Trying my hand at 'Spinning'

Another Day, Another Project.

About two weeks ago I contacted an old professor that I had in college to teach me how to spin metal on a lathe. After quickly getting a crash course on the theory behind spinning and techniques I quickly decided to try my own hand and spinning. 

Spinning is a little different than turning on a metal/wood lathe. When you turn, you use chisels or cutters to selectively remove material from a workpiece. When you 'spin' you are using leverage to move, or form, metal around a predetermined object. The previous week I spent the weekend creating the tools needed and various hardwood maple forms that I would need to push the metal around. 

I decided to use my Delta wood lathe because my wooden forms could be directly screwed onto the 1"-8 spindle. I then sandwiched my annealed aluminum disk in between my form and follower block. The "splattered" texture is the grease that I used as a lubricant. On my initial trials I forgot to add a lubricant and my forming tool was damaging the surface.

Although the preferred grease to use is a Home Depot toilet bowl gasket, I used what I had in the shop for this trial run.

It wasn't too long before I noticed the aluminum disk taking shape.

Although this is not the shape I was looking for, I do find it interesting. Notice that in the above photo there are stress creases forming at the base of the sharp curve. When you are spinning you are literally moving the material and that excess material has to go someplace. It was easier for me to move the material out further away from the center which is why I have a tight crease. Next time I use this form I will try to be more consistent and start from the center working my way out.

Here is a closer look at the stress lines.

Above you can see my first attempt at spinning. Notice the stress crack near the domed form. I was overworking the material which caused the aluminum to tear. Shortly after noticing this tear I stopped.

And finally I stopped spinning for the day because my follower block actually cracked while the lathe was still on. Luckily the aluminum disk did not spin off, but I will have to create a new follower block before I continue.

Stay tuned!