Rotating Axis Controlled by a Ballscrew

Hi,

Thank you all for your contribution. I apologise for not giving enough information here so let me correct that by sharing this video of the mechanism in motion.



Secondly, Timo you are absolutely correct about the pros and cons you listed. The cost is lower than a harmonic drive, the torque is greater due to the huge ratio. In this example over the range of travel, the average ratio of the stepper motor rotation to the b-axis is 85.2 and at a speed of 500RPM it takes 2.55s to do a full 90-degree sweep which is fine for me. If I need it to be faster I can change the ration by changes the ballscrew lead.

The thing I wanted to mention here is that the relationship between the ballscrew travel and the angle of the b-axis can be defined by a function rather than a mapping in order to get an exact and accurate relationship. It is similar to the relationship between the travel of a piston and the angle of the crankshaft, as explained in the video below.



Is there anyway I can insert this function into LinuxCNC?

Alright, I will list some disadvantages that I see. There are more moving parts and more expensive bearings. The ball screw needs to have a large diameter and be of a high grade. The biggest drawback of this drive system is that it will create not only axial loading on the screw but also radial loading. In other words, the play will depend significantly on the size of the screw.
If you decide to go another route I can give some ideas

Yes I agree that this will put radial load on the ballscrew, I didn't think of that. Ok, I'm open to other ideas please do let me know.

The best option is a worm gear like 4 axes do. The other option is something similar
www.haascnc.com/service/troubleshooting-...set---ngc-lathe.html

 

 

I think that this is a perfectly valid approach, and as you have noted, it was used by Centroid.

The "right" way to do this is probably with a custom kinematics component. That way it is solved by mathematics.

linuxcnc.org/docs/stable/html/motion/kinematics.html

Thank you Andy and thank you besriworld, I also feel this is a viable solution, Ofcourse what besriworld about the ballscrew taking radial load is true but we can fix that at a lower cost than some of the other solutions available. I will look into that aswell ass the solutions suggested by besriworld. Thank you all once again