What happened???

KnuckleDownKnives

KnuckleDownKnives

Time to make the doughnuts..
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Feb 12, 2015
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IMG_4058.JPG Ok so I hammered out most of this piece of metal by hand and today I pressed it with my 20t manual press and now it's cracked like a dry river bed. Any ideas what happened. I heated it to 1900 before pressing and only presses once per heat. It was already real close to finish dimensions so I didn't have to press it but maybe 1/16-1/8. Metal is from a large bearing, guessing its 52100
 
You sure on your temp? How quickly did your dies suck the heat out?
 
Pretty sure of the temp, not only by PID temp but it was def bright yellow. The heat dropped rather quick under pressure.
 
Yup... not hot enough. You do not want to move 52100 much below 1700F You need to start forging around 2100F.

It sucks but that bar is done.
 
The problem is probably a combination of too low heat and the mechanical press. It likely dropped the steel below the forging range ... especially in the thin edge area... before it started pressing the steel. I know there are folks using various home brew mechanical and air assisted presses, but your problem is the biggest drawback of them.
 
I've revamped my press today, I'll post some photos later. Added some heavier springs to retract the jack better and made some smaller 'actual' dies. The original jack in the press was only 6 ton and the springs were no where near strong enough for the new 20 ton jack. Going to try pressing a smaller section at a time and used solid pieces instead of using the tubular cross memeber. Think I'll try allowing the dies to get up to a few hundred degrees before doing any actual pressing to try and prevent as much heat loss. I'm not actually trying to draw it out much, just flatten out the sledge hammer blows. If this works better I may use it to draw some but I'll see how it goes. This time I won't use something I've been hammering on for 2 weeks to try it out.
 
Hoping these mods will help some. I originally just presses between the 2 cross members in the image. I didn't have any actual dies. Being that they are 2 1/2" x 1/4" tube, I think they just sucked too much heat my stock. I still need to make one more flattening die for the top out of 1 1/4" x 1 1/4" bar stock. I added a small spring to the jack pump that helps speed the process of pumping the jack. Like i said I'm really just trying to get rd of the hammer hits and flatten it out consistently.

1.jpg 2.jpg 3.jpg 4.jpg
 
Now, I see what Stacy was talking about. Those manual jacks are way to slow for a forging press. You are essentially plate quenching every time you use it on bar stock. I hate to say it but I fear that you are putting energy into a project that won't pay off. You might want to think about re-purposing it for something else, like a kydex press.
 
Rick Marchand said:
Now, I see what Stacy was talking about. Those manual jacks are way to slow for a forging press. You are essentially plate quenching every time you use it on bar stock. I hate to say it but I fear that you are putting energy into a project that won't pay off. You might want to think about re-purposing it for something else, like a kydex press.
Click to expand...

Actually Rick, it worked rather well last night with the updated dies. As said earlier I was originally pressing with just the tubular cross member. Last night I finished a set of 1 1/4" x 1 1/4" solid dies for flattening and one 1 1/4" round bar for drawing. I heated my steel in the forge a little hotter to 2100 and preheated the dies some by placing them on the shelf in front of the exhaust post on the front of the forge, and it worked very well compared to the OP. the original pressing with the tubular cross member did in fact just suck the heat right out. I know it's not ideal, but I only have $40 in it as the press frame itself I already had built. Using some C-clamps to prevent the jack from retracting farther than just enough to get me steel between the dies helped immensely as well as I only had to pump it about 3 times before it made contact and started pressing.

I'm in the process of upgrading my grinder from a treadmill motor to a 3hp 3phase and KBAC VFD so a real press is down the road a little while. My next big project will probably be a 20-30 ton electric hydraulic press, but just to get by for now I think this is going to work with the refinements. I've already got a 2 ton hydraulic kydex press. I'll be able to use this when I need to press a car bearing or something so it won't be a complete waste of time.

I'm going to disassemble another bearing to get the outer race off and start on it tonight. I'll post how it goes. The little piece I tested on last night I did in 5 mins what took me a few days to do on the anvil.
 
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