Chatter on 10 x 22 Lathe

[BobWarfield]

More rpm!

If you do the SFM calculations, for HSS, I'd run about 60 sfm. For your 1 7/8" diameter material, that'd be 500 rpm.

For the carbide, you'll have to go quite a bit faster. The books would say 3000 rpm (!), and you can't get there with that lathe. No worries, but you can go a lot faster than 150 rpm.

Chatter is a resonance effect. Just changing speed will often get rid of it. FWIW, when I first got a variable speed DC drive on my lathe, I found increasing the rpm helped more often than decreasing. I use mostly carbide, so that may be why.

Feeds and Speeds matter enough, I started using a Machinist's Calculator. First I bought one, then I wound up writing one that I call G-Wizard:

http://www.cnccookbook.com/CCGWizard.html

Cheers,

BW

 

[joeby]

BW,
I think 500 RPM is a bit high.

60 SFM
1.875 Dia

60*12/ 1.875*3.1415 = 720/5.89 = 122 RPM

Kevin

 

[BobWarfield]

Hah, Kevin, you are right!

You can use all the software in the world, but if you push the wrong button, it's garbage in/garbage out.

Cheers,

BW

 

[ozzie46]

I am just getting used to the lathe and went to change speeds yesterday when I noticed something. scratch.gif scratch.gif I was studying the chart to get the correct pulleys to change the belts to and realized I had the wrong setup for my supposed 150 rpm. oh: oh: oh:
I was actually setup for 700 rpm. No wonder it knocked the edge right off of my HSS tool bit! That would seem to also explain why the carbide gave better cut.

:idea: Now I have labeled my pulleys so I use the correct ones for the speed I want.

My 7x just had a knob to turn to change speed, I didn't have to mess with changing pulleys for speed changes.
Man do I feel like a dufus,dolt ,dummy. Take your pick.

I remember thinking that the chuck seemed to be turning awfully fast for 150 rpm.

Lesson, If it doesn't seem right it probably isn't right.

Ron

 

[doc1955]

Just thought I would post a picture of finished tool post mounted I am happy with the way it turned out works great and am glad I decided to go ahead and replace the holder that came with my lathe. I needed some practice anyway before I decide to start a motor project. I turned up a shaft and ball today and replaced the temp cap screw I had in it's place.

 

[ozzie46]

Very nice job Doc, Here is my effort of a different type. Will try yours later on.

http://www.homemodelenginemachinist.com/index.php?topic=6636.0

Ron