# carpenters
**URL:** https://boards.straightdope.com/t/carpenters/174905
**Category:** Factual Questions
**Created:** [May 13, 2003, 6:46am UTC](https://boards.straightdope.com/t/carpenters/174905 "2003-05-13T06:46:29Z")
**Posts on this page:** 9
**Page:** 1
### Author:  [@Tony\_Montana](https://boards.straightdope.com/u/Tony_Montana)
#### Post date: [May 13, 2003, 6:46am UTC](https://boards.straightdope.com/t/carpenters/174905/1 "2003-05-13T06:46:29Z")
back cut on a 10/12 pitch?
I forgot the conversoins
I know you can do it with your square
QED?
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### Author:  [@zoid](https://boards.straightdope.com/u/zoid)
#### Post date: [May 13, 2003, 1:27pm UTC](https://boards.straightdope.com/t/carpenters/174905/2 "2003-05-13T13:27:01Z")
It’s been a LONG time since I’ve done any rough carpentry but…
I understand the 10/12 part, enlighten me on what you mean by “back cut” (like I said it’s been a LONG time).
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### Author:  [@Tony\_Montana](https://boards.straightdope.com/u/Tony_Montana)
#### Post date: [May 13, 2003, 5:54pm UTC](https://boards.straightdope.com/t/carpenters/174905/3 "2003-05-13T17:54:01Z")
When you stick-frame roof rafters you cut the bottoms (tails) on 10/12’s.
Then there’s a conversion on your square to cut the tops at the corrrect angle.
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### Author:  [@Philster](https://boards.straightdope.com/u/Philster)
#### Post date: [May 13, 2003, 6:16pm UTC](https://boards.straightdope.com/t/carpenters/174905/4 "2003-05-13T18:16:52Z")
Tony, all the links I’ve checked are for books on conversions. I was motivated because I wanted to build a shed with 10/12 so I have a roof to run rafters under and store stuff in the roof space.
10/12 is a steep pitch, right?
I’ll be back.
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### Author:  [@Philster](https://boards.straightdope.com/u/Philster)
#### Post date: [May 13, 2003, 6:18pm UTC](https://boards.straightdope.com/t/carpenters/174905/5 "2003-05-13T18:18:56Z")
40 degrees. (?)
see [http://www.woodtruss.com/faqanswers/simpsonconversionchart.pdf](http://www.woodtruss.com/faqanswers/simpsonconversionchart.pdf)
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### Author:  [@Surreal](https://boards.straightdope.com/u/Surreal)
#### Post date: [May 13, 2003, 6:23pm UTC](https://boards.straightdope.com/t/carpenters/174905/6 "2003-05-13T18:23:28Z")
angle = tan[sup]-1[/sup] (10/12)
= 39.8 degrees.
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### Author:  [@Philster](https://boards.straightdope.com/u/Philster)
#### Post date: [May 13, 2003, 6:28pm UTC](https://boards.straightdope.com/t/carpenters/174905/7 "2003-05-13T18:28:57Z")
[http://www.autodeskpress.com/resources/sampchaps/jefferis\_add/jefferis\_ch20.pdf](http://www.autodeskpress.com/resources/sampchaps/jefferis_add/jefferis_ch20.pdf)
page 5-7
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### Author:  [@MonkeyMensch](https://boards.straightdope.com/u/MonkeyMensch)
#### Post date: [May 13, 2003, 6:35pm UTC](https://boards.straightdope.com/t/carpenters/174905/8 "2003-05-13T18:35:12Z")
> [@](#):
>
> \*Originally posted by Tony Montana \*
> \*\*When you stick-frame roof rafters you cut the bottoms (tails) on 10/12’s.
>
> Then there’s a conversion on your square to cut the tops at the corrrect angle. \*\*
Old framer here. You can also square-cut the tails, as on my house. Are you matching existing?
And do you own a speed-square? I find them quicker than framing squares and for stick-framing rafters they’re sufficiently accurate. Or you can get a rafter tits on and use it as a template. Templates are always a good idea.
This all may be of no help or beneath your skills, but you never know…
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### Author:  [@Tony\_Montana](https://boards.straightdope.com/u/Tony_Montana)
#### Post date: [May 14, 2003, 2:38am UTC](https://boards.straightdope.com/t/carpenters/174905/9 "2003-05-14T02:38:04Z")
> [@](#):
>
> \*Originally posted by MonkeyMensch \*
> \*\*
> This all may be of no help or **beneath your skills** , but you never know… \*\*
Nothing is beneath my skills!
Ok some self-depracting(sp?) humor there.
> [@](#):
>
> Are you matching existing?
I’m building a shed (thus the steep pitch)
Yes on the speed square, I was taught you look at the square at the “common” cuts,it lines up with 40deg mark.
Then, you add 90?
For the back-cut that is…