I've noticed several posts referring to setting up the full length sizing die so that the press "cams over". I've also seen reference to this on various reloading sites. Can someone explain what they mean. I'm not sure I understand what more can happen after the die touches the shell holder.
Importance of "Camming over"??
- Thread starter Grizzlypeg
- Start date
With a standard press, the cam changes the amount the shell holder goes up, as to the amount of movement of the handle. In other words, when the handle is fully down, the shell holder is at its highest. For the last half inch, eg, of the handle, the shell holder moves the least, thus has the most power.
If you turn the die in too far, the handle will still be up and will have far less power on the die.
To set the die for full sizing, I leave the handle fully down, turn in the die until it hits the shell holder. Then I lift the handle and turn the die down just a bit more, until the handle will still go fully down, but you can feel that cam motion, as the camming action reaches maximum.
I hope I haven't confused you, but that is my version of it.
If you turn the die in too far, the handle will still be up and will have far less power on the die.
To set the die for full sizing, I leave the handle fully down, turn in the die until it hits the shell holder. Then I lift the handle and turn the die down just a bit more, until the handle will still go fully down, but you can feel that cam motion, as the camming action reaches maximum.
I hope I haven't confused you, but that is my version of it.
If you adjust the press so that the shell holder just contacts the die without a casing in the shellholder,the extra resistance created when actually sizing a casing,will cause a slight amount of flex in the press mechanism,which can prevent the die from contacting the shellholder,and the shoulder on the case may not be pushed back quite far enough.If you add a touch of preload,the extra flex in the press will not prevent the shellholder from bottoming on the die,and the casing will be fully sized.
What Stubblejumper said--and it also helps to center the die in the threads if you tighten the lock ring with the press handle still in the "cammed-over" position. If you set a full length die to partial size this can be acomplished by putting a washer on top of the shell holder when you do the set-up.
FWIW, 44Bore.
FWIW, 44Bore.
blacksmithden
CGN Ultra frequent flyer
Cammed over: As the stroke of the ram reaches it's highest point, the handle of most presses still has a bit of travel left. Once you move the handle into that little bit extra, the ram will actually come back down slightly. So slightly that you probably can't even see it, but it does. You'll feel this as it feels like it's locked into place....the bump you feel at the bottom of the handle stroke. That's when it's camed over. It's there to let you know you've actually reached maximum stroke so that you can have consistently.
One note. When a press it near it's maximum stroke, it's developing a tremendous amount of force compared to the force that's being applied to the handle. You can damage dies if you screw them in too tight. For example (from personal experience), you can push the center right out of a Lee neck sizing die. I screwed it in so that you could really feel the cam over. I got through about 8 cases and then the top cap on my sizing die stripped out.
One note. When a press it near it's maximum stroke, it's developing a tremendous amount of force compared to the force that's being applied to the handle. You can damage dies if you screw them in too tight. For example (from personal experience), you can push the center right out of a Lee neck sizing die. I screwed it in so that you could really feel the cam over. I got through about 8 cases and then the top cap on my sizing die stripped out.
