Spokes Again...cad Help Please

Mzayd3,

Thanks for the math! Is the formula for circumference 2 pi R? I think you left out the 2? And, I don't see and understand how to calculate the offset needed for the starting position of the inside circumference? As you can see in the photo of my sample, I started with the outside circ. I simply zeroed the RT and plunged at the start of the first arc. But as anyone who has worked thru this or looked at a cad drawing of it knows, you can't start the inside also at zero, there is a required adjustment to align the corners so the spokes are square to the center of the wheel.

I wanted to see how it was going to look, so I drew on the part to line up the edges and positioned the end mill and then read the degrees from the RT. I think this turned out to be about 14 degrees? I need a hint here for this value. Is must be related to the degrees of rotation of the cutter at the outside radius?

My next question is about making the side cuts Long the spokes. Is this just a simple offset of the Y axis?

I spent several hours this morning doing the math and creating a spreadsheet.

image.jpg image.jpg image.jpg

Thanks again to everyone in this thread and the other thread about spokes!

Jim
 
I wanted to try and get my first attempt completed so I found the center of a spoke with the end mill. Then moved the Y axis to line up the cutter with the straight slots. I milled the slot and then moved to the other side of the same spoke and did the same. Repeated four more times. I also finished the inner radius by moving the Y axis back to zero and finding the end of a straight slot, then rotating the table to finish the inner radius. This was all done by eye. These are going to be the steady rest wheels on a fishing rod lathe. I am going to need about a dozen of them! It might be quicker if I convert the mill to CNC! :) Seriously, if doing this operation with a rotary table doesn't make you think about CNC I don't know what will? I also would love to be proficient with a CAD program.

Jim

image.jpg
 
looks like you did really well with my limited, bad assistance. I don't do this sort of thing much at all and always end up fumbling through it. nice work, it looks good!
 
Mzayd3,

Your info was a great start. Working thru all the math on paper made it make sense. Any thought on the angle starting position offset for the inner slot?

Jim
 
Here is a short video of my first three spoked wheels. I tested them at 350 rpm. I am told they will probably only run about 200 rpm.


Jim
 
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