Re: trouble between centers

Mark R. Jonkman

Carbide tends to give a much better finish when combining high speeds and heavy cuts which is what it was designed for. On my heavy 10 I tend toward high speed steel inserts 75% of the time unless I know the work piece is fairly hard and or its above 2" diameter. I assume you swapped cutting edges on your carbide bit to make sure you have a fresh edge? If you have a 3/8" high speed steel tool bit kicking around I'd grind it into a good shape with reliefs for holding in the quick change tool post and give it a shot.  You don't mention whether you are hearing chatter as its cutting vs a course tearing/thready type finish. You also don't mention feed rates - assuming you've tried slower feed rates and faster feed rates. Did you brush on any cutting oil to help things?

For the other guy turning the 20" between centers and complaining about heat build up. Other than using cutting oil, if you have a air compressor and a regulator, try turning the air pressure down to about 20-40 psi (maybe even less) and keep an air stream hitting the tool bit. That might keep your heat down in a pinch. I have a Cool Mist that i mount on whatever machine I'm using when I have to keep the heat down. Obviously it uses cutting fluid and air but there are others on the market I think that strictly use air (Chilly bits??? or something like that). Worth a shot and might get you by as a poor man's temporary cooling system.

Mark R. Jonkman

From: "johnnyblock1@... [SOUTHBENDLATHE]"
To: "southbendlathe" Sent: Thursday, December 10, 2015 4:18:15 PM
Subject: Re: [SOUTHBENDLATHE] trouble between centers


I am using a quick change tool post with the triangular inserts. The work is 8 inches between centers. I tried both 800 and 1200 RPM with no noticeable difference between the two.

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