Hi John,

Now we are delving into an area where I had to do a whole

lot of experimenting, and research...

'John Snyder' Kochcal@... [TekScopes] wrote:

I see some winders use a cam that provides the back and forth. It is not

clear to me what the shape of the cam is and the resulting pattern.

What is the cam shape would be one way to answer the question.

If you make the cam a circle, and mount the shaft off center, you will

develop a back and forth pattern that is a sine wave.

That will work, but the winding stylus will spend a longer than optimal

amount of time at the edge of the coil, and will be trying to stack

wire on top of wire, and the winding will not be level, but rather

will peak up at the edges.

More desirable is for the wire to spend as little time as possible at

either edge... and simply make a sharp change in direction there. So,

a better shape for the cam is one that makes the stylus traverse a

triangle wave form on the coil face.

The ratio of the coil turn and the wire back and forth can not be exactly

1:1. one of the winders on youtube looks like it is turning less then 360

and one looks like more then 360 for each back and forth.

I already told you this one. The wire has to travel from one edge of

the coil to the other in one turn of the coil, minus the thickness of

the wire, for optimal space utilization.

I assume that is the 6 degrees you talk about so does that make it 366

degrees of coil turn to 1 back and forth or 357 degrees of coil turn to 1

back and forth?

No.

If you look at one turn of the wire around the form, it will be at the

left side at the beginning, at the middle at 180 degrees, and at the

right side at about 360 degrees.

If you draw an imaginary line along the circumference of the coil half

way between the left and right sides of the coil, the winding will appear

to be about 6 degrees relative to that line.... for a 5/16 inch cam, of

course.

When trying to figure out how many turns it takes to cover the form once,

you have to figure out how many turns of wire can sit side by side at a

6 degree angle relative to the circumference.

Is the cam Round resulting in a sine wave pattern for the wire if you took

the coil cut it and flattened it?

No, see above.

So if one was to program a linear position for the wire, if the coil had a

width of 5/16 = .3125 and the wire starts on the left at 0.0" and the far

right of the coil is at .3125

Yes, minus one wire width (at whatever angle the wire travels relative to

the circumference... 6 degrees for a 5/16 inch wide coil.)

The wire, relative to the "total degrees of motor turn" would be at

.3125" * [ cos( remainder("total degrees of motor turn"/360) * 366/360) -180

deg))/2 + 1/2]

366/360 or 354/360 being the small offset for each turn

Or is the cam have some other shape and lays down something more like a

triangle wave rather then a sine wave?

Yes, see above.

-Chuck Harris