For my own purposes it is fairly simple.  If the item is round then I use silver steel (A1) which is water hardening.  If flat then I use gauge plate (O1) which is oil hardening.  Both are easily torch heated before quenching then tempered to the appropriate colour.  I have successfully made form tools and plane blades from gauge plate and haven’t felt any need to use something else.

Rod

Tubal Cain (the English one, not the US imposter) recommended using old files, softened reshaped and rehardened for cutting tools. This of course requires the kit to achieve the softening,  very slow cooling from red heat

Like Rod I just use silver steel or gauge plate depending on what is to hand and what shape I want. I also tend to quench both in water and don’t temper

As said wide cuts from a form tool are prone to chatter so you may need to build up the profile with two or more cutters depending on length  of contact area, diameter and lathe.

The other option would be some form of copy cutting where a simple filed to shape profile can be followed and a suitable lateh tool does the actual cutting.

Silver steel cutting iron. 2mm radius

Gauge plate cutting brass 9/16″ dia “ball” in brass

On 24 March 2026 at 12:11 jon hill 3 Said:

Cedric not sure what you mean by garden lime… unless you mean common lime as used in a 6:1:1  mortar mix?

When it comes to cutting and shaping gauge plate, can it work harden using say a band saw or in milling?  Also what can be done to prevent this?

 

 

Most steels can develop hard spots when working, usually caused by using tools that are not sharp or allowing the cutter to rub I e inconsistent feed rate.

Use sharp cutters and don’t dwell while cutting.

Garden Lime is the stuff that gardners and farmers use the neutralise the soil ie make it less acidic, should be available from most garden centres in the small quantities needed. It is probably the same as used in the building industry to make traditional lime mortar.

Just done a Google on lime, garden lime and builders lime are not the same, but for the purposes of annealing steel they would probably both work as all you are trying to do is slow down the rate of cooling.

Charles is right I just heat and bury in vermiculite and it seems to work well

Is that 25mm diameter or the length of the profile?

I would say 6mm or 1/4″ thick if that is the diameter and you don’t have too much length sticking out of the toolpost. That one cutting the brass is 1/8″ thick. Also used it on smaller steel parts by repositioning an drunning the lathe backwards.

There was a thread a week or two ago about large radius turning that had some example sof copy turning. Also showed roughing by co-ordinate turning and then hand finishing which can be quite quick particularly if it is a one off. Will see if I can find the thread.

That was easy enough https://www.model-engineer.co.uk/forums/topic/lathe-set-up-for-machining-large-radii-using-cross-slide-profile-follower/