Flattening thick round stock

[Shainarue]

I am trying to forge a hot cut hardy tool using what I'm guessing is a jackhammer hammer bit that I got from Billy who in turn got it from the scrap yard (in middle of pic below). I chose the one without threads, it shows a bit darker in the pic than the other bits. It's around 1.5" diameter. The skinny end was pretty close to fitting the hardy hole, just a little loose but I'm okay with that for a cutoff tool. So I got the other end hot and started flattening the end to form an edge for cutting. But as I flatten, it's puckering (dimpling?) inward - which I assume will create a cold shut and that's bad. I don't want to rotate and thus draw out - or do I? How do you go about flattening large stock? I thought I'd grind out the threads and use another one to create a fuller hardy if I can figure out how to do this cutoff one.

[Frazer]

Yes, I would address the puckering as you go. It will likely happen on the sides perpendicular to your wedge (cupping/puckering) and on the end that will eventually become your edge (fishmouth). I would only worry about the sides and grind out the fishmouth when you're done.

Working it hot and hard (ie with a striker) will minimize the amount of puckering. What's going on is the amount of force being applied is enough to move some of the thickness, but isn't sufficient to act on all of the material, leading to a sort of mushrooming effect.

If you have a welder you can run a couple of beads down the shank to make the fit in the hardy hole a little tighter.

[Frosty]

What's happening is the surface of the steel has less resistance to movement than it does deeper so the surface moves farther. It causes "fish mouthing." 

The way to avoid this is to draw tapers and points from the end towards the center of the bar. Strike your first blows directly on the edge aiming towards the center. You can grind the edges at a 45* angle to maybe 1/4 the thickness of the stock. That's the first technique I learned.

I learned drawing tapers from the end back from Brian Brazeal and have never gone back. He starts any taper on the end by first beveling, then drawing to the final point size with half face blows. That's say a sharp point on 5/8" square that goes back no farther than 5/8", the taper is of course longer than that but he measured the parent bar to show he'd forged no more of the length than the thickness.

So you have a bar with a 45* point and you're holding the parent bar at 45* to keep the forged section flat on the anvil. Then he leans the parent bar down to say 22.5* so the only thing in contact with the anvil is the corner between stock and taper and forges it down until the new face meets the point. He (I) repeat the steps until I have the desired length of taper. No  measuring stock, no calculations, fast easy and ZERO fish mouth.

On thick bar like you have it isn't necessary to forge the end to the desired edge but go at least half way and keep the parent stock elevated so the faces are flat on the anvil. 

Frosty The Lucky.

[Charles R. Stevens]

Are you talking about the sucker rod knuckles? That it pretty close to 6040. I a halt forge them the other way. I set down the roundish side of the square shank to fit the hardy hole. For a hot cut forging down the threads won’t cause any issues. 

If you watch Jenn draw about tapers she moves back from the edge and fullers down forcing the center to bulge at the end. I would call that advanced, lol.

[Irondragon Forge ClayWorks]

Those next to the RR spikes are as Charles said sucker rod ends. I have some that are 4130 steel. There are numbers on those rod ends that a google search should bring up a data sheet showing what they are made from. I use the threaded end for the hardy shank and the other end for the tool. I downloaded a sheet but can't find it now.

[patrick]

The problem you are having requires two things to correct: 1 You need to make sure you are pounding on a minimum of 3/4 inch of length as measure from the end that is being tapered and 2 you must have enough power to get deformation at the center of the cross section. Without both at the same time you will always  get that fish mouth/pucker effect no matter if you are forging by hand, with a power hammer or with a press. Another way to say this is that your die bite must be at least 1/2 the cross section of the stock and you must have a pretty deeply penetrating blow ( I typically recommend a blow hard enough to penetrate 20% of the stock cross section.  That is tough to do by hand hand with stock this big so an alternate approach is to cut or grind a taper, even a blunt taper, on the end before forging. This will put the center ahead of the surface and prevents the fish mouth effect.

[Shainarue]

Thanks everyone! I'll try to get out and get something done Tues and/or Wednesday. After that we have rain for about a week so I'll be working on stuff I can do inside, like sanding little pieces for another project, wiping stuff with blo, might bring the farm leg vice to the garage and work on that a bit too. Anyway, if I get something done, I'll keep ya posted. 

[Charles R. Stevens]

Oh, and make sure it’s fully hot. Think foster marshmallow. Tan in the outside and gooey on the inside

[BillyBones]

Kind of hard to explain but i upset the bar. I will upset the bar till it has just a bit more diameter. Maybe a 1" bar going to a 1 1/16", not much. Then when i forge it down, the corners will push straight down forcing the middle of the bar out. Like i said kind of hard to explain. 

[Chad J.]

I'll work at a steep angle  upsetting the bar like I would forging the tip of a blade until.  I'm also quick to hit any cold shuts with a hot rasp.  

[anvil]

plenty of answers. Heres a couple more suggestions. Use a heavier hammer. Forge it with a crosspeen. If you are using the flat face, then rotate the hammer handle in your hand and use the edge of your hammer face like a cross peen.