Rough Finish on 1" Hot Rolled Steel

[JRT]

Good question Frank, the scale is long gone, it’s become an experiment now. Currently running it with a brand new HAS insert and while it’s not as shiny of a finish as the carbide left, it is smoother, which is good in my book.

I have not tried to double the feed rate. Maybe I should. I just assumed that the faster the lead screw turned, it would leave more raised “strings” since I’m not running the RPM too fast. -John

 

[pontiac428]

I have not tried to double the feed rate. Maybe I should. I just assumed that the faster the lead screw turned, it would leave more raised “strings” since I’m not running the RPM too fast. -John

How are you determining your speeds and feeds? I use 90% HSS, so for me it comes out of any one of a number of reference books. Insert users can look up data on the packaging.

The reason I'm pressing is you're way off the charts.

 

[JRT]

I haven’t been, per se. Just trial and error really. Also, I was confused by all the terminology before but it is clicking now. I didn’t even understand how to read the Threading Chart inside my lathe until yesterday! Thank you for the reference material, I’ll dive in! -John

 

[markba633csi]

Cold rolled steel turns a bit better than hot rolled, but they are both carbon steel and generally always "tear" like that. You can polish with emery cloth for a better finish
Try some chrome moly steel if you want super nice finish and high strength (4130 or similar)
Why is your machine bogging down? Belt slipping?

 

[JRT]

Thanks Markba63csi, it does appear that way. I guess when I'm at the local steel supply store I'll just pick up cold rolled scraps from now on. I have used sand paper to polish before, just didn't know it was common place for these carbon steels. I will do exactly that if need be.

Good recommendation on place to source some of that chromoly?

Yeah, the belt slips when I try too large of a DOC.

 

[pontiac428]

John, since you're brand new to this, I recommend nipping over to vintagemachinery.org or our site library and downloading the .pdf of the Atlas Manual of Lathe Operation. It will teach you all the basics, the terminology, how to grind and set tools, and more. The best part is it's based on the Atlas, you can follow along with yours.

 

[francist]

We also have the Atlas MOLO in our Downloads section here too.

 

[markba633csi]

Online metals carries lots of different alloy steels and there are several other online vendors too
Shop around- Your local metals place probably has a good selection as well

 

[GT-6 Racer]

12L14 steel will be your friend. I love the stuff. It is a free machining leaded steel. Designed for screw machine work. It is 60ksi tensile so not for parts needing high strength but it turns like butter with a positive rake hss bit and gives a great finish without requiring a lot of power. Not much more expensive than 1018 for a few hobby parts. If you need more strength go with 1144 stressproof. Both turn really well. Grind a simple 10/10/10 degree tool to get started. 32nd radius on the tip. Hone by hand razor sharp careful not to round over the edge. Set it dead on center. You will be pretty happy with this as a starting point. Study up on grinding hss. It’s a very rewarding part of the hobby and is way cheaper than chipping 25$ carbide inserts while learning. Stay away from big negative carbide inserts meant for big lathes. If you want to use insert tooling keep the insert size as small as possible to do the job and go with modern high positive diamond shape inserts. They are almost as free cutting as hss on a smaller lathe. Most of all keep making chips !

 

[David2011]

Just a few days ago I decided to attempt making an arbor for slitting saws with a 1" mounting hole and to make it from 1018. I probably won't do that again but it was a challenge I set up for myself. I wanted the clearance between the hole in the arbor and the end cap to be no more than .002" and for the blade to be close enough to the cap that it had to be wiggled on. It's intended to be used in a 7/8" R8 collet. I ended up, after consulting speed/feed calculators using cheap carbide tools that I've had for ages. They use TCMT inserts on 1/2" holders. The spindle speed was 1200 rpm. The calculator recommended 2400 rpm but the carriage was moving too fast for me over short dimensions into obstructions. The hardest part was getting the 1018 to make chips instead of strings. On a few passes I got a single string for the entire pass, coming off of the lathe at over 900°F judging by the black/blue color. A deeper depth of cut got me curls instead of strings. It didn't finish like 12L14 but it did make a finish that was aesthetically and functionally adequate. For my small lathe (11x26) I'll hold out for 12L14 in the future.