The better Ball Turner??

[SPiN Racing]

Hi All.. Im sitting here at work and waiting for a mouth breather to do his job.. and simply re-load the operating system on a server so I can re-build it.. and I have been pondering a dilemma I have had for many many weeks... and I am trying to think of a solution to.

Here is the deal.
The Ball turner.. that soo many have made, and built. Consisting of a square of metal bolted to the cross slide, and a round chunk of metal with a sliding tool bit in it, that is rotated to allow cutting of a piece of metal in a curved smooth fashon.

So heres my dilemma.

I have on SEVERAL occations in the last week of two run into a situation where I needed to cut a smooth radius on the edge of a part.. and the ball turner is just the ticket.
Crank that sucker out, and make it a tight radius, and simply trim the edge of the part nicely.

Enter Crap O Cad (Im so loving that term)



BUT

The problem is.. by the time I roll that sucker under the chuck of the lathe.. and that part is mounted within a half inch of the face of the jaws.. I cant get the turner close enough to be able to cut the radius!!  The jaws are all over the top of the turner, and or cross slide.

Even if I were to be able to magically move the turner to the edge of the cross slide, closest to the jaws, it STILL would interfere with the jaws of the chuck.





SO My question is.....
If you have a really... somewhat close to the chuk part.. and want to cut a radius... And you cant drill and tap it.. How are you supposed to get a tool bit to move in a smooth arc that close to the chuck? Thithout hitting it?


Im thinking something along these lines??

Possibly somethig Really Low profile with a thin shaft as seen in other threads someplace.. and a round cutter?



Or How about.... a THIN Rotating plate.. that is in a 90 Degree Pie shape.
Have holes Drilled and tapped into the surface that are like a.... Divided head? Or.. something.. One of those disks with all the holes getting progressively further out.
And then get a hex shaft, say 1/2" that tapers up top with a round cutter, and a threaded shaft loctited into the bottom.
Then you simply screw it into the hole giving you the diameter you need, and when cutting you dont get interference?




Love to hear ideas..
Im puzzling over this.

[Divided he ad]

Hi Scott,


I've been thinking about this a little and for what it's worth here is my opinion.....


The turner I have will hit my 5" chuck with ease... But my 3" chuck, the turret slides right up close to the edge of the chuck..You just have to check the jaw positions before start up!

I have devised and used quite a few ways of getting around the issues you describe and have rarely found I need to put a curve onto anything too close to the chuck....
But if you have this problem "We the collective" can surely figure this out!?!

So here for a start is



A very rough Crap O Cad for you.  This is the basic idea I used to make the RCMT tip holder for my ball turner. Pictured in the thread link below.
http://madmodder.net/index.php?topic=282.0

Note the tip is recessed into the top of the post, This gives lateral strength to the tip, The screw is just not enough (IMHO) to hold the cutter securely, the screw in mine is M2 but the hole through the tip is larger, about 2.4mm if memory serves. This would allow for possible movement if the tip was not recessed.



I have also been thinking about your idea for the thin plate with multiple holes. A dividing plate style 1/4 circle.

like a.... Divided head?

I haven't got multiple holes in me.... Well not evenly spaced anyway!!    (dividing head!!  ..... That name has brought me nothing but trouble!!  )

Ok, Back to it....
As I see it there are a few things that would be issues and a few that should work...

Should... The holes would only have to be in a straight line from the pivot, the other holes would work but could make great swarf traps!! You could make an adjustable swarf cover for a straight line of holes.  Admittedly this option would restrict your abillity to set the sizing dependent on your spacing between threaded holes? You could use 3 rows of holes next to each other with slightly different spacing creating greater adjustment?  It could also be in a straight piece of flat not the 1/4 circle?

Issues... The pivot would take all the force unless the rotating base plate was recessed slightly into the plate it was fixed to the lathe by.
I assume that the forces will be putting pressure Both down and also away from the work piece, this would get worse as you moved the cutting tip further out from the pivot  (please correct me if I'm wrong). recessing it into the plate would allow a lateral barrier to take a lot of the force off the pivot, but it would also make a great swarf trap, That probably would cause issues?  With the round turret it stops swarf getting into the base.


That said it could work really well?!? I've never tried it... This is just all from my head! I'm not trying to knock you down, just trying to add my ideas! (just be aware of the forces on the cutter!  )

Personally I'd just have a go at it....     I've made all sorts of tools that were damn useless!!! 

I still enjoyed the builds, I like the challenge of making a thing I have thought of almost as much as I like seeing it work.... Almost

Sure it's frustrating if 4/5 hours work is not of any use.... But I sure learned a lot on the way (read through my Aoelipile thread.... You'll see the waste of time, [the cutter! ]  not all of it but some! Some of it was salvaged to make another tool    )



Well after all this writing I suppose I'd best see what I get in response ehh??



I'm hopefull that some others will add their opinions?






Ralph.

[SPiN Racing]

MUCH MUCH food for thought.


Im my original CoC drawing.. there is a swarf guard pictured... Im thinking a piece of plastic.. soft. With ONE hole in it the diameter of the cutter.
No other holes.. simply plop it over the cutter and let it rest on the top of the tool.. the majority of the swarf will go elsewhere... and if the overall diameter of the swarf guard is big enough.. it wont get under it.


Tool stresses.. thats one of the issues I think that bugs me.
The downward force is easy.
Its the lateral force of the cutter that bugs me as well.

Its almost 7AM and Im up WAY too late. (Working on a server at home all night)

Gonna sleep on it.

[Gerhard Olivier]

Soz most of that went right over my head
Here is some pics of my first ball turner I stil prefer it for single balls (it is difficult to do runs of the same size)
but it lets you complete the ball 14mm from the chuck , if you only want a half of a ball probably closer?????

It is a cast iron sleeve that has a steel rodd that screws to the boring head.  Cutter is a silver steel tip.






Hope it helps
Gerhard

[SPiN Racing]

ooooooh... soo...

THe green part attaches to the tool post? Boring head at a right angle to the part?
I gather the boring head is 28mm across?

SO it would cut from Vertical, cutting to the right, towards the tailstock?  If you were making a half ball?


hmmmm

[Gerhard Olivier]

Yes inherently centred on the tool post.  I cut from the up position down left and right for ball.  To make a round shoulder it would be from top down or right (ts end).  It it is placed on a hight ajustable tool holder it could be persuaded to do ovals as well.

The cutting tool drawn above (rcmt tc insert on top of a round post) would aready be an improvement to what I have made.

The boring head is 50mm diameter -but only the tip of the cutter is close to the chuck so this gives a bit more space.