Which tool would cut Hardened steel ?

I bought a couple of pieces of steel to work on not realising they were hardened steel ,I have a Myford Ml7 any advice on what type of tool ? would be great

If the steel is really hardened carbon steel, then you could soften it by simply heating with a propane torch until it is red hot. Soak it at temperature for a few minutes and let it cool naturally. Otherwise you are looking at carbide tooling.

If you don't know what grade of steel it is, then you are quite likely to have something that is a tough steel alloy, if so then carbide tooling is required.

Andrew.

Thanks Andrew, I have a propane touch will give it a go .

Start again with the correct material. Put what you have aside until you need some hardened steel. Life is too short for messing about.

regards Martin

As above - avoid the problem - however various carbides, ceramics or Stellite will do the job. Not sure that a ML7 would have the rigidity, speed or grunt though, depending on job dimensions, of course.

"Hardened" steel could be silver steel, possibly hardened, or high speed steel. Which is it?

It's best to buy mild steel of known provenance for these lightweight hobby lathes like the Myford etc etc. Hardened and alloy steels etc can be a bit too much for them and cause much heartache in the form of poor finish and worn and broken tooling.

Totally agree with Hopper, buy from a reputable source. Myford lathes just don’t have the rigidity and power to deal with hardened or alloy steels, neither do any of the similar sized Chinese offerings for that matter.

Thanks to everybody for your advice, being a total novice I will take more care in the metal I purchase, and have another go.

I wasted several months struggling to turn various bits of scrap and DIY store metal I'd collected randomly. Eventually, I got hold of some EN1A (one of mild-steels), and was amazed how well it cut. I was unlucky because all my scrap metal was horrible. I'd assumed a metal-lathe would happily cut any metal it was given: not so - many metals don't machine well. For example:

• Aluminium alloys intended to be extruded into window frames and the like are too soft and sticky to machine well. Avoid!
• Ordinary mild-steel (EN3) can be machined, but tears and can be difficult to get a good finish. EN1A, and - best of all EN1A-Pb (leaded steel) - are specifically formulated to machine well. Buy some!
• Hardened steels may be harder than the cutter. Some machine well with Carbide and most can be softened by heating them to red-heat and allowing them to cool slowly. An old-time recommendation was to put hard metal in a bright coal-fire and leave overnight to cool down as the fire burned out naturally. The type of hardened steel makes a difference: High Speed Steels are designed to resist heat softening, and may require a long high temperature soak to completely soften.
• Alloy steels are all over the shop. Some machine well, many are pigs. Modern seat-belt restraints are made from a Boron Steel harder and tougher than the 'Jaws of Life' used by the fire brigade to cut people from wrecks.
• Most Brasses machine well, but some are better than others.
• Bronze varies between good and bad.
• Cast-iron varies between excellent and horrible. All cast-iron is liable to have a very hard outer skin but cheap cast-iron can be full of slag and other horrors. Don't be surprised if a sash-weight is complete carp.

Bottom line on metals is they're engineered for a purpose, often not suitable for home workshops. Nowadays, I prefer to buy metal where machinablilty is mentioned positively in the description. Words like 'free-cutting'. If you have a local metal supplier, tell the man you want to machine it.

With experience it gets easier to cope with random scrap. I recommend beginners avoid unknown metals, because they can't tell if the problem is the operator, the machine, the cutter, or the material. Best to eliminate the material as a problem. In practice, I find scrap more trouble than it's worth.

Some lucky chaps have no scrap problems. I think it's down to were they live! In a manufacturing area suitable off-cuts are likely. Out in the sticks, probably not. The easy answer is to buy known materials.

Dave

Thanks Dave, I take on board what you said, I am just starting out I have no prior knowledge of lathes or metal. I have learnt a lot from the internet, I love being in my workshop I guess it is the basics that I lack But as long as I progress I am happy and thanks again ,its people like yourself keeps me going. All the very best Alan

I know it might seem a stupid comment, but how do you know it is hardened? where did you purchase the steel from? I ask these questions because it might possibly be your technique that is the problem, in view of your limited experience. It is most unusual to purchase hardened steel except from specialist stockholders. Was this a purchase from a well known internet auction site?

Hi Alan

As you are just starting out do buy free machining material. You will generate enough problems yourself without buying in more. If you are looking for some starter projects you could do worse than a couple of the Hemmingway kits especially if you find something like a workshop tool or gadget that you would find particularly usefull. The advantage is you get all the materials supplied plus drawings and notes. They make very good learning projects and you end up with something usefull at the the end.

regards Martin

If you MUST turn hardened steel, you need to use a carbide tipped tool, and run at high speed with a small depth of cut and feed, on a Myford.

I used this technique to turn down some spacers for a horizontal milling arbor.

The swarf coming off as red hot wire was quite entertaining!

But don't thrash the machine with hard material unless you have to.

Howard

Allan,

In addition to the excellent information above, I feel sure that, besides noting how a piece of metal responds when rubbed with a file you’ll begin to notice, when grinding a piece of steel, how the sparks vary one type of steel to another. I couldn't find one, but someone here will now step forward with links to show where this was a forum topic.

While this next bit is somewhat over the top, it might be useful in the future …

**LINK**

Some basic questions … Does the steel resist filing and by how much, and are the sparks dull with few or no ‘feathers’ or bright and sparkling?

A classic ‘spark’ comparison would be that between a high speed steel (HSS) tool bit, and another common workshop material, silver steel. The former showing dull red sparks with few feathery bursts, while the (high carbon) silver steel sparkles with lots of feathery bursts.

Have fun,

Sam

Thanks for the info Sam.