Cutting angles and creating an angle board story

[Jim_Rogers]

Cutting angles and angle board story by Jim Rogers 8/11/2011

I'm working on cutting some rafters for a client's shed project.

My very nicely detailed drawing shows that I need a shoulder line at 100.4° like this:



So I needed to set my bevel square to be able to create this line.

How do you set your bevel square to 100.4°? Well, first of all I can easily set it to 90° by using my framing square or some other right angle. So I needed to add 10.4° to that.

Years ago, I got a spread sheet that I have posted here on the forum that you can use to create any angle by entering the degrees you want and it will provide you with the answer in inches so that you can draw out the angle.

See this story for the basis of the "square angle worksheet":  

https://forestryforum.com/board/index.php/topic,17306.0.html

I first opened my spread sheet and inserted a new line:



That would be line 42 between 10.25° and 10.5°. And labeled it 10.4°, then I copied the formulas down to that line and it gave me the answer of 2 3/16".

Next I drew the angle on a rafter side so that I could easily see it:



Now I had a 10.4° angle. I had to now add that to my 90°s so that I could set my bevel gauge.

To do that I used my Big Al as my 90° fence and set my bevel gauge to this line:



Now that I have it set, I can now use it to layout and cut my tenon on my rafters:



To insure that I have all the angles recorded and available to use to "reset" my bevel square or any other angle adjusting tool:



I created an "angle board". Shown on the saw horse just next to the rafter.

And angle board is just a piece of wood (should have used a new piece that is clean and bright), where you draw your angles on. This is saved and if your bevel square gets moved or dropped and it gets knocked out of the correct position; you can reset your square to the bevel angle again.



Written on the board pictured above are the words "tenon shoulder cut + tenon end cut"

Also on this board is the angles for the 10/12 roof pitch created by using my framing square and the stair buttons set at 10 and 12:



Labeled on this board on the left hand angle line is "seat cut" and on the right are "tail plumb cut" + "rafter seat plumb cut".

With this board on hand I can align any of my bevel squares to these angles and hopefully all rafters will be cut to the same angles.

(I have improved the lines drawn on the board in the picture with MSPaint to make them stand out so that you can see them.)

I hope you find this story interesting and you can use some of the information here to make your layouts easier.

Jim Rogers

[frwinks]

especially helpful when not cutting all the pcs in one day ;D 
thanks Jim

[Piston]

Thanks for another good lesson Jim  ;D

[Jim_Rogers]

I cut the tongue/tenon rafter yesterday.
Today I cut the fork rafter that will pair with the tongue rafter from yesterday.

I put the two together to see how I did with the angles:



and:



and:



The next thing I did was measure across the collar beam pockets to make sure my measurements were correct:




Everything looked good, right on what the plans say it should be.

Next I measured across the rafter seat locations to see if those measurements were correct.

No way..... big mistake:



"off by that much"...... as Maxwell Smart used to say.......

Oh well, even the moderator of the forum can make mistakes......

Live and learn.....

[swampfox]

 8)  Nice Jim!  By the way where did you get that bevel?  I've seen some long bevel gauges before, but I believe they were made by the people using them.

The standard bevels you can buy get tiresome with having to run another straight edge along them..

P.S.  Are you going to change the rafter tail now?

P.P.S  I just noticed that it seems I have the dancing fellow about the mistake... No, it was for the first part.  Looks like we posted at the same time.  I made a mistake today,  good thing it was too long.

[Piston]

Oh well, even the moderator of the forum can make mistakes......

You didn't make a mistake Jim, you were just practicing so you didn't make a mistake on the one that counts!  Practice makes perfect.   :D

[Jim_Rogers]

This one counts for sure.

I don't know what the client is going to say..... maybe I should patch it.....

[Jasperfield]

As usual, another good and useful article.

How's the book coming?

[Jim_Rogers]

Well I was out there again today, cutting joints and testing the pieces together:



Not the easiest thing to do putting two 100 lbs rafters together with a 9' collar beam, alone. But I got it....

First of all I needed some shade this afternoon, so I created a new umbrella holder with my step ladder.
Worked quite well:




When you put large long timbers together up on saw horses it's difficult to see what's going on at the joint from underneath. You could put down a piece of cardboard or something like that and lay down to look up and see what going on. But I was afraid if I'd laid down, I'd fall asleep and wouldn't want to get back up :D ;D ;D

So the solution is to do it with "mirrors"....... yes my friends "smoke and mirrors"..... well no smoke, and only one mirror.



I used to have one of those nice mechanic's mirror on a wand and you could bevel it all around to the position you wanted and it had a slide out shaft so that you could reach down and put it where you needed it to be so that you could see the bottom side of a joint. But I think I loaned it out to someone at a raising one day, and it never came back to me..... But probably it's here in my shop but not where it's suppose to be so that I can easily find it.

I have used this old truck mirror many times for looking up at joints.

When you get it in the exact position you need you can really see what's going on and what the problem is that is holding the joint apart.



In this photo the two timbers are at the butt ends of the arrows. The joint you see is in the mirror.
The arrows are pointing to the spot where the two timbers are meeting. You can see that that the bevel cut on the housing isn't cut at the correct angle and this is causing the timber to bind up and not allow the joint to close.

Now that I know what the problem is, when I take the pieces apart, I can improve the housing bevel to make it the correct shape so that next time I put it back together they won't bind up. And the pieces should pull up tight when we draw bore the peg holes.

I measured across from rafter to rafter at the seat locations to make sure that they were the correct width apart and they were out by the amount that the shoulders are open. So once these shoulder are seated to their housing the pair should be the correct width.....

Some fun......

Jim Rogers

[canopy]

Thanks Jim, I wondered if a problem here or there happens even after the care and experience you must have. For me, as careful as I try to it drives me crazy when something is a little off. Maybe the reference sides are not square or straight enough, maybe I'm juggling too many numbers in my head at once, maybe I line up on the 1/12 instead of the 1/16 line on the square. Just so many things could go a little wrong and working with heavy timbers it makes everything a little tougher.

I also sometimes work with unusual angles and made a simple spreadsheet program that given an angle will tell you where to line up the framing square. Below is how it looks for your angle and I provided a link to it if it is of  interest to anyone.  I prefer the "x in 17" value over the "x in 12" when I can use it because the increased distance gives that much less margin for error.



http://www.jadeturtle.com/framing square.xlsx

[fuzzybear]

I believe it was Edison who said, (I'm paraphrasing) "I never failed, I only found a 1000 ways not to do it"
Good job Jim. I always look forward to your posts.
FB

[routestep]

I saw a different way of getting the rafters marked out in a book, maybe by Sobon, by using two framing squares.

Say for a 10 : 12  roof pitch

Set the first framing square on the rafter with 10 and 12 on the edge. Have the 12 on the blade is better, more room as the blade is longer.

Set the second square on the blade of the first square 10 and 12.

The blade of the second square will be at the correct angle to mark and cut the tenon (or mark out for the mortise).

[Jim_Rogers]

By the way where did you get that bevel?  I've seen some long bevel gauges before, but I believe they were made by the people using them.

Swampfox:

I'm sorry I missed your question back when you asked it.

I think I got it at woodcraft, but I just searched there and I don't see it listed.

I inspected it for a label and found the name "nooitgedagt" on the handle. I did an Internet search for that but couldn't that name on anything other than wine.

There is a Japanese one, that is similar, but I didn't find a site where we could easily buy one.

I like mine as it has the lock on the end not on the side.

Sorry I couldn't have been more help.

Jim Rogers