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Can someone help me with heat treating these punches?

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I need to harden and temper a round punch, but I don't remember exactly what my instructor told me to do (I was exhausted and was trying to remember other stuff when he told me). I think it was like:

1. Heat in forge, tip in first, until non-magnetic
2. Quench the bottom half in oil (the side with the tip, not the handle)
3. Put in oven at broil until a certain color
4. ??? don't remember the rest

Anyone got instructions on how to best do this? They're made of tool steel but the exact type I do not know.

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What is the material? The color/temperture changes depending on the material used.

If you are tempering coil spring or leaf spring in an oven run the part in the oven at 400F for an hour and let it cool in the oven. No need to clean it before baking. This is for coil spring, other materials may require different temperatures. If you find it too hard when cleaning/dressing then run it at a higher temperature (say 450F) for another hour

If it is a hot punch from coil or leaf spring or a "simple" steel then the benefit of heat treating will be limited since it will become drawn further through use. There is an improvement by heat treating a hot work tool, but it is limited, and only exists when the tool is kept relatively cool.


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Alternately you can "run the colors" by cleaning the cooled end on one side with a grindstone or sandpaper to bright metal. Make a line the length of the cooled end about 1/4 inch wide or wider (all the way around is best) using the residual heat in the end, watch the colors progress up the tool, (and/or heat the butt end S L O W L Y if you need to) till the tip is dark straw or purple. You want the color bands to be wide and distinct, meaning the heat is traveling slowly up the tool. Cool the entire part in oil or water when it gets to the desired color.

If when dressing it is too hard you can run the colors again and make it softer.

Again I am assuming coil spring or leaf spring


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Get the business end of the punch up to a dull orange (about 1.5 inches long) and quench it out in oil, once it is cool take it out of the oil but do not wipe the oil off. Then using an oxytorch or even over the top of the forge, heat up the punch slowly and evenly until all the oil burns off Give that a try.
Pay attention next time.

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Like Rich pointed out; TAKE NOTES! Mistake made, lesson learned, advise given, take heed. I took a class with a friend of mine and here is how it went.

The instructor said to make a penny foot, and then gave detailed instructions on how to do so, stock allowance and every step to form it. I copied the instructor's notes off of the class chalkboard as he wrote them down. My friend had made a penny foot before, and so simply wrote "Make penny foot" in his notes. About 30 minutes later, he was asking me about stock allowance, and step by step procedures in making a penny foot.
Lesson learned: Even if you "know" how to do something, write it down anyway.

Tempering is no easy process and you'll probably have to do it a couple of times to get what you want.
Here is what you need:
Angle grinder with a sanding disk on it
A bucket of used motor oil or hydrolic fluid

Heat the punch up to non-magnetic at the tip, but allow a good portion of the heat to run up into the shaft as well. Maybe a VERY DULL orange up the shaft. Quench the tapered portion (or about 2-inches,) of the punch in the motor oil. Move the punch around in the oil. Do this for several seconds and then remove and quickly sand a portion of the tapered tip until it is shiny. The heat from the shaft of the punch will "run" up into the tip bringing on the temper colors. I don't know your steel type so, start with a soft temper color. Once the tip has reached the color you want, put it back into the oil. If the shaft is still orange, bring the punch back out, sand and let the same color "run" back out to the tip. Quench again. Once the shaft has gone back to below a black heat, you can place the whole punch in oil until cool.

This works for ME on SPRING STEEL.
If you are new to tempering and are learning in a trial and error set-ep, TEMPER SOFT! You don't want you punch to shatter. If it's too soft, then retemper and go harder. (Learn the temper colors and which ones are softer which ones are harder.)

That's kind of a basic method and there are a lot of more "proper" ways to do it, but if you need a punch that will hold up for a while, give this a try.

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There are no dumb questions, however, there are dumb answers. This young man asked a legitimate question and some have decided that he needs a thorough thrashing for his slothfulness. If the question offends you, then you have the option of ignoring it.

A more helpful approach would have been to tell him that there are many posts on this site that will shed light on his problem and then perhaps give him a bit of instruction on how to use the search function to find the answer he seeks.

Without knowing the particular type of tool steel it is impossible to give the correct heat treating instructions. I suggest you go back to your instructor and explain your situation and ask him again for the correct procedure. He will probably admonish you to pay more attention and to take notes but if he is an instructor worth his salt he will once again explain how to heat treat the punch. If he won't then you have learned a very valuable lesson, he may be a world class smith, but he isn't much of an instructor.

I have trained many people in my career in a variety of subjects including Hazardous Material Emergency Response, Confined Space Entry and Rescue, and Rope Rescue, I was never concerned with the number of times I had to repeat instructions, I was very concerned that when they walked out the door they took the knowledge with them.

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Thanks for the helpful replies, especially FieryFurnace.

As I mentioned in the original post - I was exhausted. Outdoors in the heat for 3 hours, I was in the middle of grinding a piece after class when my instructor approached me and gave me directions. It was straight forward at the time and I normally don't have any issue remembering something like that - but again, exhausted and distracted and no note taking material on me at that precise second. Lesson learned.

I appreciate those who felt the need to address this and were polite about it.

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Heat, Exhaustion, PowerTools BAD COMBO!

I always tell my students to take a break *before* they make an un-recoverable mistake. (I generally don't show them my various scars to prove that I have not always followed my own advice in the past...)

If all you lost was the memory you got out fairly good.

One thing I would like to add: One poster mentioned that you did not need to clean up a piece before drawing temper in the kitchen oven; having been married for 27 years and making knives for over 30 let me say that if you have quenched in oil you better well clean up the piece before putting it the kitchen oven! It's a needed safety precaution to prevent tragic accidents happening to you when you are asleep.

Ok; another: draw temper as soon after hardening as possible!

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Who are you learning under and where?

I'm taking classes regularly at John C Campbell Folk School in North Carolina, USA.

I cannot over emphasize this point......

Remember they are instructors! They are pro's (compared to you and me,) and they have a whole lot less time to spare than you and I do. However, they are considerate enough to take their valuable time, and share their years of knowledge and experience so that we don't have to learn some things the hard way.
With this in mind, and being that they are "instructors" and our "MASTERS" (can't stress that last one enough,) when we are taking classes and we are tired and exhausted and want to quit, that's when we have to push ourselves to glean that last bit of knowledge that is shared before the close of the day. When the other students have gone on to bed, and you are the last one working or talking with the teacher, that is what will set you apart from the next guy and show the instructor that you are worthy of his time. Trust me, I've been to the exhausted point and beyond, but like I said, that's when you push yourself. At John C Campbell, we work from 13-16 hours per day for a week-long class.

The guys like Rich are not only teaching people in person, but sacrificing more time to help people out on here. They are a bit short with people who don't push themselves past the limit to take advantage of their shared knowledge, and are perfectly justified when they get a little snippy.

If you are working for a boss-man in Mc-Donald's and you forget to cook the hamburger, he's going to eat you alive. It doesn't matter how tired you are. Same here! If you make a mistake and get critisized for it, don't get too mad about it. Learn and move on! This time you forgot a note book........don't do that again! :D

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I suspect you pay your instructors, I do and I never pay someone to be rude to me. I don't believe a "professional" should be snippy. Everyone might learn in different way and at different speeds. A good instructor will recognize that and adjust his presentation. Being a master smith doesn't insure one is a good instructor.

Fiery, correct me if I misunderstood your comment on re-tempering a piece; if you tempered it soft, you can't just temper it again to a "harder" color without first hardening it again?

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What kind of steel did the instructor provide you? I was given sucker rod, which the instructor said was "blacksmith qualified" 4130, and it hardened just fine in warm water. There was an old auto coil spring in our shop which sparked high chromium, and after air cooling, it was too hard to file. A subcritical anneal got it soft enough to file a little, and probably hard enough still to use as a punch. Mild steel doesn't seem to gain much advantage with heat treatment, at least with a water quench. I wouldn't quench M-2 or even S-7 in oil. The S-7 seems to do just fine with an air quench followed by a temper at 900 - 1000F. This is a bit hot for a simple carbon steel. It is supposed to be about 42RC at this point, but my touchmark was a little hard to file. Got it touched up just fine with a carbide mill lubed with kerosene. Really depends on the steel.

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  • 2 months later...

I am getting ready to heat treat a couple punches today. Perhaps I can take some pics. I am planning to to do this like Sparky in post #8. This will be quenched in water using coil spring steel. I don't know the material specifically. I don't currently have any other medium to quench in. I have used motor oil but I'll pass on that. These were drops that Brian brought whne he visited that we made punches from. One I ruined the tip on and the other was never very round to start with. So time to redo them. :mellow: We used beesawax if I recall as a quench medium. I think that was an experiment but it worked. IF water is plane wrong well someone will say.

REgardless, that is what I am going to do. If something goes wrong I'll redo or make new ones :D

I will probably be on my own so Pics won't be very easy. I am also not an expert or even close so be gentle but please do correct me where I am wrong.

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Water may be too severe a quench for your steel, but since we don't really even know what your steel is, that's just speculation. Let me suggest that you at least use warm (say, 120-130 degrees) water for the quench. That'll help tame it a bit. Take the steel to just a shade beyond nonmagnetic before you quench. Self-tempering by letting the colors run, like FF suggested in #8, may work, although it makes me nervous. Once the piece is cooled to room temp, inspect it very carefully for any sort of cracks -- even extremely fine ones -- before you put it into service.

This is a very rough-and-ready HT. It won't work well with all steels. But without knowing what specific alloy you have, it's impossible to recommend a process that's guaranteed to work well.

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1. Heat to prep for Quench. Make sure there is heat away from the tip.
2. Quench. While quenching I was swirling and trying not to splash too much up the shaft. There may be a better way. Or maybe beacause this is COLD water I should just move it only slightly.
Mattbower, I read your comment after doing this. My water is probably in the 50F +/- 5F today. Oops maybe??? BUt one hole made so far. I am curious... Does a crack typically show up in use pretty quickly? I cleaned them on the 2x72 with 220 grit and inspected for cracks.
3. And quickly file, sand away scale to see bright metal at/near tip.

4. Watch colors. Seems most people run to straw but it depends on what you want. It was hard to get good pics of the colors. The one shown is the one that was the best as far as even seeing anything.
5. When you see the color at the tip you want to cool the tip (quench) and go back to step 3 until the colors quit running. I don't have a rulke of thumb for how far up to quench the tip. Perhaps someone does. I think I was about 1.5-2" up. If you quenched to much and the colors won't run then I guess you can do this to get some heat back in the handle so it can run into the tip.
6. Finished. Three chisels and a soon to be touch mark. Plus one hole (two heats and just a little over 1/2" thick) Didn't need to harden the soon to be touch mark but I was on a role. I may also use it the make the guide hole fit tight. Brian also said to bang the finished product on the edge of the anvil near the tip to make sure it's not too brittle. Don't want it to break when you have it in hand, near hot metal, hitting with a hammer.

If I did anything particularly wrong here please correct me and I will correct the post. I'm still a newb but I am at the stage of "do something! Even if it's wrong".... Within limits of course ;)

How do you like that Oak leaf I made... It's made out of real... Oak Leaf. :P

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I suggested warm water because many of the alloy spring steels aren't really intended for fast quenchants like water, and warming the water up will slow down the quench speed. But if it survived, it survived! (Quench cracking can have a lot to do with the geometry of the part, and punch geometry is pretty simple. That may have helped you.) As for cracks, quench cracks should show up pretty quickly. If the steel is too hard for the use you're giving it that can also cause it to crack, and those sorts of cracks may not show up right away. But if you're hot punching, the punch is going to receive extra tempering in use anyway -- to the point that you will probably have to reharden it occasionally. So if you've made it this far, just use it for a while and see how it goes. Wear eye protection!

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