From Newsgroup: rec.crafts.metalworking
"Bob La Londe" wrote in message news:10lj3hh$2cm6s$
1@dont-email.me...
On 1/30/2026 1:03 PM, Snag wrote:
On 1/30/2026 12:50 PM, Leon Fisk wrote:
On Fri, 30 Jan 2026 11:23:05 -0700
Bob La Londe <none@none.com99> wrote:
The aforementioned picture:
https://www.yumabassman.com/wp-content/
uploads/2026/01/20260130_111447-2.jpg
Yowza! Really nice handle you made there BobEfaiN+A
That is a pretty handle ! I'm surprised Bob doesn't have a ball turning attachment for one of his lathes though ...
I started to make one a gazillion years ago, and never finished it. A
few times I've thought about making one to make ball mounts, but...
unless I just take time I never have time to do the things I want.
The few round features I've done I usually CNC on a 4th axis, and then
just finish/polish on the lathe. Its amazing how close you can get that
way.
The thing is the point list and file works. First time I have done it,
but the the 4th axis and polish is a close facsimile of the process.
Basically the same process, but starting a little closer before finishing.
On thing I do fairly often that would really benefit from a ball turner
is radius turning the end of insert rods, but usually I have a round
over mill close enough, and just use it like a lathe bit. Gunner once
told me about a really fast tool for radiusing rod ends, but when I
looked it up it was crazy expensive, and you had to have one for each
size rod.
Bob La Londe
CNC Molds N Stuff
------------------------------------
That looks nicer than I would have the patience for when I needed to use it. Afterwards it could be prettified.
I ran through the G coding exercise on an Emco 5" CNC lathe and the parts
came out correctly. If I pick up 3D CAD well enough in night school I could get into CNC and 3D printing, though I see limited use for off-sized, cut-and-try repair parts.
For small radii I grind the final edge on a quarter round concave lathe bit with an upright conical die grinder stone, which gives smooth roundness and cutting edge relief, though not precise size without care but that doesn't matter for hand levers or bolt ends. My Multifix tool post allows rotating
it. Round shaft radius cutters are harder to hold securely without damage.
I turned two cast iron 5/8th spherical balls of around 3" diameter (as large as would clean up) from the halves of a dumbbell by using a spreadsheet to generate the X,Y coordinate list. I made the step size and roughing offset constants, changed between passes, to speed the roughing process. The final small steps removed little and went quickly and filing to barely remove the tool marks made it adequately spherical, they are the swivel feet for a
shear leg hoist.
The sockets are stacked plywood turned concave by rotating the compound,
which works reasonably well on wood and aluminum. I'd have to make an offset tool bit holder to cut spheres with the compound and the diameter is limited to 2". I like the look of purchased brass balls on handles that needn't be balanced. On the mill the brass ball's weight keeps the spindle and up to
1/2" drill chuck up.
The equation for a circle is R^2 = X^2 + Y^2. I rearranged it to make zero
the right end of the blank and used a dial indicator to measure carriage position, starting in the middle to infeed the bit both ways. R was the sum
of the ball and rounded bit end radii.
The TV News just mentioned that Boston is colder than Antarctica today. They predict -12F tonight. The Pilgrims had no idea how harsh the winter here
would be at the same latitude as Rome.
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