My New 8x18

[wrmiller]

I need to order some steel round stock, probably from Online Metals. My friend recommended 10L18 as a good 'free machining' steel that is easy on the machine and cutters, and decent stock for most of my tinkering.

Are you talking more like 4130 or 4140? I am needing some of that too.

I don't have as much experience with HSS bits, but I did buy some pre-ground cheapies recently (see pic). I was taking a 10-15 thou cut on that stainless bar with one and it produced a very nice cut. Was afraid to take it any further on that stainless.

What do you consider a decent DoC on mild steel?

I'd like to see how deep a cut you can take using cold rolled mild steel and a sharp HSS cutter. I don't use stainless unless I have to on the kinds of things I like to make.

P.S.: brown chips are fine for carbide.

 

[Ray C]

Sure, 1018 and the leaded (L) version are fine. -Can't weld the L-version so, keep that in mind. Actually, it will weld just fine... And the lead will go right in your lungs. You'll get a year's regular dose of lead in about 3 breaths.

My go-to metal is 1045 and I always keep a supply on hand. Eveyone has different preferences but, I find 1045 easier to work with than 1018. I find 1018 to be gummy and 1045 to be a bit more crisp and clean provided you work with it "decisively" -if that makes any sense... In other words, don't *****-foot around with 1045. It's very predictable. Treat it with authority and it behaves predictably. It think it's much more versatile than 10xx.

As for 414x... It's very similar to but better than 1045 provided it's fully annealed. I love working with 4140 best of all the ferrous metals. I've got about 400 lbs being delivered just to have around. It's a little cleaner than working with 1045 or 1018. 4140 is probably the strongest thing out there in it's price class once it is heat treated. It's about as close to working with tool steel as you'll get. My favorite tool steel is O1. It is a lot like 1095 but a little less "chalky"

...

As for HSS cutting depths... in low/mid carbon steel, HSS will certainly cut deeper than carbide. Since you have something like a 1.5 or 2 HP motor, there's no problem there. Your machine is obviously pretty rigid as, it would have buckled with a 60 thou cut in SS... I got a feeling George is eyeing your lathe...


Ray

I need to order some steel round stock, probably from Online Metals. My friend recommended 10L18 as a good 'free machining' steel that is easy on the machine and cutters, and decent stock for most of my tinkering.

Are you talking more like 4130 or 4140? I am needing some of that too.

I don't have as much experience with HSS bits, but I did buy some pre-ground cheapies recently (see pic). I was taking a 10-15 thou cut on that stainless bar with one and it produced a very nice cut. Was afraid to take it any further on that stainless.

What do you consider a decent DoC on mild steel?

 

[wrmiller]

Now that you mention it, my pistolsmith-turned-machineshop friend always liked 4140 for a lot of things. I've never tried tool steel like O1 or A1, but those could be useful too. We didn't do a lot of stainless, but I remember turning down/tapering a few stainless barrels. I occasionally make parts out of titanium, but that's another animal entirely.

Thanks again. You're quite the info repository.

Yea, this little lathe is more robust than I though it would be. A quick change would have made it about perfect, but I'm already planning a ELS for it. I will be making some other minor upgrades to it to suit my tastes, but overall I am very pleased.

Had I tried a stunt like that on my 7x16 (I wouldn't have, I'm not quite THAT stupid), either the motor would have stalled or I would have had broken parts flying everywhere. Not trying to compare them of course, they're two different machines. Now I appreciate the extra 200 lb difference.

When I worked in my friends gun shop, we did most of the lathe work on his 14x40. But he had this little Craftsman 6" that was just perfect for making firing pins and other small stuff that needed a more gentle touch. I may not be getting rid of my little 7x16 just yet...

 

[Ray C]

BTW, making stuff out of tool steel if you don't plan to heat treat it, is (in my opinion) a slight waste of resources. In their annealed condition, they're all easy to work with but things really come to life when you heat treat them and grind to final size and finish. A-type (air quenched) tools steels are not practical to self heat treat unless you have an oven that gets into the 2100 to 2200 degree range which is very difficult to achieve. W-Type (water/brine quenched) require temps in the 1700-1900 range and O-type (oil quenched) require temps around 1600-1700 range which is manageable and do-able in home shop. 4140 is actually classified as a low-end tool steel and requires temps around 1550 which is easy to do with a decent electric furnace. I only do stuff in the 1500 to 1700 range. Air quenching is easy, water/brine requires a little more care and oil requires the most care and sometimes must be two-steps of first oil and optionally water/brine. The upshot is that the ease of quenching comes at the cost of higher oven temperatures... -Take your pick.

Most commonly, "blue-steel" firearms are made 4140 or 4150. Stainless firearms are often 300-series but I'm not sure which types are most common.

... ELS ??? Sorry, that's escaping me at the moment. Could you explain?


Ray

 

[wrmiller]

Electronic Lead Screw (ELS) Using a stepper motor to maintain a pitch/thread rate as a function of spindle RPM.

No more gear changes.

 

[fastback]

Real nice looking lathe. Sounds like it runs real nice too. Just wanted to wish you luck.

 

[Ray C]

Oops, sorry. One of your questions got past me... DoC on mild steel.... Low and medium carbon steel (such as xx18 thru xx50) on my lathe and probably yours too, has a good range of 10 to 35 thou -no problem and you'll find it hard to wear-out a carbide insert. Going above 35 to 50 works very well too but, it wears the inserts a little faster. For a finish cut, I like to set it up for 12 to 15 thou. If you can go easy, do so... It's less wear/tear on the equipment.

With high carbon (xx90, xx95) just decrease the above DoCs by about 10 or 15%. This is probably true of most machines with a 1.5 to 2 HP motor and a 7" wide bed frame with 1/2" insert holders. Beefier machines can take more off but you need to get into better quality and industrial-type inserts that go along with bigger insert holders.

FWIW, carbide is really bad at DoCs less than 10 thou. -Just not enough pressure to make the carbide work properly. Finally, I can tell the difference with carbon steel (10xx, 11xx) and alloys (41xx) but both are just as easy and manageable to work with in the annealed or HR/CR condition. Don't be afraid of the alloys -there's just no need to worry. I avoid working on anything above Rockwell 35 unless it's just a layer of case hardening. Thoroughly hardened metals like 4140 are bear to work with. Anything above 45 needs ceramic inserts. I've used them but not enough to give any advice.

And finally, the high carbon steels and tool steels start to feel a lot like cast iron but less sandy/gritty. I'm not all that fond of machining CI -dirty stuff and tough on tooling. It's wonderful in the surface grinder though...

Ray

 

[Ray C]

BTW: Here's a spacer part I just made for someone. It's 1045 hot rolled and will be case hardened. Just minutes before, I was cutting some 1018 and the 1045 cuts with the same feel but makes a much nicer finish. That piece is right out of the lathe, no oil no coolant (too small to bother with) no polishing... It's much easier to get a nice finish like that with 1045. The moral of the story is don't be afraid to try different carbon steels. I think people have a fear of trying them because they might be harder material and more difficult to work on. -Not true at all so give it a shot and you'll see what I mean. The tricky stuff is stainless so, practice on Aluminum, then do mid-carbon then stainless. You'll get hooked on good quality metal and won't ever want to work on A36 again because it feels like bubble gum.

The piece is about 1.75 dia and was spun around 550 RPM. Final DoC for the finish cut was 15 thou. Diamond shape TiN carbide. Feed was 0.004 IPR.



Ray