Posted 16 September 2006 - 07:25 PM
I know this post is from a few months back. I just saw it today. Not to be critical, but in attempt to maybe make things easier, I'll jump in.
Right off the bat, there is something wrong with either your sherline or the cutting tool. The surface finnish can be much much better than that with minimal effort if everything is set up correctly. Judging by that picture, it is not setup correctly.
There could be excessive play in the machine, but with a sherline, its doubtful. The berings in the headstock shouldnt really go bad on a sherline for a LONG long time. Really excessive wear on the ways is also kind of doubtful.
It looks to me like a cutting tool problem. Either it is dull, isnt cut right, or isnt on center. Also the aluminum may not be the right alloy. If its the "mystery alloy" stuff you get at a hardware store like home depot, that stuff is not easy to cut smoothly. It gums up and leaves a poor finnish. 6061 alloy cuts great, and is very easy to find.
Post some pics of the cutting tools you are using. You will find that a properly cut and setup tool will make the cuts go much smoother, and leave a great surface finnish with little effort.