Models for grinding HSS Lathe Tools

I have never personally tried to turn either aluminum or phosphor bronze. However, my understanding is that the former is pretty hard and its machinability rating of 60 bears that out. I suspect that for these harder alloys, the typical zero rake tools we normally use for the brass/copper/bronze family will not cut well. If it were me, I would try a steel cutting tool like a square tool and see how that works.

All of these materials like very sharp edged tools so hone well.
 
I think any tool with a positive rake would be suitable for aluminium and bronzes for turning or milling.
Same for drilling into ally.
Drilling into brasses and bronzes you need to flatten the edge of the bit to a zero rake to prevent grabbing especially when about to break through. Not a hard and fast rule but it chips easier rather than create springs.
 
I just happened to see this video on Youtube today and it validates my early experiments with HSS tool grinding. Back then, about 30 years ago, Youtube didn't exist but my experiments were pretty close to what you can see in this video. I measured the power requirements of the lathe and compared them as I varied the relief and rake angles (side and back rake independent of each other) until I found what appeared to be the best compromise between rake and relief angles and edge wear. This eventually led to the design of my Square Tool.


About 5 years after my initial experiments, I learned about the Merchant Equation and the concept of the Shear Plane and how rake affects chip formation. I was then able to put together at least a basic understanding of what is happening at the cut and why altering the rake angles produces such benefit at the lathe.

I truly wish I had seen this video way back when I started. It would have saved me a lot of independent experimentation and work. I must have ground close to 300 experimental tools to learn what you will learn in this video and I hope you find it interesting.
 
Mikey, Thanks for posting that. What brand or make do you recommend for HSS tooling.
 
Happy New Year, Tom!

Most of my daily user tools like my square tools or material-specific general purpose tools, are simple M2 HSS. For the tools that have delicate tips, like my knife tool and threading tools, I use HSS-cobalt blanks because the small contact areas of these tips get really hot really fast. The higher red heat resistance of cobalt helps these tools retain their edges longer.

As for brands, I much prefer Mo-Max and ETM (Iscar) M2 HSS, although most US-made HSS will be fine. I also like HSS blanks from Japan when I can find them. When I am experimenting with a grind to see how the angles work, I use cheap Chinese HSS blanks and they seem to work just fine, although I have convinced myself that the edges don't hold their sharpness as long as high quality blanks. I doubt that you would see a difference, though.

For cobalt, I prefer Super-Mo-Max in M35 (5% cobalt) and M42 (8% cobalt). Most high cobalt Rex/Crucible blanks are good, as are the high Tungsten blanks from Rex/Crucible and Vasco. Most cobalt blanks from US makers are also very good. ETM makes some really good M35 cobalt bits but they're expensive. The Chinese cobalt stuff is okay but I do not rely on their claims of 5/8/10% cobalt because there is no documentation to confirm it. Still, I have used some Chinese cobalt and found it to be pretty okay.

If in doubt, go with US-made blanks. Mo-Max was made in the US until the late 1990's, I think. Then they moved production to Mexico but the blank quality from Mexico is still amongst the best you will find. Other US brands are Rex/Crucible, Morse, Do-All, Vasco/Teledyne and many others.

Hope that helps.
 
How does one go about getting on the list for these grinding models you speak of?
 
Darn, I thought I was going to read about Big Block Chevys :)
Very informative though:encourage:
 
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