Turning Tool And Facing Tool Questions

[Joe Pitz]

Are you kidding? Threads like this one are my favorites. I hope Joe is OK with how his thread has evolved, cause there is definitely a lot to be learned here. As far as putting me on the spot, here is what I'm planning. Just the other day I ground a 3/8" tool with front and side clearance, a small nose radius, but almost no side or back rake. This tool seemed to cut pretty well on my 12" Logan, BUT, I don't really think that I have enough experience to know the difference between a good cutting tool or a poor cutter. So I'm going to grind another 3/8" tool with the angles that you listed in post #78. Then I will cut the same steel rod, half with each tool. This way even a beginner like me should see a difference, and if it is OK with you Joe, I'll report my findings here. One thing I need from you first Mikey is, please tell this beginner what you mean by a "square tool" Thanks, JR49

JR, I do not mind at all, mikey has been helping me and providing me good info. I love all of the different views and perspectives given, I love how this post has progressed. and welcome everyone's feedback and experimentation's. I am learning a bunch.

Joe

 

[mikey]

Ok, jumping in....

For starters I'm not especially new to the mechanics of tool grinding, but I am less versed with the performance aspects of various grinds so I've been following this discussion quite closely. I think for me, the most salient take-away has been that while the textbook numbers may be tried and true based on much research, those numbers may not be the best option for smaller machines that typically don't take huge cuts or do long production runs. It's a basic factor for me, a smaller lathe user to consider, and I'm almost embarrased I hadn't taken it to my tool grinding as well.

With that said, and the coincidental arrival of five fresh tool blanks last week, I ground one of mikey's "square tools" last night. I ground it as more of a roughing shape though, and in keeping with the theme made the lead angle 15-degrees as well. Then I honed it as I always do, stuck it in my little Atlas, and fed it some 6061.

Very nice, I'm liking it! Easy-breezy cutting, nice finish, decent chip direction. I can't give a percentage-point advantage compared to what I was using before, but it just *felt* better. Where I may have backed off my DOC before, that threshold has moved further out with the new tool. And to my mind, that's improvement.

So, I can't wait to try another one. I do use my grinder though instead of the belt machine. It works for me and I made an adjustable rest that is easy to adjust and holds the angles well so I'm sticking with it.

Great discussion, guys. Very useful indeed and some really good banter.

-frank

Outstanding, Frank! I'm glad the tool seems to work well for you but am even happier that you know how to alter your tool geometry to better suit your smaller lathe. I couldn't have hoped for a better outcome - congratulations!

Keep us posted on your future efforts and if there is anything I can do to assist you, please let me know.

Mikey

 

[Tozguy]

I know you feel otherwise but I really think practicing with mild steel keystock is the best way to learn to grind a tool bit. It cuts easily and allows you to understand how to hold and angle the bit to get the results you need. Once you are comfortable with the procedure then switch to HSS. Grinding tools isn't hard to do but it takes practice to wrap your head around the process. Stick with it, Carlo - it will come.

This reflects my experience very well. It was only after getting equipped properly to grind lathe tools that it became comfortable for me. As in many other operations the right equipment is a prerequisite. Now that it is fun for me to grind, I don't hesitate to tailor angles for a specific job and keep tools sharp. It all translated into more enjoyment in using the lathe.

 

[Strtspdlx]

Mikey
Instead of quoting and wasting space for valuable information I'm hoping I can just reference your last post and there won't be confusion. So I'm going to try.
As far as mild steel blanks I only really dislike the idea because when I started I went around and bought up every piece of tooling I could get my hands on. Needless to say for less then $100 I must have well over 200 blank hss bits in various sizes. So I'm not necessarily opposed to your idea. I just don't wish to spend the money. I do firmly believe if I want to get a specific angle in any place on a tool it can be done. I do have adjustable tables and protractors and misc measuring tools for angles I just chose to never use them. Hopefully today I'll get out to my shop. I'd like to measure the current angles of my tools and adjust them to your guidelines and see what I get. Please keep the help coming if there's a better way id love to know it.


Regards-Carlo

 

[mikey]

Mikey
Instead of quoting and wasting space for valuable information I'm hoping I can just reference your last post and there won't be confusion. So I'm going to try.
As far as mild steel blanks I only really dislike the idea because when I started I went around and bought up every piece of tooling I could get my hands on. Needless to say for less then $100 I must have well over 200 blank hss bits in various sizes. So I'm not necessarily opposed to your idea. I just don't wish to spend the money. I do firmly believe if I want to get a specific angle in any place on a tool it can be done. I do have adjustable tables and protractors and misc measuring tools for angles I just chose to never use them. Hopefully today I'll get out to my shop. I'd like to measure the current angles of my tools and adjust them to your guidelines and see what I get. Please keep the help coming if there's a better way id love to know it.


Regards-Carlo

Carlo, ANYTHING you have to say has value as far as I am concerned. I also understand and accept that since you have a wealth of HSS blanks around, and the means to grind angles into them accurately then that would be your preferred route - go for it. What really matters is that you understand how to grind all the relief and rake angles the way you want them to be. I have no doubt that you'll figure it out but if something isn't making sense, we are here.

Mikey

 

[Strtspdlx]

I need to engrave the terminology in my head. Every time you refer to an angle I have to go in my book and look at exactly what you're talking about. Like you've already
Mentioned time and experience are the major things to figuring out how to do it correctly.


Regards-Carlo

 

[JR49]

Boy, this thread has really taken off. Still planning to test out mikey's angles , but presesnly i'm reading this in the surgery waiting room. (Wife is having a minor procedure), but hope to get to it this weekend. JR49

 

[mikey]

Boy, this thread has really taken off. Still planning to test out mikey's angles , but presesnly i'm reading this in the surgery waiting room. (Wife is having a minor procedure), but hope to get to it this weekend. JR49

First things first, JR. Hope all goes smoothly.

 

[Strtspdlx]

Alright guys I didn't quite measure my tooling. I tried but I don't trust my measuring tools. So I went ahead and tried threading with a hand ground 60* tool. I figured since we where on the subject of hss tooling I'd post a picture of the rough threads. These where not meant for any purpose other then to see if I could thread anything on my lathe with any success whatsoever. The material is unknown SS. I should've got a picture of the tool but I was in a bit of a hurry. So here's what I ended up with. Questions now.
When I get to a certain depth it is showing chatter
Marks along the length of the thread but I can't hear or feel any when cutting. What may cause that? Should I have back rake on a threading tool? My holder is already angled 15* up I believe.


Regards-Carlo

 

[JimDawson]

Carlo, I see a couple of things. Your work was not supported by the tailstock so I'm surprised that it didn't chatter even more, that is a lot of stick out. Normally about 3x the diameter of the work is the max. This would indicate that your tool is working just fine.

When threading, as the tool goes deeper, the cut is wider, so more prone to chatter. Run another piece, and support the end with the tailstock center and I'll bet the chatter goes away.