One tool to split and drift

[GregDP]

I had an idea recently that one could split and drift a square (diamond?) shaped hole with the same tool. But the geometry of such a tool has thrown me for a loop. I'm sure it's rather simple concept to some but I've struggled any advice would be appreciated.

Has anyone seen/made/used such a tool? (pictures would be great!)
Is there a specific name for such a tool? (Or is it just a chisel when cutting and a drift when drifting?)

I'm sure the usefulness of such a tool is highly debatable but I've set out to make one anyways if only as an exorcise.

I've had limited success so far and I don't think a lengthy post is desired here, but I've detailed my experiences in my two most recent blog entrees if anyone would like more insight into my questions.

PS: this is more of a general blacksmithing question but I don't think it warrants a second topic.. As I understand it the length of the slot to be cut is 2a - 5% ('a' being the width of one of the four sides of the the hole to be punched). In Mr Hofi's blueprint his chisel cut a rectangular hole, less of a 'split'. I'm led to believe I may need to account for the thickness of the chisel as well. Does anyone use any other formula? When I was first approaching this problem I assumed the diagonals of the square would be used to calculate.

[ThomasPowers]

As I see it one issue is that the chisel end is wider than the drift end as the 2 sides of the chisel must cut enough to make the 4 sides of the diamond.

I can envision a tool made with the wide chisel and then the "fat" diamond that gets driven all the way through the piece and falling out on the other side by making a smaller "driving end" to allow it to be pushed through and fall.

[brianbrazealblacksmith]

GregDP, There is an old thread in "general Discussion" titled "slitter Geometry" that shows the tooling for slitting and drifting a square hole on the diagonal on page 1 on the 12th post.
You could make a tool that would slit and drift, but I wouldn't advise it unless you only intend to make one hole. When you drift, you don't normally slam it through from one side. You get the drift out after a few hits when the hole starts to "shadow", and then drift through the other side after the heat wicks back. Your punch or chisel end would be damaged in the act of removing it from the hole by tapping it on your anvil or turning it over and tapping it out with your hammer.
Slitting chisels do not work as well as stitting punches. I know most people who slit and drift use chisels and that the books say to use chisels, but until you try the punches you'll never know why they work better unless you use reason to figure it out. Don't believe everything you hear or read and don't belive me! I've been making and using these types of punches long before I got around other blacksmiths, and I've tried the other ways (chisels and flat punches). There is no doubt which works best from my experience, and I have experienced all those ways. I'd like someone to show me better ways, but so far nothing.
http://www.iforgeiron.com/topic/10211-slitter-geometry/page__hl__%2Bslitter+%2Bgeometry__fromsearch__1

[GregDP]

***Please delete I'm an internet idiot - Greg***

[GregDP]

2 sides of the chisel must cut enough to make the 4 sides of the diamond.

I think I'm followinging you, to rephrase: the mass of any length of the chisel (past the cutting edge) should not be greater than the mass of an equal length of the thickest part of the drift.. or if the chisel is a rectangle and the drift is a square then they should have an equal perimeter?

GregDP, There is an old thread in "general Discussion" titled "slitter Geometry" that shows the tooling for slitting and drifting a square hole on the diagonal on page 1 on the 12th post.
You could make a tool that would slit and drift, but I wouldn't advise it unless you only intend to make one hole. When you drift, you don't normally slam it through from one side. You get the drift out after a few hits when the hole starts to "shadow", and then drift through the other side after the heat wicks back. Your punch or chisel end would be damaged in the act of removing it from the hole by tapping it on your anvil or turning it over and tapping it out with your hammer.
Slitting chisels do not work as well as stitting punches. I know most people who slit and drift use chisels and that the books say to use chisels, but until you try the punches you'll never know why they work better unless you use reason to figure it out. Don't believe everything you hear or read and don't belive me! I've been making and using these types of punches long before I got around other blacksmiths, and I've tried the other ways (chisels and flat punches). There is no doubt which works best from my experience, and I have experienced all those ways. I'd like someone to show me better ways, but so far nothing.
http://www.iforgeiro...__fromsearch__1

I've seen that the drift is usually driven through the other side of the hole after the first drift, but completely let it slip my mind when considering this project! I think that is the final flaw of many that make this idea a grade-A flop.
I'm still in need of figuring out how to make a hole that has an equal amount of material on both sides, half the the width of the stock.. kinda like the bar just grew past the inserted piece. So I'm not sure the punch is the way to go in this instance. If I knew how to upset the middle of a small length of stock like I'm working with I could probably manage with a punch. I appreciate the link, and have found it informative so far!

[brianbrazealblacksmith]

GregDP, I have made a punch and drift before but only to make a handled punch for making hammers before I had a handled punch to punch a slot for hammers, and, yes, it was a sacrificial punch and a shorter drift.

I think you may be missing my point about using a slot punch instead of a chisel for making a slot. The picture that I referred you to has a slot punch that looks like a slitting chisel like Hofi uses, but it is not used the same way. A chisel only works like a chisel when it is backed, so when you use a chisel like the books say by driving it 2/3 or 3/4 of the way through and then driving it the rest of the way from the other side; it does not cut. It only stretches and forms a bubble until it can stretch no more, and then it bursts the bubble. That is why every hole done that way with thick stock has cold shuts inside the hole, and with thin stock there is always some stretched raggedy material. Punches work better but not flat punches. Flat punches have too much surface area contact. The punches I showed in "Slitter Geometry" are not like any I have ever seen or read about, but they work better for square, rectangular, round, or slot punching. They are just not conventional Knowledge yet. Reread the thread and try it, and if you have any questions, just ask.

[bigfootnampa]

Your formula is pretty close... which is as good as a formula can be. To get real professional results you would make some test joints and adjust the tooling as needed to refine the fit and finish. Brian's slitting punches do essentially the same job as a slitting chisel. The formula would be the same in either case though the refinements might vary slightly. The way that Brian makes his slitting punches they really are closer to chisels than to standard round punches... a big advantage IMO is that the way Brian's punches are shaped gives slightly more mass at the cutting edge which helps to resist meltdown in the slot. The slugs are very small so most of the steel is pushed out of the slot just as when chiseling. By making a separate drift for your joints you could make both a slitting chisel and a slitting punch in Brian's design... then you could do test joints with each and let us know what works best for you. The reason for leaving the slot a bit short of twice the length of the sides is to allow for a slight stretch of the metal and make sure that the ends of the slot do not still show in the finished joint a slight upset in the joint area can compensate for this slight stretch for an extremely refined fit if such is desired.

[brianbrazealblacksmith]

No, no, no. There are some good points in the last post, but some other point are totally incorrect. Sorry, man, it's all about the metal to me.
In the first post I made, I included the "Slitter Geometry" thread. In that 12th post it has a picture of 2 different holes punched with the slitting punch that is pictured and drifted with the diagonal slot opening drift for that sized slot which is also pictured. One of the holes is left as drifted and the other on the diagonal has been hammered as stated to square it up and bring it back to plane from the hollowing out you will get from any punch or chisel, so there is no need for upsetting.
One of these days I am going to get High Speed Photogrophy and show the whole world what I've been talking about.

Lyle, and everyone out there that has punched holes this way, tell them what you see!

[brianbrazealblacksmith]

Peacock, Do you remember when Tom called you up and asked if it was possible to punch this way? I had punched a square hole in a 1 3/4 inch cube that I made in the power hammer class that William Bostas taught that day with a square punch that I made out of mild steel. The punch was 1/4 inch at the end, and I had to cool it frequently, but I punched a small plug out, and the punch held up. Tom asked me why I didn't use H13 or S7 because he had plenty of that. I told him that I was trying to prove a point. The geometry of the punch has more to do with the amount of work done and the proprer use than the need for super steel. Tom said he called you and said that you said that it might be possible.

[GregDP]

Mr BrianBrazeal I think I'm on the right track of logic now. I kid you not that it came to me lying in bed this morning trying to get just 30 more minuets of sleep but my mind kept wondering. Imagine how happy I was to see you'd taken the time to explain what hadn't sunk in yet. "Cold shunts" would be that odd thin collared ring of metal that formed inside my first two test slots. I'd previously attributed to male-aligned slots and i nexperienced. I read last night that the plug "takes the path of least resistance"... I've only done small round punches and they even have very small slugs that are popped out.. but for some reason in my mind punches displace metal (to the floor), were as I thought chisels moved metal out of the way. What you're saying is that with your "chiseled punches" is that they have less resistance than a flat punch to make working easier. But when the time comes to either "pop the bubble" or "punch" a nice clean even hole.. then they have just enough resistance to get the job done. No upsetting required because the amount of metal removed is nominal and it avoids what is apparently a problem for folks with a little more time at the anvil as well.
If I remember correctly typing isn't your strongest trait so thank you for taking the time to repeat yourself. I should have taken more time to read and reflect before writing off what you had to say.
I hope that I can put your advice to use (safely) with the steel I have on hand. Even though it's no fancy tool steel I've had decent results with coke dust and a 5 gallon bucket of water.

[LDW]

Hey Greg looks like you got the idea, but there will be no need for the coke or coal dust. The punches work efficiently without sticking. When we punch a hole through a round blank sometimes the punch will stick right before the slug pops out, but a shocking blow straight down usually frees it.
As Brian said when drifting a punched hole, the drift will cool the hole therefore when the steel turns black around the drift you can hold the top of the drift and hit the bottom of the drift on the anvil and it will pop right out. Makes you look like you know what your doing. This will allow the heat to wick back in and you can flip the steel over and drift from the other side resulting in a beautiful clean drifted hole. The one thing I did not see mentioned is to use a matching hole to your drift to set the metal on to keep from hollowing out the surface being drifted. This also backs the slotted hole better to keep from pulling as much metal through. Here is a picture of fieryfurnace on the last hit of the drift. In the next picture he flips the metal to drive the drift from the other side. You can see Brians "dial a hole" underneath the metal.
https://picasaweb.google.com/106506050631612810521/DavesLastDayAtBrians#5721927395590079554

[Francis Trez Cole]

GregDP you are over thinking it Brian is the man and his method works very well. I punch and drift 2 1/4" stock all the time using his method. make the punch and punch and drift 10 holes then come back and share what you have learned.