Author Topic: BALL TURNER TOOL GEOMETRY  (Read 3601 times)

Offline ieezitin

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BALL TURNER TOOL GEOMETRY
« on: November 09, 2015, 07:13:39 PM »
 I have made a micro small ball turning head for the lathe, does anyone have a simple COC for tool geometry? and while your at it whats the secret of getting the diameter precise.

Anthony.

Thanks...
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Offline sparky961

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Re: BALL TURNER TOOL GEOMETRY
« Reply #1 on: November 10, 2015, 07:30:31 PM »
Disclaimer: I've never owned, used, or held one of these.  I'm not likely qualified to give an answer.

But despite the lack of qualification I'll throw in my pair of pennies.  I recall seeing a video of a commercial version recently that had pins used for setup.  The pins, if I recall, were mounted on the fixed part of the tool at the centerline.  This way you could probably use an indicator or reference surface on the part to get to a known position.  Makes sense to me anyway, even if I'm just making it all up.

Well, maybe not a complete solution but I think if you get creative with an indicator you can probably figure out a workable solution.  If I didn't have access to a really nice CNC lathe at work, I'd probably want a ball turner too.

Offline Hopper

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Re: BALL TURNER TOOL GEOMETRY
« Reply #2 on: November 11, 2015, 08:45:00 PM »
Getting the diameter right depends on getting the pivot point of the ball turner in line with the centreline of the work, and then having the toolbit point the correct distance from the pivot point.

I start off with the bar tuned to the OD i want, then set the ball turner up so the toolbit just touches the OD at front and back when swung through 180 degrees. This sets the pivot in the right place and sets the size at the same time.

One thing to watch out for when turning the ball is that if you take the toolbit back past the centre of the revolving work, it can tend to dig in and move the cross slide if there is any slack in the feedscrew/nut or it is not locked down. This then makes the next cut too deep and the ball ends up too small.

As for toolbit, I just use a regular turning tool, nothing special.

Offline Arbalist

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Re: BALL TURNER TOOL GEOMETRY
« Reply #3 on: November 12, 2015, 05:20:38 AM »
I use a standard insert on mine, not sure of the nomenclature for it. What hopper said,  I also scribed centre lines on my jig though when I made it to aid setup. I Don't expect my turner to produce accurate balls though, it's purely for decorative use on handles etc.


Offline Manxmodder

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Re: BALL TURNER TOOL GEOMETRY
« Reply #4 on: November 12, 2015, 07:42:38 AM »
That's very nicely made,Arbalist. :clap:

The insert looks very much like a VBMT or VCMT type. I use them quite often in right and left hand lathe tool holders.

Did you make the part that the insert is mounted in,or is that a bought in item?......OZ.
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Offline Arbalist

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Re: BALL TURNER TOOL GEOMETRY
« Reply #5 on: November 12, 2015, 11:14:28 AM »
No, I made all of it. I found a suitable size bearing in my box of bits so I stuck that into the mount to make it nice and smooth.
Not sure if it really needed it though.



If I'd had a boring head I would probably have made a different type but this one works well enough for rounding the odd job.