Cutting tang for HSS blanks

[bertterbo]

I bought some HSS blanks to make my own scrapers. But one thing I hadn't considered would be just how difficult (slow) it would be to cut the tangs.

The blanks are rectangular shaped, about 6mm thick and 15mm to 30mm wide. So need to remove a fair bit of material to form a thinner tang.

I've tried with both a bench grinder and a disc sander, but it's incredibly slow.

Next step is trying an angle grinder, with a thin 1mm disc. But from past experience, I know that's slow too.

Do you think it would be worth while heating the end of the blank to remove some of the hardening?

Utoolmart HSS Lathe Tool Bit 6mm x 20mm x 200mm, Square Lathe Turning Tool Blanks, High Speed Steel Rectangular Fly Cutter Mill Blank https://amzn.eu/d/7xP953B

https://amzn.eu/d/1N591Fd

 

[Paul Hannaby]

I would have thought an angle grinder would be the fastest option because you can cut a wedge off rather than having to grind it all away.

 

[Phil Pascoe]

Not too difficult with a thin disc on an angle grinder. HSS wouldn't get any softer for the heating.

 

[--Tom--]

If it were me I’d use a diamond slitting disc for metal in the angle grinder

If you’re going to grind, a 36grit ceramic in a belt linisher running at top speed with high pressure would do it fairly quick

 

[bertterbo]

If it were me I’d use a diamond slitting disc for metal in the angle grinder

If you’re going to grind, a 36grit ceramic in a belt linisher running at top speed with high pressure would do it fairly quick

I tried 60 grit on my disc sander (lathe) at 3500rpm. Would take far too long and just eat up belts.

It's hard stuff.

I looked up diamond discs and it says they're for masonry or ceramic? Do you have a link to what you meant please?

 

[--Tom--]

https://www.toolstation.com/dewalt-extreme-metal-cutting-disc/p19663?

 

[--Tom--]

With the abrasive route I doubt you’re using something like cubitron 984 or 997 on the lathe- the type of abrasive makes a big difference and is often an overlooked variable when people aren’t used to grinding high hardness steels

 

[bertterbo]

The belts I bought for my Pro Edge were P36, but the product details just say "Ceramic" and no other details.

Do you think buying some Cubitron ones would make much of a difference over Ceramic?

https://bndabrasives.co.uk/3m-984f-...x-780mm-for-sorby-proedge-belts-pack-of-6-p36
Bearing in mind the Pro Edge runs pretty slow.

Can't seem to find any 150mm or 200mm discs.

 

[--Tom--]

Need high pressure and high speed- I run 50mm by 2m belts and need to upgrade the 2kw motor as can slow it under load.

Doubt a pro edge has the grunt to get them working properly- you’ll end up dulling the belt

 

[bertterbo]

How would it dull the belt? do you mean due to the low speed?

 

[niall Y]

I made a set of heavy duty scrapers, a few years back out of O1 tool steel. I first drilled out the shoulders using a hole saw, Not the usual ones , but those designed for metal.. I then marked and cut the tangs, upright in a vice with a hacksaw.

One thing I discovered, when using a grinder, is that the metal becomes incredibly hot and air hardens on cooling. This means that you then have to anneal it if you need to switch to a file or hacksaw.

Attached are a few photos to show the process

 

[Phil Pascoe]

Which is fine, but irrelevant to working HSS.

 

[--Tom--]

How would it dull the belt? do you mean due to the low speed?

They keep sharp by fracturing to expose sharp edges, and dull grit being knocked off, low pressure and low speed needs different types of belt.
I use fresh belts for grinding bevels where the fresh sharpness is needed, once they’re starting to wear they then get used for profiling where the lower contact area means can apply more pressure, and the 90 degree approach angle will knock off the high bits of grit that have become dulled which freshens them up.

It’s the alloying elements in the hss that influence grindability as much as the hardness, as the resultant carbides are wear resistant

 

[niall Y]

Oops!..... should have read the post properly. These are the sort of blanks I grind to profile for my metalwork lathe. I must admit I do use them to cut exotic timber components on this, but not sure I would make a tanged scraper out of it.

 

[Barry Keen]

Not too difficult with a thin disc on an angle grinder. HSS wouldn't get any softer for the heating.

I have softened hardened steel but it involves a rather long and complicated procedure, involving heating to cherry red as slow as possible preferably in a kiln and then cooling as slow as possible by burying in sand and letting it cool overnight,
I think other suggestions given are more appropriate

 

[--Tom--]

I have softened hardened steel but it involves a rather long and complicated procedure, involving heating to cherry red as slow as possible preferably in a kiln and then cooling as slow as possible by burying in sand and letting it cool overnight,
I think other suggestions given are more appropriate

Whilst this may work for typical tool steels HSS is more involved

To anneal M2 ( a typical HSS)
Heat at a rate not exceeding 220°C per hour to 830-840°C, and hold at temperature for 1 hour per inch of thickness, 2 hours minimum. Then cool slowly at a rate not exceeding 25°C per hour to 530°C. Continue cooling to ambient temperature in air.

So 4 hours to heat up, 2 hours to hold, and 12 hours controlled cooling.

Places that do this professionally will do it in a vacuum furnace so that you don’t have oxygen present which will decarburise the steel and form scale. At home you could flush the kiln with argon, weld the piece inside a canister with some powdered charcoal to burn out residual oxygen, or use a specialist coating like condursal.

You’d then have to reharden, I won’t post the whole process but it involves careful preheating and then taking the piece to 1200°C before a controlled quench.

Hss heat treatment is something to leave to professionals as they will have the kit to do it properly.

 

[dannyr]

Whilst this may work for typical tool steels HSS is more involved

To anneal M2 ( a typical HSS)
Heat at a rate not exceeding 220°C per hour to 830-840°C, and hold at temperature for 1 hour per inch of thickness, 2 hours minimum. Then cool slowly at a rate not exceeding 25°C per hour to 530°C. Continue cooling to ambient temperature in air.

So 4 hours to heat up, 2 hours to hold, and 12 hours controlled cooling.

Places that do this professionally will do it in a vacuum furnace so that you don’t have oxygen present which will decarburise the steel and form scale. At home you could flush the kiln with argon, weld the piece inside a canister with some powdered charcoal to burn out residual oxygen, or use a specialist coating like condursal.

You’d then have to reharden, I won’t post the whole process but it involves careful preheating and then taking the piece to 1200°C before a controlled quench.

Hss heat treatment is something to leave to professionals as they will have the kit to do it properly.

Yes - just because it's HSS and can take a much higher temp in use than carbon steel, doesn't mean it isn't affected by heat.
Grinding wheel and sanding should have little effect on hardness, but the high speed of an angle grinder could be quite different (up to melting at the edge), so at the least may need re-heat treatment (not easy, as tom says), you may also spoil the microstructure around the edge.
Also beware of thinking diamond in an angle grinder is the obvious answer - at high temp in air the diamond can burn (literally) - might need water cooling - careful.
As Tom suggests - the pro way to do what you want is to soften, shape and re-heat treat - the latter depends on which HSS (there are many) but typically needs a quench from 1200C or more and preferably double or treble temper for optimum hardness etc.

I'd try to rethink the need for a thin tang - do you have another way of holding these bits? - then you can concentrate on just grinding to shape the cutting edge on a grinding wheel.