Re: Running Board Support Sander


Jack Mullen
 

On Wed, Nov 4, 2020 at 08:59 AM, Aley, Jeff A wrote:

 

               It’s hard to get a good measurement on something that small, but I measure 15 degrees (or you could say it’s 180 – 15 = 165 degrees).

 

               However, if I were going to make a new one, I’d measure a prototype drawing (or a model I’m trying to fit) and use that measurement instead.

I made a quick pass through the '40 Cyc with a digital protractor measuring the included angles of roofs in box/auto car end or cross-section drawings.  I get a range of included angles from a bit over 166 deg to somewhat under 170. The mean is 168 more or less, which is a good fit to Murphy and Viking roofs as found in these drawings. But a 2 degree range in roof slope only makes about 3/8" difference at the center of a 20" running board.

That said, this ain't rocket surgery. You may find that the folded sandpaper leaves the apex somewhat rounded, and need a more acute angle to compensate. As Jeff said, match the roof you're trying to fit. Then check how the pieces fit, and tweak the tool accordingly.
This dates me, but quite a few years ago I used folded sandpaper glued to the middle of a piece of Northeastern roof stock.  Later switched to cutting with a chisel blade guided by a hand-filed brass jig.

Jack Mullen

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