Help need in Milling a gear with 72 teeth

[brianklein]

I need help in generating the G-code to machine a gear like the one in the picture below. the total diameter of the gear is 1.375", the root gear is 1.295" there are 72 teeth cut like a "V" and the length of each line that makes up the "V" is .050". I'm not very knowledgeable in CAD programs, and wondering if a CNC vertical Machine center could be used to cut the gear , and what type of end mill would i need to cut the "V's" in the gear??? Thanks in advance for any help.

[cam1]

Hi: If the profile of the V has to have a 0 radius, then you would be better off using a form cutter, or a gound single flute cutter with the included angle of the V, with the blank setup on a rotary table.
The VMC would make a number of passes to get to final depth, and then the gear would be indexed 1/72 of 360 (manual indexer would be fine). If you lie the gear flat on the table, and machine the profile of all the teeth with a small cutter, you may end up with a tapered profile, and a radius in the V.

just some thoughts

regards

regards

[brianklein]

Thanks for your idea. I'm trying to figure out if it possible to cut the gear in a CNC Machining center.

[Andre' B]

If the CNC is a 4 axis or at least setup with an indexer then yes.

If you insist on milling it as a profile then you have to answer the question of how big a radius you can have in the bottom of the V grove.

If you can have a 0.010" rad then you can use a 0.020" diameter end mill, Harvey Tool catalog has some 0.020 dia. end mills with a 0.060 DOC and a 0.170 reach, you will need something in the range of 50,000 RPM or better to use them.

Edit:
The other option (and likely the one used to produce these ratchets) is and rotary broach in which case you just need a Z move.

[cam1]

Brian:
My answer was tailored to your desire to use a VMC, I didn't know if you had a 4th axis (do you?}

regards