Jump to content

What happened?


Recommended Posts

Hey everybody, got a question. I believe I know the answer but I figured why not run it by you guys. So I started work yesterday on trying to forge a hot cut Hardie tool. The stock I was using was an old jackhammer bit that someone long before me had cut off and was using as a large chisel judging by the mushroomed end. I did some searching and did a spark test and from what I read and what the sparks show me I assumed it’s a 1060-1075 or so Steel. So I started forging out a taper on one end and found that at anything under a very bright orange bordering on yellow that my hammer blows were pretty ineffective. So I kept gradually raising forge temps until I got to a heat that I was able to actually start moving the steel. I know some of my issue is still in technique and I’m trying to learn more effective ways of forging. Anyhow I worked pretty hard to achieve the taper and I called it quits after that. I came back after price had cooled only to find a crack that goes almost all the way thru. I will add that at one point I burned the end, about the same amount the broke off was just starting to throw little sparks when I pulled from the forge st one point. So I’m guessing I burnt that thinner end of my stock. And then I also  probably worked it when it was too cool so I’m thinking the combo of burning it and then stressing that portion by working it too cold caused the issue. Any input from the pics and my description would be appreciated I am still very much a novice and I am hungry to learn and grow and develop my skill set. I’m not embarrassed by mistakes or by asking stupid questions. So any tips would be great on how to work heavier stock like that.

C1E677D7-7B85-408B-B229-A728CC248B7E.jpeg

B179937F-2E9B-4087-A76F-A5793B746AA2.jpeg

B28E80B4-9936-424D-9145-4654BBFEBBB2.jpeg

810B799F-F249-46D1-BBA1-90169E02B27A.jpeg

Link to comment
Share on other sites

Which end did you forge down? If the mushroomed end it was already stressed by who knows how much cold hammering. The grain in the break is very large especially in the center. Too much time above critical temp without adequate forging to refine the grain is what it looks like to me. How heavy is your hammer? 

Why were you forging such a long section? into a square taper? Hot cuts are wide and typically not very long. I usually don't like to recommend a heavy hammer but this might be an exception. You have to  move the steel to refine the grain. Perhaps normalizing cycles would help but that's speculation on my part.

If you check rental companies they discard old jack hammer bits pretty regularly, the Home Depot near us sells bits for $5.00 ea. If you tell them what you're doing they may just give them to you but you might have to take them all. Spade bits only need: sharpened, shortened and a shank to make fine a hardy.

Frosty The Lucky.

Link to comment
Share on other sites

Well I don’t honestly know why I made the taper so long lol, I was just going for the Brian breazel style hot cut I saw images of. I started out with 2.5 lb hammer and switched to 4 lb. I cut off and discarded the mushroomed end thinking just what you mentioned about it being stressed from cold work. I’m pretty sure now that too much heat for too long like you mentioned is probably the cause. Like I mentioned ,I’m still very much a novice. I’m a fairly knowledgeable woodworker and it took me many years of trying new things and failing and learning from those failures to get where I am in woodcraft.I fully expect to have to put in the same effort into blacksmithing. There is just a lot more sweat and physical exertion involved in making mistakes in blacksmithing lol. Thanks for the input so far.

Link to comment
Share on other sites

Don't sweat it Anthony we learn from these things. Making too long tapers is a normal beginner's hammer control issue. You are moving the work and hammer around too much. Index your tong and hammer elbows against your hips. Strike half face blows in ONE spot on our anvil and make a blunt point. I mean BLUNT 45* is a little acute but okay. Remember do NOT strike glancing blows sliding the a hammer on the work is a waste of effort and energy. Angle the blow but aim for the center of the anvil. Remember to lift the stock to match the angle you've forged on the end. Do NOT hammer back on the stock, hit ONLY the taper where you've struck before. It'll get longer as you draw the taper do NOT  chase it. strike the same place every blow.

Then take it to the horn laying the bar lengthways on the horn. The horn becomes a fuller and orienting the bar lengthways will spread it sideways. With the stock at forging temp (It's thick so let it soak a little you need the center at temp too. Lay the stock so ONLY the corner where the BLUNT taper transitions into the UNFORGED shank. Strike heavy flows on the upside corner.

This technique does two things: First it limits the contact area with your anvil and lessens the heat drawn from it. Secondly it limits the contact area to both anvil and hammer so the energy from the blow is on a smaller area and the force generated is greater. Lbs. per SQ inch, reduce the area increases the force. Yes? Steel is moved by the force per area effected.  Drawing it on the horn directs the force laterally. 

Does that make sense? 

Now, hit a rental place and buy or bum another jack hammer bit, cut a piece away from either end so you're not dealing with hammered stock and give it another try. Oh go ahead and use a sharpened spade bit for a hardy but forge one from the shank, it's a good skill.

I have to get jumping, we have a meeting today and I need to load my forge in the pickup. See you guys later today.

Frosty The Lucky.

Link to comment
Share on other sites

Assuming this is a used jack hammer tool, and we have at least some evidence of that, you may not have done anything much wrong as it could heave easily been hiding a stress fractuer from a former life. I've brocken my fair share of them in use in a jack hammer and I'm sure there are plenty on here have been employed resharpening/shaping them over the years.

Not withstanding, the good advice above is still relevent.

Link to comment
Share on other sites

On 5/12/2018 at 11:12 AM, Frosty said:

Don't sweat it Anthony we learn from these things. Does that make sense?

Thanks frosty, that does make sense and you pretty much summed up why my taper ended up so long. I will give it another go and try and employ the advice given. And thanks to everyone else that weighed in.

Link to comment
Share on other sites

  • 2 weeks later...

Hey guys I appreciate the input you guys gave on my original post. I decided to try again my hand at making a hot cut hardie. This time I decided to sacrifice a spare set of front axle shafts from my 96 Ford. After some input from you guys I had a better idea of how I should go about it. I whipped up a quick spring fuller and forged this out. Pretty happy with how it turned out. I included a few pics before a little filing clean up and after a few after a bit of filing and quenching. Just need to temper now. I read a few threads and I e read some guys saying not to bother heat treating cause the hot steel will ruin it and other guys saying to go ahead. I see the logic in both but I felt that heat treating is t gonna hurt and if it gets softer oh well. It took a nice hardening. I’m still very low on the actual finished product count so it feels food to make a useable tool from scratch. Something very satisfying about creating a useful tool. I get a somewhat the same feeling when I create a piece of functional furniture but something aliitke differt about forging out a tool from a round piece of stock. I appreciate your guys help. I’m learning every time I light the forge.

5955F75B-4066-4EDC-B215-DDC15D47FC47.jpeg

D670E8A0-5AD2-4F31-991D-CBF2CC3DD791.jpeg

55DE7DE6-FA0B-4FC5-9A39-B422345BB6F0.jpeg

A248A15F-A755-406A-8639-B4041837ABAC.jpeg

D0D6A13F-E77D-40F8-A288-902F01219BBB.jpeg

Link to comment
Share on other sites

Nice bit of forging there Anthony. One problem though, the shape of the shank is a wedge it WILL drive into the hardy hole and jam. This is bad in two ways, first it's really hard getting them out and from here I can't tell if it extends below the heel of the anvil. Second this is the weakest part of your anvil and you're driving a wedge into it like you were splitting a block of wood.

You forgot to shoulder it. Brian likes a tapered shank but it's not THAT tapered, it's just enough it slides into and out of the hardy hole easily. Done the way he does it there isn't a lot of shank in contact with the hardy hole but there's plenty to keep it from wobbling. Bottom tools like a hardy have to rest on a shoulder that provides a smooth contact surface on the anvil's face around the hardy hole. 

The shoulder is upset on the shank after the shank is forged, BEFORE the tool end, hardy, fuller, swage, etc. A Hardy has a blade that needs to end in a big shoulder at the beginning of the shank. Where you've fullered the shank in it needs to have EXACTLY the opposite profile. The shank needs to expand like you were looking at a bold head, it has to stop flat on the anvil face. 

Don't pitch the one you've made, it'll be a fine top cut just wrap a rod handle around the fullered section and strike the shank's end. I don't think there's enough meat left to punch and drift a handle eye but a wrapped handle works well. 

For the next act remember forge the shank then heat the large section, bright yellow and let it soak to make sure it's HOT all the way through. Drip the shank in the hardy hole and drive it in with a sledge hammer. This will set the shoulder on the anvil's face. If it jams don't sweat it let it set a few seconds the anvil will draw heat and the shank will shrink to you can TAP it out from below. Do NOT hit the bottom of the shank hard or you'll pien it like a big rivet and you'll have to drill and grind it out. Don't worry about the heat on the anvil face it's only going to be there a few seconds so it isn't going to draw a temper.

Don't go have lunch the steel's still HOT get to forging the hot hardy next.

See what I'm saying?

Frosty The Lucky.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...