Embarrassed to ask, but haven't found an answer to this with pictures - carbide angles relative to workpiece

Bit was centered. Set a 5 degree angle of attack. Cross slide gibs were tightened. Now minimal chatter running at 2500 rpm. Facing cuts on steel are much smoother now, but still not showcase. I was able to take 0.001" cuts although they weren't as nice and smooth as I remember using HSS.

To get a smooth burr free chamfer using carbide what does one do? I still feel a burr. It's like the metal wasn't cut that cleanly. Almost pushed aside.
 
Slowly, but surely, I'm getting the message. Big grin.
It will be a week or so before my belt grinder comes in. Then I'll pester the tool grinding thread.

Oh, I call it the dungeon because it's underground and like a cave. 54F. Got to get a little heat in there. It gets cool after a while. I have a dehumidifier running to ensure it doesn't get too damp. Don't want my new stuff rusting!

Thanks for at least getting me going. Everyone has been incredibly helpful, it's greatly appreciated.
 
Carbide needs a deeper depth of cut. Since it’s cutting edge is more “rounded” than sharp, 0.001” cuts are too small, carbide would tend to rub or smear the surface more than cut it at 0.001” depth of cut.

With carbide try 0.010” or 0.015” depths of cut.

Also what material are you cutting. Some steels are more gummy and getting a nice surface finish can be difficult.
 
Yes, seeing smearing. I don't want to go much further on facing this end. Going to run out of total length if I'm not careful. Wish I knew the kind of steel. It's a Crosman airgun barrel, not some high end barrel steel.

My example bits came in from @Z2V. Also a belt grinder, which I'm not sure if I can modify appropriately. Hoping to try out HSS within a week.
 
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WobblyHand said:
Ordered some TCGT110204 inserts. What's another $10?

Back to the dungeon :D
Click to expand...

I think you'll be amazed at the difference - free cutting and beautiful finish. I used a CCGT insert to turn and bore a couple of CrV sockets this evening, worked beautifully. They also work really nicely with aluminium too, no edge build up which I found to be a problem with HSS. Honestly, HSS works fine and is cheap as chips. xxGT inserts work better and are almost as cheap - all I use HSS for on the lathe now are parting blades and form tools.
 
mattthemuppet2 said:
I think you'll be amazed at the difference - free cutting and beautiful finish. I used a CCGT insert to turn and bore a couple of CrV sockets this evening, worked beautifully. They also work really nicely with aluminium too, no edge build up which I found to be a problem with HSS. Honestly, HSS works fine and is cheap as chips. xxGT inserts work better and are almost as cheap - all I use HSS for on the lathe now are parting blades and form tools.
Click to expand...
Just as a follow up, these TCGT110204 are pretty darn good! Both on steel, aluminum and brass. The turning finish was mirror like on aluminum and brass. Facing steel is so much nicer than those awful inserts that were originally supplied. Very little chatter, even when I was playing around trying to make a square out of a round. Fortunately the stock was 6061, and the carbide didn't break. As I understand, interrupted cuts are bad for carbide.
 
very neat, I'm glad that they're working well for you. Your experience pretty much matches my own :) Interrupted cuts will be fine, just don't get too crazy if you're doing it in steel. Thing is these inserts are so cheap you can push things a bit until you chip a tip, rotate the insert and try and remember not to do that again. Stalling the tip in the work kills tips in my experience, other than that they last a good while in steel and a long time in everything else.
 
DAT510 said:
Carbide needs a deeper depth of cut. Since it’s cutting edge is more “rounded” than sharp, 0.001” cuts are too small, carbide would tend to rub or smear the surface more than cut it at 0.001” depth of cut.
Click to expand...

You can use a diamond hone on the edge of the carbide insert. Sharpen it enough to take those 0.001, 0.002 cuts.
 
That link that Mitch posted is a very slick site with a good description of turning theory. I like it! Everyone should review it.
I am confused about this:
"So, TCGT are a positive rake version of the TCMT " That doesn't sound right.
Position 3 is the tolerance of the insert if I understand correctly?
I do not understand how the rake angle is coded. Is it based on the tool holder or the insert? All my tool holders are zero so far. Do I need a negative rake holder?
Cutting radius is coded in position 7 in 64 ths of an inch?
Position 5 is inscribed circle. Is this based on the radius or diameter?
I am running a "TT321" insert routinely on aluminum. (1/2" tool holder) That should have a 1/64" tip radius. Does any one have a better recommendation? If so please explain why it will be better. I like to know the theory behind all this.
Robert
 
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