JohnGreco
Member
OK metal lathe owners...can a metal lathe turn hardened steel? This may be too open of a question, but I'm trying to find out what the limits are. Could it turn something like a piece of railroad track? Thanks in advance!
Metal Lathe Turning Steel?
- Thread starter JohnGreco
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I have ran into a type of steel we could not get cut with acceptable results for a finish on hardened too steel. We may have not had the right carbide bit to cut it with. We were using Mike Roux's 1236 lathe and we had to give up. It would cut it barely. Sherline.com has some videos of them cutting tool steel and other types of metals on their lathes that show it can be done. They show different cuts on different materials and have chart for different feeds and speeds on different metals.
Heres a link
http://sherline.com/testcuts.htm
Heres a link
http://sherline.com/testcuts.htm
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Paul in OKC
Member
Metal lathe, yes. Mini lathe, I think it would be tough. Not sure what rail road tracks are steel wise. I think hard steel as something like 4140 or 4340 HT, which is pre-heart treated to around 30 on a Rockwell C scale. Tool steel is tough to cut, even on a big machine. Smaller lathes just mean lighter cuts generally. You can cut about anything with good tooling.
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Bit has to be harder than the steel being cut, lathe and tool post has to be rigid enough to hold it without any flex, and light cuts with lubricant/coolant are usually essential.
Only thing I've ever found myself unable to cut was some chromed shafting, and that is probably doable with the right tooling and lathe.
Overall, you are better off annealing hardened steel if it is at all possible and re hardening it after cutting. Annealing is pretty simple, heat treating to re harden it a bit more involved.
Only thing I've ever found myself unable to cut was some chromed shafting, and that is probably doable with the right tooling and lathe.
Overall, you are better off annealing hardened steel if it is at all possible and re hardening it after cutting. Annealing is pretty simple, heat treating to re harden it a bit more involved.
Wingdoctor
Member
Usually steel will be machined before hardening. If the steel needs further turning due to warping during heat treatment a tool post grinder ,or larger specialty grinder, is used to true up. The cutting bit must be harder than the steel being turned. I do not know how hard a railroad rail is. I do know that the rail is handled with a crane and is moved off the car as it is laid in position. It does bend (sag) some as it is laid so it is probably not super hard. Try cutting it with a file. If the file just skates across the surface it is probably too hard to turn.
Dalecamino
Local Chapter Leader
May I ask, what part of the railroad track you plan to turn? Rails are extremely hard iron. Consider what travels on them. Spikes are softer. I was told that metal lathes don't like interrupted surface contact with the tool. I assume this to be true, since I know the guy pretty well. If you are considering separating the head of a rail from the web, and turning THAT part, take this into consideration. Good luck.
BradG
Member
Tensile strength of steel
The tensile strength of steel is measured in units of newtons per square millimetre. Mild steel has a tensile strength of about 430 N mm-2. (This means that a wire with a diameter of 1.4 mm could support the weight of a 70 kg man.) A high carbon rail steel, by comparison, may have a tensile strength from 900 N mm-2 to over 1200 N mm-2. (To support the same man, the wires diameter could be reduced to 0.8 mm.)
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The tensile strength of steel is measured in units of newtons per square millimetre. Mild steel has a tensile strength of about 430 N mm-2. (This means that a wire with a diameter of 1.4 mm could support the weight of a 70 kg man.) A high carbon rail steel, by comparison, may have a tensile strength from 900 N mm-2 to over 1200 N mm-2. (To support the same man, the wires diameter could be reduced to 0.8 mm.)
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