Picture 506 is a Swanson Speed Square and Picture 507 is a Johnson Rafter Square.
My question is, what are the lines which I have circled for? I had one framer tell me that it was for the Rafters Heel Stand or the (height above the plate). But on the Rafter Square that would only explain one of the lines.
Kyle.
The most common way to make your own parging mix is to use either Type S mortar for block or Type N for brick and add a concrete bonding additive.
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Replies
You use those lines to true up the black diamonds on your tape measure.
Jon Blakemore
Interesting that you should bring this particular question up because...
I always carry my Swanson in my back pocket. It's the speed square I use all the time. The particular line you are refering to (on the swanson) is for drawing your heel cut on the rafter.
HOWEVER... when I explained this to one of the guys, and he used the method I described to mark the heel cuts, they were all wrong!!!
Why? Because he used the large speed square with double lines in your second picture and the lines just didn't work out the same for the different squares.
I assumed that swanson had a patent or something on their method, so the other manufacturers had to use a different method.
Basically, you line up the dashed mark wth your plumb line measured down for the length of the rafter. Then, you slide your square until it hits your degree mark and you should be at 3 1/2" for your seat. Of course, even though I save every bit of paper I get with every tools I buy, I can't find the Johnson explanation.
That's why I wasn't sure.
I always use the swanson, but I just purchased the Johnson Rafter Square for the bigger boards.
I couldn't figure out why they would be different.
I guess window R.O. and the stand marks on squares will probably be two things the manufactures never agree on.