What's a decent cut for a 9x20 import?

[RaisedByWolves]

Very impressive for a 5" lathe!

I’ve got secrets.

It will do better, but there’s no sense in pushing it.

 

[stupoty]

When i had a 9x20 lathe , I found the limit was the feed mechanism, some have a proper power feed and some (like my old one) just use the lead screw for power feed.

Too much of a heavy cut seems to put a lot of wear on the half nuts, I wore mine out quite quickly. owch.

Stu

 

[verbotenwhisky]

When i had a 9x20 lathe , I found the limit was the feed mechanism, some have a proper power feed and some (like my old one) just use the lead screw for power feed.

Too much of a heavy cut seems to put a lot of wear on the half nuts, I wore mine out quite quickly. owch.

Stu

Yeah, that is why I like a lathe that doesn't depend upon the lead screw to drive the carriage for anything other than threading.

 

[durableoreo]

That's a great example. I'll try it out.

 

[stupoty]

Yeah, that is why I like a lathe that doesn't depend upon the lead screw to drive the carriage for anything other than threading.

it was my second lathe , my first two lathes taught me all the things I needed to look for in my third lathe

Stu

 

[durableoreo]

I've been working on this job again. I was having several issues, including chip management. At 600 RPM I can take a 0.030 deep cut, 0.005 in/Rev. The chips are small but they accumulate in the bore. I was getting a bunch of bad noises, sort of a rumbling. I eventually realized it was chips getting swept under the boring bar. It tried all kinds of things to clear them. The final attempt (which was successful) was compressed air their the boring bar. I put foam in the chuck and hooked the air up to a pedal. There is a 3D printed adapter on the end of the boring bar but it wouldn't stay without some vinyl tape.

I also bought the silly 3" indicator from Shars to keep track of the carriage position. It's comically large but when you're working 1.375 deep in a part, it helps.

All these improvements really helped. I dreaded this job but now it is easier and faster.

 

[Huub Buis]

For internal turning I use a TCMT or DCMT insert to have a greater clearance angle between the stock and the cutting edge. This give a better chip evacuation. In stead of compressed air, I use a vacuum cleaner at the back or front (blind holes) of the spindle to get the chips out of the bore.

 

[Larry$]

gearing down increases power as the output speed is reduced

There is a problem with terminology. You can increase torque with gearing but you can not increase power. No matter what you do, you can't get more "power" out than you put in.

Metal removal often has a sweet spot where DOC, Feed and SF/M all combine for the particular tooling you are using. Sharp tools cut freer but dull quicker. My carbide inserts, that are for aluminum, cut steel beautifully but dull relatively fast. The nicest thing about them is being able to take a very fine cut in steel much like my HSS tooling. I can even sharpen the "for aluminum" carbide inserts a couple of times on the tool & cutter grinder.

Just play with the variables until you find what works best for you.
I've tested to see how much material I could take off in a given time. Pretty amazing actually.

 

[Janderso]

I've been taking 0.015 per pass

That will take some patience!
I take .050" or more per pass.
I have a 15" x 50" lathe with 7.5 hp though.

 

[Huub Buis]

I've tested to see how much material I could take off in a given time. Pretty amazing actually.

Some years ago, I made a video to show the cutting capabilities of my mini lathe. It was (and is) impressive.