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HELP. Measuring lengths on a bowed and cupped timber. Please explain.

Started by pizza, July 21, 2020, 09:58:10 PM

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pizza

How is it possible to ACCURATELY measure the length from say shoulder to shoulder on a post that's bowed in two directions. I don't think it's really possible because you'd have to have an absolutely dead straight rod and then you'd need to drop the measurement from that rod down to the bowed or cupped surface all while holding the theoretical rod absolutely parallel to your reference line.

For instance if you were to lay your flat tape measure on the bowed surface to layout the shoulder to shoulder distance, since the surface is curved, that measurement would be theoretically too long because it's not a straight shot to the mark. Same goes for a cupped surface except that distance would be too short.

Am I being too analytical here? I am building a small timber frame shed and have this situation on a post as well as several others and was just wondering about this conundrum. And worrying about it. I am using the snap to centerline method on all my timbers since all are bowed and cupped to some degree. This particular post is 97.75" long overall and rises 3/16"+ right about in the center of it AND it is curved in 2 directions!

How is it EVER possible to even use square rule on any timber frame project when timbers are rarely square and straight? I don't see how it would be possible.

Thanks



Den-Den

"This particular post is 97.75" long overall and rises 3/16"+ right about in the center of it AND it is curved in 2 directions!"

3/16" rise in 8ft will cause a TINY error in length measurement.  That measurement is the least of your worries in my opinion.
You may think that you can or may think you can't; either way, you are right.

firefighter ontheside

I would agree that the error would be negligible unless the timber is bowed a ridiculous amount and then I'm sure you would not be using it anyway.  As far as drawing "square" lines, I wouldn't be too worried about that.  When building houses, we use a speed square that is only 7" long which is not highly precise, but should be accurate enough for your purpose.  The phrase "we're not building a piano" comes to mind.
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