Inconsistent Full Length Resizing

[mtenenhaus]

from the Zediker article:
"Some reloading presses, and RCBS comes first to mind, are designed with eccentric linkage. The concept involves circular motion and linear motion, meaning that when the ram traveling in a linear path reaches full extension, the linkage, which is traveling in a circular path, can move through the 0-degree mark and go to a negative degree."

[fguffey]

I thought that the Forester press wasn't supposed to cam-over - I also am not sure how cam-over would effect the headspace

Press cam over; reloaders have been trained to say "cam over", they have no clue what it means nor do they know how it got started.

F. Guffey

[fguffey]

Unless you are adjusting a stop on the press linkage which changes how far the handle moves the ram, you can not adjust a press to cam-over or not cam-over.

Not true,

I nave 3 Rock Chucker presses, none of them are cam over presses. I have 12 Herter presses, all of my Herter presses cam over. I sent a box of equipment instructions to Uncle Nick, some of the instructions went back to the mid 50, everything a reloader wanted to know about 'cam over' was in the box. And then came the Internet.

My Rock Chuckers will not cam over because the Piggy Back 1 & 2 have a one way clutch.

F. Guffey

[ar15barrels]

not to drive this thread too off topic - I though I knew what cam-over meant but after this thread and the subsequent couple of hours that I spend reading different post on multiple different forums, checking a couple of books and falling into the youtube vortex I can't find a definitive answer... though I think I came close with a 10 year old post by Guffey on a differnt forum

could someone give a clear and concise answer as to what exactly cam-over is

Cam-over is when the press linkage passes top-dead-center.
You will FEEL the applied pressure slightly drop as you get past TDC if you have a load on the press such as while sizing a case.
You will not feel it without a load unless you have a die adjusted in such a way that the press is in tension without a case in the die/shellholder.

[Bastard]

Cam-over is when the press linkage passes top-dead-center.
You will FEEL the applied pressure slightly drop as you get past TDC if you have a load on the press such as while sizing a case.
You will not feel it without a load unless you have a die adjusted in such a way that the press is in tension without a case in the die/shellholder.

Thanks!

my old Pacific/Hornady does this and is what I have always believed cam-over meant, but then you start reading a bunch of forums and you begin to doubt yourself... like I said, I read a post by Guffey where he talked about camming vs binding/hard stop which made the most sense but still left me unsure

[fguffey]

Unless you are adjusting a stop on the press linkage which changes how far the handle moves the ram, you can not adjust a press to cam-over or not cam-over.

Not true, I could see that happening if your dies did not have threads and that goes for the press also. Reloaders are so obsessed with 'bumping'; they believe they can bump the shoulder of the case back when sizing, they also believe than can move the shoulder back on a case when sizing with a die that has case body support.

In the beginning there were no bumpers, they did not start a sentence with "I bump", today they take the easy way out. They make it up as they go.

Cam over press: the cam over press was also know as the bump press before the Internet. The impossible concept that is impossible for a reloader to understand about the cam over press is the cam over part.

Reloaders have been conditioned to add the phrase 'cam over' when describing the travel of the ram. On a cam over press the ram travels up to the top of the stroke, it then stops and then reverses direction. While all of this is going on the reloaders does not have to think, all he has to do is operate the handle.

If the reloader had shop skills and a few tools he could attach a dial indicator
to the ram when it gets close to the top of the stroke. A cam over press ram will go up, stop and then start back in the other direction.

Again with a small amount of shop skill the reloader could determine how much cam over the press has with a dial indicator. The amount of cam over in the old days was a way to determine the amount of 'bump'. Because! When the ram hit the top of its travel the shell holder on the top or the ram 'bumped' the bottom of the die.

This is the reason reloaders became 'bumpers' 'too much information'.

When adjusting the die to the shell holder on a cam over press the reloader has decisions to make. I make these decisions automatically. If I choose to size the case at the top of the stroke I adjust the die to contact the bottom of the die. If I choose to take advantage of the cam over design I can bump the bottom of the die after the ram when stops on the way down.

Reloaders have been trained to adjust the die 1/4 turn after the shell holder contacts the bottom of the die. On a non cam over press that would mean the die was lowered .017", if the same technique was used to adjust the cam over press with an additional 1/4 turn the reloader would have to remember the amount of cam over and then add the .017" to the amount of cam over.

I used an A2 RCBS press that had .032" cam over; problem, the owner of the press could not lower the ram after sizing a case. He called me. To lower the ram I backed the die off 1 1/2 turns (.138") and then lowered the ram. I did not agree with the case lube he was using and I did not agree with his case cleaning methods. After I got him set up he did not change his cleaning methods nor did he change his case lube.

F. Guffey

[fguffey]

Thanks!

my old Pacific/Hornady does this and is what I have always believed cam-over meant, but then you start reading a bunch of forums and you begin to doubt yourself... like I said, I read a post by Guffey where he talked about camming vs binding/hard stop which made the most sense but still left me unsure

I have three Rock Chuckers, at one time I had 5, none of them would cam over. For 20 years I have not found one reloader that would push their way away from the keyboard long enough to examine their Rock Chucker. One day a member of another forum reported me to RCBS. The RCBS reloader at RCBS gave his name and extension to the complainer; he instructed the complainer to tell me to call him.

RCBS is the same company that sold me 2 Piggy Back press with the understanding the PB 1 and PB 2 will not work on a cam over press; at the time I asked them If that was the reason the PB 1 & 2 have a one way clutch? They explained the progressive press can only turn in one direction. And then I ask them; "like the clutches in planetary of an automatic transmission? And then they aske me what would happen with a one way clutch if it turned backwards? I said the one way clutch will be rendered scrap. And then I ordered a replacement one way clutch, after receiving it I hooked it up and it worked, once the clutch was installed the drive for the shell plate would only turn in one direction.

When the Rock Chucker ram hits the top of its travel the ram misaligns because the toggle gets tangled up with the linkage and then the ram goes into a bind. The top of the ram is forced forward and the bottom of the ram is forced to the rear.

If reloaders were thinkers they would think the ram/shell holder would not align with the die. Bless their Hearts.

F. Guffey