Graver Hardness Comparison

[Martin Strolz]

As there was some interest in tools lately, I today have tested a few gravers for hardness. The tools came right off my bench, all these I use for my own engravings. Testing was done in the HTL-Steyr using the Rockwell C process. First I tested the machine itself for presicion by measuring a steel probe of known hardness. The final result was an error of +1,2 HRC. In order to be correct the indicated values of the list below must therefore reduced by that ammount.

What may surprise you is the fact that unalloyed tool steel is at minimum as hard as HSS. Hardness alone is not enough to make a tool performing well.
I also have tested a Perazzi shotgun action, giving a indicated value of 39 HRC.

HSS Gravers
Glendo/GRS , USA, GlenSteel Graver, Square graver 2,35 mm, 64 HRC
Glendo/GRS , USA, QC Onglette, a few tested, 63 -64,5 HRC
Glendo/GRS , USA, GRS X 7 HSS, Square 2,35 mm, 67,5 HRC
Ngraver, USA, HSS Cobalt, Square graver 2,1 mm, 64 HRC
Glardon Vallorbe, Switzerland, Square graver 2,5 mm, 61 –61,5 HRC
Glardon Vallorbe, Switzerland, Flat graver, 64 HRC
Maker unknown, Chisel made of hacksaw blade, 2mm thick, 64 HRC

Tool steel
Glardon Vallorbe, Switzerland, Square graver 2,5 mm, 66 HRC
F.D. Dick, Germany, Square graver 2,5 mm, 65 HRC
F.D. Dick, Germany, Fllat graver, 65 HRC
E.C. Muller, NY, USA, 2 Flat gravers tested, 64,5 HRC

Carbide
Glendo/GRS , USA, Square graver 2,2 mm, 71 HRC

 

[Sam]

Martin: Thanks for this excellent and informative post. I have added it to our Tips Archive.

I am also surprised with the hardness of the tool steels. Lynton McKenzie used to claim he could get a sharper edge on tool steel gravers but they wouldn't last as long. I'm not sure I agree with that as I can get all of my HSS gravers razor sharp. I don't have much experience with tool steel...everything I have is either HSS or carbide. / ~Sam

 

[Martin Strolz]

He was right without doubt, I have the same experience! Maybe a very, very small burr on the heel and on the side edges of the gravers face gives that feeling. Tool steel is suitable for bulino or shading on relatively soft steel and it is easy to grind by hand on a silicon carbide stone. Sharpness AND a nice handling for a push engraving tool is not easy to achieve.
If using a Power hone, the hardness of the tool cannot be felt much. Sharpening tough HSS and carbide tools only takes longer.
Martin

P.S. My friends and I have voted already, Sam!

 

[sdcoxx]

Martin,
Very informative and helpful for my next graver purchase....
Thanks for sharing,
Stephen

 

[Marcus Hunt]

An interesting post Martin. When I was first apprenticed the only gravers we used were tool steel which we hardened by heating to red hot and then quenching in engine oil, then we tempered them to light straw colour. These tools sufficed for many years but gradually the gunmakers started using what they called 'higher quality steels'. To the engraver this meant tougher steel. HSS gravers helped a lot but sometimes, if I got a softer action (e.g. Spanish AyA or Union Armerra) the traditional 'tool steel' graver would give a cleaner cut. And this is something that I've noticed over the years, that the harder gravers generally give coarser cuts. It must be something to do with the crystaline make up of the steel alloys. Momax was dreadful for this and I'd only ever use it on the toughest of steels as it would literally tear through the metal. I don't know how this applies to softer metals such as gold and silver because Sam uses carbide on his jewellery because it holds a bright polish better.

Can you enlighten us any more Sam (or anyone else) on how you find differing hardness of gravers works on other metals?

 

[Sam]

Thanks Martin!
That's interesting that you have had the same experience as McKenzie with tool steel. I have some tool steel gravers, but have only used HSS my entire career, so my experience with them is very limited. I think my liners are tool steel.

I used to hand sharpen with india and arkansas stones, but now only use the Power Hone, so as you said, I probably wouldn't feel a difference.

Cheers / ~Sam

 

[Sam]

Can you enlighten us any more Sam (or anyone else) on how you find differing hardness of gravers works on other metals?

Marcus: I'm not sure I notice a difference, but I should pay closer attention and maybe do an experiement to see. I use carbide for much of my work in precious metals, and being the hardest of all graver materials, it cuts smoothly and beautifully. I have limited experience with it in steels. In fact I avoid using it in steel because if chips so easily. Yes, a test would be interesting!

~Sam

 

[KCSteve]

Over in the various knife forums there's often discussion of various steels and 'which is best'.

Hardness is just one factor, as everyone's noted. Benchmade hardens most of their knives to (I think) 58 - 61 RH - just slightly softer than the gravers tested. They don't go harder than that because it would make the blades too brittle and they'd snap like graver points.

So, on the knives the hardness of all of the steels is essentially the same, so how can there be such big differences?

Well, one that matters a lot for knives is toughness, also called 'wear resistance'. A simple stainless steel has low toughness so it dulls easier. Sharpens easier too, which can make it 'better' for some applications than a 'super steel' like S30V that has such high wear resistance you do not want to let the edge get too dull between sharpenings.

The size of the carbides in the steels matters too - the finer the grain the smoother the edge you can get.
D2 tool steel is nice for knives but you'll never really get a really smooth edge (well, you will but only until you make the first cut). Of course for some applications the microscopic 'teeth' that result from the coarser carbides are an advantage.

Somewhere out there is a fantastic paper on blade sharpening and such with electron micrographs of various edges.

It would be very interesting to see a thorough study of graver composition / geometry and how it interacts with various metals. Anyone at ESU giong for a doctorate? Make a dandy thesis project.