I have a mitre saw with a ruler that works great for 90 degree cuts. But when I want to cut something in an angle this ruler doesn't work anymore. Now I want to make a small calculator with an arduino + screen and some knobs to calculate the offset I need to add/substract to the ruler value for acurate cutting.
I think the fact that the ruler doesnt work means that the pivot point of the saw isn't lined up with the ruler. I took a couple of cuts and wrote down the offset. I plotted these points on a graph and it give me a mathmatical shape that looks like an inversed cubic function (like y(offset) = -x(angle)^3, but isn't. How can I figure out what type of equation I should use to make this offset calculator?
My measurements were done on material with a width of 35mm. I did find out that the distance from pivot point to ruler is 14mm.
See below for the list of datapoints and a plotted graph.
Many thanks for pointing me in the right direction!
Do you want answers only from people who are familiar with mitre saws? None of that language makes any sense unless you are. Please post diagrams and/or images to make sense of the language.
Thanks for your reply!
I figured it out, I was looking in the wrong direction trying to find a cubical function... I needed a tangent function instead.
for example: with angle of 30 degrees I put:
tan(30 * pi / 180) = stock material - known material offset (14) / ruler offset
so ruler offset at 30 degrees = (35-14) / tan(30 * pi/180) = 36.4
Since this question was purely about mathematics I think I put it on the wrong forum. It doesn't have much to do with arduino's other than the fact I'll use the arduino to do the math for me. I realized a bit late...
If you want true accuracy, the best solution by far would be to actually MEASURE the geometry of the TWO rotational axes (rotation and tilt) of the saw relative to the ruler, and create a mathematical model of the kinematics of that configuration. It will surely require some iteration and/or trial and error to come up with the exact correct dimensions, but once you have them the model will give you precise corrections every time. I would suggest you set it up so you can input the two angles, and the desired final dimension, and then calculate the ruler setting to use to achieve that final dimension.
Because the pivot point of the blade is behind the fence, so the location where the blade crosses the fence move as the cut angle changes.
Carpenters don't measure, they MARK. Much easier & more accurate to cut the mitre at the mark than to try and measure the end point on a piece of 8' molding.
Chop saws aren't that accurate. If you're trying to compensate for short pieces that fit the fence, it sounds like you're trying to make octagons or somesuch -- a mitre saw isn’t accurate enough.
