How to cut 1 inch thick steel in a timely fasion?

[Pmedic828]

I have acquired some unknown type of 1 inch steel from the surplus shop that I want to make a fly cutter out of. The blank is about 5 inches in diameter but had a piercing hold burnt into it when whomever had it to make a circle cut. I wanted to reduce the diameter to around 3.5 to 4 inches to make the body of a fly cutter. I copied the circle on the blank, used a bandsaw to cut as close as i could straight lines tangent to the circle so I would not have to turn excess steel. Here is the question... Should I grind some type of Right Hand tool cutter with an extended nose and attack the steel cutting a circle and facing the trash outside the circle off, or attempt to keep turning the no so round blank round in the lathe using a 4 jaw chuck?

 

[Tony Wells]

Use your 4 jaw and a HSS tool with a generous nose radius for toughness and turn it down. Take light cuts if you have a light lathe. That's about all I can say without knowing your particulars.

 

[epanzella]

I just did something similar to make a 5C drawbar hand wheel. If you have a machine that will make aggressive cuts just turn it down. My piece was way too big and I don't have a bandsaw so I used a parting tool to cut a 4 inch circle out of the middle. Obviously side clearance on the outside of the circle makes it impossible to just plunge thru so I stepped the hole a bunch. The inside of the circle provides it's own clearance. Be advised that a torch cut hardens the steel. When turning a torchcut piece one time I was just chewing up HSS cutters. After spending more time sharpening than turning I grabbed a carbide cutter and it went thru no problem. I was reluctant to try the carbide for fear of chipping in the interrupted torchcut but it went right thru.

 

[Rick Leslie]

I just finished a 4" arbor for a diamond grinding wheel a friend gave me. I used HSS and went slow with plenty of cutting fluid.



Started with a 4" chunk of 1018 (I believe). Roughed it in with small cuts.











Finished with a sharp HSS tool and slow feed rate.




Didn't mean to highjack, but I just wanted to show the cuts progressed much faster than I initially though they would. The whole thing was done in a few hours.

 

[Craig_J]

Rick:
Your part is very pretty, but I have a Grizzly G0602 (10x22), and carving all of that steel off would take quite a while, not to mention making a lot of expensive swarf. While not in direct response to the original question, my first thought is why not get the large blank in approximately the right size for the face (less the shaft), and bore for the shaft as a separate piece? If this is to be for a diamond wheel, you will not be putting huge forces on it laterally near the rim. If you bore the shaft hole undersize, you could set up a very tight press fit and have the option of using a harder material for the shaft- such a ground and polished drill rod. Final facing would be done on the assembled part with the shaft chucked in a 4-jaw, or for faster setup in an accurate collet (I have a ER-40 collet set with an MT-4 shanked chuck that is both very accurate and quite cheap). Done this way I think the resultant part would be cheaper, a lot quicker, and probably just as strong.

If I did have to hog off all of that material, I might want to make or buy a tangential tool holder. Grinding the tools would be a lot quicker, and because the TTH puts the forces in compression, it has been reported that much deeper cuts are possible without chatter. It also allows cutting the shaft and facing without changing the tool or compound angle.

My two cents...
Craig

 

[Rick Leslie]

I originally planned a two-piece arbor, but ran up on the round stock on line for 5 bucks. I cut it on a worn-out Southbend Heavy 10, but trued it in the mill with the lathe cutter in the mill vise. I plan a different arbor design for the other wheel on the bench grinder, so I won't be whittling down another huge chunk. I hope we haven't gotten off topic. My original point was it cuts down much faster than I thought on the lathe.

I also have plans for a tangential tool holder one day. It looks like a great set-up. And I never thought of a ER collet set in a MT holder for the lathe spindle. I've been trying to come up with the bucks for a 5C set-up. Thanks for the ideas.

 

[iron man]

I dont know if this will help anyone but and old fella showed me how to make this cutter he called it a chip breaker it allows me to take a 1/16 cut on my Atlas lathe with no vibration. It does not leave a real bad finish either try it sometime. Ray

 

[Craig_J]

Rick:
More about the ER40 collet. My G0602 has a 26 mm bore, and I wanted a precision collet system to take advantage of the full bore. I got a full set of collets in 32nds up to 1 inch and an MT4 - ER40 collet chuck from tools4cheap.net for $186. (Had to make a drawbar.) Runout <<.001 if you clean the taper carefully. (I also use them in my RF-45 clone mill with an r-8 chuck adaptor). But to get the ability to chuck a long shaft, I needed a holder that screwed onto the 1 3/4 - 8 threads of the spindle. I wound up turning this, which was my first project with large internal threads, tapered bore, and metric threads, and in 4142 alloy to boot! Works fine; pics here. The nut was from a commercial chuck. But yes, I am proud of it.
Craig

 

[Rick Leslie]

Craig, that sounds like what I need. Making the draw bar or other items won't be a problem. (Finding the time will.) Unfortunately, I can't see the pics. I'm not a Yahoo member (I don't think). I had already settled on the ER 40 collet system for my mill, just hadn't considered it for the lathe. Now I am. My SB has a huge spindle bore and 2 1/2 (?)-8 TPI thread pitch. I'm pretty sure the spindle taper is MT4.
Please post the pics of your work.

 

[Tony Wells]

Craig, that group makes the pictures inaccessible to non-members.