TOPIC:

Some thoughts....
The ball would be a pig to do by hand, would modifying a (Broken) original axle be a viable option? - maybe a sleeve that fits over a shortened axle & holds the bearings,
OR maybe reclaim the ball part from a busted axle & make it an interference fit on a new tube?

There are ball turning attachment designs out there, but I just haven't got time to build one at the mo.

was afraid of that, no the original parts aint no use its cast aluminium and I wouldnt change an original one that is still useable/intact, the ones were the end breaks off are so brittle that they probably wont survive long even if we would manage to make the hole for the bearings.

I think I will have a go at having it 3D printed first, just to see if it will fit/work.

but not in a hurry with this project, its just an idea i had to get the M38s that are beyond repair up and running again. (and the hex conversion would be a solution for those that are running out of tires)

I remind that my dad mounted monster beetle wheeles on the lunch. I was very cool with its gold rims

Things I would buy and build if I had a suitable toolshed for metal working.

Lathe
Mill

and then make things like this Ball Turning Toolpost (Steve Bedair's )

I haven't seen a ball turning tool like that one before, but there & again it's not much use if you wanted to do a ball of a different size/radius - there doesn't appear to be any adjustment on it....
Of course, these tools are for model engineers, the parts are usually 1-offs & only have to look right, I bet he can't make another dimensionally identical part!

For Willy-balls, you'd need a method that is repeatable & a way to position/measure the ball fairly accurately. Without CNC, I would say you'd need DRO to position the ball, & either a tool ground with the correct radius, or a dedicated size (Or adjustable) ball-turning attachment similar to that in the vid. All time consuming & not financially viable to do as things to sell - it would be easier/quicker/cheaper to find a way to reclaim/modify broken originals. Either that, or find a source of cheap, correct-size balls to fit to a plain tube, to fabricate the axle rather than try to machine it out of solid bar.

Why don't you invest in a (Chinese) mini-lathe if you fancy having a go Waterbok? They're not hugely expensive & hold their resale value well if you decide you don't want it after all. New ones are only around 300-400gbp & they're small enough for the smallest of shed benches (I'd considered getting one for doing small bits indoors...).
Be aware that the model engineers love them (Which is why they hold their money) & a new one won't be much more expensive than second-hand, but it won't be worn out/broken like a 2nd hand one

its adjustable, the part that holds the cutting bit can be moved from and to the center of the tool.
its used in the second video and also can do concave

problem is, the sound isolation of my 'workshop' (basement) aint so good, the misses already complains when i am drilling a small hole in aluminium or use the hacksaw or a file. Dont want to create a row with the other tenants.

How do you know what radius you've set, or how much you're adjusting it by? How do you set the tool at the correct radial distance from the centre of the workpiece? - unless you know these things, you'll cut a pellet rather than a sphere.
It's a nice compact design, but if I ever get around to making one, I'd have to think about how to sort out the above problems - possibly "setting-tools" rather than graduated adjustments (ie, so you "set" the thing at a repeatable known dimension & work from that)

You might be able to fit a micrometer head to the sliding part (probably with something to lock it in position).
If you wanted to do that I have some micrometer heads that you could have. They were returned from a customer because the mounting was wrong (plain instead of threaded) and were replaced by my supplier FOC (their mistake) so they don't owe me anything.

Yes, the design/drawings I have here use a mic head for adjustment.
Cheers for the offer Martin, but I shouldn't worry, it's very unlikely I'll get around to making one any time in the near future!
Don't bin them though, I'll have them if that's going to happen

Been thinkering with my newly aquired Unimat

my first handturned prototype (and the first thing turned since 20 years )



now I only have to fabricate a ball turning tool that fits

here's my sketch what should come out at the end