Unknown Steel

Pitchfire

Pitchfire

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A friend mentioned to me that he has a large quantity of large Steel rod that he bought to weight commercial crab pots but ended up not using. He brought one over for me to play with and it is 18" long by 2.25" diameter steel rod with some light surface rust/scale in places (these were not used in crab pots as he tried a few out and decided against the idea). It looks extruded. So I drilled the end and it was hard but drilled okay so I threw it in the lathe with a live center and played with it. My hss bits can't do much with it. I started at a moderate speed and slow feed, then slower speeds with slow feeds and nothing worked. I tried getting a little more aggressive with the feed in but it balked. I tried using a grooving tool and cutting past the scale, but it didn't get any better (just shinier) in a ways. I don't know what the steel is, but I can't do anything with it. My bits are sad and need reground and I need to get a chunk of aluminum to drown my sorrows in!:whiteflag: It also begs the question of how big/heavy is too much for the little Grizzly G0602 lathe? Kinda sucks to lose a line on a pile of stock, but oh well...
 
Did he buy the stuff new? If so he should be able to go back and get the specs. Did he buy it all used? If so, any chance he stumbled on a load of pre-hardened tool-steel, or that it's not really steel but titanium or cobalt or kryptonite?
 
He bought it years ago down South. Not sure what it is, but me no likey. I couldn't even weather light cuts with a newly ground hss bit at moderate speeds.
 
If it rusted a bit, and you were still able to drill it, I'm guessing that it's probably some sort of alloy steel in a hardened state. The size should not be too large for your lathe, I have turned larger (not by much mind you) on my little 7x14. If it is hardened, you may be able to anneal it. Any chance you know anyone with a heat treating furnace? The trick is, you don't know what type of steal it is. Ultimately it may not be worth the trouble.
 
Your lathe is a 10x22 with a 1 HP motor. It should be able to handle any basic non-hardened steel up to low/medium carbon (1040 for example). One of my lathes is about the same specs and it's able to do that reasonably well.

What kind of a cut are you taking? I'd probably spin that around 500 RPM (give or take a little) and would be inclined to increase RPMs rather than decrease and start with a hand fed 5 thou cut. Are you starting from a clean edge at the TS end? If you're starting from the middle of the shaft, that's always a tricky proposition and I usually use a cutting-type bit (like a parting bit) for that kind of situation.

Also, the outer layers are probably oxidized and "self hardened" down to the first 20 thou or so. I've found this often to be the case with old metal that's got scale on it. In that situation, I usually use some cheapo C2 RH carbide bits to get past the crud. You'll need M2 HSS at least and it will dull quickly until you get to the nice and juicy insides.

If that metal happens to be cast iron, you're not going to do well on anything but C2-C3 carbide. If it's got scale and pits, don't use higher (C5-C7) carbide as it will fracture easily.
 
I started at 720 rpms since I had it set there and was too lazy to change belts and figured the larger diameter piece would require a higher rpm than the smaller .25" stuff I had been doing previously (but not at that higher rpm) and decreased from there after it balked coming from the right end. (I made a few very light short passes first to get the edge cleaned up). The bits are pre-ground hss "turning tools" from Grizzly that came in a set. (http://cdn0.grizzly.com/pics/jpeg1000/h/h5871.jpg The two on the right side, center). On the smaller diameter stuff I can take .010" a pass no problem, so I tried a coupla thou that scratched the rust and then .005" and it didn't like that but worked at it a while. After making a few short passes and trying a pass at .010" and constant lube, I changed the belt and slowed things down (couldn't go up since my breaker trips at higher rpms, so might as well try slower). When I was playing with depth of cut I cut a shallow groove, so I changed holders and put on a grooving/parting bit to get at the groove I had started and see if it got better going deeper. I got down an either of and inch or so well into the shiny metal, but things didn't improve so I called no joy.
 
Since the general idea of cutting speed is in SFM (Surface Feet pr Minute) and is a constant, the larger the stock, the lower the RPM. If HSS won't do it, even as a slow speed ~200 RPM, try and get some carbide, brazed bits are pretty cheap, and if it has been sawed to length and the sawcuts are bright, and the OD scaled, that tells you a HSS (likely) sawblade cut it. If you have 1 HP, just slow it down and using the torque you get from that, you should be able to cut it. If the ends are the same color as the OD, it may have been heat treated after sawing. Is it magnetic? Build a roaring fire in your fireplace and shove it in and let it heat a few hours and slow cool in the ashes and try it again.
 
I bought hardened mystery steel in 1" x 3 to 4" x 12"+ in a junkyard. Was hardened and drawn to a brown temper(straw). Quite hard. I put 3-4 bars in my woodstove,stoked up the fire and set the stove to slowly burn all night. I let the stove go out and removed the bars,which were quite annealed after that. Your 24" might be too long,but as tony said,a real good bonfire might do it. Just let it burn out and cool down on its own.
 
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