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cybor462
05-02-2007, 11:01 AM
Ok I know this has been up quite a few times. I spent hours looking at the other threads but I have seen the question asked but never really answered. So I Want to ask again.

How the heck do you make a nice ball with the ball turning tool?

I made one a copy of Steve B but I had to adapt it to my lathe. This in itself has created problems.

I had to remove my compound and make a plate to fit. I do not have a slotted plate just a bore with 2 bolts. Second problem chips are getting in the slide ( I thought they had a way out) but no I had to fish them out by hand.

I intend to modify this and make it fit the QCTPT nut on the compound. Not sure how it will work out but first things first.

How do you use one of these ball turning tools

http://bbs.homeshopmachinist.net/showthread.php?t=23739&highlight=radius+cutter

My cutter is like the blue one. I messed with it a while and was not able to get a ball although I did get some neat shapes.

Is there a post or can someone explain how with this type of tool one can turn a ball?

I will be in your debt forever, or 5 minutes whichever comes first.:)

mklotz
05-02-2007, 11:26 AM
Sounds to me like you're not setting the tool up correctly.

In order to turn a sphere, the axis of rotation of the ball turning tool must be aligned with the center of the ball to be turned.

Exactly how you achieve this initial alignment is a function of the design of the ball turning tool.

Your Old Dog
05-02-2007, 11:29 AM
I may not understand your question complete but.....

You know the entire blue mass revolves on its own axis via a round stud at the bottom not shown in the picture don't you? The slide is simply to adjust for the size of the ball you would like to make. As the slides bit approaches the centerline of the stud I just mentioned the ball would of course be smaller. Move it to the other extreme and the ball would be larger.

I'm not the brightest knife in the drawer so I'm not sure I'm answering the real question you have in mind. You might be going over my head and I just think I'm on your wavelength. If so I'm sorry, don't mean to sound too simple.

SGW
05-02-2007, 12:39 PM
What Marv said..... Be sure the pivot point for the ball tool is directly under the center point of the to-be ball.

cybor462
05-02-2007, 01:33 PM
Ok let me try to explain.

YOD I do understand the tool and actually made a better one, actually a better copy of it. Instead of grinding the post screw (holds down main post) to get required clearance for swivel I tapped the whole way thru and inserted a set screw from the top so all you do is adjust your clearance for swivel by adjusting how far down the set screw is. When you tighten the mount screw it bottoms on the set screw.
This way when your swivel starts to wear (my whole tool is aluminum) you can take out the excessive play and always have a perfect clearance and a smooth tight swing.

I just need to make corrections to the base and main tool to fit my machine.

I centered the tool on the center of the ball. The tool itself is centered to the machine center when milled. I brought the tool to the center of the work and started making passes. My tool is not correct for my machine as I run out of travel on the slide to the outside (backside) at the exact center of the work.
Also my main post I made 2.5" high because I had a 2" bar that size also needed quite a bit to hit machine center. When I was done I found the post is too tall (hits work over 1") so I need to shorten it. I also need to make a longer base so I can get my travel I need on the slide, and make the base design smaller in width (base now hits jaws). I was actually thinking of mounting it on the QCTP T nut. Again clearance to work may be a problem. Then I have to deal with the chips falling into the slide cavity.

I was able to play a bit and maybe I am doing it wrong. I also was forced to bring the cutter front (cutter now sits on center of tool) which could be a problem as it reduces the arc.

I know that is my problem, right! Just hit me.

So I need to redo the mount and get the cutter to the out side of the dia. of the tool and I bet it will work.

To make the swing for the backside of the ball near the chuck, is that why the handle should be bent to get more clearance?

Ok Ok I know I just answered most of my questions.

Did I answer them right?:o

BadDog
05-02-2007, 03:56 PM
Sounds like you've got it figured out.

Just look at it from above, stick a ball on the end of a piece of bar stock if it helps, and imagine the tool path as it traces from spindle C/L axis, around the sphere, and to the stop point. Use a normal lathe bit if it helps, but see how it moves, and where it (and the handle) is going to be getting close to the chuck. So the shape of the holder tower thing is generally made to facilitate getting closer to the chuck without interference with the trade-off near the c/l axis. But that's not generally a problem on that end since you can just swing past the c/l...

ligito
05-02-2007, 04:05 PM
Did you make a copy of the tool in steel, so it doesn't wear out so quickly?

Lew Hartswick
05-02-2007, 06:13 PM
I've just been doing a few balls in brass just under 1/2 inch so if I
can figure out how to get the silly home page set up so it can be
read I'll post the pix here in this thread. It may take a day or so. :-(
...lew...

cybor462
05-02-2007, 11:11 PM
Did you make a copy of the tool in steel, so it doesn't wear out so quickly?

I did not have steel for the main body or base. I did make the actual tool holder out of steel. The way I have devised the adjustment for the swivel will keep it usable for a long time.

Lew.. look forward to your pics.

I need to remake the whole tool and will let you guys know what happens.

Thanks to all. Feel free to make any suggestions you like.