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Working with Scrap Jackhammer BIts?


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*large* flat springs: dump trucks, RR cars

Large coil spring: got one from an earth mover that was about 1.5" in diameter stock---and *snapped*!

I would suggest looking for a heavy equipment repair place and asking them about broken stuff...A box of doughnuts for the office/floor staff will often pay off *handsomely*! (As well as explaining what you are trying to do; smithing fascinates a lot of folks.)

Note that the section down the hardy hole does NOT need to be high carbon steel and traditionally wasn't

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You could do like they did in the old days and forge it out of Iron and forge weld on a strip of high carbon steel. I'm sort of half kidding. I have a friend that uses a piece of hot rolled angle iron with a shank welded on it as his hardie. He has the one side sticking up sharpened It works but it is far form ideal. 1045 will work too but it will have to me made thick if you want it to hold a good edge. A lot of people have hardies that are ground like cold chisels. This is wrong and is a bad habit. It makes for a more uneven cut and takes more effort to cut. They should be forged thin like a hot chisel. As for the curved top I don't like that because it can be harder to keep the steel on the hardie. I forged my hardie from S-5 it is thin it cuts with a minimum of effort when it gets worn down I sharpen it with a file. Periodically I will reforge the edge when it has gotten too thick about once a year. But I also was forging a lot of stainless steel when I made this so I needed a high performance hardie.

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What I would suggest is to make the hardy with a straight edge and use it for awhile.If it doesn`t work as you had hoped then it`s easy enough to grind a camber into the edge and try it that way.
I agree with Southy about grinding it thin in either configuration.

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Once you start forging that jack hammer bit, it's going to fit quite snugly in the hardie hole. You will be forging square, so if you hit it on the corners first, it's going to upset larger than 1 inch, then just taper until it fits the hardie. I do endorse the Brian Brazeal type rounded hardie. You have to treat your tools like they deserve to be treated. The rounded shape allows you to easily start with the heated steal on the far side of the semi-circle and to roll the material toward you as you cut, then you can push it away from you with your hammer head and cut as you roll back toward you. This allows you to avoid overheating any one section of your hot cut. It also provides for a more efficient cut, because the rounded shape of the blade reduces surface area contact. No need to bulldoze your way through the material.

Mark

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Wow. It has been something of an odyssey to get it this far. Certainly a learning process. I appreciate all the information provided in this thread. I have been working on the hardie and the steel in the bit has been quite tough, certainly more resistant to forming than mild steel. However, in its defense, my anvil is only a small farrier's anvil. Id love to get a good blacksmith anvil but I am afraid finances don't permit at the moment. I have chronicles the effort up to now in pictures.

I started with a jackhammer bit and cut it on either side of the collar because my small forge cant take the whole thing. I then heated it to yellow and then cut the propane and buttoned up my brick pile forge tight to let it anneal (or normalize, I wonder what the line is between the two in time cooling). Perhaps that was an unnecessary step but I was worried about the stresses the steel had been through and also it was a good way to burn off lubricant that could not be removed via cleaning.

After annealing I began to forge the hardie shaft. I first squared off two opposite points of the hexagon and then knocked down the flat sides slightly in order to get a near square that was very close to fitting in my hardie hole. This took multiple heats and I experienced something I never have in my admittedly short time of smithing. When striking along the flat side, the metal wanted to jump up off the anvil after each hit and I had to set it back into position. Anyway, after I had it close I was ready to try the final fitting. It was close but not exact. So I took the shaft and put it over the hardie and then slammed it down into the hardie as an improvised swage block. It took three successive heats but it finally seated in the hardie and quite tightly at that. I figure if it is too tight I can grind off a bit from each side if necessary.

During the driving of the hardie shaft in the hardie, I noticed that I had managed to upset the metal on the top which suited me fine as I wanted it a bit wider on the sharp side than the original bit. I also managed to knock it off center as you can see but I think I can fix that with a heat or two. If I had proper tongs It would be easier but I have to make do with vise grip clamps at the moment.

Then I started working on the taper for the blade of the hardie. At this point I learned first hand about fishmouthing Apparently the outside of the material is moving but the inside isn't. I am not sure how to fix that or prevent it from happening again. I could always grind off the current fishmouth but if I dont know how to prevent it, I will just end up in the same situation again.

And that is where I am now. I had thought of tapering the shaft a bit more on the bottom inch to make inserting in the hardie as well as increase the length and be able to knock it out of the anvil if it gets a bit stuck again. I had also thought to first round the stock above the colar then square it and finally taper it with one straight flat side and the other side beveled.

Comments or suggestions are appreciated.

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Robert, you are doing great! You have built a functioning gas forge, you are making your own tools, and proving your tenacity. Learning is what this is all about anyway.

Normalising is never wasted when working tool steel, for the reason you provided.

Fitting a hardy tool, hot, in the anvil is the right way to go. Beware though that slighty too cold steel and too hard blows can break the heel right off.
Also, when completed it should fit loose enough that you can grab it out of there quickly with just your fingers.

Maybe your next project should be tongs? It's always hardest in the beginning when you need the most and have the least. Vice grips are tough for hot work because they are so short. Giant channel lock pliers might help.

Fishmouthing; at this point you best grind off ONE side, since you are going for a butcher style IIRC. I would then suggest using your hardy hole and carefully upsetting the remaing edge a little, asuming you want the tool edge wider than it is currently. Then spread it using the pein end of your hammer, with the pein oriented in line with the length of the tool. Peen, flatten, etc. This will taper and spread the end, and will cause it to asume a radius shape as well.

For preventing fishmouthing, bevel the end by strinking at a an angle at the very end. Push the outer metal as low as the center metal. In this case do this work from one side since you are making a single side cutter. You may have to use the part of the horn near the waist since the collar will keep the tool from sitting flat on the face. Hope this helps.

Don't hesitate to use a grinder for corrections, if it will prevent cold shutting, fishmouthing or piping. As you become more proficient this will be less necessary.

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Robert,although the metal may act like it has a mind of it`s own it really is only going where you direct it and doing what you tell it to do by way of the hammer.
My own personal approach is to make small corrections while the work progresses and with practice and a good eye these will become second nature to you and you`ll do them without even thinking.
I`ve known smiths who use the bash now and correct later approach and even have a few friends who still chide me about how picky I am.The end result is the real test,if the tool operates in a safe and satisfactory manner then the rest is eye candy.

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It is jumping off the anvil for one reason: It is not held/struck flat to the anvil

Since color is relative to many things, is the slag (scale) liquid when you pull the part?

Arftist is right about the fish mouth. Looks like mine did at that stage. If you close the mouth then there will be a crack formed by the metal not welding together (cold shut). You can cut one lip off with a grinder, or forge a little more and use a hot cut chisel to take the lip off. Do not try closing the mouth. It is possible to forge a lip in and make the mouth disappear, but be careful to not form a cold shut.

Looks good, you will enjoy using this tool when you are done!

Phil

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At a more advanced stage that fishmouth can come in handy---it can be cleaned up and used as the slit to drop in a piece of higher carbon steel and then forge weld it together.

Not worth the hassle at your starting stage and as I mentioned once you get a working tool you may find out that you would rather make other things than to go back and re-do things already made.

I find that a curved hardy is easier to set the piece onto it and you can walk the cut if you need too.

My project this weekend is to forge 2 hardies from high carbon small wedges, (leborg? with a falchion trademerk?) I picked up at Quad-State. My goal is for each anvil to have it's own tooling which I will then colour code for my classes and having a small hardy length will help avoid hitting it with a hammer---a lot of my students seem to work on the shotgun principle when they hammer "close is good enough"

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Nice work, especially considering that you don't have good tongs! Being able to hold the work securely makes a tremendous difference.

There are many ways to correct the fish mouth problem. In addition to cutting or grinding it off, and correcting it as you go by foring the corners back in (as others have suggested), you can anticipate it, and forge or grind in (i.e., bevel) the corners on the end of the stock before you start reducing it.

As for its causes, it's basically a question of the force of the blows. I can't really explain the physics, but relatively light blows tend to move the outer layer of metal, whereas relatively heavy blows (relative to the size of the stock) tend to move the center. A light hammer will tends to spread the top surface and give you concave sides, whereas a great big power hammer tends to cause swelling in the middle of the work, producing convex sides even on very large stock.

I know what you're thinking, "but I'm using a 4 pound hammer, and I'm hitting it hard!" I believe you. But it's pretty big stock, and you're only using a 4 pound hammer and a 70 pound anvil.

As Phil said, if the work is jumping off the anvil, it's because it's not being held flat against the anvil. Just takes practice. Striking the work when it's not flat can hurt sometimes, which has educational value. :o

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You can also try using half face (half hammer) blows on the edge of the anvil, Brian Brazeal would call this "choosing dies." With a half face blow you have a smaller contact area and force is localized more, so on this thick stock you will move the metal a little faster.

Phil

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Just excellent information. Thanks guys. I will use my new ryobi 8" grinder and cut off the fish mouth. Why only one side?

I am wondering if ti would be easier if I rounded up and then squared the Cutting part of the tool first before trying to bevel it. Also do you think it would be a good idea to set the flat side of the final tool down a bit more so it is more in the middle instead of way off to one side? I wanted to have one flat side and one bevel side.

As for the heat, I was running the propane at 15psi for a while until the bottle started to freeze. It was as hot as my little forge will get it. I will have to get more BTUs to get it any hotter. I have plans for a better forge based off of frosty's design but not the finances alas.

Finally yeah, tongs need to be next. I started working on some small ones but I need some bigger stock to do large ones.

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Just excellent information. Thanks guys. I will use my new ryobi 8" grinder and cut off the fish mouth. Why only one side?



Nice grinder.

You are drawing the edge out thin, the fishmouth is already thin and partially drawn out, so it is to save effort (and material) in the long run. It will be easier to move the "lip" to the position desired than to draw out another edge. In a sense you will be moving the edge of the cylinder to form the cutting edge instead of taking material from the center.



I am wondering if ti would be easier if I rounded up and then squared the Cutting part of the tool first before trying to bevel it. Also do you think it would be a good idea to set the flat side of the final tool down a bit more so it is more in the middle instead of way off to one side? I wanted to have one flat side and one bevel side.


Going round is extra effort since you cannot draw out round, you have to draw out square (or rectangular) You do not really need to go round at any step while making this tool.

About edge position, I made mine symmetrical, it is tall enough that I can choose my bevel by raising or lowering the bar as I cut. If I raise the held end then the held end can have a flat cut, with more of a point on the cutoff piece, and if I lower the held end then the held end will have a blunt point with the cutoff being flat. If I hold the bar level both ends have blunt points.

Nothing wrong with asymmetrical, might even be easier to maintain the edge, but it's not what I did. A butcher shape will tend to act like one end of the bar is elevated making one blunt point and one flat side.

Put a crown on the edge. As mentioned some make the edge a half circle, and some make it straight. The crown will make it easier to sharpen the edge. Also if the edge is hollow you increase the likelihood of hitting the edge with a hammer or chipping the corners of the tool off.


As for the heat, I was running the propane at 15psi for a while until the bottle started to freeze. It was as hot as my little forge will get it. I will have to get more BTUs to get it any hotter. I have plans for a better forge based off of frosty's design but not the finances alas.

Finally yeah, tongs need to be next. I started working on some small ones but I need some bigger stock to do large ones.


Get a trashcan or tub and fill it with water. Stabilize the propane bottle in the water so it is pushed down some. Propane gasifies nice to a bit below 0F, so you can have a good block of ice form without worries. Starting with warm, but not hot, water is best but I typically use cold tap water.

Do you have bricks to use as front and back doors? Once you are running hot limiting your exits will increase your temperature some due to less heat loss.

Phil
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Well, I have made some progress. I have the blade tapered and fanned out a bit. It isnt quite perfect but for a first timer I am pretty happy. Hopefully it doesn't look horrible. I had the thing fishmouth a couple of times while tapering and went to the bench grinder to grind it off completely before proceeding. Then I got my son (age 14) to help as my striker with a 4# hammer which moved the metal much faster than I could have alone. Finally I took the result to the grinder and ground a bevel in the metal. In the picture below it might look like there is a low spot in the grind but its just a trick of the light. You can also see how it fits in the anvil.

In the process I finished my coil spring center punch by heating it yellow, quenching it then heating it slowly with my torch until the end was tempered purple.

Let me know what you think.

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Well, I have made some progress. I have the blade tapered and fanned out a bit. It isnt quite perfect but for a first timer I am pretty happy. Hopefully it doesn't look horrible. I had the thing fishmouth a couple of times while tapering and went to the bench grinder to grind it off completely before proceeding. Then I got my son (age 14) to help as my striker with a 4# hammer which moved the metal much faster than I could have alone. Finally I took the result to the grinder and ground a bevel in the metal. In the picture below it might look like there is a low spot in the grind but its just a trick of the light. You can also see how it fits in the anvil.

In the process I finished my coil spring center punch by heating it yellow, quenching it then heating it slowly with my torch until the end was tempered purple.

Let me know what you think.


Good job Robert! Now aren't you glad you didn't have really nasty steel? The punch "might" be a little soft. It's a shape that that can handle being a little hard. Good on ya!
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How`s it work?
I`ve made(and continue to make) some incredibly ugly stuff that is real handy to have around.

The next one will be more refined in both the visual and operation end of things.I find if I hammer up something that`s just good enough after I use it for a while I find ways to improve it.Once I have enough modifications in my head to warrant making new I go for it.
I also make it a point to keep some of the ugliest stuff around to both keep me honest and to remind me how far I`ve come since the first one was made.

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Well, I have made some progress. I have the blade tapered and fanned out a bit. It isnt quite perfect but for a first timer I am pretty happy. Hopefully it doesn't look horrible. I had the thing fishmouth a couple of times while tapering and went to the bench grinder to grind it off completely before proceeding. Then I got my son (age 14) to help as my striker with a 4# hammer which moved the metal much faster than I could have alone. Finally I took the result to the grinder and ground a bevel in the metal. In the picture below it might look like there is a low spot in the grind but its just a trick of the light. You can also see how it fits in the anvil.

In the process I finished my coil spring center punch by heating it yellow, quenching it then heating it slowly with my torch until the end was tempered purple.

Let me know what you think.


I think it looks great.
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Very cool, Robert. Nice job indeed.

I'd caution you that when you say yellow steel, I think temperatures of ~1800 F and above. And those are awfully high temps to quench spring steel from. Not only does it increase the risk of quench cracking, but temps that high promote grain growth in all but the most highly alloyed steels, and grain growth leads to brittleness. Generally speaking, the only steels that we (should) harden from that high are highly alloyed, air hardening, tool and stainless steels. For low alloy and carbon steels -- including the medium and high carbon 10xx steels, 5160, 6150, 4140, etc. -- the appropriate hardening temps tend to run in the range of 1500-1600 (usually closer to the low end of that range). To me, in a somewhat dimly lit shop, that looks like about a low orange, but for most things I use Tempilaq rather than trusting my calibrated eyeball.

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"Ugly stuff": I too have some early stuff I forged that is "ugly". I have always promised myself that when it broke/wore out I would re-make the items with benefit of my increased experience.

Unfortunately(?); some of them have not broken after about 30 years of use. Guess I got them right even if ugly back in my beginning days!

I'm slowly replacing them; usually as a demo for a student who needs to make something similar.

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Good job Robert! Now aren't you glad you didn't have really nasty steel? The punch "might" be a little soft. It's a shape that that can handle being a little hard. Good on ya!


Why soft? The chart I have for tempering says for punches it should be purple. Are your referring to another source of info?

Oh and thanks for all the compliments folks.
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Very cool, Robert. Nice job indeed.

I'd caution you that when you say yellow steel, I think temperatures of ~1800 F and above. And those are awfully high temps to quench spring steel from. Not only does it increase the risk of quench cracking, but temps that high promote grain growth in all but the most highly alloyed steels, and grain growth leads to brittleness. Generally speaking, the only steels that we (should) harden from that high are highly alloyed, air hardening, tool and stainless steels. For low alloy and carbon steels -- including the medium and high carbon 10xx steels, 5160, 6150, 4140, etc. -- the appropriate hardening temps tend to run in the range of 1500-1600 (usually closer to the low end of that range). To me, in a somewhat dimly lit shop, that looks like about a low orange, but for most things I use Tempilaq rather than trusting my calibrated eyeball.


I am cheap, and Tempil products for these temperature range seem hard to find, unless buying a case for $100+.

I have a ceramic doughnut magnet (5 for $3 at Radio Shack) hung on a piece of copper wire from inside a phone cable. Non-magnetic happens to correspond with the correct temperature for hardening many varieties of steel (look at a phase diagram for your particular steel to be sure) If the magnet is attracted to the steel it is magnetic, and if the magnet swings naturally then it is non-magnetic.

I have had good results with leaf and coil spring at a bit above non-magnetic and a canola oil quench. I have not made many hardened tools yet though, so there may be a better temperature and quench.

Phil
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Nonmagnetic is 1414 F, which is a tad cool even for simple steels, if you hope to max out the martensite. The magnet is certainly much better than nothing, especially assuming you swing a little past non-mag before you realize you're there (which you are very likely to do). But I find the Tempilaq easier to work with. I bought mine Brownells, and in my previous post I linked to another place you can get it. You can also find it at McMaster under "temperature indicating paint." One bottle goes a pretty long way.

Warm canola is actually a very fast quench. Maybe a bit too fast for some of the oil hardening steels. That's something you just have to experiment with.

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