Measurements

Apollo1617

Apollo1617

Member
It took me a bit to figure out that the measurement changes on your SEL, if you set it to the dimensions in SP. I set the stop at 2". I cut 1 piece @ 90* & it was exactly 2". But when WTP or SP tells you the SEL is 2", you can't set the stop for 2". It adds a few 32nds to the length. Is there a formula for this??
 
The measurement that WTP or SP gives you for the SEL is measured along the angle and not at 90 degrees to the blade.

Another member came up with this formula for EXCEL if you want set the stop for the SEL measuring at 90 degrees.

Stop Distance = SEl * COS(RADIANS(MiterAngle/2))

Excel uses radians hence the conversion of degrees to radians must be done.

A degree divides a circle into 360 equal parts. Radians measures angles based on the circles radius.


This thread discusses SEL versus actual blade to stop distance.

SEL versus actual blade to stop distance

Have you ever considered adding the actual distance between the blade and the stop used on the saw to get the correct SEL for the angle the of the segment being cut. I have watched many videos of people using the SEL to set the saw stop. This gives a segment that is actually longer than the SEL...
woodturnerpro.com
 

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Without this correction, the SEL will be 3.6% longer than expected on a 12-segment ring. For more segments per ring, the error will get smaller. Sometimes I make the correction and other times I just take the longer SEL and ring OD as a bit more tolerance on my tool control. It depends on how careful I do or don't want to be that day.
 
I'm familiar with Radians. I used to do extreme long distance shooting (shot a mile at a 3'x3' target in Arizona) which involved Mil Rad's or M.O.A. I prefer your way of measuring to the stop block. K.I.S.S. It was actually a 17 year old that was in my shop when I was test cutting (wasting) segments because the SEL was never right. He said" why not make your 1st miter cut, measure from the long point to the length you need & set the stop block." Out of the mouth of babes.
 
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