- Joined
- Jul 26, 2011
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- 4,142
I can't recall a lot of screeching when turning full hard steel,or HSS. Maybe your speeds has something to do with it.
I had to turn down the shank on a 3/4" drill to 5/8 to fit my chuck last night, it destroyed 5 of my cheap Chinese made brazed carbides before I was done.
No great loss as I got them free and they did the job.
But that was the hardest turning and loudest screeching I have ever done.
The chips coming off it were a kind of Blue, almost Turquoise in color.
Dogs were going crazy barking and whining.
Wife was too. (she was Whining that is, no barking) LOL
The older I get,the more time has passed without me remembering when I heard something!!
There is a wide band of different grades of carbide; some won't even hardly touch hard steels, but others will cut hard steel freely; the best I have used is the Kennametal K-6 grade, renamed to another equivalent grade in later years. It is recommended for cast iron and non ferrous work, but is very good for hard part turning as well. Also of note for this sort of work are ceramic inserts and CBN (cubic boron nitride) these are the analog to diamond cutting tools for machining hard steels where diamond tools are not advised due their interaction with the carbon in the steels and subsequent degradation. Also note that there is a wide world of difference in the hardness of HSS tools; some that are made for heavy roughing operations are significantly softer than those intended for fine finish work on harder materials.I made a set of headspace gages for a 30m1 carbine out of dowel pins using carbide tools in the lathe. the carbide tools turned the dowel pins ok wasn't easy but got it done!