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General Category => General Shop Discussions => Topic started by: PJ on Aug 11, 2025, 09:59 AM
Interesting little project I picked up over the weekend at the marina.
Guy wants me to remove an inch off the diffuser ring of his boat propeller. I'd prefer to cut it on the lathe but sadly I only have 11" swing and the prop is like 15" My next thought is to clamp it to the mill table via the center hole and use a boring head to "turn"" it down. It's fairly thin wall cross section (.070) and cast S.S.
In theory it seems like it will be ok but maybe you guys have other suggestions. I have limited tooling for the boring head so I'll need to check and see what's available in my tool box. The other thought was to just walk it around X/Y hand cranking with a carbide endmill. but it seems like that might end up like a raccoon went after it.
Apparently all the boring bars I have are the cheap import brazed carbide ones with the inserts chipped out and stick out way to far so I ended up using a 1" endmill. Ended up working good but I have a feeling that particular flute is a little fudged up now. Oh well.
I have used HSS on 303 stainless with very good results, but I have no idea what would happen if you attempted to use a HSS boring bar on that cast SS prop. It is anybody's guess as to what alloy that might be.