Hi
Currently saving up for a Sherline head, either the head driven by a spare servo motor laying around or the whole lot. But before that ... I'm currently using a couple of Kress 600W mains heads and getting tired of the incredible noise they make. They date from 1995, speed controllers burnt out after about a year and I run them off a variac which is a big 1950's toroidal variable transformer. They Still work fine, no torque at low speeds, not since new, but run forever, I mean 20 hours of 2 hour milling, no problems. Many years ago I picked up something cheap called a Proxon bfw 40E, basically a 40VDC 250W head with a nice speed controller. Collets leave a bit to be desired but once you've made your own, runout is good. Despite relatively low power it's OK on 1/8 bits and small fly cutters, quite high torque. Careful examination of the destructions says 10 minute duty cycle, yes, it does gets red hot after 1/2 hour or so, so I never use it. But, it's almost silent and much more versatile the Kresses as long as you can live with 3000rpm or so and, keeps it's rpm! Whilst mucking about with a compressed air dust blower aimed at the dust extractor it occured to me that I could cool it, make a jacket (it's cylindrical) and use the exhaust as the blower?
Any thoughts? Anybody done this with a limited duty cycle motor to extend its life? It's sealed, no vents at all, maybe an inlet and an outlet drilled into the body, simple and no jacket? Air supply is clean, filtered, no water etc. Longer term idea is to drip suds into the air stream (post motor), have two suds pumps for lathe / manual mill. It must be able to run unattended.
Tom