ball turning tools ?

The Radford design is a shaft that rotates horizontally in a bearing box in the tool post. The shaft is at 90 degrees to the lathe axis. On the end of the shaft is a tool holder. This tool will prescribe a circle when the shaft is turned, the circle having its plane along the axis of the lathe. By making the tool point on the vertical centre line of the lathe axis the tool will now cut a ball end (hemisphere) if turned through 90 degrees top to horizontal. By rotating the tool over 90 degrees an almost full sphere can be produced but of course the work will need a lot of clearance away from the chuck for this to occur and is not usually practical.

You can see my Radford design here:

Alan

Quick reply as I'm going down the pub for a swift half or seven.

Don't bother with a ball turning tool, buy an el-cheapo 2" boring head and a couple of arbors. Fitted to the toolpost they make a good ball turning tool, fitted to the tailstock they make a brilliant taper turning attachment and if you are really desperate fitted to the mill they make a decent boring head.

Pic's later when sober.

.

-- Regards,

John Stevenson Nottingham, England.

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Check out another fellow contributor's fine work:

cheers for the pics , i get it now ! ive got a cheap chinese boring hea

as well . thanks folk ! i can feel a project coming on

-- willowkevi

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OK nearly sober now. Pic of a boring head converted to a radiusing tool is here:-

In this case it's the head fitted to a parallel arbor in a bushed tool block. By rocking the lever the tool will go over the top of the work to form a ball.

Taper turning attachment is here :-

The boring head is fitted to the tailstock by a standard tapered arbor and a small centre fitted in place of a boring tool with a centre drilled hole in it. The chuck carries the same fitting and the work is dog driven and sits on two ball bearings to prevent side loading on the centers. The head can be adjusted to the required set over. Advantages of this are that you can do longer tapers than the top slide can handle, fits any machine, with or without taper turning and you can use power feed. Can also do steeper tapers than allowed by a lot of dedicated taper turning attachments or setting over the tailstock.

Pictures of a boring head being used as a boring head are restricted and if I were to post these I'd have to kill you.

-- Regards,

John Stevenson Nottingham, England.

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I'm going to show my ignorance now (never having turned any balls), but I'd expected the tool to be moved in the horizontal plane to keep it on centre height - how does it give a good finish when moving vertically?

Dave

>

>

taper

restricted

vertically?

Dave,

All the tool has to do is describe the required arc - it doen't matter where it starts and finishes. Think of an upside down rear mounted parting tool as an extreme case.

AWEM

All the tool has to do is move in a plane that has the spindle axis in common.

Nick

lucky me , ive found an online drawing which just suits a piece o

square bar ive got ! project 1 for my student ! a question tho ! th thread on my boring head is either .862"x20tpi or 22mmx1.25 ,i'm unsur which !ive cut a practice thread with a 20tpi pitch which fits th boring head ok (55deg) but is that the right tool angle ? and whats th thread depth suposed to be

-- willowkevi

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Andrew Mawson wrote: ... snipped

Well, I was right about one thing: exposing ignorance :-) Blindingly obvious now, thanks!

Dave

Once again excellent tips from Mr Stevenson