Rotation control help on A axis

[turmite]

Ok I have to ask.....what cam sustem are you using? Is that pedestal show as cut or have you sanded it? If it is as cut, what finish stepover did you use? That is some excellent looking machine work.

Mike

[pointcloud]

Originally Posted by turmite Ok I have to ask.....what cam sustem are you using? Is that pedestal show as cut or have you sanded it? If it is as cut, what finish stepover did you use? That is some excellent looking machine work. Mike

It is as finished with by the machine.
I used Rhinocam plug-in for this, but I use Bobcad too with the bowls. BCC has a sucky 4 axis.. It will do it but you gotta have more time than me..
I just downloaded nc plot to verify with and I love it...

Marc

[jcc3inc]

Art,

I like your ring gear approach. If you used a large diam gear with a small motor pinion which is spring loaded into the gear, the backlash can be zero. We used to load all our motor drives into the gear rack. We used 20 degree gearing in order to have smoother operation. You can calculate the loading (spring) force from Tan(pressure angle) which is the separating force due to the pressure angle. For 20 degree gears it is Tan(20) = .364 . So you will have to provide .364# of loading force for every pound of rotating force. If the tangential force on a 12" gear (6" radius) is 50#, for example, you need 18.2# of spring load of the motor pinion into the driving gear. And the resulting force at the 6" radius will be 50 x 6 = 300 pounds.

Regards,
Jack C.

[pointcloud]

When you make that ring gear and pinion I would absolutly positively LOVE to see that....

It's going to be huge too... I like the spring idea, sounds like you are going to get some really tight tolerances with that spring to allow a little loose motion.

Just build one like huflungdung said and you will not have to worry.
He was right about the whole thing. I am in the process of building one, after I finish I will post pics.
I ordered 2 wormes, a worm gear, 2 bevel gears, 6 tapered bearings, and some aluminum plate for the housing. I have some shim stock, and the shaft meteral. I should be able to finish it with in 24 hours of receiving the parts. Next week....

later..PC