HSS vs KYRO vs PM........

[odie]

Has anyone heard of chipping of the pm steels. I haven't. I've been using them for a while now and pretty much abused them by turning solid aluminum, brass and some extremely abrasive woods.

John......

I'm not really sure where I heard that. Since I've never had anything but carbon steel, and HSS (non PM) steel in my lathe tools, it certainly isn't from my own experience. Saw that chipping was happening with PM steels somewhere online, I guess......

I do know that carbide is very prone to chipping, and is generally a harder composition than HSS. We use quite a few carbide cutters where I work.....and chipping is a common problem with them. I'm making a wild assumption that the hardness of the steel, and chipping might be related somehow.......?

otis of cologne

 

[Richard Baker]

Some educational reading above. A couple of folks have touched on an idea that may be relevant for some. Simply put, a lot of variables being more or less equal, a tool that goes three times as long between sharpenings as another tool but only costs twice as much is a better investment, saving you $$ as well as maybe a little bit of time. Granted that this is of no particular value to folks with the resources to obtain any and all tools they might want.

 

[john lucas]

Odie I agree about the carbide. I don't know the stats but assume that it is harder than the HSS and PM steels. At least after they've been tempered. It would be interesting to find out. I photographed for a whole day at a PM plant in Tennessee and asked a lot of questions about the stuff. This was when the PM turning tools were pretty new. I don't remember the details but he talked about the metal having higher wear qualities dues to a particular hardness. He said that because you could add more metals and you have more control over the properties of the steel. Wish I could learn more about this stuff.
I currently use a lot of Hunter tools as well as the Thompson. The Hunter tools are carbide and I have chipped one of those. I think I bumped it with another tool. The Thompsons are my go to tools and get used and abused with no special care in handling. So far they work great. I have even run the skew into the chuck. It cuts the chuck quite nicely. It did dull the tip pretty bad but it didn't chip.

 

[Matt Owen]

I do know that carbide is very prone to chipping, and is generally a harder composition than HSS. We use quite a few carbide cutters where I work.....and chipping is a common problem with them. I'm making a wild assumption that the hardness of the steel, and chipping might be related somehow.......?

The carbide is harder and consequently much more brittle than HSS is, which is what allows carbide to hold an edge longer than HSS, assuming you don't chip it. HSS can chip as well, but usually gets pretty dull before that happens.

 

[steelguy]

Hss Vs Kryo Vs Pm.....

More steel info - pretty soon you folks may get a Met. Eng. certificate!!!

Mother Nature is not fair - harder generally means more prone to chipping, and more wear resistance generally means more prone to chipping. Grades that have high levels of Cobalt for red hardness are generally less tough as a result. and so on.... Carbide tooling has extreme wear reistance and red hardness, but next to no toughness when compared to PM HSS alloys.That is why in metal cutting most carbide tools are well supported inserts with very little vibration desired during use. Woodturning translation - use carbide for finishing work, not roughing a stump!!!!!

I have no direct knowledge of sources of supply in tools referring to HSS with "60" in the descriptor, but there are well known PM HSS called ASP 60 and 2060 and they are the same compositions.

The typical hardnesses shown on the data I provided were for metal cutting applications. In wood operations, I would guess that the tools are somewhat under hardened for optimum toughness. That would indicate (again no direct knowledge) that the PM super highspeeds such as CPM Rex 45, 76 and ASP 60 would probably be a point or two lower than shown on the chart. Typical for M4 would be 62-63, not its full hardening capability of 65. For more examples of typical hardnesses, see Lacer article in AAW journal, last summer.

Tool life is complicated and involves combinations of wear resistant particles, matrix hardness, and toughness and the material being turned - e.g. MDF vs Pine. Sometmes wear is the result of micro-chipping first, then dulling......

The carbide based tooling we see in the wood turning field use very small pieces extremely well supported, so that the shank is taking the beating.

There is a proper place for every tooling material but when making tools for the open market, manufacturers have to assume the worst and apply safe processing. As a result, maximum attainable hardness is probably not supplied.

Very highly alloyed PM tools can be more difficult to re-sharpen, and care must be taken to assure no edge damage. They can be burned just like any other tooling. However, I know of no general tendency or reputation for chipping.

The reason why CPM 10V (A11-generic versions) has been so successful in woodturning is that it is simply an extremely highly wear resistant tool steel - not a PM HSS. It exhibits very good toughness and resistance to chipping and contains no red hardness enhancing additions, which are not needed in woodturning. It is routinely used for blanking and stamping other metals, so turning wood is a piece of cake for it. Jerry Glaser figured this out over 20 years ago!

There are lots of great, well made tools on the market. Evaluate your goals, your pocket book, and your skills and choose accordingly. Tools do not make the turner - creativity, practice, and a positive outlook do.

But wait, with a new tool, a new lathe, a new turning smock, a new chuck, and a great piece of wood, I'll bet I can...........

Jerry Wright

 

[Doug Thompson]

Thanks Jerry, that is a great deal of information about the steel that we use.

If anyone wants to make tools from A11 Crucible will sell stock any size you need, Steve Worcester and a few other have made scrapers then sent the stock to me for heat treating (no charge) this is a way to make custom tools.

 

[odie]

Thanks Jerry, that is a great deal of information about the steel that we use.

Ditto for me, too, Jerry........

It has been informative.....and, I'm sure Doug and I aren't the only ones who appreciate the effort you are putting into this thread.

You are definitely right about one thing........tool steel really isn't the ultimate critical choice one can make when choosing lathe tools. It's the hands, and the mind that control those hands, that make the ultimate difference. (You can buy a $1,000,000 race car, but that won't put you in the winner's circle......but it will help the right driver to get there!) In the case of lathe tools......in the right hands, plain ol' carbon steel can create works of art the "money boys" will drool over!

otis of cologne

PS: Doug, I've been cruising around on your internet site some.....I'm impressed! Eventually, I'll get around to trying out one or two of your tools.....but, you know that I'm really stocked up well with tools for my use. If I didn't buy another lathe tool, I'd probably have enough to last me most of the life I have left!

OOC

 

[Gordon Seto]

.....but, you know that I'm really stocked up well with tools for my use. If I didn't buy another lathe tool, I'd probably have enough to last me most of the life I have left!

Using the same logic, some of us should have stopped buying clothes and shoes a decade ago or even longer. We slowed down because we ran out of closet space.
This economy is built on "we want"; if it goes back to "we need", this recession may not end in our life time.
The advancement of lathes and lathe tools is the result of woodturning hobbyists. Simply because they don't have to justify the cost. It won't surprise me if the tools that the production turners use, to make the imports from Far East, were made out of leaf springs recycled from old trucks.
In our budget, we can't justify a Rolex or one of those that I can't pronounce the names; my Timex is accurate enough for me. My second heart rate monitor Timex that I wear to gym has more functions than I can remember. But if others can afford one or more of the expensive watches, they think they feel better if they own them; it is their choice. I am not going to talk them into the value of my Timex, the saving in insurance. Or tell them they are never punctual anyway, a less expensive watch that run couple seconds faster in a day would be more practical.
I was spending on my Rolex budget that I haven't spent yet. That is the reason I have so many turning tools. I am sticking to it.
BTW, I have found out tools won't make me into a turner long time ago. I slowed down because I ran out of room in my garage.
Sorry for bringing this slightly OT. The guys who really know about steel have spoken.

 

[john lucas]

Jerry Thanks for the info. It's been really interesting. I hope I can sort out all those facts.
Boy will I agree that it's more about the skill of the turner than the tool. However when you turn with 2 tools side by side you quickly form a decision on which one works better for you. It might be the edge holding, it might be the flute shape or the grind. Probably all 3. Unfortunately the only way to really know is to use them which of course means buying them. When you go to the symposiums look closely at the turners tools. You will see all sorts of variations on the grinds we see in the magazines. We each learn to use what we discovered, either by accident or by design. I guess in the long run all we can do is listen to people like Jerry and Doug and professional turners like Mike Mahoney and Stewart Batty and try to make an intelligent choice on the tool we want to use.