What's wrong with using my right hand turning tool for facing?

[tweinke]

Take a peek at this thread where Mikey shows HSS grinds that he uses and has taught us how he does it. The nice part is you will get some understanding of how the angles work and why. His method may not be necessarily the textbook grinds that you see but they will cut nicely on smaller lathes. He also encourages to try different grinds to see if you can get a tool that can work for you. That thread brought me from chicken to try to let's try this and see what happens with enough confidence to get a tool that works and the why of it.

Models for grinding HSS Lathe Tools

In a recent thread by @Darkbluesky, http://www.hobby-machinist.com/threads/lathe-accessories-tools-ideas-of-what-to-buy.62043/#post-511618, @ttabbal joked about sending me blanks to be ground into lathe tools ... he was joking! But it got me to thinking ... yeah, I know it's not a good thing...

www.hobby-machinist.com

 

[Janderso]

Take a peek at this thread where Mikey shows HSS grinds that he uses and has taught us how he does it. The nice part is you will get some understanding of how the angles work and why. His method may not be necessarily the textbook grinds that you see but they will cut nicely on smaller lathes. He also encourages to try different grinds to see if you can get a tool that can work for you. That thread brought me from chicken to try to let's try this and see what happens with enough confidence to get a tool that works and the why of it.

Models for grinding HSS Lathe Tools

In a recent thread by @Darkbluesky, http://www.hobby-machinist.com/threads/lathe-accessories-tools-ideas-of-what-to-buy.62043/#post-511618, @ttabbal joked about sending me blanks to be ground into lathe tools ... he was joking! But it got me to thinking ... yeah, I know it's not a good thing...

www.hobby-machinist.com

+1, very helpful

 

[twooldvolvos]

As long as the tool does the job, who cares what it's called? Once you understand the whys and wherefores of the various angles, you will find yourself grinding some very interesting tools. I once ground a tool that came to be known as the "flying V" for a special purpose job. It would plunge straight in and turn in both directions to a square shoulder on either end. Saved a lot of tool changes.

As long as the tool does the job, who cares what it's called? Once you understand the whys and wherefores of the various angles, you will find yourself grinding some very interesting tools. I once ground a tool that came to be known as the "flying V" for a special purpose job. It would plunge straight in and turn in both directions to a square shoulder on either end. Saved a lot of tool changes.

It is interesting to note that Mr. Pete's

I notice that the angles on the tools that Mr. Pete grinds look much different than the angles on insert tools. I also notice that they both work just fine. I am only a casual hobbyist, but I suspect that there is superstition involved in choosing cutter angles.

Good observation. I just took a look at a Right Hand turning tool in the "How to Run a Lathe" compared to the Right Hand Turn tool I learned from Mr. Pete. They are close but definitely not the same.

 

[mikey]

The shape of the tool is defined by two angles - the side cutting edge angle and the end cutting edge angle. They are the least critical of all the angles on a turning tool and can be changed to suit the access needs of the tool. How well the tool cuts depends on the relief and rake angles at each of these edges.

What the OP is referring to is the lead angle of his tool. When turning, the tool is held more perpendicular to the work axis so that the side cutting edge is literally cutting a chip. When facing, the side cutting edge is also used but the tool shears instead of cutting a chip; here, the contact point is just behind the nose radius and it makes no difference if the cutter moves towards or away from center in use.

The lead angle of the tool (the angle the tool is fixed at in use) has a definite impact on cutting forces, finishes and accuracy. You should learn to use the lead angle to suit your needs. And no, it has nothing to do with superstition.

 

[Firstram]

I'm not superstitious but, why take a chance!

 

[twooldvolvos]

The shape of the tool is defined by two angles - the side cutting edge angle and the end cutting edge angle. They are the least critical of all the angles on a turning tool and can be changed to suit the access needs of the tool. How well the tool cuts depends on the relief and rake angles at each of these edges.

What the OP is referring to is the lead angle of his tool. When turning, the tool is held more perpendicular to the work axis so that the side cutting edge is literally cutting a chip. When facing, the side cutting edge is also used but the tool shears instead of cutting a chip; here, the contact point is just behind the nose radius and it makes no difference if the cutter moves towards or away from center in use.

The lead angle of the tool (the angle the tool is fixed at in use) has a definite impact on cutting forces, finishes and accuracy. You should learn to use the lead angle to suit your needs. And no, it has nothing to do with superstition.

Well stated. Thank you.

 

[JPMacG]

Sorry gentlemen. I chose my words poorly. "Superstitious" was a poor choice.

Speaking just as a hobbyist with a small lathe using easy to machine metals, my observation is that the angles are not critical. I have had some fun grinding HSS cutters - I actually kind of enjoy it. The nice thing is the cutters work well even when the angles are wrong.

My recommendation to beginners is just start grinding. Don't get too concerned with making them exactly like the experts say they should be. I think you will be pleasantly surprised.