Single piece, simple ball turner.

[tonyfoale]

The ball turner axis, when extrapolated, must intersect the rotation axis of the part. Is that wording more to your liking?

ha, ha. I can't fault that statement. Whether the wording is more to my liking is immaterial because I understand the geometry. i was just concerned that the previous may not have been clear to all.

[Y-geo]

Ralph,
Tool post pivoted ball / ogive turner in close up action :-

better yet only 5.75 mins long

[tonyfoale]

Duh OK it is "starting" to settle in. I now can understand the pivot. Now I have to work on the operation geometry.

That video sure will help.

Ralph et al.

Here is the video. The video quality seems to have suffered on its journey from PC to youTube. I was aiming for under 7 mins but it grew to nearly 10.

Here is how I would do it in a mill. Virtually zero setup, just add some G-code and away you go. click on pic. for full size.

[tonyfoale]

Ralph,
Tool post pivoted ball / ogive turner in close up action :-

There many similar examples of this on the net but they have missed an opportunity.
They have placed the rotational axis of the tool assembly on the centre line of the cross slide, just like mine. That was forced on me because of my decision to use the existing compound rest as the basis. However, it would have been very easy when building the complete thing from scratch to move the axis on the plate forward toward the chuck. maybe even overlapping the edge of the cross slide with the plate. So those designs suffer needlessly from the same problem as mine, they both need a lot of work piece overhang to provide clearance from the chuck.
Another aspect which could be easily improved is the tool holder. There is no need to machine the guts out of it to make an "L", If just enough is machined away to provide clearance for the largest ball then it would be more rigid and have more mass. Rigidity and mass are very desirable properties on any machine tool.

[Ralphxyz]

Thanks Tony, I sure hope I can find this thread when I get around to actually making a ball turner.
I am actually working on closing up the space in my shop to receive my Craftsman 12x36 lathe which has been sitting outside my shop in a crate for the last 8 months waiting for me to finish that section of my shop.

My todo list keeps getting bigger and I seem to keep getting slower, must be that dam AGE virus that is going around.

Still not fully grasping the geometry but I think when I am at my lathe it will sink in.

If it is this simple why does anyone build the more complicated ball turner?

Thanks for the video that really helps.

Ralph

[Ralphxyz]

Thanks Tony, I sure hope I can find this thread when I get around to actually making a ball turner.
I am actually working on closing up the space in my shop to receive my Craftsman 12x36 lathe which has been sitting outside my shop in a crate for the last 8 months waiting for me to finish that section of my shop.

My todo list keeps getting bigger and I seem to keep getting slower, must be that dam AGE virus that is going around.

Still not fully grasping the geometry but I think when I am at my lathe it will sink in.

If it is this simple why does anyone build the more complicated ball turner?

Thanks for the video that really helps.

Sorry if this gets duplicated the forum software is messing with me.

Ralph

[tonyfoale]

If it is this simple why does anyone build the more complicated ball turner?

Ha, I often ask myself that about a lot of things. I am lazy so I tend to find simple solutions. In this case my solution is perfect for my stated and immediate need but it is in general not as flexible in application as some of the purpose built versions. I was constricted by the pivot being set back from the edge and so chuck clearance is a problem to such an extent that I can't do much in the way of small concave shapes. Big ones will be fine.

As to finding the post again, you only have to search the forum archives for a phrase like "ball turner" or else search for topics under my name, then you will get all of my offerings.

[Wmrra13]

Thanks Tony!

BTW, is that a Bultaco or an MV in your Avatar?
I used to race a liquid cooled 350 TSS years ago.

[tonyfoale]

Thanks Tony!

BTW, is that a Bultaco or an MV in your Avatar?
I used to race a liquid cooled 350 TSS years ago.

Neither, it is an Aermacchi 350 in my chassis. I raced one in the early 1970s and now I race a copy of my original. There is more info in the Aermacchi folders at
https://get.google.com/albumarchive/...99061223276003

Click for full size
Original and current.

I rode an aircooled TSS 350 in my first visit to the island. I lived in Australia and the boat bringing my 'macchi over had engine trouble in mid ocean and the bike didn't arrive in time. Geoff Monty lent me the Bultaco at the last moment. Here it is at Ballaugh.

[old_toolmaker]

Nice job, Tony! Gets the job done.

I made an over the top ball turner that uses a 2" Criterion boring head mounted in a QC tool post. Works great and I don't have the overhang issues you mentioned.