XL pulley groove profile

[ozzie34231]

A few years ago I made an XL timing gear 3 tooth cutter. (Published in Home Shop Machinist)
At the time I used a profile published for the belt of such a pulley. That was fairly accurate, but not exact. The most glaring error is that the depth is wrong. In the belt it is 0.050", but a pulley groove is closer to 0.060".
The effect is that while the cutter works, the machining is touchy as to depth of cut, diameter of pulley.
Since the cog of a belt is the same regardless of the pulley size, the groove (space between the teeth) of a pulley must be constant. Therefore a single cutter should work for all sizes of pulleys.
How/where can I get the exact dimensions of an XL pulley groove?
Ozzie

[ArtF]

Generate one in Gearotic and analyse its tooth shape would be easiest.
The tooth shape itself should be in the dxf..

Art

[ozzie34231]

I exported a dxf which I opened in Fusion 360. Unfortunately the curves seem to be unmeasurable; must be chords. I'm now remembering I had this problem before which might be why I used the belt specs.
However, since what I ultimately want is G-code, I should be able to get that from F360. Might be tricky because the path I want is on the inside of the profile.
Thanks,
Ozzie

[ArtF]

Hi Ozzie:

  Gearotic only puts out line segments, so Fusion must be converting to curves on the
way in. .. I have heard that before.

Art

[ozzie34231]

No, that's the problem, F360 IS bringing in segments, making it hard to measure the radii or their centers. I'm sure with a little trial and error I can approximate the size of the curves. Accuracy to tenths isn't needed.
I don't see a way to create a rack with XL profile. Is there a way?

[ArtF]

Hi Ozzie:

  Ahh, I see. Vexx in future may be able to make them back into arcs for you to measure..

No, I never added a rack capability for pulleys.. gears are easy, just prssure angle lines, but the
pulleys would have required a bit of a job to do...not sure itd be worth it, to use a pulley as a rack
driver may as well swap the pulley to a gear..?

Art

[ozzie34231]

I tried a thousand teeth and the closeup looks about rack like, good enough for me to get a profile and G-code.

I use my cnc lathe along with John Stevenson's method to make a three tooth relieved cutter. I never met him but I sure will miss him. He left us so much on the pages of machining sites; I'll think of him often.
Ozzie