Making drift punches. . .a couple of questions? | The Tools of the Trade | Forum

OK. . .so here goes, I'm not trying to sound like a dick, but there is a balance between how hard/brittle you make something. If you know what you are doing, you have a reference, and you you have a method to test the outcome then there is absolutely nothing wrong with hardening a struck end. . .are your hammers dead soft. No they are not. . .

. . .they have been quenched and tempered. . .true if you only quench something and do not draw it back then it will be brittle. . .that is the whole reason you temper something, to find the balance between hardness and ductility that you are looking for.

I used the drifts today. . .the holes were 3/4" diameter to start with. . .I heated the part up, drifted from 3/4" to 7/8", then reheated and drifted from 7/8" to 1". . .took one heat per drift.

Just because you quench and temper something doesn't mean it will blow apart when you hit it. . .look at jackhammer bits, they are hardened S7; the steel and the heat treat are selected for the job, the same for shears. . .L6 quenched and tempered. . .it is my job to make these types of tools on a daily basis, but I am only a beginning hobbyist blacksmith. Applications are different for blacksmithing than they are for what I do on a daily basis. . .I am trying to pick up on the specifics of the trade. . .so like I said I'm not trying to be a dick, but heat treating is part of my trade. . .

The very first blacksmithing class I took we made hot-cut and cold-cut chisels from S7 and H13. . .guess what, they were Q&T. The method was not as controlled as what I do (digitally contolled heat treating oven. . .we used a magnet to make sure we were above the transformation temperature and then tempered using color of the steel) but they work, and they have not chipped/broken in a year of use. . .tempering is the key. . .yes if you only quench then they will be harder than a goat's head and they will be brittle. . .tempering is where the "magic" is. . .I was hoping someone here would be willing/able to share what drifts are tempered to. . .but if you leave the drifts as is they will mushroom very quickly and you have to remake them that much sooner. I have chisels and punches from my Dad, who got them from his Dad, who still have not had to have the heads reground from mushrooming because the people who made them did their homework when it came to heat treating.

Neil Gustafson;17149 wrote: Good Morning,

Going back to your original question regarding how much taper to use when creating a punch. There is no magic formulae for this, quite often punches for power hammer work have quite a bit of taper. This is because the punch will release from the workpiece very easily when finished, but it takes quite a bit of effort to drive the punch through. When punching by hand hammer it is easier to drive the punch when the taper isn't as much. This also means that the punch will/can stick in the punched hole and it is best to hit the cheeks of the punched hole while the punch is still in the hole, to spring the punch free. Most of the punches that a Blacksmith use are forged not machined so it is a function of using the eye and drawing out a reasonable looking taper.

That makes sense about the power hammers vs. hand hammer process. . .the taper getting stuck also makes sense. . .I can relate that to self-locking and self-releasing tapers in mills used in my trade. I figured you would reach a point of diminishing returns with either too much taper (too much effort) and not enough taper (too easily getting stuck). . .the 5* total taper I used seemed to work pretty well, I could drift the hole to a larger size in one heat and if I flipped the work piece over the drift would fall out.

Neil Gustafson;17149 wrote: I'm glad you made up your mind to just get on with your job at hand. It is a simple function.

Something I have not always been good at, but I'm working on.

Neil Gustafson;17149 wrote: When we use the punches for making our other tools, like hammer heads and other handled tools, the punch becomes quite hot and the temper temperature has been exceeded thus causing the heat treating to be a non-item.

In that application that makes complete sense. . .I was working some 1/4" plate steel so the amount of heat I would pick up in that application is quite different from making a hammer head or a tomahawk where I have heard many people leave the mandrel/drift in place during the forming process to keep the eye from becoming deformed.

Neil Gustafson;17149 wrote: I don't know where the information came from that jackhammer bits are S-7. All the ones that I have seen, used and reforged for customers are not S-7.

I was going by word of mouth here. . .a construction guy I know had said he had a 5 gallon bucket full of used up S7 jackhammer bits and Coal Creek Forge has made several damascus style tomahawk heads which are supposed to have been made using S7 jackhammer bits, so that information entirely could be wrong.

Thanks for the info. . .