Re: [CAD_CAM_EDM_DRO] Helix Angle

Hi,

Isn't it difficult making one understood when it has to be written down.

Yes the helix is 3 start but each of the starts is 8 tpi indexed 120 degrees
to each other. This should give about 0.040" between each slot. I am doing 1
and a half turns on the short couplings, two turns where the length permits
and a double set of helix's on the very long wider couplings for type 34 and
42 steppers.

They are machined up on the lathe first to finished sizes with holes down
the centres, relief bored and the ends sized to fit the shafts before the
helix is machined on the horizontal miller. The smallest slitting saw I can
get is 2" in dia and the slots will be 0.025".

I have just finished the design of the jig and last night wrote the program
to machine on the lathe. Unfortunately the miller is not CNC yet.

Regards,

Terry

> Okay, now you've changed your parameters... The original post didn't say
> anything about 3-starts. So, with the new data; 18mm times 'pi' equals
> 2.2263255 inches. Then, 3 starts at 1/8" each equals 0.375", so the angle
> with a tangent of .375 / 2.2263255 equals 9.5611 degrees. Do you bore a
> 'rough' hole thru the center of the couplings first? How many 'turns' on
> the coupler? Your AutoCAD drawing should be a true 'sine-curve', not a
> straight line. Also, the cut you make will not be a true, straight-walled
> slot, but will be tapered wider, toward the outer surface, due to the fact
> that you're beginning cutting somewhere 'off' that sine-curve. G' Luck!