Peter’s Metalwork: Hot Air Engine: Parting off

Parting off

Posted 2006-08-27. Permalink. Send Comment. Next. Prev.

Unfortunately, I did not take any pictures, but hopefully I will remember to take a picture of the part when I am next at the lathe.

First, I center drilled the crank (a ⅛ drill). This may have been a mistake, as the ⅛ shaft is somewhat of a looser fit that I would like, but since it is meant to be silver soldered in, it probably will be ok as long as I can keep it square while soldering.

Then I parted it off. The parting went very well, I'm not sure if that was because it was brass (probably good machining brass), because I've slowed the lathe down, or (and I think this may be it) because I recently learned that when setting up the parting tool you should use the dial gauge to get it perfectly square. This is obvious in hindsight, but many things are obvious in hindsight!

The parted face is almost as smooth as the faced face (not quite, but almost), although a thin circle of brass protrudes from the center drilled hole (my parting tip should have been angled slightly to avoid this, but since I do not have a grinder and have never learned how to make my own tools, I use what I have. Still, with a bit of filing (or perhaps using a drill bit by hand to very mildly countersink the hole), as well as a bit of filing around the circumference of the parted side will have it nicely finished off.

Remaining for the crank is to drill and tap the outer hole and to mill away large parts of the crank. Since I have never tapped a hole, and my milling experiences have had rather poor results to date, this may prove interesting!

Posted 2006-08-27. Permalink. Send Comment. Next. Prev.