Lathe Ball Turning Attachment

[Russell AllsopParticipant @russellallsop49444]

Can someone recommend a ball turning attachment for a VM210 8×16 mini lathe.
Are these attachments any good for use on brass, aluminum and mild steel.

The ones that bolt on the cross slide would appear to be more rigid than the ones that connect to the tool holder.

Any advise would be appreciated.

[Chris CrewParticipant @chriscrew66644]

I have no knowledge of your lathe but what I would say is that all spherical turning attachments rely on the axis of the tool being at exactly centre height, otherwise all you will produce is acorns. I made the Radford spherical turning attachment, which was later improved by GHT, and if I were to be making it again I would incorporate the refinements, gib strip etc. I don’t know, because I have never used a commercially available attachment, but I would suggest they would require some care in setting up to ensure the tool axis is precisely at centre height. If you make your own attachment, e.g. the Radford or GHT, it is bored on the machine it is to be used on whilst being mounted exactly as the finished product is mounted. Therefore, whenever it is in use on the lathe it is always at the correct centre height. I can attest that the Radford type attachment produces reasonably accurate spheres, they are not perfect as I found out when I made some for the Radford design of U/J, but they are very cosmetically acceptable.

[bernard towersParticipant @bernardtowers37738]

Chris. Not sure why your radford tool only turns out acceptable balls as the design with the secondary tool slide always scribes a perfect circle wherever its adjusted, the only thing that could be wrong is thaty the tool point is not exactly halfway across the blank. I have a similar tool and it turns out balls to within a thou as I have used it for making ball joints. With regard to Russel’s question is how good does he need the balls to be circular, if only for ball handles then the cheap and cheerful version should suffice as they are for looks and handling.

[Chris CrewParticipant @chriscrew66644]

Bernard, I do not consider myself to be a particularly skilled worker, I just do my best so there may be some slight inaccuracy in the construction of the Radford device. It doesn’t have a gib on the slide being just a close fit in the V’s so there may be a little ‘shake’ when in use. This was one of the design faults GHT rectified but I followed Radford’s drawings and notes before I was aware of the modifications. I know the spheres turn out to be within a few thou. but they are not perfect as you would expect a ball-bearing to be, or at least the ones I made for some U/J’s were not. When I assembled the U/J’s, to Radford’s design, I detected a slight binding at certain angles of rotation, nothing that could not be rectified by re-mounting them on a spigot and lightly easing them with some fine emery in the lathe. It just proved to me that they were not perfectly spherical although they looked pretty good by eye.

[bernard towersParticipant @bernardtowers37738]

Maybe retrofitting a gib might cure your very small inaccuracies. Best of luck with the set up for remachining!

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