Stellite 98M2 tools

Hi,

My old friend gave me a bundle of HSS square blanks which he was going to throw away.

Between those I have found 2 unusual bits. They didn't rust, they are non-magnetic and they have written on them Stellite 98M2.

I was looking on web and found that such blanks are in fact quite expensive, comparing lets say to HSS.

What they are good for?

Apparently not as hard as ordinary HSS but work well even when red hot.

On my lathe it is unlikely that tool is going to turn red hot anyway.

So what they are good for?

Finishing cuts because they are not difficult to mirror - polish?

Bearing scraper blade for the same reason as above - easy to mirror polish what suggest good quality of blade?

Parting off (assuming I first slice and then grind them (have diamond saws)?

Internal threading bits (can be brazed without loss of hardness).

Any other ideas?

Edited By Martin Dowing on 21/10/2020 19:09:54

Hi Martin,

You seem to have covered most uses. I used the Stellite toolbit like HSS many decades ago. They are wear resistant and, as you say, can be used even when red hot. Now I tend to use tungsten carbide tipped tools and use HSS for the finishing cuts.

Thor

I use 1/4" square Stellite tool bits in my tangential turning tool holder all the time, they last way longer than HSS before needing re-sharpening. Usually just a lick over with one of those cheap plastic diamond files now and again.

Phil

Many thanks for your comments.

So these tools are looking useful and they certainly have some specific applications. Regarding tangential toolholder - it will be one of my projects in near future. Ready made from Eccentric Engineering are rather expensive.

Once made it should help to save substantial quantity of blanks.

Martin

If the blanks are new, study the ends. One one edge you should find a little ground notch. This notch should be the top edge of the tool in use, it orientates it for maximum strength.

Thanks Pete for your comment. I have found this notch. Now I know what it is meant for.

Fair bit of info in this Practical Machinist Thread.

This comment made me smile: 'In general, knowing about Stellite lathe tools qualifies you automatically for Social Security and is the free pass to the old folks home.' A little unkind as it turns out, but it seems decades ago Stellite 98M2 was the hot dog cutting alloy above HSS for hard materials before Carbide was perfected.

Still much used for high-wear resistant edges on paper cutting machines, gun-barrels and the like but not for lathe tools. The number of applications favouring a tool performing between HSS and Carbide is limited; stainless steel perhaps. Got some disadvantages too. The significance of the notch already mentioned, but also don't dunk whilst grinding because Stellite is prone to crack. Pricey as well.

My take, put it away for a rainy day! Won't perform better than HSS on anything other than unusually hard materials and carbide mostly deals with them better than Stellite would. Might be just the thing for an exotic job one day though. As it's getting difficult to buy don't waste it on ordinary work.

Dave

If you have oxy-acetylene you can melt the end of a piece of Stellite and "drip" it onto a steel component to give a very hard surface, rather like case hardening but harder. Useful for pushrod ends and similar parts which need a hard surface.,

Rod

@SillyOldDuffer,

Yes, it is good idea not to waste these on jobs where HSS would do te trick.

My observations of surrounding world are telling me that economic collapse now pending may bring a very bright future to those still capable to operate manual machinery and some non carbide tooling.

CNC is great but without cad file is not suitable for making an odd part, neither it is of much use in repair jobs.

Somehow I think that while our civilization is going downhill, we will surely enter recycling era and engineering is going to get new lease of life. Hopefully those who can recognize stellite will get out of social security at that point (if only still alive and fit...)

@Rod,

One time I have made myself in.

Have offered one guy to repair housing of ball valve in his pump by drilling out damaged bit and inserting a proper one "which will never wear off".

So I have taken a piece of 316 Stainless, cut out few short bobbins, made recess with drill and countersink and then welded in Stellite (You can buy cobalt/chromium/vanadim/tungsten alloy in form of welding sticks).

Next part of plan was to turn it to shape. This was already problematic. HSS have failed (despite of welding rod specifications of only 40 HRc, standard carbide struggled but have managed.

Then I had to drill hole through this stellite. Here HSS-Co did work but bits were getting blunt one after another. I could drill about half way (few mm) but next few mm I had to drill with resharpened drill. Failing that material was somehow work hardening and then nothing would drill through. Carbide drills were tending to brake in it btw.

Finally housing for ball had to be cut. Only high grade carbide mill could do it and I have damaged one in the process.

So job was done and these valves (with silicon nitride balls now installed) are working very well for years, but at the end I have subsidized my customer.

When he has asked me to repair other pumps for his company specifically in exactly the same way like first one was done (he was obviously impressed with performance) I gave price 10 x as high as for the first one.

Sadly he didn't come back, though he was phoning few times attempting to get lower price.

Edited By Martin Dowing on 23/10/2020 20:57:54

Martin

Wow! excellent anecdote, I would not have thought that possible.

I watched a guy build up a pushrod end on a commercial diesel engine with melted stellite. The end had eroded badly, perhaps it had not been hardened properly from new, but it was a real mess when the engine was stripped.

The mechanic then ground the stellite coating back to an approximation of the original contour on the bench grinder. It took a long time and he eventually said "that will have to do" in exasperation at the time it was taking and the hardness of the stellite. As far as I know the engine went back into service without problem. Mechanics were resourceful and spares hard to source in those days and, as ever, time was money.

Rod

Hi Guys,

In time long gone, I've used Stellite to hard face shaft bearing surfaces prior to regrinding them.

Somewhere in my tool boxes I have a Stellite scriber !

Certain grades of Stellite are still used today, on heavily interrupted cuts on Nickel or Cobalt based Super alloys. I actually had a blank approx 40mm square x 200 long, never needed it and has now gone "Walkabout "

I use stellite for form tools, ACME threads and the like. Losing an edge on a HSS tool when you're most of the way through cutting a critical thread is not much fun.

Interesting thread on stellite. I have a load of the stuff 'under the bench'somewhere. its not a regular size, about 1/4" sq by about a foot long. where would i go and buy some of this stuff if i wanted it.

Looks like its for welding, whats it worth

Martin,

I cannot recall the grade of Stellite used for the triangular drills in our toolroom. The drill tip had a (very) negative rake. The three notches are about how I remember them, although they may have been a bit wider.

As an apprentice in the early 50’s I had the task of drilling through the nitrided skin of the cavity of a compression mould.

Once through the skin the rest of the drilling exercise was with a conventional HSS twist drill.

The operation required that enough downward pressure was applied to the drill to virtually melt the mould steel. Drilling was more about pushing the metal out of the way. A quick Internet scan shows that nothing seems to have changed to the drill-tip geometry .

Worn screws and barrels of plastics extruders can be restored in a process called ‘hard-facing’. Stellite and other hard materials sprayed onto surfaces replaces in particularly, worn screw flights.

I find it hard to believe it's more than 65 years ago, and carbide was beginning to appear.

Keep safe people,

Sam

Sam,

Many thanks for your comment about these drills.

As per my experience, I have managed to drill through 60HRc with cheap masonry drill sharpened on the grinder to give it some "bite".