Hemingway Spherical Turning Tool

[Allen Smithee]

Looking at their page on this I see they say it does internal (recessing) as well as external (ball-turning) work, but I'm struggling to see how it would do an internal cut. Is there a different tool-holder or something, or has the advert copywriter just got a little carried away?

AS

[steammachine]

Looking at their page on this I see they say it does internal (recessing) as well as external (ball-turning) work, but I'm struggling to see how it would do an internal cut. Is there a different tool-holder or something, or has the advert copywriter just got a little carried away?

AS

Yes, it can cut internal (concave) surfaces. If you envisage how the tool works, the axis of the tool holder is perpendicular to the axis of the work & the closer the cutter tip gets to the tool holder axis then the smaller diameter ball it will turn. If you keep moving the tool so the tip passes through the axis line of the tool holder it will then cut a concave surface into the face of the work. Hope that makes sense, easier to envisage when you see it working than to describe!

Martin.

[Allen Smithee]

Yes, I get that in principle, but how does the cutting edge get inside the recess - surely the tool holder will stop it going beyond the front face of the part?



AS

[Don1966]

Allen there are two attachments to use and one is for internal curves and arcs. The one you see on the tool is for outside balls and arcs. I did a thread on it in tools and machines.

Don

[Lew Hartswick]

I don't know anything about the Hemmingway  but have done complete hemispheres (even slightly recessed beyond the max dia) with
a Holdridge and a tool I came up with. This was with an aprox. diameter of an inch .
   ...lew...

[paul gough]

Could someone inform me of the maximum dia. ball that can be machined with this tool. Paul Gough.

[Allen Smithee]

Could someone inform me of the maximum dia. ball that can be machined with this tool. Paul Gough.

Hemingway suggest up to about 2"

AS

[paul gough]

Thank you Allen, I will probably need 3"-4". But this tool looks nice. Maybe I'll build one and then make a big one. Regards, Paul Gough.

[chris evans]

I have just had some cast iron parts made loosely based on the Steve Bedair (Spelling) design. I have not got round to machining them yet but worth a look as it is very simple. No real need for it to be cast all can be from solid bits in the scrap bin.

[Nick_G]

.
I have recently seen similar to this on youtube using a boring head.

Nick