Gallery, Projects and General > How do I??

Ball Turning - using cutting schedule (Software: Ballcut by Marv Klotz)

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bogstandard:
Chris,

Marv Klotz is well known to a lot of us, and produces some very workable programs, but only if you understand machining and mathematics. He is a brilliant physicist who doesn't suffer fools gladly. Most of his progs are mathematically based, and if you don't understand it, you will get no leeway if you ask the wrong question.

His ball turning prog does work, and the tool he is on about is like a parting off (a plunge grooving) tool which has a square end to it.

That particular program gives you a stepped ball, and is dressed back with files to produce the finished article, just like Ralph said. I do the same sort of thing, but freehand by eyeball, and have had some acceptable results, without all the hassle of co-ordinated turning. It is all down to experience and trial and error.

Bogs

raynerd:

--- Quote ---He is a brilliant physicist who doesn't suffer fools gladly. Most of his progs are mathematically based, and if you don't understand it, you will get no leeway if you ask the wrong question.
--- End quote ---

Surely the cutting tool width will have some bearing on the cutting pattern?  If you are working from the equator then the "plunge" of your first move will effect the  schedule of your next move? The programme doesn`t take into account the width of your cutting tool. I totally understand the sort of stepped shape you are trying to achieve and then the need to file it down at the end, I just can`t get into my head how the tool size isn`t going to effect things?

Clearly I am wrong, I appreciate you have just said this link is a reliable site and an the author an excellent physicist and machinist, I`m just trying to convey my confusion!

Ralph - when I have a little more experience and skill I may very well take you up on your offer!

Chris

DavesWimshurst:
Chris,
If I might muddy the waters a little.  When using the incremental method as Bernd and Bogs have said you start from the equator and work to the poles.  What may not have been said is that when working the tailstock side of the ball the left hand corner of the tool traces out the ball as you work to the right.  For working the other half of the ball Lautard's description (p77) then tells you to rezero the right hand corner of the tool to the equator.  You then will be using the right hand corner of the tool to trace out the ball as you work to the left.  When you rezero you take the tool width into account.  I would use a wide tool for this method for rigidity.  I hope this helps.

Dave

bogstandard:
Chris,

I tried to do a post last night to explain exactly as Dave has done. But the site wouldn't let me post it.

But I did do a C-o-C to explain that the width of the cutter has no bearing on the job, as when you go 'over the top' as Dave states, you take into account the width of the cutter.

So here is the sketch.

John

Bernd:
Dave,

You put into words for what I was looking to say.

Bernd

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