Ball Turner

[steamingbill]

Found this plan for a ball turner - thought it was clever - I need one to turn bobbles on the end of various chess pieces.

https://books.google.com.au/books?id=wCoDAAAAMBAJ&lpg=PA244&dq=ball+turning+attachment&pg=PA165&redir_esc=y#v=onepage&q=ball%20turning%20attachment&f=false

Picture below shows progress so far - the mdf tool holder is a mock up to check size and shape for tool holder to fit on the 9" Hercus.

Am aware of the issue of scrubbing the cross slide with swarf and was wondering about putting a 1mm Al sheet between the main plate and the lathe cross slide.

I had to make one to better understand them and then decide what the best one for my needs might be.

Bill

[BaronJ]

Hi Bill,

I use one of those silicon baking sheets to protect the ways on my Myford lathe. A couple of magnets under the chuck to secure it, the other end nipped under a brass strip fstened to the saddle. I give it a squirt of oil underneath now and again. It causes it to stick down and not ride up when the saddle gets near the chuck.

Have a look at this site for some ideas.
Another Ball Turner (http://www.conradhoffman.com/ballturner.htm)

[steamingbill]

Jig completed and first pawn made.

Now to figure out a workflow to make 15 more identical pawns. See photo pawn is 38mm high x 19mm diam.

I found the best way to understand how the thing works is to always know where the centre of the cutting circle is and then consider whether or not you want a ball or a cavity.

Very rough finish - cheated and used sandpaper - need to grind a better cutter - put a radius on the nose - have never been particularly good at that - favourite finishing tool is a shear tool or a knife bit turned around to rub almost on the flat.

Wonder how a shear tool would work with this jig. Will have a go.

Having a ball turner in front of your eyes is a big help in understanding the pros and cons of the other varieties.

[12bolts]

Bill,
Try using a stone to put the radius on your tool. Much better control than grinding it

Cheers Phil

[steamingbill]

I got frustrated with the lantern toolpost, quite awkward to use.

Realised that its possible to clamp a toolholder straight on top of the compound slide and achieve proper tool height.

Far easier to use.

Did some doodling to check the new holder and at one point had a nicely proportioned rough cut for a queen but then got a bit too adventurous and lost the pleasing proportions - might be able to rescue something from it. See photo.

Discovered that I can use a shear tool on the ball turner and get a nice finish on the ball ends and has the added benefit of slicing through the annoying tiny protrusion caused by a low set cutting tool.

George Thomas has some good notes worth reading regarding ball turners in his red book, The Model Engineers Workshop Manual.

After I get a good finish, how do I polish these things - is it done on the lathe with autosol and paper towels prior to parting off, or do I need to get cloth buffing wheels for my grinder ?

[BaronJ]

Hi Bill,

Nice work. I use green abrasive "Scotchbright" pads and discs to both clean, deburr and polish steel items. You can get various grades of them. The green ones are a bit rough on brass and alloys. I get mine from MSC, they are quite inexpensive.

PS. They work well on wood too.