The QUENCH depends on the steel... The TOOL will tell you what you need to Temper it to- If it is high carbon like 1095 or an oil hardening like O-1 (Drill rod) then here are the steps I would take it through. Caveat: I make knives and have done some punches from coil springs- all have withstood use fairly well. You can look up what kind of steel you have for what quench you will need- if it is any type of air stainless or high corrosion steel you will need temps you cannot achieve easily and inert atmospheres that are harder to work from.
For High Carbon and "Most" Oil hardening/Drill Rod steels- Heating to "Red" is not what you want- heat it to NON magnetic- the structure changes internally enough at that point you will get maximum hardness with a proper quench.
1- Normalize metal 3x: heat to non-magnetic and let cool in air to touch- this assures all the internal stresses are equalized (less prone to shatter from quench)
2- Heat whole punch to non-magnetic and immerse in oil/water/quench of choice- keep in till cool to touch. Keep object moving in the quench to circulate cooler quench fluids around the hot metal
3- A punch needs to be hard over the tip/lower shaft and softer on the hammer-strike end- wire brush or steel wool the tool till shiny- you want to see the colors as they march UP the steel
4- hold the punch at 45 degrees with the hammer-end DOWN and the impact point UP (heat travels up easier when you are using a torch to do this part) and begin heating the hammer end- slowly and deliberately watch the colors march up the shaft.
Here is a chart I refer to often and have printed over my bench-
http://www.engineeringtoolbox.com/tempering-colors-steel-d_1530.html
-Remember you can slow the color marching by holding the torch farther away from the hammer end- play the torch over the lower half until colors begin approaching the tip
You are trying to get the colors JUST BEFORE PEACOCK BLUE along the tip area. You may have to do this several times or at least practice a few scraps... you will get the feel for "painting" the heat on with the torch fast if you have several clean shiny scraps ready to practice on before you do your real piece.
Colors will move FASTER when the shaft tapers to a point due to thermal mass so heat SLOWLY
5- once you get the color you want- QUENCH- You are trying to "freeze" the crystals at a certain internal point. Some folks put the tool in the freezer or dip in acetone and dry ice to get a "Sub-zero" quench- but its just a punch so unless you are trying out a tool prototype- don't worry about that.
Now the hammer-end should be soft and mushroom nicely when you strike- and the tip should be hard and ready for whatever you toss at it!
If you are feeling froggy- take the "Scraps" and temper them to different points and see- take one out of the quench without tempering it and whack it with a hammer- shatter it and look at the shards (wear your goggles and apron for this).
Hope this helps- be safe and let us know what works for you!
