Thread: Harding and tempering temps

Arron
I have ground lathe tools from HSS for years and the only time I have seen a loss of hardness is when an extremely thin section of a special profile has been overheated
If your stuff doesn't hold up to ironbark then I would say its a very poor quality

The thing that prompted me to post however was when you said you ground the tool while wearing gloves
Mate that is dangerous you should never and I mean never wear gloves when grinding . If you touch the wheel with your fingers you can lose a bit of skin and pull back , but with gloves the wheel can drag the glove between the wheel and rest and you can lose a finger or more.

As to drilling some holes in the HSS blanks ( I assume to fit a handle ) You could try a stick welder and weld a spot to both sides Good centre pop then drill through the weld .
Use a cobalt drill they only cost a couple of $s you can get them at mitre 10 And this may even drill the HSS without the welder I know they drill stainless like butter.
You can also make a blue tac pond around the spot you are drilling and fill with water to keep the temp down as you drill
Hope this helps



The trouble with life is there's no background music.


Ashore

Thanks for the safety tip, Ashore. It seemed as though I was doing something wrong while doing it - didnt quite realise what though.

Arron

Ashore, I'd give you a greenie for the safety tip, but it won't let me.

I'll remember that one - safety is an issue we should be continually reminded of, and its weekend warriors like me that need the reminding the most.
Thanks

Just a quick tip about that nice MAPP gas thing you have.

You will not get something to 2,000 degrees just sticking it in the path of the flame. The steel will dissipate the heat faster than you can stuff it in, and you might be lucky to get it close to 1,000 degrees.

I have a MAPP gas thing back in Oz, and used it alot, but always had trouble doing silver solder to copper. Big lumps of copper at least. All that heat got sucked away before I could get the solder hot enough to flow.

And yet yesterday, using a home made kerosene burner, I made 2" x 1/4" mild steel bar bright yellow within a few scant minutes. Simple because it was sitting inside a small furnace that not only holds the heat, but also avoids the steel being able to dissipate it to the open air.

Really easy to tie knots in thick steel when it's that hot too.


As for drilling your HSS, I'd reach for one of the solid tungsten bits I have, but you might get away with a common masonry drill, with the tips sharpened up to cut rather than smash. Cobalt drills also work wonders, and I wouldn't buy another HSS bit if cobalt was only double the price. They are that good.

Heck, when I first got my nice Sutton CoHSS set, I went and drilled a drill bit. Really easy to do.

Actually, I was meaning 2000 farenheit, not celsius. However I have a small 'microfurnace' which is simply a few firebricks stacked together - with a gap at the back in which the MAPP nozzle can be inserted. I think that will get me up closer to 2000 celsius but I am wanting to learn a little bit more about the safety side before experimenting further.

Re the MAPP gas on copper - if by 'big lumps of copper' you are meaning long copper pipes then my MAPP gas has no problem at all getting the silver solder flowing like water. It takes a few minutes of heating up - then its gone. Could you possibly have been working on pipework with some residual water in it ?

Anyway, today I ground three blanks up into marking knives. I wanted to attach the handles using cutlers rivets but didnt have the gear to drill the HSS yet, so just stuck the scales on with epoxy. Couple of coats of varnish and they are done. I know these are no-brainers and nothing much to be proud of - but an acceptable result from a couple of hours work. The edges are reasonably durable and very sharp. They were ground without quenching (and not wearing gloves this time).

cheers
Arron

Knives look useful. I think the rivets might look better though.

The big lumps of copper meaning 150mm copper pipe a few feet long, some 75mm, reduction joiners, tees, etc, etc. Oxy would do it easily, but I didn't have oxy.


You need to go find some oil or water quench steel to play with. Any old spade bit is a viable doner. Even the cheap and nasty chiwanese spade bits (and other tools) have usable steel in them.

Only reason I say this is because HSS is too finicky to do without a couple grand of gear. Water quench you can do for free, oil needs some oil but other wise free too. Much easier to work with and far less frustrating.

Originally Posted by Arron

Hi, anyone know the hardening and tempering temperatures for the HSS tool blanks sold by McJing's.

thanks
Arron

There are a lot of different metal alloys sold as HSS and they have differing heat treatment requirements. One of the common ones used for wood turning tools is M2 grade which has a tempering range of 538-727 degC and a hardening range of 1190-1218 degC but I don't know the times.

Originally Posted by Schtoo

The big lumps of copper meaning 150mm copper pipe a few feet long

Right, MAPP would have no hope of doing that. I thought you were talking about domestic water supply plumbing.

I ruined a couple of spade bits today striking nails. Thanks for the tip. They are almost the right shape for a shoulder plane blade - which is good because I have been wanting to make a shoulder plane for some time. What sort of temperatures do you think the average Chinese cheapo spade bit would need for hardening ? I know they could vary a great deal and the only thing to do is experiment, but where would you start? Ditto time.

thanks
Arron

Take torch, spade bit and a magnet.

First, make the spade bit glow, then put it aside to cool down on it's own. If you can file it, it's good to work into shape. I usually grind it, then the belt sander and finally file to a suitable shape.

Make the spade bit cherry-orange and check regularly with the magnet. When the magnet doesn't stick to the steel anymore (use a 'junk' magnet) drop the thing into a bucket of water. You could use oil, but I use water. Not a critical thing here, nor is it top shelf steel. If it pops in water, ie: cracks or severely warps, make a knife out of it.

To temper, I would suggest looking up 'oxide colors' on google. There should be a cross reference to what colour works for what particular use. I usually go to a light straw colour, because I like my blades to be very hard.

And to see what the colours really look like, take a piece of mild steel, clean it up so it's raw steel for 4-6" and gently heat one end. Once the heated end turns blue after waving it around the flame, stop. Now you have a tempering chart. Cool huh? Just clean up your blade, and slowly from the non-working end heat it up.

Once I tire of melting metals down, I'll invest some time into a kiln/oven to do heat treating and ceramics. That would certainly be the easy and consistant way, but playing with a small hunk of steel and a torch is the best way to find out what works and what doesn't on the cheap.

With these thin, light bits of steel, don't worry about heat soaking and all that stuff. Just make it glow, clean it, pick a colour and go to work with it.

Oh yeah, just made my first castings today and they actually worked.

Save a few gas pockets.

Like the marking knives Arron.
I did a similar thing- bought a blank at WWW show and ground a bevel- i thought i would have to re-harden it as it turned slightly blue, but after reading this thread re HSS, i just polished it on a water stone and magically got a shiny surface again!!
Robert

Yes, I've learnt a lot with this thread, like how to easily make small tools with edges which are not first class but good enough to be useful - especially for tools that dont need a really robust edge. I'm looking forward to making some blades for my Stanley 45 from HSS. The original blades were never very hard anyway so they should be easily duplicated.

Arron

http://www.buau.com.au/english/b_2265.htm

If you download the documents for the various steels, they show the temps and times for annealing, stress reliving and hardening, as well as all the techo information.

Might help some, espesh if you can identify what steel you've got.

Hi Arron and crew,
Just reading this one again, and I have naught but drill bits and one lathe tool made of HSS for experience, but Schtoo's comment about using more manageable steel for tools hit home with me! Its near free! And you get to practice sharpening if its too soft! I know such a slack approach doesn't suit the high quality tools you're making, but had to say it anyway!
One reported flaw with shaping by grinding alone is that it doesn't follow the grain of the steel impressed by the forging/hammering process, and when directed towards the bevel of a shaped blade its called "packing". The steel is apparently stronger where its packed. Now, I don't know about the realities of that, but it makes sense to me.
BTW Handy looking knives there too!

Cheers,

I really should join the 20C and get into these techo steels...?:confused:

Quote Schtoo;
"Make the spade bit cherry-orange and check regularly with the magnet. When the magnet doesn't stick to the steel anymore (use a 'junk' magnet) drop the thing into a bucket of water. You could use oil, but I use water. Not a critical thing here, nor is it top shelf steel. If it pops in water, ie: cracks or severely warps, make a knife out of it. "
When hardening the spade bit it is best to hold the piece with a pair of tongs & plunge into the water / oil vertically & move about in the liquid in order to stop the liquid boiling off around the surface of the metal. This is what usually causes distortion & cracking of the metal ( uneven heat dissipation ? )
Take good care,
Barry.