Cutting Speeds

[duncan webster 1]

On duncan webster 1 Said:

On SillyOldDuffer Said:

On duncan webster 1 Said:

Sorry SOD, your definition disagrees with that used by that used by legions of engineers. Referring to Silver Steel, Tubal Cain (page 25 of Hardening, Tempering & Heat Treatment) says ‘these steels are carbon steels with additives to improve performance’. …

I’m surprised this is controversial, because, with all due respect to Tom Walshaw, the definition I quoted is that of the American Iron and Steel Institute.   This is the crowd who:

… in the ’30s, it became apparent that the industry’s technical terminology had become chaotic. The Institute came to grips with the problem, and out of its efforts came the AISI steel products manuals. They provided makers and users of steel with generally recognized definitions, descriptions and practices pertaining to the manufacture, chemistry, metallurgy and adaptability of steel products.

The AISI definition isn’t unique to them.   This is from the Chambers Dictionary of Science and Technology:

By that definition, Silver Steel is not a Carbon Steel, because it contains Chromium.  Ditto Drill Steel and Gauge Plate.

Perhaps the confusion arises because two different approaches are used to classify steels.  Hence what British buyers call EN1B-Leaded, will actually be 9SMnPb28, 9SMnPb36, 11SMnPb30 or 11SMnPb37.   One approach categorizes steel by Usage & Mechanical Properties, the other by Chemical Composition.  Not making it up, I am quoting the official chemical definition of Carbon Steel.

Dave

 

But I’m not an American. They can call it what they like. In the UK silver steel is a carbon tool steel.

Not according to the British Alloy Steels Research Committee!

 

And this is the equally British Newnes Engineer’s Reference Book:

Dare I suggest Tubal Cain put a misleading sentence in his book, that’s been misquoted ever since?  He said,  It is in fact a 1.1/1.2% carbon steel with the addition of about 0.35% Manganese, 0.45% Chromium, and 0.1/0.25% Silicon.   Do folk not bother to read past: It is in fact a 1.1/1.2% carbon steel?  Sorry to upset the apple-cart, but Silver Steel is an alloy steel.   It ceased to be a Carbon Tool Steel the moment Chromium was added.

Dave

 

 

 

 

[duncan webster 1Participant @duncanwebster1]

I suppose we have to give it to SOD that the addition of 0.5% chromium means silver steel is not a plain carbon steel. After all, we refer to EN16 as a low alloy steel, and that is pretty much EN8 (which I think we’ll all agree is a medium carbon steel) with the addition  0.2/0.35% molybdenum. However, the British Standard for silver steel is entitled ‘High Carbon Bright Steel’, suppliers refer to it as high carbon, although one does call it lightly alloyed high carbon, and common usage has it as carbon. Let’s abandon the semantics and get on with some engineering, or in my case trying to dry out the workshop.

I do use silver steel turning tools for making tiddly boring bars. The surface speed limitations in a small hole don’t matter, you just have to be careful when grinding it, overheat it and it’s gone.

[Clive Foster]

On Clive Foster Said:

When it comes to multi-variate queries like Justins it’s annoying that the art of making nomograms seems to have been largely lost.

…….

It would seem trivial to generate a nomogram from a spreadsheet file but I’ve never found a suitable computer program.

Clive

I’d forgotten about nomograms but used to use them a lot.  The hard work seems to be in casting the equations in a form that a nomogram can handle, which Excel isn’t good at, though it could do the plotting.  There seems to be a Python package called pyNomo which does the hard work though you do need to write some scripts.  Maybe one of the Pythonistas here could look at it?

https://lefakkomies.github.io/pynomo-doc/index.html

 

 

[Anonymous]

I’ll try and cover answers to a number of posts.

Unfortunately the conversations about an article on surface roughness, and finish on turned parts, was with MEW, not ME, as I thought MEW was more appropriate.

I looked up 1095 carbon steel and found a UK supplier, it is only available in fairly thin sheet. Not really surprising as the intended use is knife blades. Interestingly a US knife making forum said that 1095 was not suitable for making cutting tools as it doesn’t have enough carbon.

The definition of carbon steel seems to depend not on whether it is only iron and carbon, but precisely what else it is alloyed with. Some elements are allowed, orthers not. That’s too complicated for my little brain. As an engineer rather than modeller I will stick with the duck (*) definition and continue to make cutting tools from silver steel and gauge plate, treating them as basically carbon steels.

Andrew

(*)  If it looks like a duck, swims like a duck and quacks like a duck then for all practical purposes it is a duck.

Translated:

If a material hardens like carbon steel, tempers like carbon steel and looses hardness when hot like carbon steel then for all practical purposes it is a carbon steel.

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