Mini lathe internal dome tool

[Stevohdee]

Gday fellow tool fans, here's my latest gadget born from necessity. A somewhat challenging build with a few unique tips, I hope you enjoy the build,
All the best, stevoh

[DIYer]

Thanks Stevohdee! We've added your Internal Dome Tool to our Lathe Accessories category,
as well as to your builder page: Stevohdee's Homemade Tools. Your receipt:

Internal Dome Tool by Stevohdee

tags: lathe

[Toolmaker51]

I don't watch a lot of tool builds. This one caught me, you circumvented the common solution; a yoke. I like it.
Extending the hinge pin, allows a reference to set accurate radii, via height gauge. Another method would leave holder in place, referencing with a known size block against a surface, zero a dial and back up, then set protrusion of cutter.
A hint on lapping. Cutting action improves by alternating straight strokes, rotating the part 15°-45°, produces a crosshatch [aka 'lay'] before final desired finish. Another technique is tracing figure 8's.

Yoke in this case provides movement to swing cutter, essentially a hinge.
https://www.google.com/search?q=hold...l87LWMCxqNU18M

A hemisphere is produced by the tool tip distance [radius] from hinge centerline. Extended, it forms a concave. Retracted, generates convex.

[Stevohdee]

I don't watch a lot of tool builds. This one caught me, you circumvented the common solution; a yoke. I like it.
Extending the hinge pin, allows a reference to set accurate radii, via height gauge. Another method would leave holder in place, referencing with a known size block against a surface, zero a dial and back up, then set protrusion of cutter.
A hint on lapping. Cutting action improves by alternating straight strokes, rotating the part 15°-45°, produces a crosshatch [aka 'lay'] before final desired finish. Another technique is tracing figure 8's.

Thanks for your advice, I had to Google yoke but came up with a thing to align two bullocks but a bit more digging found some pertaining to machining, still confused. I'd have to see one in action to fully understand how one would make an internal dome. Was thinking of center punching a dot in the middle of the hinge pin then using a divider or compass to set radius. Will try your tips on finishing on the next build, thanks, regards steve

Hang on, found it... A ball/radius turning attachment has a yoke, so it can be set up to do inside radius, got it, thanks again

[old_toolmaker]

That was an interesting video!
Great work!

[Stevohdee]

Thanks for the link, I've seen plenty of ball turners but never realized they could be used in reverse, otherwise I would have made one... Only prob would be chatter by extreme overhang with large radii I guess, your info much appreciated, cheers

[Stevohdee]

Thanks Dick, always a pleasure to get accolade from someone with your talent, regards steve

[Toolmaker51]

The assorted commercial & DIY ball turning apparatus are proportioned to lathe swing; the largest have substantial form tools to dampen vibration. Few get used in roughing out radii, chatter can be reduced in ways to include wrapping with rubber or lead, tapered holder/ cutter, rpm, feedrate and tool form.

[Skun Knuckles]

Good job,I have never seen a die holder like that is it something else you’ve made?

[Stevohdee]

Good job,I have never seen a die holder like that is it something else you’ve made?

Thanks skun knuckles, love the name, haha, yep made die holder, it simply slides over the tailstock quill, cheers