Ball or Parabolic Turners- What are they and how do they work?

[HMF]

Dear Folks,

I have been reading again.

How are ball turners or parabolic turners used on a lathe to turn concentric shapes? (Photos would be awesome!)


Thanks,


Nelson

 

[Pacer]

Heres a post I made over at the 'other' forum a few months back. It was following a previous post on a ball turner tool I had built (second link) and had a bunch of questions on - kinda like yours

Even today, I am turning up the 2 ball cranks for my rebuild of the SB10L - replacing the badly rust pitted ones.

http://bbs.homeshopmachinist.net/showthread.php?t=46995&highlight=ball+turner

http://bbs.homeshopmachinist.net/showthread.php?t=46967&highlight=ball+turner

 

[Pacer]

Since I was working on the handles, thought I'd get a pic - this will be the cross feed.

When I get the last ball cut, I will take a .125 cut off blade and set the compound to about 3-4° and get the slight taper between balls

 

[HMF]

Nelson -- Yer losen it. You asked a similar question about cutting concave in a cylinder. The info there will help you here.

http://hobby-machinist.com/index.php?topic=2708.0

"Bill Gruby"

Ack, Bill- yer right! Sorry!


Nelson

 

[Pacer]

Yes, I did make the turner - and several others, hah! It is indeed the one from "Tall Grass Tools" as Bill Gruby shows in the link.

For what its worth, "Hemingway Kits"
http://www.hemingwaykits.com/acatalog/Spherical_Turning_Tool.html
has one very similar, They are in England, and not too practical for us here in the states, but some one not so affected by this...

 

[Tony Wells]

So, about this parabolic turner........where is it?

 

[randyjaco]

I have 2 ball turners that I seldom use. A parabolic turner would be an interesting project. I have never seen one, but shouldn't be too difficult to fabricate. The bigger problem would be finding an actual need for such a device. I don't fabricate many parabolic reflectors. I am presuming it could be fabricated using a scheme similar to that for generating ellipses.

It sounds like one of my many round tuit projects. ;D

Randy

 

[MarkBall2]

Mine is a bit different, but basically turns a ball shape when I ask it to.

 

[Tony Wells]

Parabolas tend to be generated, normally, so I am curious about an attachment for a manual lathe that will cut them. Pictures or references, anyone?

 

[Pacer]

Bill,
I just looked at my turner and was immediately struck with the apparent thinness of that dimension!! It must have slipped by me, or I would have probably doubled it - at least. I am not one to "color in the lines" so to speak, and often change dimensions, appearance features, or add something... Speaking of which - I added one feature to my turner that you may want to use. I drilled a 1/4" hole in the center of the main shaft for a pointed pin to allow quickly finding the necessary lock down points of the size ball youre turning. See this post for pics of using it--

http://bbs.homeshopmachinist.net/showthread.php?t=46995&highlight=ball+turner