ball turner

[Oldmechthings]

A ball turner is kind of a unique accessory for your lathe. Most every machinist at one time or another will have a need to turn spherical shapes. The easiest way is with a ball turner. You can buy one, but they are simple enough to make yourself, and there are all kinds of instructions out there on building them. Usually the cutting tool travels in a circular arc in a horizontal plane or else in vertical plane along the centerline of the workpiece. I have built a couple of them, one quite large with a capacity of about 6" diameter and the other smaller, with maybe 2" diameter. I'll just show the small one today. I need to mention this is a demonstration picture. Normally when I'm turning ball ends I hold the work in one of those 5C collet chucks. That way I do not risk having the chuck jaws strike the ball turner, and cause all sorts of commotion.

On this one I used some features of a plan that I found, but modified it so that it would work on the quick change tool post. I have found it handy for making the balls for fly ball governors, ball ends for guard rail posts for railing around models, etc. One use was to form the ball ends on a helping hands work holding fixture for silver soldering.

For this demonstration picture I just clamped three pieces of brass and positioned them together. From here it would be a simple task to daub the joints with flux and silver solder it together. To assemble that same configuration without the fixture would be a difficult task.

By the way if you do not want to build your own helping hand fixture Harbor Freight has an in store coupon sale going on right now, till Feb. 11, for $1.97. (normally $3.99) It is smaller and does not have as many joints to move and position things as my home made one, but at that price I could not pass it up, even though I already had one. They also include a magnifying lens. Take that off attach a nice handle and do a little detective work on the side.

In closing I suppose a ball turner could be compared to a bull on the farm. It is not the amount of work it does to earn his keep, it's the occasional service it performs.
Birk

 

[Mcgyver]

i too despise those third hand pos....made my own contraption but i like those arms & clamps you made....any chance of some larger format photos and details?

thanks

 

[Oldmechthings]

When I built my "helping hand" I just looked at some pictures in jewelry supply catalogs, and then did my thing. I think GRS, and also Rio Grande, carries them under the name "Third Hands". Try www.riogrande.com I'm pretty sure they have their catalog set up on a web site so you can look at the pictures of their products.
Birk

 

[Mcgyver]

I see, like

http://www.ottofrei.com/store/product.php?productid=8175&cat=1331&page=1

jeez nobody likes large pics

mine is a different sort of structure and I want a similair type of arm as an attachment....the idea was to use ball bearings silver soldered on. you can see the start of it in the pic, but i haven't yet carried through with the arm & pincers. the elbows just get tightened into position? how about the pincers, are they spring loaded? any other info or shots on how you design/made it is appreciated

thanks

http://i20.photobucket.com/albums/b201/michael0100/McgyversthirdhandcloseupII.jpg
http://i20.photobucket.com/albums/b201/michael0100/3e5f7733.jpg
http://i20.photobucket.com/albums/b201/michael0100/universal swivel/usingthethirdhand.jpg
(bit of a messy job on the brazing & SS now that i look back on it)

Marv also had some neat ideas for third hands, a v block arrangment iirc, something that would lend itself well as an addition to your or my rig....can't remember where it was posted...Marv?

 

[mklotz]

The topic was titled "Two vises are better than one" and can be found here

http://www.homemodelenginemachinist.com/index.php?topic=987.0

 

[wdp67]

Hi everyone,

How do you use a ball turner to cut more of a nose cone type shape? I built a ball cutter similar to the Bedair website over the weekend, but have not had a chance to try it out yet. I need to cut an ogive type shape and now am wondering if anyone can steer me in the right direction.

Thanks
Walt

 

[cfellows]

Turning a sphere requires that the pivot axis of the ball turner be directly under the axis of rotation of the workpiece. To make more of a cone shape, the working radius of the ball turner is increased and the tool's axis of rotation is moved rearward, away from the workpiece axis of rotation.

I hope that's clearer than it sounds...

Chuck

 

[Divided He ad]

Hi Walt,

I am just uploading a vid on to the 'tube' showing a ball/knob I cut today (was asked to do this after my recent post in 'Tips and tricks')
it may be of a little interest to you? (should be on here by the morning... erm 6 hours away!)

As for the shape you require... apart from the possibility (probability!!) you will make a few accidentally on initial set up runs,(I know I did!! : ) Chuck has clearly nailed this one! ;D

Ralph.

 

[zeusrekning]

Ralph there is no nice way to say this but I you ball skills are marvelous. :bow: I did get a little sea sick from the video though. I went back and seen you are the guy with the camera mounted on the lathe. It looks great but it looks like your spindle was moving in and out in Z. Even in person , watching a CNC spindle move the part instead of the cutter moving makes me queasy. This is defiantly a project on my list of to do's.
Tim

 

[Divided He ad]

:big: All I can say to that is I saw it first and it took me a minute to get my head around it too!!

Thank you Tim, much appreciated.

Ralph.

 

[wdp67]

Thanks a bunch for the replies!! So how do I get to your video?

Walt

 

[BobWarfield]

Turning a sphere requires that the pivot axis of the ball turner be directly under the axis of rotation of the workpiece. To make more of a cone shape, the working radius of the ball turner is increased and the tool's axis of rotation is moved rearward, away from the workpiece axis of rotation.

I hope that's clearer than it sounds...

Chuck

Fellas, I'm still not getting my head around this one.

It seems to me that no matter where you move the axis, or what the radius is, the cutter is still going to describe an arc of a circle. Nose cones are more parabolas or elliptical unless I am confused about what is meant by a nose cone. I can't see how you get a ball turner to make a parabola or an ellipse.

The axis does need to move, but it needs to move along the axis, not perpendicular to it. Now if you could somehow engage the power feed and cause the pivot to be synced while moving the center of rotation from one ellipse focus to the next, you get an ellipse or segment thereof. Think of it as a taper turning attachment connected to a ball turner in some nefarious way. Some sort of cam connecting the power feed motion to the rotation of the ball turner would allow you to modify the nose cone shape. Better yet, a tracer attachment makes more sense. Alternatively, perhaps a talented operator could freehand the ball turner well enough while the power feed was engaged.

I did draw some examples in Rhino3D of what happens if you simply move the center of the turning tool and increase the radius. It cuts a torus, which may or may not be helpful. Assuming you don't dip into the flat spot on the end, I guess you can make a useful shape, but still doesn't seem like a nose cone shape to me.

OTOH, this is all in my head and I may be completely confused! LOL

Cheers,

BW

 

[CallMeAL]

I made a ball turner and it will cut some fairly weird shapes if you mess with it a bit, here a a couple of examples:

This is what I came up with for a ball turner, kind of a conglomeration of several I had seen on line:

Sorry for the fuzzy photos.

 

[Brass_Machine]

Nice looking ball turner Al. I gotta make me one.

Eric

 

[bentprop]

I thought I'd try my hand at a ball turner.I slightly modified the Steve Bedair design to suit my 13x40 lathe:

The handle is a temporary stand-in,until i can fit a ball to the real handle.Some durn fool cocked up a measurement somewhere,hence a piece of HSS parting tool under the tool holder.I'll fix that one day.I know it looks a little "agricultural",but it is here to work,not sit on the shelf and look pretty :big:.
Here's my first attempt at a ball:

A bit rough,and the shape isn't quite there yet.Perhaps a longer handle will allow me to control the tool better.
Are there any specific points to setting up the tool for a nominal size ball?
I started with 20mm stock,and the ball is about 18.7.I could find no mention of that anywhere I've seen this style of tool.
At least it "sort of"works,which is a novelty in my toolmaking efforts ;D
Your comments,garlands,and house bricks are invited.
Hans.

 

[kvom]

The radius of the ball will be equal to the distance between the tip of the tool to the center of rotation. Given the geometry of your turner that could be tricky to measure. I'd suggest scribing a line acroll the top of the turnitable from which you could measure.

To get a spherical shape the center of rotation needs to be on the centerline of the lathe.

The turner I used a school has a long handle (about 10"), and turns using bearings. Getting a good finish needs a very slow, steady turn. That said, you could certainly polish up the ball you made.

 

[Lew Hartswick]

What sort of bearing and brake arangement did you put in that? I'm in the process of doing a different
sort of design and have most of pretty well designed but the pivot and brake (drag) are still up in the
air. I'm having to incorperate a small amount of vertical adjustment to alow for use on 8 different lathes
with some variation in spindle height. Where is the article you refrenced, Steve ... ?
Thanks.
...lew...

 

[tel]

http://www.bedair.org/Ball/ball.html

 

[Circlip]

It might be a drag Lew, but only way to get the most rigid height adjustment is by using packing spacers between the tool base and the lathe cross slide? Not trying to teach you to suck eggs, but the basic rigidity can only be compromised by trying to achieve fine height settings anywhere other than as low as possible. I think ball turners must be one of the most "Better mouse trap design" tools in ME.
Regards Ian.

 

[Divided He ad]

Hi Hans, I thought I would recycle my old posts a little... I went through a whole load of setting up tips and the likes.
It might help you sort it out?

From the look of your ball the tool tip is probably set to slightly larger than the radius of your bar (from the centre on which the tool rotates)

Read through the two posts I tried my best to explain it all in there



http://www.homemodelenginemachinist.com/index.php?topic=1721.0

http://www.homemodelenginemachinist.com/index.php?topic=1633.0


Just one final note... When you come to make a new tip holder, set the height by turning a sharp taper in the chuck and using that (left in the chuck!) to mark the height for the top of your tool on the blank.... The slight error I had with mine is that I set it originally using a centre in the tailstock... which was slightly out !!!


(this is the most usefull tool I ever made ;D )


Good luck, and happy explorational turning ;D




Ralph.