tailstock mounted ball turner ?

This topic has 11 replies, 7 voices, and was last updated 3 October 2017 at 11:36 by BW.

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2 October 2017 at 12:13 #319672
BW
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@bw
I've often seen this sort of ball turner mounted on a toolpost.

Would it be possible to mount it in the tailstock ?

Would have to mount the handle so that it doesnt crash into the workpiece. That should be possible.

Anything glaringly obvious and dumb that I'm not seeing here ?
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2 October 2017 at 12:13 #8894
BW
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@bw
2 October 2017 at 12:42 #319676
Michael Gilligan
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@michaelgilligan61133
I think it would depend upon; (a) the design of the tailstock, and (b) the scale and accuracy at which you want to work. … The design limitation being that few tailstocks are 'micrometer adjustable'.

I can't see any objection to the general concept though.

MichaelG.
2 October 2017 at 13:03 #319678
JasonB
Moderator
@jasonb
You would have no way to adjust the depth of cut it would have to form the ball all in one go. If you tried to take a shallow cut off the end of the rod the undercut would be too near the tailstock

Would only work in a tailstock if you were rounding the end of a rod
2 October 2017 at 18:03 #319711
Chris Evans 6
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@chrisevans6
Apart from athe above comments few tailstocks have a good close fitting guide pin. I think this could lead to chatter.

I made my ball turner loosely based on the Steve Bedair design and it works well.
2 October 2017 at 18:37 #319722
Clive Foster
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@clivefoster55965
Agree with MichealG that mounting in the tailstock is, in principle, workable. Needs to be good solid tailstock with a depth reading dial. Many high end lathes, like my S&B 1024 have such as standard. Geo.H Thomas published a decent design for the Myford 7 series that could be adapted to other machines. Probably requires a depth stop device too that could be set up at the maximum travel point with successive cuts incremented towards it via dial readings. Actual cut needed for each traverse isn't particularly precise. Just needs to be sufficiently small. So a fairly crude rotational indicator device on the tailstock hand wheel should suffice if you don't want to sort out a dial and are prepared to be that bit more careful. Providing the tailstock barrel were locked for each cut the device ought to be sufficiently rigid and any guide pin or keyway slack irrelevant so long as the device is held against the key or pin when the barrel is locked.

These swinging U frame ball turners are not my favourite examples of the breed. Producing significantly more than a hemisphere requires considerable workpiece extension if the frame is to move beyond 90° of sweep and still safely clear the headstock and chuck. The smaller the job the worse the problem as extension is defined by the swinging frame size not ball size. Theoretically some sort of support bearing bored to fit the job could be arranged on some sort of vaguely Z shaped bracket to reach inside the frame supporting the job close to the cut but its all getting rather complicated.

Trying to use such a device with a job mounted in the chuck strikes me as being far too dangerous with fingers inherently swinging towards the rotating jaws. More acceptable with a collet.

Clive.

Edited By Clive Foster on 02/10/2017 18:38:49

Edited By Clive Foster on 02/10/2017 18:52:45
2 October 2017 at 18:40 #319723
Emgee
Participant
@emgee
There was a really nicely made compact ball turning device exhibited at Forncett Steam Museum, intended to be used on the cross slide or top slide, seemed it was fully adjustable over quite a large range of diameters. Samples of the ball ended levers made using the device were around 1/2" diameter balls.
If the builder is a member here perhaps he could confirm his design, perhaps one for Neil !!!!!

Emgee
2 October 2017 at 19:22 #319732
JasonB
Moderator
@jasonb
Clive I don't see how advancing the tailstock will work. As you advance the tool will take a cut off the half of the ball nearest the tailstock but be moved further away from the half of the ball nearest the headstock. Each advance of the tailstock will in effect move the centre of the ball to the left!
2 October 2017 at 20:39 #319749
Clive Foster
Participant
@clivefoster55965
Jason

Just deleted a long reply! Getting at cross purposes (again).

I was thinking more terms of producing a rounded end or small bobble on the workpiece, rather than a full ball, without requiring objectionable depths of cut. Obviously a hemisphere needs 90° of rotation taking the tool from parallel to the lathe bed to perpendicular to it.

Having produced a hemisphere its possible to go bit further round the back with the tailstock extension fixed but clearly the depth of cut required rapidly becomes very large. Could always rough shape the backside of the ball with a form tool or similar. Realistically thats probably the best application of this tool to ball turning when mounted in the tailstock. Its quite difficult to produce a true ball with form tools, even assuming you are set up to grind one accurately. However given an over long, slightly ellipsoidal, starting point a tool like this should probably be well up to converting it to an adequate ball. Produce the front hemisphere first, almost removing the join, then swing round the back. Have too be careful not to pull it out of the taper socket tho'. Or arrange locking collar.

Clive
2 October 2017 at 22:57 #319780
BW
Participant
@bw
Thanks for the responses. Was considering bobbles on the end of rods ie tool handles, chess pieces.

Must admit I didn't consider the possibility of accidentally pulling the taper out of the socket.

Do the ones mounted on the toolpost ever get pulled out of the socket ?

The attraction was leaving the toolpost set up as normal and having the bobblemaker mounted separately on tailstock. Maybe mounted horizontal or even vertical swing. Does it matter, the tool will always present to the workpiece in the same orientation.

Made me think of the tailstock in a slightly different way, as a toolholder rather than a drill chuck holder or a steady. Doesn't seem like such a great idea now.

Bill

Bill

Edited By Bill Wood 2 on 02/10/2017 23:03:04
3 October 2017 at 07:35 #319800
Brian H
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@brianh50089
I was at Forncett and was intrigued by the ball turner so took a couple of pictures

Brian
3 October 2017 at 11:36 #319837
BW
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@bw
solid looking
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