Author Topic: Ball Turning - using cutting schedule (Software: Ballcut by Marv Klotz)  (Read 9936 times)

Offline raynerd

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Hi

When I re-purchased a lathe a few weeks back, I was transfixed on YouTube -DivideHeAd`s Ball-Turned video - I thought it was very impressive and turning a ball is something I have wanted to try! A ball turner is too hard to make for me at present and I have no mill, so would struggle.

I was searching the net and came across this, which I guess must have been linked on here hundreds of times - the site contains many many programmes related to machining: http://www.myvirtualnetwork.com/mklotz/

Programme 2: Ballcut will provide you with an output cutting schedule to create a ball.

First question, has anyone ever used this sort of programme and does it work? If so, some specific help with this programme - it doesn`t seem to take into consideration the width or shape of the cutting tool? The help file says: "make a number of plunge cuts with a cutoff tool ground with a squared off end.  This yields a 'staircase' shape that approximates the shape of the ball" But it doesn`t tell you the tool width (infact I`m not even sure of the shape it means) and the programme does not seem to take into consideration tool shape and size either. Am I missing something?
It does ask for "angular step size" and I`m not sure what this means - is this something to do with the tool size?

Any help appreciate - probably way too advanced for me but I am interested in understanding how this will work. I can kind of picture it, just that tool size confusion....

Chris

ja2on

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Good link I have not seen that before  :thumbup:

I googled the guy's name in the ballcut description and found he wrote a book about it http://lautard.com/ballbook.htm
I know that is probably not much help but it's all I could find about the process hopefully somebody will though

In case you purchase a mill or a mill attachment  for your mini lathe in the future here is a set of plans to build one specifically for your machine
http://www.toolsandmods.com/library/ralph_patterson_ball_turning_tool.pdf

or if you want to  cheat ::)
http://cgi.ebay.co.uk/MODEL-ENGINEER-MINI-LATHE-BALL-TURNING-TOOL_W0QQitemZ290312135128QQcmdZViewItemQQptZUK_Home_Garden_PowerTools_SM?hash=item290312135128&_trksid=p3286.c0.m14&_trkparms=66%3A2|65%3A10|39%3A1|240%3A1318
« Last Edit: April 23, 2009, 04:56:54 PM by ja2on »

Offline raynerd

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Hey Jason

Thanks for the links to the download - I have saved the plans and will make this a long term project aim - making one of these would be an excellent accomplishment but I can image this is well in the future until I have both the tools and skills. I wouldn`t like to cheat and buy one as I have no real need - I just like the idea!

Still interested in my original post idea - using the cutting schedule and normal tools.

Offline Divided he ad

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Hi Chris,

I've a certain feeling of a glitch in the matrix!!


Been through all this on a site not so far away.... It's a little complex as I see it! But I'm assured by some of the "talented" ones out there it's doable?!


The way to make it accurate is to use a program like this to get the "rough" shape made and then use a forming tool made from something hard like a file.... Never tried it but have seen the pictures and the results.... Does as it should! (not too sure about sticking files etc on stuff spinning in my lathe though.... Yes, I know... "But I used my lathe with a chuck on it to polish stuff..."   I cured that!)

I'm very sure that if your willing to be patient then a mini ball turner could be made by yourself..... You make all the round bits on your lathe and I'll let you use my mill for the flat stuff and the slots etc. Your call.




Ralph.

I know what I know and need to know more!!!

Offline Bernd

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Guy Lautard wrote this method up back in 1986 in his first Bedside Reader. It's an incremental method of cutting a ball. Bascially you cut a bunch of steps and then use a file to smooth the steps to turn it into a ball.

A cut off tool is used. They come in different widths. They basically have a squared off cutting edge. That's all that is needed. The tool shape doesn't figure into the steps to be cut. When you start out cutting the ball you start at the equator and work your way to the poles of one side of the ball. Then back to the equator and then to the other pole. Then use a file to smooth over the steps. It's very simple.

I haven't tried it but I've got the book right in front of me so I can see how it's done. No pics mind you, but lot's of drwings. This method lets you make many other shapes also besides a ball. For example file handles can be made or odd shaped cutters to mention just a few.

I would highly recomend Guys 3 Bedside Readers for any upstrat machinist. Very well written and entertaining as well.

bernd
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bogstandard

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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

Offline raynerd

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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.

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

Offline DavesWimshurst

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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

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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
« Last Edit: April 24, 2009, 03:57:30 AM by bogstandard »

Offline Bernd

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Dave,

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

Bernd
Route of the Black Diamonds

Offline raynerd

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Re: Ball Turning - using cutting schedule (Software: Ballcut by Marv Klotz)
« Reply #10 on: April 24, 2009, 10:32:38 AM »
Right, yes I am understanding this a little more now! The side of the cutting tool is actually over the top of the work cut so the width doesn`t have a bearing! thanks for the writing  David and Bogs for the drawing, together they have helped me understand!  :smart:

May I ask one last thing - what is the  "angular step size" -default at 5 degrees that it asks you to input? I guess this is something to do with the angular increments that the steps form the ball. If you decrease this, you will have more cuts but a better shaped ball unfilled? If you increase this I presume less cuts, but a more stepped ball and therefore more filing to do?

Chris