Clever checkmaker
- Thread starter Spindrift
- Start date
Tomme boy
Well-Known Member
OK Ian, I want one for 35 cal for the Legend! LOL
The punch needs to be hard. When I worked at a forging shop the punches were al hard. They would go about 500,000 of cycles before needing to be replaced. Imagine a ball joint on a car or truck. It starts out as a cup. Then the top would be punched out. I am talking a 1/2" hole about 3/16" thick. This was just one operation for it. This was done with a cold forging. Now the hot forging presses would run a few Million nuts or washers before the punch needed to be replaced. They ran at about 120 parts per min. They would shear of a piece of steel from round stock then punch and form the basic shape. Once up and running they don't get shut done very long because the heat needs can not get too low. It takes a special warm up cycle to prevent warping the rail and framework. So tooling has to last.
The guy that is making this is not using heat treated parts. He is doing this on a mini Harbor Freight lathe.
The punch needs to be hard. When I worked at a forging shop the punches were al hard. They would go about 500,000 of cycles before needing to be replaced. Imagine a ball joint on a car or truck. It starts out as a cup. Then the top would be punched out. I am talking a 1/2" hole about 3/16" thick. This was just one operation for it. This was done with a cold forging. Now the hot forging presses would run a few Million nuts or washers before the punch needed to be replaced. They ran at about 120 parts per min. They would shear of a piece of steel from round stock then punch and form the basic shape. Once up and running they don't get shut done very long because the heat needs can not get too low. It takes a special warm up cycle to prevent warping the rail and framework. So tooling has to last.
The guy that is making this is not using heat treated parts. He is doing this on a mini Harbor Freight lathe.
Ian
Notorious member
Mini-lathes can handle O-1 tool steel no problem and the working surfaces can be hardened and normalized without much drama.
Studying this some more, I think the design we're looking at would be much better suited for an arbor press. I just don't see how there will be room to run the cutting stage near press cam-over due to needing clearance for the material strip passing through the slot. The challenge with flipping the setup over is drilling a long punch for the press ram all the way through (tough material, probably need to drill at least 2" through, likely 2.5") and then finding a way to make the gas checks fall out the bottom of the punch and not scatter everywhere. A slit window would help show when it was full and would be taken off the press ram and dumped.
If swapping ends, the punch could be machined with a simple rim to fit a common shell holder like .223 or .30-'06 and that would serve as a stop for the checks at the bottom as well. The top could be made in two pieces, the cutting/forming piece with the insert would be at the top and a plain threaded body on the bottom. The two could be joined with a standard 7/8" NF nut that had a window cut through it. Thread the top and bottom die body pieces together until the desired clearance is achieved between them and lock each in place with a thin jam nut. This would eliminate slitting the die and make it possible to produce a much finer, polished cutting edge for the discs.
Studying this some more, I think the design we're looking at would be much better suited for an arbor press. I just don't see how there will be room to run the cutting stage near press cam-over due to needing clearance for the material strip passing through the slot. The challenge with flipping the setup over is drilling a long punch for the press ram all the way through (tough material, probably need to drill at least 2" through, likely 2.5") and then finding a way to make the gas checks fall out the bottom of the punch and not scatter everywhere. A slit window would help show when it was full and would be taken off the press ram and dumped.
If swapping ends, the punch could be machined with a simple rim to fit a common shell holder like .223 or .30-'06 and that would serve as a stop for the checks at the bottom as well. The top could be made in two pieces, the cutting/forming piece with the insert would be at the top and a plain threaded body on the bottom. The two could be joined with a standard 7/8" NF nut that had a window cut through it. Thread the top and bottom die body pieces together until the desired clearance is achieved between them and lock each in place with a thin jam nut. This would eliminate slitting the die and make it possible to produce a much finer, polished cutting edge for the discs.
Ian, my daughter who does happen to be a manufacturing engineer who works with presses and such says an angle would be bad. Too easy to get egg shaped parts and she feels the forces may actually be worse as you are now cutting their what is essentially thicker material do to the angle.
I agree that hardened parts would make sense. O-1 is the official choice.
I agree that hardened parts would make sense. O-1 is the official choice.
A2 should machine about like O1 if I read things right.
Just hear to proper temp and let it air cool? Then anneal for proper time and temp.
I need a small heat treat oven in the future. No oxy-acetylene on hand so I need something to get it hot enough.
Just hear to proper temp and let it air cool? Then anneal for proper time and temp.
I need a small heat treat oven in the future. No oxy-acetylene on hand so I need something to get it hot enough.
KeithB
Resident Half Fast Machinist
Just checked stock in shop. I have a 1.25" dia x 6" long hunk of A2 in my exotic material drawer and 6'-8' of 7/8" dia A2 on the rack. I don't have enough time right now to mess with making a checkmaker, although I have some ideas. But if someone has the tools and time to do it I would be glad to donate one of my Lee type die bodies and enough A2 to make the parts.
Ideas? I love ideas.
I can easily order 24” of A2. Die bodies I have many of, seems that if you send Keith money he sends you boxes of them!
I do need to get a slitting saw, I don’t see a practical way to get that slot any other way. At least not ina precise way
I can easily order 24” of A2. Die bodies I have many of, seems that if you send Keith money he sends you boxes of them!
I do need to get a slitting saw, I don’t see a practical way to get that slot any other way. At least not ina precise way
Ian
Notorious member
My problem is time. I already committed to the non-toxic bullet gig.
If we made the die bodies out of Keith's 1144 blanks I think the punch would need to be a press-fit insert of tool steel since the stress-proof doesn't harden well.
My suspicions are confirmed about the slanted hole. Looking at disc broaches and hole punches I keep seeing a double-saddle, four-point design. We have to consider how the punch shape will draw the metal and make an even skirt on the gas check. Since the punch also forms the check, it needs a continuous belt just inside the cutting edge to press the check over the mandrel and getting too fancy with the cutting edge geometry could affect the way the punch draws the check and could draw it out in a square or with creases. I was and am just thinking out loud.
If we made the die bodies out of Keith's 1144 blanks I think the punch would need to be a press-fit insert of tool steel since the stress-proof doesn't harden well.
My suspicions are confirmed about the slanted hole. Looking at disc broaches and hole punches I keep seeing a double-saddle, four-point design. We have to consider how the punch shape will draw the metal and make an even skirt on the gas check. Since the punch also forms the check, it needs a continuous belt just inside the cutting edge to press the check over the mandrel and getting too fancy with the cutting edge geometry could affect the way the punch draws the check and could draw it out in a square or with creases. I was and am just thinking out loud.
