Forging down to quarter size thickness

[Grouser1741]

So I heard the old saying Forge down to quarter size thickness heat treat at dime-sized thickness. Does this apply to someone like me who does everything from forging to heat treating in coal? Seems like if I grind down to a dime thickness and then heat treat, I stand a good chance of eating the edge off. What about the old adage Forge thick grind thin? Thanks for your help

 

[Lieblad]

Sounds good plan to me. Especially burning coal.
Depending on the part, I wont go less than about 70thou. Grinding cleans up and removes any decarb.

 

[lanternnate]

I’ve seen pics of folks using a muffle with a coal forge to avoid the burn up issue, but I haven’t tried it. I now have a propane forge, but the way I learned in a bladesmithing course and used to do for heat treating in coal is to heat it spine down. That way your thin edge doesn’t overheat. Set the spine down into the hot coal and slide back and forth for even heating.

 

[Grouser1741]

I’ve seen pics of folks using a muffle with a coal forge to avoid the burn up issue, but I haven’t tried it. I now have a propane forge, but the way I learned in a bladesmithing course and used to do for heat treating in coal is to heat it spine down. That way your thin edge doesn’t overheat. Set the spine down into the hot coal and slide back and forth for even heating.

So I missed your answer do you hammer down to dime-sized or do you grind down to dime-sized?. I bought call coal and use coal cuz I want to use Old School Technology. And I guess I'm having a battle over whether to hammer to shape or grind to shape. I don't want to feel like I just do stock removal, I want to forge a blade. So did I just answered my own question? Where is the line? I would suppose in the olden days you forged it down to where you could remove the rest with just a hand file. If I had to do that now would be a lot more hammering going on,,, a lot more hammering. But since I just bought a new 2 by 72 grinder I want to use that thing you know what I'm talking about. Thanks for the tip about turning the blade up I appreciate it.

 

[Stacy E. Apelt - Bladesmith]

The more modern saying is, "forge thick, grind thin."

The point is that you need to leqve plenty of room for refinement of the dings and bends of forging. The place to quit forging is when the edge is a bit fatter than .060" - 1/16" or a tad less than the thickness of a quarter (.070").
Once you have ground the blade to shape, the edge should be between .030 and .050" ... or a bit less than the thickness of a dime (.050").

The way to get good HT in coal is make your forge into an oven. Get the coal right and set two firebrick on each side of the hot area. Set a couple more firebricks across that to make a "tunnel" over the coals. Put the blade on the coals and work the blower to keep the heat just where you want it. Pump the blade through the coals and the "oven" space until it is evenly heated. When the blade is evenly heated and red, start checking with the magnet. When the blade stops sticking, heat a little redder ( about 75 degrees hotter) and quench.

 

[lanternnate]

So I missed your answer do you hammer down to dime-sized or do you grind down to dime-sized?. I bought call coal and use coal cuz I want to use Old School Technology. And I guess I'm having a battle over whether to hammer to shape or grind to shape. I don't want to feel like I just do stock removal, I want to forge a blade. So did I just answered my own question? Where is the line? I would suppose in the olden days you forged it down to where you could remove the rest with just a hand file. If I had to do that now would be a lot more hammering going on,,, a lot more hammering. But since I just bought a new 2 by 72 grinder I want to use that thing you know what I'm talking about. Thanks for the tip about turning the blade up I appreciate it.

I’ve never measured it by pocket change but yeah personally I forge to what is probably roughly quarter thickness or just a hair more and grind to around dime size before heat treat. No matter how good your hammer work, you will need some wiggle room to get things clean and flat. My second tip, don’t try to grind forge scale. Soak that blade in vinegar after forging for 24 hours and it will feel a lot less like you are doing a lot of grinding after forging.

I too started a bit more traditional. I switched to propane because it was easier to fit in forging time around life without dealing with the startup/cleanup time. Nothing you can’t do with that coal forge. Have fun!

 

[Grouser1741]

I’ve never measured it by pocket change but yeah personally I forge to what is probably roughly quarter thickness or just a hair more and grind to around dime size before heat treat. No matter how good your hammer work, you will need some wiggle room to get things clean and flat. My second tip, don’t try to grind forge scale. Soak that blade in vinegar after forging for 24 hours and it will feel a lot less like you are doing a lot of grinding after forging.

I too started a bit more traditional. I switched to propane because it was easier to fit in forging time around life without dealing with the startup/cleanup time. Nothing you can’t do with that coal forge. Have fun!

thanks for the advice sir,,,

 

[Grouser1741]

The more modern saying is, "forge thick, grind thin."

The point is that you need to leqve plenty of room for refinement of the dings and bends of forging. The place to quit forging is when the edge is a bit fatter than .060" - 1/16" or a tad less than the thickness of a quarter (.070").
Once you have ground the blade to shape, the edge should be between .030 and .050" ... or a bit less than the thickness of a dime (.050").

The way to get good HT in coal is make your forge into an oven. Get the coal right and set two firebrick on each side of the hot area. Set a couple more firebricks across that to make a "tunnel" over the coals. Put the blade on the coals and work the blower to keep the heat just where you want it. Pump the blade through the coals and the "oven" space until it is evenly heated. When the blade is evenly heated and red, start checking with the magnet. When the blade stops sticking, heat a little redder ( about 75 degrees hotter) and quench.

Funny you should mention the Fire Brick Trick, I just figured that out my last forging session. Build a little cave it was a lot easier that way. Thanks