? Will any "O" type press cam over?


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ironworkerwill
July 11, 2014, 11:20 AM
I've used Lee Challenger and Classic Cast presses and I don't think they were advertised to cam over, but they do. I'd like to hear from other "O" type owners.

I suppose a ''C'' type would or could, but would it be bad for the press?


I've never used a turret or progressive. I assume they will not cam over. Is this true?

Thanks.

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fguffey
July 11, 2014, 11:41 AM
I've used Lee Challenger and Classic Cast presses and I don't think they were advertised to cam over, but they do.

I have Os, Cs, Us, I have variations. I have presses that cam over, I have presses that do not cam over, one very popular press has been claimed to be a cam over press by reloaders. It is used with an attachment that includes a one way clutch. If the press was a cam over press it would be tuff on the one way clutch.

I measure, if the ram goes to the top and starts back down before the handle goes into a bind the press is a cam over press.
If the ram goes to the top and stops before beginning the return trip, the press is not a cam over press, if is a jam up, cram over, lock up press, the linkage goes into a bind and limits travel. I have modified rock Chuckers to cam over.

The RCBS A2 is a cam over press. Without a die in the Rock Chucker the ram kicks forward when the linkage is jammed together at the toggle.

All of my Herter presses are cam over presses. I have instructions that include directions for adjusting a cam over press and a non cam over press.

The cam over press is also a bump press. It is possible to measure the amount of cam over/bump.

F. Guffey

higgite
July 11, 2014, 11:49 AM
Depends on your definition of cam over. If you mean can they be made to "bump" or toggle over at the end of the stroke, yes they can, by manipulating how far the die is turned in. It "locks" the mechanism at the top of the ram stroke by putting the press mechanism in a bind.

If you mean does the ram go past top dead center and start back down at the end of the stroke, so do, some don't. My Lee Classic Cast and Classic Turret both have stops built into the mechanism to keep them from doing that, but I can set the sizing die to make them toggle over. My CH4D press has no built in stop and it cams over in the sense that the ram goes past TDC and starts back down at the end of its stroke IF its travel isn't restricted by a die.

I can make my progressive press toggle over at the end of its stroke by manipulating how far the dies are turned in. Some call that camming over, some don't. ymmv

ironworkerwill
July 11, 2014, 12:29 PM
The cam over press is also a bump press. It is possible to measure the amount of cam over/bump.

Right! I see how that would indicate "CAM"

My Lee Classic Cast and Classic Turret both have stops built into the mechanism to keep them from doing that, but I can set the sizing die to make them toggle over.
Understood. I'd always call'd it cam over.

Potatohead
July 11, 2014, 12:31 PM
Ive read the Lee Classic turret doesnt "cam over" but Im not sure. If anyone could enlighten me to exactly what "cam over" is, I could tell you. Well, I see Higgite is kind of getting at what it means exactly.

ironworkerwill
July 11, 2014, 12:37 PM
Cam is the ram sligltly lowering after the ram has reached its highest point. On the up stroke of the ram that is.

I suppose most progressive presses have stops on the linkage to prevent cam over?

918v
July 11, 2014, 12:44 PM
You don't need it to actually cam over. You need to be able to bottom out the die against the shell holder.

Catpop
July 11, 2014, 01:05 PM
Won,t any press cam over? I like mine to flat out bottom out. That way I know where I am. IMHO catpop

Potatohead
July 11, 2014, 01:31 PM
Cam is the ram sligltly lowering after the ram has reached its highest point. On the up stroke of the ram that is.

I suppose most progressive presses have stops on the linkage to prevent cam over?
Thanks IWW

savagelover
July 11, 2014, 02:40 PM
i have often wondered about this cam over thing....If the ram is at the end of travel why does it have to cam over ?It makes no since to me what so ever...If at the end,then it's at the end..:banghead:

ironworkerwill
July 11, 2014, 03:00 PM
If at the end,then it's at the end
Take my Challenger for example: Being made of aluminium, the frame will flex more than a cast frame of a similar design.

If I was to bottom out the die on the shell holder and go 1/8 more turn on the Challenger press- I'll see "day light" between the holder and the bottom of the die while sizing.

If I turn the die in 1/2 turn in after contact, then the shell holder will flush up with the bottom of the die.

gamestalker
July 11, 2014, 04:01 PM
I have an old RCBS "O" frame press I bought some years back at a garage sale that doesn't cam over. I'll have to dig it out to see what model it is, but it's a tank, very heavy cast iron press. My RC and my RS 2 both cam over.

As for whether it matters or not, I don't know. I need to dig that big boy out and give it some loading time really.

GS

horseman1
July 11, 2014, 05:34 PM
As far as I can tell, my Redding Boss press has stops for the linkage and stops with the ram at the top of the stroke. There is no going back down, unless I were to remove the steel stop pins, and then the linkage would probably hit the bench after going much further. I certainly hope this is of no concern. The press has worked brilliantly for me so far with no detectable slop that I can tell.

rsrocket1
July 11, 2014, 06:30 PM
A cam over press is difficult to adjust for bump. Since you are trying to stop the upstroke of the brass into the die, a cam over press will stop its upward motion and go back down based on force rather than stop at a certain point regardless of force. If you are neck sizing with the Lee collet neck sizing die, you can crank the die way down and the press will stop even if it is a cam over press and it will never get to the cam over spot.

If you are trying to bump with a full length die, you may never know whether you bump to the right spot because the press will cam over based on force rather than length. If all your brass is of equal softness, you probably will never have a problem, but if the brass hardness is all over the board, you may have big variation.s

tightgroup tiger
July 11, 2014, 07:03 PM
Ok, you all have me confused also. The ram on my press doesn't cam over but my linkage does right at the end of the stroke. I know this because when I preload one of my rifle dies I can feel it when it goes over. I don't see the ram starting back down. How do you define that?

This is a RCBS Rock Chucker Supreme I bought about 25- 30 yrs ago( I think). Does this mean my linkage is worn out or is it the way the press was supposed to work?

Either way, I will continue to use it because it still works beautifully for me.

tightgroup tiger
July 11, 2014, 07:13 PM
Look at the linkage at the bottom of the ram, if it cams over then it's a cam over press. My Rockchucker definitely cams over even though the ram doesn't start back down. The cam over is greatly exaggerated at the linkage compared to watching the ram. My ram doesn't appear to move back down but the linkage clocks at say 1:00 o:clock, when it hits the stop. I can't see it in the ram but I can definitely feel it.

That, to me, is definitely a cam over press.

ironworkerwill
July 11, 2014, 07:16 PM
From what I understand from this is if the ram lowers after top dead center it is a "cam over".

And if it is just past a die kiss on the shell holder on a non camover press, then it's a toggle.

Though I've called them both cam over forever.

918v
July 11, 2014, 08:28 PM
If I was to bottom out the die on the shell holder and go 1/8 more turn on the Challenger press- I'll see "day light" between the holder and the bottom of the die while sizing.

If you bottom out the die against the shell holder with a case in there, frame flex becomes irrelevant.

ironworkerwill
July 11, 2014, 08:54 PM
Yeah! That's why I have got to go past 1/8 to get a full length size.
So in the Challenger press that equates to 1/2 turn past. Or was I unclear?

The cast iron press is much less flexible. 1/8 is ok for most applications.

fguffey
July 12, 2014, 12:18 AM
I suppose a ''C'' type would or could, I suppose a ''C'' type would or could, but would it be bad for the press?QUOTE]

In the beginning it was a design of the press, the reason or rational for the design has been lost and or forgotten.

[QUOTE] but would it be bad for the press?

Cam over was a functional design, I have 3 Rock Chuckers, not one of the three will cam over. All three will lock up and or go into a bind/ A disturbing feature of the bind/lock-up is the effect it has on the ram. When the linkage goes into a bind the ram is forced out of alignment.

A video was made and posted on the Internet, the video was made while recording the ram coming up without a die, something like a no-lode condition. As soon as the ram reached to top of its travel the ram kicked forward.

Without a case and die installed in the press and no load condition the Rock Chucker appeared to be worn out. If the Rock Chucker was a cam over press the linkage would go into lock up after the ram reached the top and started down. There are RCBS presses that cam over, RCBS has published instructions on adjusting a cam over press and instructions on how to adjust a non-cam-over press.

When discussing the cam-over press they refer to the ram completing the trip up and then down as 'bump', the cam over press bumped on the way up and again on the way down, depending on how the die was adjusted.

F. Guffey

fguffey
July 12, 2014, 08:48 AM
If I was to bottom out the die on the shell holder and go 1/8 more turn on the Challenger press- I'll see "day light" between the holder and the bottom of the die while sizing.


The case won, the case whipped the press, the case has more resistance to sizing than the press has to overcome case resistance to sizing, to increase the presses ability to overcome resistance to sizing screw the die in an additional fraction of an turn.

When sizing a case I am sizing the case for a chamber, I have chambers that do not require full length sizing to restore the case to minimum length. As before, I have a chamber that requires a .014" gap between the die and shell holder. Avoiding contact between the die and shell holder is a press friendly habit, that is the reason all the leverage comes when the ram is at the top, avoid full length sizing when not necessary.

F. Guffey

Andrew Leigh
July 12, 2014, 09:20 AM
Thinking about the pro's and cons of cam over!

I almost exclusively use Lee Dies in an RCBS Supreme Press.

Rightly or wrongly, all my Neck and F/L die set-ups are set to allow the for the press to cam over. My reasoning has been this;

On the Lee Neck / Collet Die it is possible to apply varying pressure to the press handle which alters the degree of the neck sizing. Now some will point out that the mandrill stops this, in my experience this is not true as you can deform the brass which alters the neck tension. This in my case, led to very poor results as my press arm is not calibrated to any specific pressure.

Setting the die to allow the press to cam over means that you can achieve a consistent pressure each time.

Secondly, I shoot with no headspace and tune this out through setting the sizing die. As a result most my sizing dies are set off the case holder such that when chambering the round that the case shoulder meets the chamber shoulder with the slightest of pressure. This means that the only way to know you are through the stroke is for the press to cam over and bottom out.

Anyone else on the same page or should I start reading a new book?

918v
July 12, 2014, 10:30 AM
Yeah! That's why I have got to go past 1/8 to get a full length size.


How'bout you go a full turn past?

That way the shell holder bottoming out acts as the stop instead of the press linkage.

higgite
July 12, 2014, 10:46 AM
Andrew - I'm on pretty much the same page as you. I set up my Lee neck sizer such that the press just barely toggles over at the right pressure to size the case necks consistently to what I want. Easier than trying to calibrate my arm to 25 lbs of pressure on the press handle, as Lee instructs. And it works for me.

Sizing for headspace, I adjust the die and measure the sized case until I get the headspace I'm shooting for. No eyeballing daylight. No feeler gauges. No smidgen turboencabulators. When it measures up to what I want it to be, it's good to go.

fguffey
July 12, 2014, 10:46 AM
I almost exclusively use Lee Dies in an RCBS Supreme Press.

I own Lee dies, I do not use them but I have them just in case.

Thinking about the pro's and cons of cam over!

I do not have that luxury/choice, my presses either cam over or they do not cam over. I can use a dial indicator to determine if the press cams over, with a dial indicator I can determine how much cam over the press has.

Secondly, I shoot with no headspace and tune this out through setting the sizing die. As a result most my sizing dies are set off the case holder such that when chambering the round that the case shoulder meets the chamber shoulder with the slightest of pressure. This means that the only way to know you are through the stroke is for the press to cam over and bottom out.


Me to, I use a feeler gage to adjust the die off the shell holder. With the die adjusted off the shell holder the press can still bottom out as long as the reloader does not get confused with bottoming the die out against the shell holder.

Sizing for headspace, I adjust the die and measure the sized case until I get the headspace I'm shooting for. No eyeballing daylight. No feeler gauges. No smidgen turboencabulators. When it measures up to what I want it to be, it's good to go.

There are reloaders promoting the Redding competition shell holder, I have one set. I spent $5.00 for it, If not for the great price I would not have one set. I checked the deck height, three are off by .001" each, not a problem.

Sizing, measuring and sizing and measuring and measuring again? I measure the length of the chamber first, I transfer that measurement to the press, die and shell holder.

F. Guffey

rsrocket1
July 12, 2014, 11:04 AM
The cam over acts like the locking action of a vice grip. The problem is you can keep screwing the die in lower and with enough strength, still achieve a cam over until the linkage breaks or the carbide die cracks.

gamestalker
July 12, 2014, 08:48 PM
At the end of the day, it's all about how much shoulder bump is needed to get zero head space brass to chamber fit. Not difficult to accomplish, and easily repeatable if one logs those die measurements. For those who don't shoot competitively, this is accurate enough and to within .001" or less, and with most standard commercial quality brass, RP, Win, FC, and such.

GS

fguffey
July 12, 2014, 11:46 PM
The cam over acts like the locking action of a vice grip.

lever lock, snap lock with unlocking lever. Jam, cram or lock.

F. Guffey

buckbrush
July 13, 2014, 04:43 AM
My C&H Heavyweight Champion cams over.

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