Ball turning tools

[Sub MandrelParticipant @submandrel]

Why are all teh links being replaced with **link**? Even ones put in using the 'link button'?

Neil

[JasonBModerator @jasonb]

It's not all, mine are not but quite a few appear that way.

J

[Peter Wood 5Participant @peterwood5]

I recently bought one of the horizontal type of ball turning attachments. It came with a short length of 5mm tool steel which did not appear to have been shaped.

Can anyone advise on how the cutting edge should be ground?

It seems to me that the tool geometry on this set up ie cutting on the top of the rotating work, is totally different to normal side cutting and therefore must need a different presentation of the cutting edge.

[Les Jones 1Participant @lesjones1]

Hi Peter,
If by horizontal type you mean the type Chronos sell then from the pictures it looks like the tool bit is used like the tool bit in a tangential tool holder. If this is the case then just grind the end of the tool at an angle to give top clearance. It looks like the tool is mounted at a slight angle to give the required front clearance.
I have made a ball turning tool based on the "Bedair" design and it works well.

Les.

Edited By Les Jones 1 on 22/12/2012 10:28:47

[Peter Wood 5Participant @peterwood5]

Les

Thanks for the prompt response.

In fact the tool came with an angle ground on the end which I now realise was the front clearance. Not realising that the tool holder was drilled at a slight angle I then ground a small angle on the tool shank which effectively gave more front clearance.

In fact I discovered the tool was at an angle yesterday and assumed that the holder had been badly made!! I have almost completed making a new one with the hole drilled concentric with the holder body .

I guess I can throw it away now.

Peter

[Les Jones 1Participant @lesjones1]

Hi Peter,
When I looked at the Chronos website I could not see any angle between the tool bit and the horizontal which made me think there would be no front clearance. When I used Google to find more information there was a picture showing the angle between the tool and the horizontal thus providing front clearance as in a tangential turning tool.

Les.

[NobbyParticipant @nobby]

Hi Peter & Guys
In this picture you can see the HSS tool > I dont know if it helps

Nobby

[John Stevenson 1Participant @johnstevenson1]

Plus 1 for using a boring head.

Reasons are it's 3 tools in one and none are specialised and can be moved from machine to machine, even mill to lathe.

1 It's a boring head.

2 It's a ball turners as in previous photo's

3 It's a taper turning attachment that can do taperes longer than a taper turning attachment or even steeper.

John S.

[NobbyParticipant @nobby]

Hi John and Guys
Brilliant picture . What sort of centre do you use when turning these steep angles ?
Nobby

[Peter Wood 5Participant @peterwood5]

Les

I reground the tool with just an angled flat on its end (top clearance) and relied on the angle of the tool holder for front clearance. It worked OK but I was not too happy with the quality of cut I got.

I am making railing stanchions ( to go around the platform of a beam engine) from 1/4'' stainless steel.

On looking at the tool after turning several ballends I noted that a flat had worn whnere there should have been front clearance.

I also found it extremely difficult to centre the ball on the pre drilled cross holes which will carry the rails. In the end I turned the ball ends and then drilled the holes.

I am somewhat disappointed in this design of tool and am considering the type shown by Nobby for future projects.

Peter

[Les Jones 1Participant @lesjones1]

Hi Peter,
The design of the tool effectively creates a round nose cutting tool. I would be tempted to grind the end of the round tool bit to form a pointed end with an angle of about 60 Deg. between the faces. The point of this cylinder with the two flats would be the cutting edge. You could stone a small radius on the point. To try to clarify what I am trying to explain looking at the end of the tool bit the end would look like a triangle but with the top curved to the original round shape of the tool bit. This shape would also allow cutting closer to the bar supporting the ball.
I have never used this type of tool so these are just suggestions. Others may reply that have used this type of tool. Good luck.

Les.

[Sub MandrelParticipant @submandrel]

Hello Peter

I made smaller stanchions for my 3 1/2" gauge loco. In the end I drilled a hole in a steel block, then cross drilled it. I used this as a jig to cross drill short brass rod blanks at each end.

I then used a semi-circular form tool to make the balls – it was much easier to line the form tool up with the hole than drill a small ball accurately!

I threaded the ends by putting a shirt piece of rod through each one in turn and 'screwing' them into an 8BA die by hand.

Neil

[nigel jones 5Participant @nigeljones5]

Ive got the RDG on a ML7…great but you cant work close to the chuck. Well built, to last.

[Peter Wood 5Participant @peterwood5]

Les

I have still got a couple of stanchions to make so I will try your suggested tool shape.

Another weakness of the Chronos design is that it does not turn perfect spheres.

As the tool goes over tdc towards the chuck the cutting pressure increases as it begins to bite into the bar. This tends to force the tool away from the chuck back into the ball.

Perhaps Neil's approach is better at this size but I don't know how well a form tool would handle stainless steel.

Peter

[John Stevenson 1Participant @johnstevenson1]

Nobby, you take a piece of 1/2" mild steel in my case and drill a centre hole with a centre drill, that goes in the boring head.

You then do the same but leave that bit in the chuck. This way you know it's got to be running true.

Then you locate the work using two ball bearings held with a dab or grease and drive with a lathe dog.

Doesn't matter how much off set the ball bearing will cope.

You can then dial in the taper you wnat by adjusting the boring head.

And before some Herbert starts rabbiting on about the head being on a horizonal centre there are simple ways to set this and if you are worried about the play in the key on the tailstock barrel,

FIX THE DAMN THING

[TerrydParticipant @terryd72465]

Posted by Stub Mandrel on 17/05/2012 20:58:03:

Why are all teh links being replaced with **link**? Even ones put in using the 'link button'?

Neil

Hi Neil,

It is because of the problem of long links causing the message column to become wider and getting covered by the adverts on the right. If you don't like it you can attach your links to a suitable word in the text,

Seasons greetings and best regards,

Terry

[NobbyParticipant @nobby]

Hi John & Guys
Thanks  for reply . Brilliant . 1/2 is the size of the one I made . I have used mine 1, 2, &3 also as a
a flycutter . ( Slapped wrist for that one ) my centre hole i made to run true so at a push you can use say a 1/4" shaped D bit and widen the form you are cutting .
Merry Christmas & a Happy New year
Nobby

Edited By Nobby on 23/12/2012 12:34:31

[Les Jones 1Participant @lesjones1]

Here is a picture of my version of "Steve Bedair's" ball turning tool with a modified tool holder to use 3/16" HSS tool bits.

Les.

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