# Chappell Framing Square



## chappellt (May 24, 2009)

*very versatile tool*

The Chappell Universal framing square has all of the same info on its tables as the old framing square, but where it really comes into its own and shows its muscle is when it comes to our new Unequal Pitched and Polygon Rafter tables. *For the first time ever on a framing square!*

Now for example you can decide to build a 12/12 Main roof(A) with a 14/12 dormer(B), and look to the Chappell Universal Square for all of your critical angular and length information. *Take a look at how extensive the information is.
*
The Square Gives you; the Hip/Val rafter pitch =37.208º
The run of the Dormer(B) for every inch of Main(A) roof run=.8571"

The run of the Main roof for every inch of dormer run=1.1667"

The length of the Hip/Val rafter per inch of Common run on either roof
Main(A) = 1.654"
Dormer(B) = 1.929"

Difference in length of Jack Purlin per inch of Common Length (both sides)
This number is also: the Purlin Top Cut Layout Angle/1",
and the Sheathing Angle/1"  (ex. you would layout angle by moving decimal place and using 6.061"/10" on square)
Main(A) = .6061"
Dormer(B) = .7593"

Difference in length of Jack Rafter per 1" spacing
it is also the Jack Rafter Top Cut Layout Angle/1"(ex. you would layout angle by moving decimal place and using 16.50"/10" on square)
Main(A) = 1.650"
Dormer(B) = 1.317"
This allows you endless flexibility on your Jack spacings 

The Bevel/Backing angle on Hip/Val
this is also the Top Cut Saw Angle for Jack Rafters or Jack Purlins
Main(A) = 27.399º
Dormer(B) = 35.203º

The Purlin Side Cut Layout Angle/1"
This is also the Fascia Face Layout Angle for 90º rafter tails(Miter Angle)
Main(A) = .6061"
Dormer(B) = .8858"

The ratio of the Housing Angle of Purlin to (Hip/Val)/1" (Used on Purlin when housing Purlin into Hip/Val
It is also the Hip Valley Side Layout Angle to Purlin Header.(marked on Hip/Val, there is a small rotation here from perpendicular to roof and this is it)
Main(A) = .278"
Dormer(B) = .4377

The Mitered Fascia Saw set angle for 90º tails (Bevel Angle)
Main(A) = 27.399º
Dormer(B) = 29.612º

As you can see the information is extensive, and it is just as complete for both the Polygon Tables and the Equal pitched Tables. 

With this square you have the freedom to compose your masterpiece.


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## mike86 (May 30, 2011)

I got to have this framing-square:thumbsup:


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## mike86 (May 30, 2011)

chappellt said:


> The Chappell Universal framing square has all of the same info on its tables as the old framing square, but where it really comes into its own and shows its muscle is when it comes to our new Unequal Pitched and Polygon Rafter tables. *For the first time ever on a framing square!*
> 
> Now for example you can decide to build a 12/12 Main roof(A) with a 14/12 dormer(B), and look to the Chappell Universal Square for all of your critical angular and length information. *Take a look at how extensive the information is.
> *
> ...


Why is this square 108 dollars?

There is not a single piece of information on that square that I don't already know,I'll stick with my $15 swanson and my programmable calculator:thumbsup:


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## Winchester (Jun 29, 2008)

Quick 180 there, Mike... :laughing:

I'd probably buy one if I did more roof framing.

Now if you made an awesome speed square.....


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## Kent Whitten (Mar 24, 2006)

mike86 said:


> Why is this square 108 dollars?
> 
> There is not a single piece of information on that square that I don't already know,I'll stick with my $15 swanson and my programmable calculator:thumbsup:


Who would buy a $ 500 Festool sander when a Dewalt ROS is $50 at Lowe's? Add on top of that a $500 dust extraction system? 

It's stainless among other things that give it value. 

How do you react to a potential client who responds to your quote that way? What do you tell them? I can easily find someone cheaper than you to get the same job done.


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## Kent Whitten (Mar 24, 2006)

Winchester said:


> Quick 180 there, Mike... :laughing:
> 
> I'd probably buy one if I did more roof framing.
> 
> Now if you made an awesome speed square.....


I was thinking the same thing Ryan. A 7" and 12" would be awesome.


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## Warren (Feb 19, 2005)

KentWhitten said:


> I was thinking the same thing Ryan. A 7" and 12" would be awesome.


I disagree.
A speed square is simply made for speed and convenience. You don't see many timber frame guys using one. I use my speed square a lot, but it does pretty much everything I need it to. The big square always comes out for the difficult sticks. 

I am still trying to wrap my head around this new square. I appreciate the attention to detail, but quite frankly they may have put too much on there for my liking. The price does seem a bit high too, but for someone who utilizes many of the functions, it will pay for itself many times over.


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## mike86 (May 30, 2011)

KentWhitten said:


> Who would buy a $ 500 Festool sander when a Dewalt ROS is $50 at Lowe's? Add on top of that a $500 dust extraction system?
> 
> It's stainless among other things that give it value.
> 
> How do you react to a potential client who responds to your quote that way? What do you tell them? I can easily find someone cheaper than you to get the same job done.


Sorry but I just can't see $108 for this square.


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## katoman (Apr 26, 2009)

I think the normal alluminum framing squares are $50-60 bucks. So 108 seems like a reasonalble price to me.


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## Tinstaafl (Jan 6, 2008)

katoman said:


> I think the normal alluminum framing squares are $50-60 bucks. So 108 seems like a reasonalble price to me.


Swanson Tool Company 16" x 24" High-Vis Aluminum Square

$13.58.

That's the sort 90% of the guys in this field will use, and they are never going to be interested in the mental gymnastics required to learn to think in 20ths of an inch.

OTOH, I doubt that's the target market.


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## chappellt (May 24, 2009)

mike86 said:


> Sorry but I just can't see $108 for this square.



We are a small American startup, building quality tools using top of the line materials and technologies, 100% made in the USA, (which really mattered to us). If you would rather use a Swanson for $15 then I won't begrudge you for that. 

Perhaps I can interest you in this http://www.breseplane.com/contact.htmlhttp://www.breseplane.com


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## Kent Whitten (Mar 24, 2006)

chappellt said:


> Perhaps I can interest you in this http://www.breseplane.com/contact.htmlhttp://www.breseplane.com


:blink: Holy...


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## Ninjaframer (May 28, 2011)

Good lord! Are those diamond studded knobs? Is that some exotic wood only found on one tree deep in the Congo guarded by killer apes? Can I ride that thing to work?
Good lord!


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## J.C. (Sep 28, 2009)

The biggest problem I've had with framing squares is finding one that is actually square. I'm not sure why but, we have 6+ framing squares at work and no 2 are the same. I hardly ever use a framing square but I wouldn't mind having a nice one that is actually square. I'm not sure how much I'd like the 20th markings though. That might be hard to get used to.


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## chappellt (May 24, 2009)

J.C. said:


> The biggest problem I've had with framing squares is finding one that is actually square. I'm not sure why but, we have 6+ framing squares at work and no 2 are the same. I hardly ever use a framing square but I wouldn't mind having a nice one that is actually square. I'm not sure how much I'd like the 20th markings though. That might be hard to get used to.


 Well, we do assure that our squares are square to .003", I can't believe that isn't priority number one with other manufacturers


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## 2ndGen (Apr 6, 2006)

chappellt said:


> We are a small American startup, building quality tools using top of the line materials and technologies, 100% made in the USA, (which really mattered to us). If you would rather use a Swanson for $15 then I won't begrudge you for that.












I'm not a wouldn't call myself a Carpenter, but damn; I want that framing square. 
My hat's off to you. I have a great appreciation for high quality hand tools. 
And I definitely believe in praying a premium for a product made in The USA. 
Japan & Germany are my runner-ups for great hand tools. 

Best of luck to you and as soon as I'm able, I will be picking up one of your squares. 
I'd love to add one of your squares to my collection of the best of the best gear (Occidental, Stiletto, Tajima, Stortz, Belden, etc...). 

:thumbsup:


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## chappellt (May 24, 2009)

*http://www.contractortalk.com/f14/remind-me-how-do-107283/*

I thought the following thread, http://www.contractortalk.com/f14/remind-me-how-do-107283/ was, a ringing endorsement of the power of the Chappell Universal Square. Sometimes it is really handy to have a reference tool on the jobsite for all of those things you always think you will remember but never do.


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## Warren (Feb 19, 2005)

c\happellt said:


> I thought the following thread, http://www.contractortalk.com/f14/remind-me-how-do-107283/ was, a ringing endorsement of the power of the Chappell Universal Square. Sometimes it is really handy to have a reference tool on the jobsite for all of those things you always think you will remember remember but never do.


I couldn't agree more. A framing square isn't something that, uses batteries, is made of paper and subject to being thrown away, or is so fragile that I would be afraid to leave it out and subject it to damage. 
At some point I am sure I will spring for one of these.

Attention Nathan:

When the Timberaland contest ends, how about having a promotion for these?


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## Kent Whitten (Mar 24, 2006)

chappellt said:


> Well, we do assure that our squares are square to .003", I can't believe that isn't priority number one with other manufacturers


Tait, I have checked the squareness of every square I ever owned and not one was square. A simple diagonal measurement always came up short. Brand new squares. Usually at least 1/32" off, but most were damn near 1/16".

Guess what I did when I received your square :laughing: 

I have checked speed squares too and they are all off as well. 

One thing I am counting on is longevity. In the time that I have used it, it seems to take jobsite usage pretty well. It would seem to me that the edges would shrug off wear much better than just a standard square.

Here's what I notice with the material from other squares. Granted, I have been pretty rough on my tools. Steel squares rust and the paint peels off out of the blade etching. 

Aluminum has much more positives than steel (IMO) that it weighs less, doesn't give you third degree burns when picking it up in the hot sun and usually the blade is just etched and no painted hash marks or numbers. But the issue with aluminum is it's softness. Just a matter of time that everything gets rounded off. The builder I am working for right now has an aluminum square that the sealer is wearing off and it really looks like it has leprosy or something.

Now I guess I have a question about how the etching is. It says it is photo etched? What does that exactly mean? Will this eventually wear out like the steel blades? I hope not. That would be disappointing. I was only assuming that it was laser etched meaning that it is a permanent look.

I know for some guys here that the price is too much to justify and I can empathize with that. I shake my head at the titanium hammer fad. So I'm sure we all have our wants and needs. Some will like the square enough to buy it, some won't.


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## chappellt (May 24, 2009)

*Photo Etched Markings*



KentWhitten said:


> Tait, I have checked the squareness of every square I ever owned and not one was square. A simple diagonal measurement always came up short. Brand new squares. Usually at least 1/32" off, but most were damn near 1/16".
> 
> Guess what I did when I received your square :laughing:
> 
> ...



Hey Kent, No worries of wear on these. Photo etching is a process where a photo negative is made of the information on the square, and laid over the Stainless Steel. It is then put into an acid etchant bath where only the clear portion of the negative is subjected to the acid and "milled" away, yet the parts with 'Photo resist' covering the remaining metal remain untouched. It is a very precise burr free process and can be done to varying depths depending on the amount of time it bathes in the acid. 

We have had our squares etched extra deeply!

As you can see in the photo, these markings are deep, and blackened. With the hardness of the Annealed 304 stainless steel they are sure to last a lifetime.


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## chappellt (May 24, 2009)

Warren said:


> I couldn't agree more. A framing square isn't something that, uses batteries, is made of paper and subject to being thrown away, or is so fragile that I would be afraid to leave it out and subject it to damage.
> At some point I am sure I will spring for one of these.
> 
> Attention Nathan:
> ...


 Yes, tell me more about this concept...


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## Dirtywhiteboy (Oct 15, 2010)

KentWhitten said:


> Brand new squares. Usually at least 1/32" off, but most were damn near 1/16".
> I have checked speed squares too and they are all off as well.


 Wow Could it be your tape measure was off that much:blink: or were you using the The Chappell Universal Center Rule:blink:



chappellt said:


> Hey Kent, No worries of wear on these. Photo etching is a process where a photo negative is made of the information on the square, and laid over the Stainless Steel. It is then put into an acid etchant bath where only the clear portion of the negative is subjected to the acid and "milled" away, yet the parts with 'Photo resist' covering the remaining metal remain untouched. It is a very precise burr free process and can be done to varying depths depending on the amount of time it bathes in the acid.
> 
> We have had our squares etched extra deeply!
> 
> As you can see in the photo, these markings are deep, and blackened. With the hardness of the Annealed 304 stainless steel they are sure to last a lifetime.










Love the close ups:thumbsup: I think I'm sold:clap: When viewing tool P0rn we love the close up:whistling



chappellt said:


> Yes, tell me more about this concept...


 Check the week 5 question:blink: I think I could have won the work boots but my feet too wide to wear em so I passed:laughing:


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## Kent Whitten (Mar 24, 2006)

Dirtywhiteboy said:


> Wow Could it be your tape measure was off that much:blink: or were you using the The Chappell Universal Center Rule:blink:


Randy...I am quite certain I know how to measure for squareness. You might want to check yours.


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## FramingPro (Jan 31, 2010)

KentWhitten said:


> Randy...I am quite certain I know how to measure for squareness. You might want to check yours.


was it squarallel?


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## Winchester (Jun 29, 2008)

FramingPro said:


> was it squarallel?


No, I think it was squarpendicular


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## FramingPro (Jan 31, 2010)

Winchester said:


> No, I think it was squarpendicular


 o please. doesn't roll off the tongue like my verbally engineered term :laughing:


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## Winchester (Jun 29, 2008)

FramingPro said:


> o please. doesn't roll off the tongue like my verbally engineered term :laughing:


I think my tongue is just more flexible than yours :whistling


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## RS Sam (Feb 9, 2009)

I absolutely can't stand using an out of square "square". Have babied my squares all my professional life but stuff happens and the next thing you know your square is a usedtobesquare . I suspect most of us want a good dependable accurate square but not so much for laying out rafters and such. Maybe to mitigate the costs for those who just need accuracy produce a version of the square without all the info. I can get that stuff out of my Audels or on The Google. Just a thought...


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## Dirtywhiteboy (Oct 15, 2010)

FramingPro said:


> was it squarallel?


Is that anything like a squarallelgram:laughing:


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## Dirtywhiteboy (Oct 15, 2010)

Kent I read something about tuning your square with a center punch once:blink: Did you ever read that:blink:


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## FramingPro (Jan 31, 2010)

Dirtywhiteboy said:


> Kent I read something about tuning your square with a center punch once:blink: Did you ever read that:blink:


i read that, i need to do that


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## Birch (Jul 20, 2009)

Tweaking, or tunning, a framing square is done by expanding the corner metal to push the blades back into perpendicular alignment. If it needs closing up then expand the outside corner. If it needs to open up then use a punch to the inside corner. I’ve gently used the round end of a ball peen hammer to open one up once. (A cheap Swanson’s “Thick” model, really soft aluminum) It doesn’t take much and over doing it will fatigue the metal and crack the square in the corner. 

Most square are not absolutely perfect when testing. They seem to get worse with age and I think misuse is to blame for it, sweeping the floor with your framing square for example. They’d have to been pretty far out to warrant tuning. If they’re so far out you really think it needs tweaking, then can’t really hurt.


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## Dirtywhiteboy (Oct 15, 2010)

Birch said:


> Tweaking, or tunning, a framing square is done by expanding the corner metal to push the blades back into perpendicular alignment. If it needs closing up then expand the outside corner. If it needs to open up then use a punch to the inside corner.


YES this is exactly what I was talking about:thumbsup:


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## WarnerConstInc. (Jan 30, 2008)

I am late to this party but, any sort of precision square or measuring device is pretty expensive. This being right around a 100 bucks seems right in line to me.


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## Inner10 (Mar 12, 2009)

I must admit before I buy a square I check a few to make sure they are square. I have 3 aluminum squares but they bend easy and next thing you know you are hammering the corner to get it square again. 

I like everything about this product except for the 20th of aan inch.... Isn't that why the metric system exists?


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## moorewarner (May 29, 2009)

Dirtywhiteboy said:


> Wow Could it be your tape measure was off that much:blink: or were you using the The Chappell Universal Center Rule:blink:
> 
> 
> 
> ...


:laughing: :sweatdrop:

ixnay on the ornpay... :whistling: :laughing:


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## chappellt (May 24, 2009)

RS Sam said:


> I absolutely can't stand using an out of square "square". Have babied my squares all my professional life but stuff happens and the next thing you know your square is a usedtobesquare . I suspect most of us want a good dependable accurate square but not so much for laying out rafters and such. Maybe to mitigate the costs for those who just need accuracy produce a version of the square without all the info. I can get that stuff out of my Audels or on The Google. Just a thought...


 Perhaps one of our smaller squares will do the trick for you, they are more affordable and still guaranteed square to .003". 

We have the master framer 18x24, the traveler 12x18 both with our new comprehensive patented tables, two centering squares 9x12, and 6x8, and finally a small gauging square at 3x4


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## chappellt (May 24, 2009)

RS Sam said:


> I absolutely can't stand using an out of square "square". Have babied my squares all my professional life but stuff happens and the next thing you know your square is a usedtobesquare . I suspect most of us want a good dependable accurate square but not so much for laying out rafters and such. Maybe to mitigate the costs for those who just need accuracy produce a version of the square without all the info. I can get that stuff out of my Audels or on The Google. Just a thought...



I will say that we all know we can look these things up on google, or here at CT, or in Audels, but in the real world we are on site working on something else, and during the day progress to one of these situations where the Chappell Square really shows its worth. Once you get to the facia miter angle question or any various other headscratchers, your not going to stop work and look it up in Audels (which is not at the jobsite anyway, but on your bookshelf as it should be). Even if you can spend time on your smartphone looking stuff up, that is time.... 

The value of this tool is both a material value because of its inherent quality, attention to detail and precision and also an immeasurable value in terms of time savings by providing answers to some of the most classic mind benders in roof framing. There is no debate, or string line and torpedo with a speed square hackery. you just have the answer and proceed. I feel there is real value in that... I hope I am not alone.


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## RS Sam (Feb 9, 2009)

Actually, I'm one of those who are OK with $ 108.00. I can appreciate the value - great material, superb accuracy, loaded with info, and made in the USA. Can't argue with that. I will very likely get myself a "traveler's square" (when I can afford it :whistling). I just proposed the idea of making a version without the encyclopedia printed on it as a way to produce a less expensive framing size square. It would be very useful in a cabinet shop too.


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## Ninjaframer (May 28, 2011)

Chappell- does it have solutions for non- right triangles on it as well? Like tables with trig ratios for common pitches?


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## chappellt (May 24, 2009)

Ninjaframer said:


> Chappell- does it have solutions for non- right triangles on it as well? Like tables with trig ratios for common pitches?


 I am not sure I understand the question, please elaborate.


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## Ninjaframer (May 28, 2011)

Like in the example I gave in another thread for dormers with shed roofs that don't intersect at the ridge. They create a triangle without a right angle. I just wandered if you had tables on the square with the sine, cosine, tan for pitches from say 2/12 to 12/12. It would be handy if it did.


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## neill (Sep 29, 2011)

Ninjaframer said:


> Like in the example I gave in another thread for dormers with shed roofs that don't intersect at the ridge. They create a triangle without a right angle. I just wandered if you had tables on the square with the sine, cosine, tan for pitches from say 2/12 to 12/12. It would be handy if it did.


really? you run into that problem enough you need a table for it? 

this square seems to give as much info and more than a carpenter could need. but sometimes we need to pull out the old calculator, no?


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## chappellt (May 24, 2009)

*re: remind me how to do this...*



Ninjaframer said:


> Like in the example I gave in another thread for dormers with shed roofs that don't intersect at the ridge. They create a triangle without a right angle. I just wandered if you had tables on the square with the sine, cosine, tan for pitches from say 2/12 to 12/12. It would be handy if it did.


 Well it had the answer to that scenario you asked about. and it has the same sort of information for a *lot* more of those situations. I still don't quite understand the question. I attached a skp. file to play around with along with the steps I would use to get there. Or you have the square and BAM!! Set the saw and cut.


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## Ninjaframer (May 28, 2011)

The same problem arises with shed porch roofs of different pitch than the main pitch. But no not that often. This square had everything else so I just wondered. I'm so used to the calculator that I would have to take a class to learn how to use this square.


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## Ninjaframer (May 28, 2011)

This is the kind of stuff I'm talkin about


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## chappellt (May 24, 2009)

Ninjaframer said:


> This is the kind of stuff I'm talkin about



This is how I would go about doing it to find all my lengths mathematically. intersect that obtuse angle create a 90º and use my givens; roof pitch, shed pitch, dimensions, etc. 

If your question is what that top angle at the Shed/Main junction. That is just a straight subtraction of angles (in 2 dimensions) its not compound there are no rotations.


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## Ninjaframer (May 28, 2011)

That still leaves a triangle at the top or bottom ( depending where you put x )without a right angle and you have the same problem. Like I said I know how to solve it usin the law of sines, and of coarse all triangles add up to 180. I just wondered if your square had any trig tables on it.


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## Ninjaframer (May 28, 2011)

chappellt said:


> This is how I would go about doing it to find all my lengths mathematically. intersect that obtuse angle create a 90º and use my givens; roof pitch, shed pitch, dimensions, etc.
> 
> If your question is what that top angle at the Shed/Main junction. That is just a straight subtraction of angles (in 2 dimensions) its not compound there are no rotations.


Sorry didn't see the pic at first, is there another way to solve beside the law of sines? How would you solve for x or the rafter length. Of coarse you would have all angles becouse you know your pitches and you would know the run and rise at the wall but that's it without some trig, right?


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## chappellt (May 24, 2009)

Ninjaframer said:


> That still leaves a triangle at the top or bottom ( depending where you put x )without a right angle and you have the same problem. Like I said I know how to solve it usin the law of sines, and of coarse all triangles add up to 180. I just wondered if your square had any trig tables on it.


 This is what i meant by intersecting the obtuse angle. 
solve for side x then downhill side of the rafter(X/TAN(SHEDº), then using side x and complementary shed pitch minus complement of main roof pitch (X/TAN(TOP SHEDº)figure the uphill side of the rafter and voila. you can go on then to figure length up main roof if you would like (X/SIN(TOP SHEDº).

But no there is not a full set of trig tables on the square, now that would be a lot of info


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## Ninjaframer (May 28, 2011)

I see, then you just work pathagorean backwards. Law of sines is faster 
So does this square of yours come with a video or something. If I got one I'd want to know what everything on it was and what it did.


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## Kent Whitten (Mar 24, 2006)

Ninjaframer said:


> I see, then you just work pathagorean backwards. Law of sines is faster
> So does this square of yours come with a video or something. If I got one I'd want to know what everything on it was and what it did.


Comes with a 48(?) page book which I posted the free pdf file link in my first post


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## chappellt (May 24, 2009)

Ninjaframer said:


> I see, then you just work pathagorean backwards. Law of sines is faster
> So does this square of yours come with a video or something. If I got one I'd want to know what everything on it was and what it did.


 There is a 48 page booklet that comes with the square that highlights line by line what the square will do.

You can download the PDF here:


http://www.foxmaple.com/Chappell_Sq_Bklt.3.pdf


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## Ninjaframer (May 28, 2011)

All right, I'll probably have to live on top ramen for the next six months but I'll buy one. It's just to darn cool not to have it!


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## Ninjaframer (May 28, 2011)

You should make an instructional video for it though. I do way better if someone shows me how to do something.


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## chappellt (May 24, 2009)

Ninjaframer said:


> You should make an instructional video for it though. I do way better if someone shows me how to do something.


 There are plans on doing some instructional videos with Lie Nielsen on their you tube channel in the near future.


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## mike86 (May 30, 2011)

Here's the geometry of a porch roof,in the picture I'm using a 8/12 main roof and a 4/12 porch roof.


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## Ninjaframer (May 28, 2011)

mike86 said:


> Here's the geometry of a porch roof,in the picture I'm using a 8/12 main roof and a 4/12 porch roof.
> 
> <img src="http://www.contractortalk.com/attachment.php?attachmentid=58851"/>


And as long is you knew your run (Wich you would) you take the run divided by the sine of 15.26 x sine of 146.31 (71.57+74.74) = rafter length. Right?


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## Ninjaframer (May 28, 2011)

If the run was 8' the rafter would be 16' 10" 5/16


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## chappellt (May 24, 2009)

Ninjaframer said:


> And as long is you knew your run (Wich you would) you take the run divided by the sine of 15.26 x sine of 146.31 (71.57+74.74) = rafter length. Right?


 that would not work, you need a right triangle and would need to figure those two rafter length sections independently by trig(if not law of sines). Mike has an accurate drawing but not a real life situation as you would have in the real world. You are much more likely to have a know pitch for your porch and a known main roof pitch and a known porch width which are all *design decisions*.


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## Ninjaframer (May 28, 2011)

chappellt said:


> that would not work, you need a right triangle and would need to figure those two rafter length sections independently by trig(if not law of sines). Mike has an accurate drawing but not a real life situation as you would have in the real world. You are much more likely to have a know pitch for your porch and a known main roof pitch and a known porch width which are all design decisions.


That is the law of sines. A over sine a = B over sine of b. or in other words A divided by sine a x sine b is =B
You don't need a right angle with law of sines.


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## chappellt (May 24, 2009)

Ninjaframer said:


> That is the law of sines. A over sine a = B over sine of b. or in other words A divided by sine a x sine b is =B
> You don't need a right angle with law of sines.



http://en.wikipedia.org/wiki/Law_of_sines


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## Ninjaframer (May 28, 2011)

I'm exactly right! Law of sines used when one side and two angles are known (Wich is a silly way to say it since if you know two then you know all three). And when an equation is written A over sine a = B over sine b = C over sine c the way you solve is with cross division or multiplication. Thus A divided or multiplied by sine of a then multiplied or divided by sine of b to =B Same with C.
I just added the run being 8'. It's right though, check.


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## Winchester (Jun 29, 2008)

Ninjaframer said:


> Sorry didn't see the pic at first, is there another way to solve beside the law of sines?


Depends on what information you know and what you need to figure out. There is also the law of cosines :thumbsup:

http://en.wikipedia.org/wiki/Law_of_cosines


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## Timuhler (Mar 7, 2006)

mike86 said:


> Here's the geometry of a porch roof,in the picture I'm using a 8/12 main roof and a 4/12 porch roof.
> 
> View attachment 58851


That is how I figure them.


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## mike86 (May 30, 2011)

Timuhler said:


> That is how I figure them.


Hey chappellt that looks like a "real life situation" to me



> Mike has an accurate drawing but not a real life situation


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## chappellt (May 24, 2009)

mike86 said:


> Hey chappellt that looks like a "real life situation" to me


 That's correct it looks exactly like both of our drawings did That wasn't the question. The fact that It contains both; known pitches and *known dimensions*, and they are used to figure out the unknowns, was more my point. 

Mike, you had a good drawing. I meant no offense. Ninja was trying to learn the process, and I just felt that your drawing was a bit like turning to the back of the textbook to show somebody the answer without explaining how you got there. 

But I can see how you you would have gotten there from your drawing too, to each his own I guess

Thanks for the pictures Tim...


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## Birch (Jul 20, 2009)

I agree with, “to each their own”. So here is another simple solution for Shed Runs.

With; A = Main pitch, B = Shed pitch, and p = projection of Shed Roof, the Run of the Shed rafter can be solved as;

Run = (B/(A-B) x p) + p

or for the 5/12 (B) and 12/12 (A) w/ 8’ projection scenario above

(5/(12-5) x 8’) + 8’

(5/7 x 8’) + 8’ 

5’ 8-9/16” + 8’ = 13’ 8-9/16” 

or 

68.571” + 96” = 164.571”


And of course it doesn’t get any easier than the Shed Roof being half the pitch of the Main Roof. 
Shed Run = (p x 2)


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## chappellt (May 24, 2009)

Ninjaframer said:


> I'm so used to the calculator that I would have to take a class to learn how to use this square.


 The Chappell square is very easy to understand. Everything is given as a simple ratio to 1". if it is a total length your looking for, multiply your *given number* times the answer in the table. If its an angle move the decimal point one place and use over 10 on the square to gauge the angle.

*Ex.* Line 1 Equal pitched table *Length of common rafter per 1" of run* @ 18/12 = 1.803
The run of the roof in inches x 1.803 = common rafter length.

* Ex. *line 8 Equal pitched table *Purlin sidecut layout angle over 1"* @ 18/12 = .8321
Move decimal place 1 position and use 8.321"/10" to mark the purlin sidecut angle.


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## Ninjaframer (May 28, 2011)

Why can no one use simple examples? This is simple, right and easy to understand. This is what I hoped for with the square cut facia question. Something easy to understand. Not crazy math formula that doesn't show how you got there.


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## Ninjaframer (May 28, 2011)

Timuhler said:


> That is how I figure them.


Using my method , law of sines-
95 1/2 divided by sine of 21.38, then multiplied by sine of 140.19 to give the rafter length of 167 3/4


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## chappellt (May 24, 2009)

Ninjaframer said:


> Using my method , law of sines-
> 95 1/2 divided by sine of 21.38, then multiplied by sine of 140.19 to give the rafter length of 167 3/4


 There appears to be something off in your calculations?

What do you get for our example of a 5/12 porch to 12/12 main with 96" wide porch?


it should read;


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## Ninjaframer (May 28, 2011)

chappellt said:


> There appears to be something off in your calculations?
> 
> What do you get for our example of a 5/12 porch to 12/12 main with 96" wide porch?
> 
> it should read;


96 divided by sine of 22.38 multiplied by sine of 135 = 178 5/16


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## chappellt (May 24, 2009)

Ninjaframer said:


> 96 divided by sine of 22.38 multiplied by sine of 135 = 178 5/16


*you're right*, don't know what I was looking at:laughing:

This isn't the way I normally solve this problem, but I do like it.


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## chappellt (May 24, 2009)

Ninjaframer said:


> Why can no one use simple examples? This is simple, right and easy to understand. This is what I hoped for with the square cut facia question. Something easy to understand. Not crazy math formula that doesn't show how you got there.


I think the fascia question is a bit different because it isn't so simple, there are complex rotated angles so it does become a bit more complicated. your drawing becomes 3 dimensional.


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## Ninjaframer (May 28, 2011)

chappellt said:


> you're right, don't know what I was looking at:laughing:
> 
> This isn't the way I normally solve this problem, but I do like it.


Thanks! My highschool math teacher taught it to me. I failed his class 3 times, usually got kicked out when I managed to show up. I went to him about 4 years ago asking how to solve this ( he lived down the street) he said I was the last person he ever expected coming to ask about trig


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## Ninjaframer (May 28, 2011)

chappellt said:


> I think the fascia question is a bit different because it isn't so simple, there are complex rotated angles so it does become a bit more complicated. your drawing becomes 3 dimensional.


Ya sorry about that post, I was getting frustrated. I just hoped for a simple formula of " take this angle, devide by whatever, times by that then whala!" I didn't get any response like that so I got frustrated. Again thanks for everyone's patience but I still don't have a clear understanding of the formula for square cut facias that I can whip up on my construction master pro trig.


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## Kent Whitten (Mar 24, 2006)

chappellt said:


> *you're right*, don't know what I was looking at:laughing:
> 
> This isn't the way I normally solve this problem, but I do like it.


Sssssoooooo.....does this mean there's a new table on the square coming? :laughing:

I didn't want to say anything but Ninja had it awhile back. It is a handy little formula to have. I usually did it in a two step process with the CM like you show Tait.


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## chappellt (May 24, 2009)

KentWhitten said:


> Sssssoooooo.....does this mean there's a new table on the square coming? :laughing:
> 
> I didn't want to say anything but Ninja had it awhile back. It is a handy little formula to have. I usually did it in a two step process with the CM like you show Tait.


You know it might not be a bad thing to have on there??

Just the graphic at least as a reminder, It'd be hard to find the room though. 

We may have to design another tool, who knows maybe we'll call it the *"ninjaframer"*:thumbup:

a/SINA = b/SINB = c/SINC


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## Ninjaframer (May 28, 2011)

Lol! I'm extremely flattered. 
You know it's funny how knowledge is passed on- I was just teaching my little brother how to lay out a rafter for the dog house he's building.

The sad thing is there are very few who are even remotely interested in the math behind roof framing. The common philosophy is that "it's my job to get this done and that's where it ends". To me a carpenter is what I AM and I want to be the very best I can be, that means I want to understand every aspect of what I do. 
My father is a well driller and he's allways said " to be a good driller you need to be half geologist and half machinist"
I think to be a great framer you need to be half mathematician and half circus preformer


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## Dirtywhiteboy (Oct 15, 2010)

chappellt said:


> We may have to design another tool, who knows maybe we'll call it the *"ninjaframer"*:thumbup:
> a/SINA = b/SINB = c/SINC


That's it I'm waitin for the _NinjaFramer_to come out:clap:


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## chappellt (May 24, 2009)

you can check out a review of the Chappell Square here:
http://www.sbebuilders.com/Chappell/


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## chappellt (May 24, 2009)

*Lee Valley Woodworking Catalog*

The good folks at Lee Valley felt that we were deserving of the back cover of their June Woodworking catalog!! Thanks.


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