame. You can easily hook your tape on the frame to measure.

If you want the frame to overlap the picture, subtract two times the overlap distance from the length and width.

Rich
In furniture 1/32" is a Grand Canyon
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Old 09-03-2018, 05:20 PM
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It's not quite that simple ...

You have two issues that need attention, the "gap" around the picture for easy insertion and expansion of the frame AND the depth of the rabbet.

The OP spoke of a 6 mm rabbet. If you need a 2 mm gap all around the picture, that leaves 4 mm of frame to secure the picture. If you have a 1 mm gap all around, that leaves 5 mm to secure the picture.

Other issues are whether there is a glass in front of the photograph/picture or is there a mat like around a water color painting, or is this an oil painting with no glass? All these need to be taken into account when framing artwork or photographs.

This is why I like working with a story stick or an actual length stick to see exactly what's happening and where to make my mark for the remaining miters. I like to leave an extra 1/4" or so to trim away for the final miter dimension.

The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)
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Old 09-03-2018, 06:33 PM
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Like most everything else it can be as simple or as complicated as you wish to make it.

Wise men speak because they have something to say; fools because they have to say something -Plato

FrankC
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Old 09-03-2018, 07:04 PM
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Just need to wait on Chris to find out if we have further confused him with the different methods we have posted here.
Steve Neul is offline
Old 09-04-2018, 12:55 PM
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I had a picture framing shop. My miter saw (dedicated picture framing miter saw) measured the rabbet length. I did no calculation on that part.

I can help with other aspects of the framing process. Keep in mind that as a picture framer we had to work to a much higher standard than a normal wood worker for miters. We not only had to have perfect miters, we also had to cut them on pre-finished moulding without chipping the finish.

When the 12" blade on my DeWalt chop saw cost \$95.00 in the 90s (as I recall), the 12" blade on my sliding table saw cost \$250.00. It is simply a more demanding process.
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Old 09-04-2018, 01:57 PM
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Quote:
Originally Posted by FrankC View Post
No formula required, measure the photo or mask and transfer it to the frame:

Attachment 365670
we build many picture frames, and this is how I give the carpenters to build, i'll write the dimensions on that 8" x 10". their rule is to add 1/16" for glass imperfections (e.g 8 1/16" x 10 1/16"). And, as shown in the drawing, that is where the measurement is taken and marked and cut.

I add an additional dimension, the height of the rabbet. I measure the glass, matte, picture, and backer board for the total height. we use flush tabs to hold it all in.
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Old 09-04-2018, 02:19 PM
where's my table saw?

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Yup, and you just did that very thing ....

Quote:
Originally Posted by FrankC View Post
Like most everything else it can be as simple or as complicated as you wish to make it.
However, I think that's an gross oversimplification. You really can't simplify some simple operations, take cross cutting a board on the table saw, for instance. There are many factors that come into play here. The type of blade used, the setting on the miter gauge, the height of the blade above the work, the length of the board and off fall, if there a blade guard on the saw, the type of wood being cut, whether the cut is at 90 degrees or other angle, ...... etc. You had better thought this through before just whacking off a chunk of wood, UNLESS of course, that is your sole intention.

Ripping is also a simple operation, until you think about it. I won't go into detail, but are many factors involved here as well., but get my drift.

The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)
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Old 09-04-2018, 03:49 PM
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Quote:
Originally Posted by woodnthings View Post
However, I think that's an gross oversimplification. You really can't simplify some simple operations, take cross cutting a board on the table saw, for instance. There are many factors that come into play here. The type of blade used, the setting on the miter gauge, the height of the blade above the work, the length of the board and off fall, if there a blade guard on the saw, the type of wood being cut, whether the cut is at 90 degrees or other angle, ...... etc. You had better thought this through before just whacking off a chunk of wood, UNLESS of course, that is your sole intention.

Ripping is also a simple operation, until you think about it. I won't go into detail, but are many factors involved here as well., but get my drift.
Whaaattttt............????/
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