Models for grinding HSS Lathe Tools

Mikey,
I forgot to mention that I haven't put a NR on it yet!

And thanks for the comment. It's all because of your patience and teaching. I think I'm finally learning what it all means, not just the numbers. Clearly worth learning.
Tim
 
OK...well, it works, and well. I normally use an IPR of .0062 @ 450 rpm for 12L14 with my square tools on my Logan, and 750 for roughing. I played a. little with IPR, @450 rpm, and it seemed immediately happier at .0077 IPR, also @450 rpm. My Logan is never comfortable turning deeper than .015 at a pop, and I was pretty leery of turning the ebonite more than .005. But that worked well, as did .010. The pictures show the two depths of cut. It parted off really easily, like cutting into a frozen stick of butter. I didn't want to cut into a longer piece, stuff is a bit dear, so only did about a half inch of .500 wide at at time and didn't bother supporting it. But having drilled the stuff before, I am really happy it didn't just crumble under the blade.
First pic shows the faced end, second the piece of ebonite, third the chip. The thinner chip is .005, thicker is .010. Don't think I'll be going deeper.
I must admit, everyone has said turning this stuff is nigh unto impossible. Not true.

best,
Tim


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Can you show us the section you turned? It's possible we can improve the cut if we can see what the current geometry is doing.
 
Here it is...turned .010 deep, .0077 @450. This time it was supported. Quite smooth. You can see the cut rings, but it polishes easily, and I predominantly create parts you'll never see.. Ebonite is compressed granular slurry, so this is what it looks like.
Tim

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You might try taking a very light cut with the end cutting edge, just behind the nose radius. Turn the tool tip towards the chuck and touch the work just behind the nose radius and see what happens. You should be able to take a 0.001" cut and improve the finish. Be sure the tip is on center height.
 
So what would you say a much smaller radius for the tip of the tool to keep that finish?
 
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