Bracing kit from LMI

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darren
Posts: 794
Joined: Sun Apr 19, 2009 9:26 pm
Location: Williams Bay, Wi
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Re: Bracing kit from LMI

Post by darren »

johnnparchem wrote:A radius dish is very nice but if you want to make a tools with the correct arcs go to http://liutaiomottola.com/formulae/sag.htm.

It shows you how to draw and arc of a big radius. From there you can cut out the arc from a board and use it as a sanding surface for the radius.

I hate sanding so for a 15" radius I also have found I can first get really close with a plane by taking a brace and marking it mid point. I mentally and loosely divide each half in quarters do four strokes on the end quarters 2 strokes half way from the mid point of each half to the end and a stroke from the 3/4 point on each half to the end. I check that against a guide to see how I am doing matching the curve and adjust the strokes accordingly. It takes me a few rounds of this and I am loose enough from where I start that I smooth out any facets I may be making. You can see you are progressively taking less off as you approach the center. For the 25 ft radius I start with fewer and longer strokes making less of a curve.

I clean it up on a radius disk, but a sanding bar with the correct radius will work as well if not better.
+1 to all that.

a plane will do this pretty quickly:



Also - There are plenty of radius spreadsheets and pdfs on the interweb. see attached...

(edit - credits to Mario Proulx, Charles Tatton, and Steve Senseney for the video and pdfs)
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Darren
naccoachbob
Posts: 477
Joined: Thu Dec 03, 2009 9:25 am
Location: Nacogdoches, Tx

Re: Bracing kit from LMI

Post by naccoachbob »

Thanks all. While gathering things for this one, I bought two radius gauges off Ebay and last night went to the garage and traced the 15' on a board, used a band saw to rough it out and will sand it sometime soon. Of course that also gave me the opposite side of that radius for whatever uses I come up with. I figure to use a flush bit and cut another couple of them to add sandpaper and do my braces. I'll do the same with the 28' gauge I bought.
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