Angle of HSS turning tool to work

Okay, big lathe, low speed. You can grind a general tool shape and use the rake and relief angles found in any lathe tool angle table.
 
The youtube channel "thatlazymachinist" has some in depth videos on grinding the angles on HSS with some interesting results that are worth watching as well as "mrpete222".
 
Rockytime said:
From a watchmaker's lathe, to a Sherline, to a 7" MaxiMat to a 12" lathe, I have always left the top of the cutter un-ground. Perhaps I suffer from some inefficiency, I don't know. I guess it is because the things I cut brass, aluminum, 12L14 and some cast iron. These materials are so easy to turn I have to problem. Perhaps with more difficult steels I would have a problem. Another reason is it is one less face to grind. Another reason to use inserts, even on my Sherline.
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What is the maximum depth of cut you can take on your Sherline with those inserted tip tools or with a flat topped HSS tool in say, 12L14?

I ask because I also own a Sherline lathe and I can easily take a 0.050" deep cut in 12L14 with a good HSS tool. On my 11" lathe, I can easily take a 0.20" deep cut before I have to step the gearing down; and then I can go deeper. Tool angles enable a lathe to work much more efficiently than most of us realize.

Edit: @Rockytime , I re-read my post and it sounds like I'm being confrontational. My apologies as that was not my intent. What I really meant was that when we use side and back rake to full advantage it greatly reduces cutting forces and cutting temperatures so as to make a smaller lathe more efficient. I am not challenging your preference not to use them but I am suggesting that perhaps it might improve your experience. Again, my apologies - I sounded like a real dick and I didn't mean to come off like that.
 
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So this is why a solid tool post won't work if you use HSS ground tool bits.?
 
If you only use inserted carbide tooling then the tool post can be fixed. If you plan to grind HSS tools with their profiles fixed, meaning you will grind a tool for roughing, facing and finishing for each material class then sure, you can fix the tool post. However, if you plan to use general purpose tools then you need the ability to alter their lead angles for different operations and that means the tool post cannot be fixed.
 
mikey said:
What is the maximum depth of cut you can take on your Sherline with those inserted tip tools or with a flat topped HSS tool in say, 12L14?

I ask because I also own a Sherline lathe and I can easily take a 0.050" deep cut in 12L14 with a good HSS tool. On my 11" lathe, I can easily take a 0.20" deep cut before I have to step the gearing down; and then I can go deeper. Tool angles enable a lathe to work much more efficiently than most of us realize.

Edit: @Rockytime , I re-read my post and it sounds like I'm being confrontational. My apologies as that was not my intent. What I really meant was that when we use side and back rake to full advantage it greatly reduces cutting forces and cutting temperatures so as to make a smaller lathe more efficient. I am not challenging your preference not to use them but I am suggesting that perhaps it might improve your experience. Again, my apologies - I sounded like a real dick and I didn't mean to come off like that.
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Hi Mikey, Absolutely no offense taken. I do understand that proper grinds are necessary when doing production work. Time saved is more profit in the work. I, however, do mostly small projects such as making clock repair parts. Most often I am cutting brass and aluminum and occasionally 12L14, the 12L14 usually used for making small screw. At present I am building the PM Research small mill engine with aluminum castings with only a 1/2" bore. Very small engine. That is why I don't bother grinding the top relief.
 
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