Making chips with HSS

J

Jack C.

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Thanks to Toag and others for steering me to HSS instead of carbide. I spent about 1 hour today grinding my first tool, R.H. turning. There really is a lot of science behind all these angles. Much to my surprise when I tried it out - IT Worked!! Actually left a better finish on my alum. practice piece than my carbide insert. I have a long way to go but it's always nice to get a positive result the first time out. Back to the books and videos.

Jack C.lathe 002.jpglathe 003.jpglathe 001.jpg

lathe 002.jpg lathe 003.jpg lathe 001.jpg
 
Yes, it does take a little practice to learn to grind your own but it is well worth it. I usually use a wheel to rough out and a belt to put a polish on them.
Michael
 
Thanks for the tip. Sounds like a great idea.

Jack C.
valleyboy101 said:
Yes, it does take a little practice to learn to grind your own but it is well worth it. I usually use a wheel to rough out and a belt to put a polish on them.
Michael
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Hey;

That is a good idea, and it would be nice if you have a sander that allows you to get close enough to the edge of the belt to refine the back rake as well. Something to look for when shopping for belt sanders! I'm not sure if you've come across this tip or not, but very often dressing the edge of your freshly ground tool with a stone will clean up any burrs and put a very fine edge on them. Even ever-so-slightly rounding off or deburring the cutting edge will give them a better micro structure, offering better finishes and a longer lasting edge.
 
Jack,

What back and side rake angles did you use on your bit?
 
Redlineman said:
Hey;

That is a good idea, and it would be nice if you have a sander that allows you to get close enough to the edge of the belt to refine the back rake as well. Something to look for when shopping for belt sanders! I'm not sure if you've come across this tip or not, but very often dressing the edge of your freshly ground tool with a stone will clean up any burrs and put a very fine edge on them. Even ever-so-slightly rounding off or deburring the cutting edge will give them a better micro structure, offering better finishes and a longer lasting edge.
Click to expand...

When I use a belt sander to touch up a bit I used the bottom drum.
 
As a retired Tool&Die Maker, over the years, I discovered that, IMO the most important angle on a tool bit, is the relief just below cutting edge--just enough to clear work. This is most critical with heavy cuts.
In the shop I worked, it was expected to use a cutting tool to the max. This meant that the tip if the cutter would be ground slightly lower then the body of the tool. When re sharpening a bit, it is much faster and easier to grind the top cutting angle but this weakened the tool bit. We were instructed that--for instance--a maximum of 1/8" ground off the top was acceptable on a 5/8 bit but any more grinding should be taken from the end of cutter. I have seen 1/2" bits that were ground to basically a 3/8" or 1/4" bit and the tool was only 1/3 shorter then new bit.
As I stated, this is most critical with heavy cuts.
 
Giles said:
As a retired Tool&Die Maker, over the years, I discovered that, IMO the most important angle on a tool bit, is the relief just below cutting edge--just enough to clear work. This is most critical with heavy cuts.
In the shop I worked, it was expected to use a cutting tool to the max. This meant that the tip if the cutter would be ground slightly lower then the body of the tool. When re sharpening a bit, it is much faster and easier to grind the top cutting angle but this weakened the tool bit. We were instructed that--for instance--a maximum of 1/8" ground off the top was acceptable on a 5/8 bit but any more grinding should be taken from the end of cutter. I have seen 1/2" bits that were ground to basically a 3/8" or 1/4" bit and the tool was only 1/3 shorter then new bit.
As I stated, this is most critical with heavy cuts.
Click to expand...

Hear.Hear

That is where tangential tools shine.You get correct relief angles everytime without doing anything.The top plane angle does not matter really for hobbymachinists,unles they use foot driven (treadle?)lathes.
 
Side rake is 6 deg, side relief is 8 deg and end relief is 10 deg. Back angle is only a couple of degs. I did use a stone to radius the nose and sharpen the cutting edge.

Jack C.
Dan_S said:
Jack,

What back and side rake angles did you use on your bit?
Click to expand...
 
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