Turning Tool And Facing Tool Questions

[Bill C.]

Well here's a picture of
My most commonly used tool. As I had said before I watched some videos and measured some angles sometimes and I never got the results I desired. My tools may not be correct or at an exact angle but they work for my purposes. The first picture of bar is a piece of unknown ss I turned the next is mild steel. Hopefully this helps if not let me know and I'll try to answer to the best of my knowledge. View attachment 107038View attachment 107039View attachment 107040View attachment 107041View attachment 107042View attachment 107043View attachment 107044View attachment 107045View attachment 107046


Regards-Carlo

Good looking bit you are holding. Thanks for sharing.

 

[Bill C.]

I learned to grind lathe tools and drill bits free hand years ago. It works well, but I came up with something a bit simpler recently. I bought a Harbor Freight Mini Tool Grinder off a guy cheap ($10). I sanded off the tool rest, put Dykem on it, and laid out lines at 59 and 30 degrees from both sides. The beauty of this little thing is that you can position it exactly as you want and it's not intimidating at all. I plan on getting another wheel for the other side, cutting down a protractor, and affixing it to the base. You can buy one new for less than $25 if you use a 20% off coupon.
View attachment 107083

You could use a small piece of flat stock and a vise-grip to clamp it making a temporary guide using your lines if you are grinding several bits.

 

[Joe Pitz]

Hey Charles, what is the thin wheel on the left, is that a cutting wheel or a diamond wheel.

I like the dykem on the rest idea. looks good.

Joe

 

[Charles Spencer]

It's a regular cutting wheel. All I've used it for is to sort of notch round stock that I'm going to cut on my vertical bandsaw. It helps getting started.

 

[Joe Pitz]

thanks Charles, good idea

 

[benmychree]

Free hand grinding just take little practice, keep in mind the tip and the left side of the tool ( for a right hand tool) is doing all of the work, everything else is just clearance. The angles are not critical. If the tool grind does not produce the desired result, then try again with slightly different angles.

While I do have a tool grinder with green wheels, I normally just use my cheap Chinese bench grinder with with a standard aluminum oxide gray wheel. You just have to push a little harder. On the other hand, I do a lot of things that aren't ''normal'' IMHO, as long as shop safety practices are observed, anything goes in machining. There is no ''right way'' to do an operation as long as the part comes out the way you want it to.
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There is an alternative to the green grit grinding wheels for carbide grinding; the shop that I apprenticed in did not have diamond wheels, at least that were available on the shop floor, instead, they used a grey colored straight type wheel in a bench grinder. In practice, one would undermine the carbide if a lot of carbide needed to be ground back, and then use the grey wheel to finish the job. These wheels were not the typical light grey of aluminum oxide, but a dark charcoal grey, and I presume they must have been silicon carbide. The tendency to chip the carbide was much less than with green grit wheels that I have typically seen, although perhaps the fact that most seem to be overly coarse grit may make a difference also. The wheel specification follows:
Radiac
A.P. De Sanno & Sons
C 100 - H02 - VD2
The size we used was 7 x 1 x 5/8

 

[Joe Pitz]

Thanks bennychree for the info on silicon carbide wheels.

Joe

 

[mikey]

Carlo,

Not to hi jack this thread and make it about grinding HSS tooling. But... You're making me feel like I need to learn a lot more about how tool geometry effects the loads on a machine. I have a little atlas 10". I work with what I have though which is a little ryobi bench grinder with an aluminum oxide wheel I believe it's 60. And then I just hone the cutter to death.
Regards-Carlo

Carlo, I think its great that you've experimented with various tool shapes and angles but I do wonder if you realize how much potential you have at your disposal. I have not worked with an Atlas 10 but my understanding is that these are not the most rigid lathes in the world. Accordingly, it would be good to know how to reduce cutting forces by changing the various tool angles. For example, just a few more degrees of side relief and side rake will significantly reduce cutting forces and allow a tool that would previously chatter to cut smoothly and more accurately. Cutting force reduction isn't only for roughing. A tool that cuts with less forces will also size more accurately and finish better so it is worth the time to learn how shape and alter tools to suit your needs.

The roughing tool I showed above can easily take a 0.030" depth of cut in mild steel on my little Sherline lathe. A similar tool with modified relief, side/back rake can take an 0.050" deep cut with less strain on the lathe with a far better finish. That same tool will shave off 0.001" off an OD, too. And it won't chatter.

My point is that you can tailor the tool to your needs but you have to know how to grind it and modify it so it does what you want it to do - predictably.

 

[JR49]

The roughing tool I showed above can easily take a 0.030" depth of cut in mild steel on my little Sherline lathe

Mikey, How about a Tutorial on the different degrees of the angles used , and for what purposes. I posted on the first page that I felt I was pretty good at tool grinding, BUT, after reading your posts, I'm not so sure anymore. I'm sure Carlo, and myself, and Joe, would like to learn more. Thanks, JR49

 

[Joe Pitz]

JR49 and all,

mikey sent me some articles that he wrote on the proper way for new guys like us to grind lathe tooling.

http://www.machinistblog.com/grinding-lathe-tools-on-a-belt-sander/
http://www.machinistblog.com/grinding-lathe-tools-on-a-belt-sander-part-2/
http://www.machinistblog.com/grinding-lathe-tools-on-a-belt-sander-part-3/#more-5897

I am currently reading them and they are great. Clears up many questions I have on proper tool geometry.

Thanks

Joe