This might help tempering at 10 min inAs above, I tried to do this to a centre punch I made when I started my apprenticeship at 16, and failed to harden/temper correctly then using the heat to cherry red/quench/heat to 'straw coloured' and allow to cool method.
The instructor got us to to the 'heat to cherry red and quench' bit, then we gave 'em a quick scrub with wire wool and he then took a mates and heated it, saying "look, you can see the straw colours starting to come", I couldn't see anything other than the bright, flaring light from the oxy-acetylene torch but being 16 and not want to look a twerp in front on the other apprentices said nowt I didn't try again, just bunged it in my toolbox and forgot about it, and since then got by with the one my dad made when he did his apprenticeship (hard as a diamond!) and bought one.
Rooting through the tool drawer the other day I came across it and decided to have another go.
I used a Rothenberger MAPP torch which may not have been hot enough? Heated it to what looked to me to be cherry red (glowing red hot), quenched once I'd got to the tap in the utility room (how critical is the heat-to-quench time?) and then heated carefully until the end 10-15mm was to my eyes 'straw coloured' (light golden-brown).
One tap on a piece of mild steel, no 'dot' and the end of the punch was flattened once again. I really want to get this to work so I can close out a 32-year chapter in my life, any advice at all please?
For bob A bit of stellite I thinkView attachment 200832
If it was intended to be a punch I would expect it to be silver steel.I agree but the op had a bit steel from school so I doubt it’s was any really fancy. Alas I could be wrong again and it would not be the first time or last
If it was intended to be a punch I would expect it to be silver steel.
As above, I tried to do this to a centre punch I made when I started my apprenticeship at 16, and failed to harden/temper correctly then using the heat to cherry red/quench/heat to 'straw coloured' and allow to cool method.
The instructor got us to to the 'heat to cherry red and quench' bit, then we gave 'em a quick scrub with wire wool and he then took a mates and heated it, saying "look, you can see the straw colours starting to come", I couldn't see anything other than the bright, flaring light from the oxy-acetylene torch but being 16 and not want to look a twerp in front on the other apprentices said nowt I didn't try again, just bunged it in my toolbox and forgot about it, and since then got by with the one my dad made when he did his apprenticeship (hard as a diamond!) and bought one.
Rooting through the tool drawer the other day I came across it and decided to have another go.
I used a Rothenberger MAPP torch which may not have been hot enough? Heated it to what looked to me to be cherry red (glowing red hot), quenched once I'd got to the tap in the utility room (how critical is the heat-to-quench time?) and then heated carefully until the end 10-15mm was to my eyes 'straw coloured' (light golden-brown).
One tap on a piece of mild steel, no 'dot' and the end of the punch was flattened once again. I really want to get this to work so I can close out a 32-year chapter in my life, any advice at all please?
It is very easy to “burn out” the carbon in a steel alloy or ruin its properties by overheating. This is especially true for fine tips and thin edges. Even a high quality carbon steel alloy will eventually fail if you keep repeating the hardening/tempering process.
This is especially true for mystery metal where you’re never really sure what you’ve got to start with. You can be fairly confident it won’t be a particularly high grade being handed out to apprentices.
one trick you can try is indirect heat. Place the chisel, scribe, blade, punch inside a sacrificial tube or length of box section. That keeps the flame away from the workpiece (which can help prevent oxidation) and should even out the heat stopping you from burning the thin sections.