For something just temporary, any hot rolled steel including the cheapest rusty scrap would do just as well as the most specialized and expensive. Without making this too complex, Young’s Modulus, https://en.wikipedia.org/wiki/Young%27s_modulus shows that basically all steels have so similar attributes for bending, stress resistance, compress ability etc. That in the real world, there’s no real measurable difference between them.

More specialized steel alloys to be heat treated for wear resistance and increased durability are of course a bit different. But the same Youngs Modulus numbers still hold basically true for them as well. For people like us and your tool block, choosing a known steel with better machinability characteristics would certainly help though.

But fwiw, and unless you can absolutely guarantee your lathe bed is bolted down in a stress free and non twisted state. And if any tail stock support is being used, it’s exact alignment to the head stocks center line is also known to be true. Any test cuts to try and detect an excessive amount of bed wear will tell you nothing of any real use.

Now if you do have an accurate machinist’s level, a magnetic base indicator holder and indicator. And can verify your lathe bed has or can be set up in that stress free state, and if the tail stock end of your lathe bed looks to have very little wear or damage, which it shouldn’t. It’s not hard at all to measure the amount of wear that’s present. If you can do that, then ask and I’ll explain how with none of that test cutting.

What SOD said. For machinability I would order them 3, 2, 1, for durability 1, 2, 3.

Machinability is a bit hard to predict, it will depend on the machine and tooling. In a larger, robust machine you can just plow through any of these materials. High strength steels are actually quite nice to work with as they break the chips and produce a good finish with heavy cuts. OTOH nearly red hot chips might not be your idea of fun.

Softer steels are easier to cut on weaker machines, but often produce stringy chips and might not give a good finish.

On 19 February 2026 at 20:36 Sonic Escape Said:

I ordered today a 70x70x120 piece of S235JR. And half a meter of 12×12 to make four T nuts for it.

On 19 February 2026 at 03:47 Pete Said:

Now if you do have an accurate machinist’s level, a magnetic base indicator holder and indicator. And can verify your lathe bed has or can be set up in that stress free state, and if the tail stock end of your lathe bed looks to have very little wear or damage, which it shouldn’t. It’s not hard at all to measure the amount of wear that’s present. If you can do that, then ask and I’ll explain how with none of that test cutting.

The lathe is sitting for a few months on some rags. It can’t be less stressed than that 🙂
But I don’t have an machinist’s level. What are you thinking? A variation of Rollie’s Dad’s Method?

With a used lathe it’s far more likely than not that it may never have been set up and properly adjusted. Or at least at some point in its life it wasn’t. Lathe beds and because of there shape and the iron castings there built from aren’t exactly the most rigid part even with the factory designing in cross bracing and additional casting material added to help stiffen the bed. Bolted down to a slightly twisted bench top and over a long enough period of time can in some cases put a permanent twist in the bed. With proper and ridged enough mounting, any twist like that can also be removed.

No not that Rollies Dad method, if the bed is known to be true and without twist. Then the tail stock can be removed and the lathe carriage moved to the right as far as it will go. I’d also remove the top slide for slightly better rigidity reasons, or if there’s room, just attach the magnetic base to the top of the cross slide. On 99.999% of the lathes out there, the carriage seldom to never gets to that furthest to the right location, so any wear from use will or should be almost nothing. Positioning the carriage at the tail stock end, and as I said, the magnetic indicator base can be magnetically attached to the cross slide top surface, the indicator tip extended a few inches ahead of the left edge of the carriage and the dial zeroed.

Being very gentle to create the least vibration and indicator tip movement, the carriage can then be slowly traversed towards the head stock by hand. As long is the carriage is moving on the least worn bed areas, the indicator tip ahead of the carriage will measure the amount of bed wear between the unworn tail stock area and through the most worn spot that’s usually around the head stock. However the indicator can only check and measure one way surface at a time. Your Emco should if it’s like most V way lathes use the lathe beds front V way and the rear flat way for guiding and supporting the carriage along the lathe bed. So each side of that front V way would need to be indicated as well as that rear flat way. Don’t indicate the flat area on top of those V ways. It’s usually not a precision ground surface or used for any alignment purposes so it can be ignored. And in case you don’t already know, for the best accuracy, then its also important your indicator is set up as closely as possible to have the indicators shaft at 90 degrees to the surface being indicated. Doing that by eye would be close enough.

Your lathes tail stock should use the rear V way and front flat way for it’s guidance along the lathe bed. So it’s way surfaces would be the least worn in the head stock area since the tail stock never gets there. With the usual .001″ or .025 mm reading dial indicator, these measurements and the method isn’t to a very high accuracy level, but it will measure close enough to what the bed wear might be. There’s other methods as well, but those may involve tools most of us don’t have. This is the most simple and cheapest I know of.

Any bed twist is vastly different. And it’s effect is further increased due to the distance across the bed ways and most important, the cutting tips elevation above those bed way surfaces. Lets say for example your lathe bed has only .001″/ .025 mm of twist in it over the full carriage travel between the head and tail stock. That DOES NOT mean it will produce a shaft taper of only .001″/ .025 mm. Because of the geometry and the cutting tools elevation, any twist is multiplied because of the tools elevation above the bed ways. Visualize what happens is the tools cutting tip being either slowly rolled towards or away from the shaft being turned as it travels through any bed twist along the whole lathe bed. And because a shaft being turned is being cut around it’s circumference, the measurable effect caused by any bed twist on the parts diameter is also doubled.

It would be extremely slow and in my opinion be absolutely frustrating. But there is another method of lathe ‘leveling’ without having a proper and high accuracy machinist’s level using not much more than a length of pipe, a piece of string, and a plumb bob. The height of your ceiling above the lathe and the length of the pipe used does dictate the actual accuracy that’s possible. I’ve never done it that way and wouldn’t as long as I have my level. https://www.youtube.com/watch?v=2qIdsnl5vpg Any random air currents and waiting each time for the plumb bob to come to a complete stop would drive me up a wall though.

On 19 February 2026 at 20:36 Sonic Escape Said:

I ordered today a 70x70x120 piece of S235JR. And half a meter of 12×12 to make four T nuts for it.

On 19 February 2026 at 03:47 Pete Said:

Now if you do have an accurate machinist’s level, a magnetic base indicator holder and indicator. And can verify your lathe bed has or can be set up in that stress free state, and if the tail stock end of your lathe bed looks to have very little wear or damage, which it shouldn’t. It’s not hard at all to measure the amount of wear that’s present. If you can do that, then ask and I’ll explain how with none of that test cutting.

The lathe is sitting for a few months on some rags. It can’t be less stressed than that 🙂
But I don’t have an machinist’s level. What are you thinking? A variation of Rollie’s Dad’s Method?

Just take a light cut along a piece of 25mm bar sticking out of the chuck about 100mm and measure the taper. Put shims under one of the two lathe bed mountings at the tailstock end to correct it. If the test bar is larger diameter at the tailstock end, shim the front mounting. Smaller, shim the rear mount.

This real-world  method takes into account cutting forces and bed wear. All other methods are theoretical and depend on a perfectly rigid and unworn machine. Who has that in their home workshop?

On 25 February 2026 at 12:57 Sonic Escape Said:

On 25 February 2026 at 12:24 JasonB Said:

 

Your cutter is not making good progress in the video so may be blunt or of poor quality or both. This will make th edeflection worse

How do you know it’s a problem? Apart from today, I have only milled twice with an industrial milling machine. I don’t really have a reference to compare with. This is the cutter. It’s in a morse 3 collet. Before cutting the slot I cut about 1-2mm from a 70x70mm area. Can this significantly wear out the cutter?

In the video the cutting depth is 0.4mm at 1500RPM. I noticed that at 0.6mm the spray starts to move around on the mill table from the vibrations. Only the quill was locked. The gibs are well adjusted. The mill weighs ~120kg. Is this normal?

1500rpm is pretty high for any HSS cutter over 6mm diameter. Can’t tell from your post what diameter it is. But too much rpm will quickly wear those cheap HSS cutters.

And your job is sticking up a long way out of the vice, adding flex to the set up.