Ball Turning another way

[Paul LousickParticipant @paullousick59116]

A different method for turning a ball end on a lathe.

https://youtu.be/CWvtB6tGODc

 

[JasonBModerator @jasonb]

Is it any different from copy turning? Just the choice of where to mount the template that is “different” But quite a good way to simply mount a small template and arrange the follower

[noel shelleyParticipant @noelshelley55608]

A neat idea. Using a cone and some form of varying The height would also give different size balls ? Noel.

[Nigel Graham 2Participant @nigelgraham2]

Thankyou for that, Paul.

 

Well, yes, as Jason says it is copy turning with a different approach to the template, but certainly effective and worth knowing.

I’d ask:

Would using a button tool achieve a better finish? It won’t plunge cut very well so you’d probably need use a parting tool as shown to remove the bulk. It may also need a cylindrical follower of the same diameter as the button.

If the ball is to finish on a shank, such as for a control-rod end, would it be best to grind or oil-stone a tiny radius on the parting-tool to produce a root fillet?

Would using self-acting feed make life easier by giving you both hands to control the depth? If so it would be safest to use it in the receding direction, i.e. towards the chuck for that “side” of the ball, towards the tailstock for the outer “side”.

I was always taught if you must use a file in the lathe, use a slow speed and keep the file moving across the work. Holding it still can quickly produce blunt areas.

 

Noel –

It could do. An alternative may be a vertical pin that carries rollers of differing diameters, or a bar that carries pins of differing shank diameters above a constant grip diameter.

How elaborate you make the thing might rather depend on how many balls of different sizes you intend making. Or the method inspires you to make!

 

The independent balls at the end are intriguing. How does one complete them? The ball will almost certainly snap off as the shank reduces to near-nothing, especially at larger diameters (hence masses), leaving a pimple to be removed somehow.

 

.

On presentation, I could have done with no “call-centre music” but instead a few words and some shots making the operation of the slides a bit clearer. Was the turner using purely manual feed or a combination of self-acting feed with manual depthing?

[bernard towersParticipant @bernardtowers37738]

By the looks of the rest of the video finishing off was done by hand which is why they didn’t show it and measurements not shown either!!!!

[FulmenParticipant @fulmen]

Clever. I wonder if you could make a sort of “inverting copy turner” by having the tool holder swivel freely. This could even enlarge/reduce size by varying the geometry…

[Julie AnnParticipant @julieann]

An interesting variation, sort of like copying but not quite.

Picking up on one point, when using a hydraulic copy unit the stylus and tool shape must be identical or the workpiece will not exactly mirror the template or master part. The shape of the stylus will reflect the shape of the part. While a round stylus, and tool, are often used sharp internal corners would mean that a rhombic stylus/tool would be needed.

Hydraulic copy units are mostly set at an angle other than perpendicular to the work axis as otherwise a face perpendicular to the work axis would need an infinite feedrate from the copy unit. Due to the tool movement geometry a hydraulic copy unit cannot produce perpendicular leading and trailing faces on the same pass.

Here is a picture of a hydraulic copy unit at work cutting a valve coupling rod for my traction engines with a 3mm diameter tool and stylus:

Screwcutting 3/8″ BSPT blowdown plugs, note the 55 degree stylus to match the tool profile:

The finished blowdown plugs:

Julie

[BazyleParticipant @bazyle]

One of those odd coincidences as I am giving a talk about a curvilinear slide at the St Albans club tonight.

[Nigel Graham 2Participant @nigelgraham2]

Bernard –

Good point.

The chap did wave a vernier caliper over it at one point but finishing by file and emery-paper can’t have been quite to ball-bearing quality. Perhaps he did not need that.

It would have been interesting to see what that ball engages, if it was not simply a demonstration piece. The title implies a coupling but that can be anything from an accurately part-spherical socket for a precise machine-control link, via tow-bar hooks, to something like the lamp-stand clamp using the ball between two jaws with round holes in them.

…..

There is another technique I have seen described but have never tried, that I recall a bit vaguely uses a boring-head in a vertical mill, with the work held in a dividing-head or rotary-table inclined with respect to the table. It takes a lot of calculation and setting-up, though.

[Nigel Graham 2]

On Nigel Graham 2 Said:

.. …It would have been interesting to see what that ball engages… ..

I know him well – they’re for hip replacements..

[FulmenParticipant @fulmen]

@Julie: Nice setup. But does the stylus shape really matter when following a straight line?

[Bo’sunParticipant @bosun58570]

Very interesting, and what a simple idea.  Relatively inexpensive with the use of cheap bearings.  With a suitable follower, it may even work with plain templates rather than bearings.  I guess the required precision might dictate which.  Also, I think I’d be tempted to use a round nose tool and follower.  As Nigel suggests, the finishing technique will dictate the final use of the ball(s).

[Fulmen]

On Fulmen Said:

@Julie: ….does the stylus shape really matter when following a straight line?

No it doesn’t, but most of my copy turning has involved curved shapes where stylus shape is important, so I naturally make the stylus the same shape as the tool. Even if not strictly necessary.

Of course commercially tapered threads wouldn’t be single pointed. So does anyone know what this is:

For the record I do know what it is, but suspect I will never use it.

Julie

[FulmenParticipant @fulmen]

I see. No need to apologize for good habits, I just wondered if I had misunderstood something. Which I did at first, I got the image of a serrated guide plate for threads stuck in my head and I couldn’t figure out how that would work  🙂

I’m guessing the thingamajiggy is a self opening die head, we have something similar at work but I’ve never tried using it. It takes a fair amount of setup so it’s only needed for large series.

[Nigel Graham 2Participant @nigelgraham2]

Julie –

I’d say a die-head but by which maker and for what machine I would not know. Perhaps Coventry: the basic outline suggests that?

I don’t recognise the base assembly and can’t think what that protruding (link?) does, and I wonder if it’s actually a “special” add-on, not part of the original tool. Perhaps this die-head was used on something other than a large centre- or capstan- lathe?

[StevePParticipant @stevepye68246]

I’m not sure this will be of interest.

About 40 years ago I designed and made this attachment for machining prototype Fresnel mould tool inserts.

The inspiration for the design came from a radius dressing attachment which came with a large cylindrical grinder newly purchased by the company.

It works  by transferring the point of rotation into free air in front of the fixture, to cut the Fresnel prism angles the point of the tool is set on the centre of rotation,  this means the angle of the tool can be altered without its position moving in the Z or X axis, the attachment also  has a built-in sine bar at the rear for accuracy.

The majority of the lens made were based on a 1mm radial pitch, the centre portion  being simple Dioptric prisms ( every prism having a different angle and simple refraction) and at a point where the efficiency had decrease to a level the prisms changed to Catadioptrics ( light enters one face on the prism is refracted and then gets reflected off the other face of the prism and  exits the face of the lens) , each prism having two different angles.

All this to capture and control light from a bulb and turn it into a parallel beam.

To prove the concept worked the original tools were made from H S S steel but then tools were manufactured from natural  diamonds ( not any use for jewelry as they were brown!)

It really wasn’t possible to polish the machined surfaces because the accuracy would have been  lost. The diamond tools produced, combined with a air bearing and turbine driven spindle a surface finish that our Talysurf gave meaningless results.

To turn the prototype lens into production tool inserts, the lenses were Nickel plated for days until the desired thickness and then built up with copper plate to thickness of about 15 mm, the lens was removed and the plated copy was machined to fit the tool.

To cut a radius the tool would be positioned either forward of centre ,concave radius or rearward of centre to produce a convex radius.

Steve

 

[StevePParticipant @stevepye68246]

I’d like to apologise for my previous post,  when I reread it, it SMELLS of showing off , I like to think I’m not that sort of person.

If I could have removed the post I would have, I’ll take more care when I post articles in the future.

I think we are all very luck to have such a varied and interesting hobby , which I hope  to convey.

SteveP

[Steve P]

On Steve P Said:

I’m not sure this will be of interest.

.

.

.

 

Steve

It IS absolutely of interest!

Please do not even think about removing your post, in fact I for one, would appreciate knowing more about both the jig and the manufacturing process.

Thank you Steve

[renardiere7Participant @renardiere7]

SteveP,

Definitely not showing off at all.  There is nothing wrong with taking pride in your work and sharing an idea like that may well spark off the germ of an idea in someone else’s brain or indeed provide a fully fledged solution.

I for one, love to see and read about work like this and would be happy to see more of your work solutions.

 

Cheers  Alan

 

[Steve P]

On Steve P Said:

I’d like to apologise for my previous post,  when I reread it, it SMELLS of showing off…..

Definitely not! Always interesting to see other work and ideas. If we all worried about showing off then nobody would post anything about anything.

Anyway I have a poor sense of smell!

Julie

[DiogenesParticipant @diogenes]

Yes, I totally agree with all these responses- any procedures / processes and accompanying hardware ‘out of the normal run of things’ are always very welcome..

[Nigel Graham 2Participant @nigelgraham2]

Oh, Steve, by no means remove that!

It is a fascinating view into making something that would likely not occur to many of us, beyond knowing Fresnel Lenses are used at large scale for lighthouse optics (with separate glass prisms), and small scale for moulded-acrylic, wide-angle reversing-viewers on vehicles like motor-caravans.

[Roderick JenkinsParticipant @roderickjenkins93242]

Very interesting Steve, thanks for sharing.

Rod

[FulmenParticipant @fulmen]

@SteveP. Of course it’s showing off, that’s why we’re here. It’s allowed, especially when it’s that bad ass. Consider my mind thoroughly boggled. Even my flabbers are gasted.

[StevePParticipant @stevepye68246]

Thank you, for all your positive comments I was really surprised by the number, thank you again.

I was extremely lucky ,to have had  some really interesting jobs,  working with some great designers and engineers on new designs and technology, so coming up with ideas to solve problems was aways encouraged, it’s true renardiere7, one idea can generate some completely different and novel ideas.

I’ve also had a few jobs ,that by lunchtime on the first day I new, I’d made a mistake and was looking for a different job that evening.

The one thing that’s keeping my brain active at moment,  is a little petrol engine I’m making.

Steve

 

[Author]

Posts