Can anyone tell if if it is possible to make 2-1/4" to 4-1/2" diameter spheres on a lathe starting with cylindrical stock? And if so, what king of jig and tooling would be needed?
Thanks a lot.
Darren Harris Staten Isalnd, New York.
Yep, it is possible to make balls of that size on a lathe. You need to be able to get the slide under the ball in order to do so.
-- Why do penguins walk so far to get to their nesting grounds?
there was a discussion recently here about it. i'm sorry though i can not remember what the subject line is/was. i vaguely remember there were a few ways do to it, there was some computer program that would tell you where and how deep to make slots, etc. maybe there's a applet in the dropbox? i assumed someone would've already replied to your post. maybe try to do a search here.
b.w.
You need a "ball turning attachment", something like
Regards, Bob Headrick
There's special fixtures you can buy just for this.
For occasional use, I mount a tool bit right over the center of the compound. Then slightly loosen the compound holding bolts. Attach a lever arm to the compound, I just use a Kant Twist clamp. Radius of your ball is set by adjusting the compound screw. Turn in the amount of your cut and grab the lever to rotate your cut around. Both concave and convex shapes can be done this way.
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On Marv's site:
Lots of other good programs there too.
Lots of ways to do this, Guy Lautard had an explanation of how to calculate X-Y coordinates so you can sort of do a manual CNC type of thing on a lathe in one of the Machinist's Bedside readers. Most ball-cutting attachments will have a pivoted cutter, one sort just has a simple lever attached to the cross-slide or compound. The cutter distance is adjusted from the center of the pivot to give the required radius. Usually the pivot has a centered hole for a spud so that the radius can be accurately set. Another sort has a semi-circular gimballed cutter holder, some I've seen had a worm and wheel at the top for tracking the cutter around, some just had a lever attached. This is a little fancier, you can get commercial versions, not cheap, and I'm not sure it works any better than the simpler units. A lot depends on what you expect to do with the final product. If all you're turning is handle balls, Lautard's X-Y tables will do. If you're doing ball and socket joints, you're going to need something that will give you a good finish. Back issues of hobby publications like Model Engineer or Home Shop Machinist would have drawings of ball turning attachments.
Here's one of the latter sort you can buy:
Stan
This is my OLD web site - really surprised it is still there - really. But it sticks around - has some stuff.
I used a 2" boring head with a 1/2 bar with a triangle cut lying flat on the end
- so it, a point, pointed straight down on the metal. The Head was attached to a shaft and the end of the shaft to a wheel. The turning wheel is a little small for steel but for brass and Al - easy.
Mine used an iron slab that was in a step holder - stepped since my milling vice that plugs into the tool post on my lathe - holds this - :-)
I can do 'balls' that are 4" from center - e.g. do a round on a turning wheel! Not just balls.
So if you can elevate the turner - it opens up more - do outside lips on cylinders....
Martin
Martin Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net NRA LOH & Endowment Member NRA Second Amendment Task Force Charter Founder IHMSA and NRA Metallic Silhouette maker & member
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