Modding the Area 419 Zero Press for less flex

[MagnumW]

what I was referring to with the die is when the ram is at top dead center and the case is inserted into the die, how much play is present. The answer is effectively zero, you are in a Class V press fit situation, or as a friend described it doing a cold extrusion. When the forming of the case is taking place the only "play" between the case and the die would be a few molecules of lubricant. Before that case emerges from the die it is as concentric as the bore of your die. Considering that dies are made using a through reamer, that would be as close to perfect as it gets.

Just my theory here but I think the necks are bent out of concentric during the downstroke when the expander ball passes through the neck and the sides of the neck. The brass is unsupported by the walls of the die at that point and logically that is the only time it can happen

In regard to the shellholder having zero vertical clearance, that is false. If it did you would have a heck of a time getting that case in and out of the shellholder without some sort of mechanical assistance. The best you could hope for there is a Class IV transitional fit and the normal RCBS shellholder would be a Class I loose fit

The bottom line is that the purpose of a press is simply to allow you to do a press fit into the die and mechanical aid you to remove the case from the dies. The die is where all the forming of the case takes place whether you use a press or a hammer to get it in.

Well stated. The press has an o-ring under the shellholder which allows play until compressed - I took that out so there is zero play UNDER the shellholder. The fit inside is loose of course.

No expanderball. When the ram is at top dead center with the die properly positioned the brass will be sized .002 shorter at the shoulder each time plus or minus some variation.
This variation of force depends upon uniformity of brass used ( number of firings and diffent loads) , state of annealing, amount of lubricant, and CONSISTENCY OF PRESS FLEX.

To achieve maximum consistency many use sized shell holders so when the brass is bumped .002 the shell holder is firmly against the base of the die - more force won’t shove the brass in further. So while it may take 30# force on handle to size the brass with shellholder you can go a bit higher to ensure shell holder is touching the die. This is the method recommended in Area 419 video’s.

Like stated as long as you are consistently getting the brass in the die the press is doing its job. You can ignore the turret flex just crank the die down more to make sure its contacting the ram.

 

[JimSC]

This variation of force depends upon uniformity of brass used ( number of firings and diffent loads) , state of annealing, amount of lubricant, and CONSISTENCY OF PRESS FLEX.

The key here is applying the same amount of force with each stroke, any flex in the metal will be the same if equal pressure is applied each time. Due to the elastohydrodynamic lubrication principle, the lubricant does not play much of a role and annealing would only come into play with spring back.

I know that this will upset many people, but the bottom line is that a press's only function is to amplify mechanical force so the dies do their job. The brass prep before the case meets the die is where the meaningful precision comes in

 

[ebb]

I think its like fishing lures, most lures were designed to catch fishermen first and fish second.

 

[Murray Brook]

I know that this will upset many people, but the bottom line is that a press's only function is to amplify mechanical force so the dies do their job. The brass prep before the case meets the die is where the meaningful precision comes in

So very true. I have always felt that good ammo is the product of good dies and procedure. Any decent press will do as long as it isn't damaged. JMO

 

[MagnumW]

So no one gets their pants in a bunch I agree with murray - its not the press that makes good ammo. That said I’m used to an O-press with no flex yet I like the Zero turret concept so Im playing with it to make it meet MY expectations which are beyond its design expectations. With a locking plate on only one side of the turret it flexes on the non-locked side with my loads.

I’ve stiffened it to where it has near zero flex for my use which requires 35# force on the handle. Will it matter on sizing consistancy? I’ll test and find out. See mockup pic. Then to 3D print or mill a comparable strength bridge piece that fits look of the press.

Enjoy a laugh at my crude mockup done for testing - it did the job just fugly and I don’t want it to block more than 2 holes. Just fooling around in the reloading room. I can think of at least 3 more ways to do the same thing but this required no press modifications.

 

[J.d. Popkes]

There is a reason that most presses are made like a "O". It would be pretty hard for me to choke down paying that kind of money for a press, and then have to come up with a solution for a significant flaw in the design.

All presses flex during sizing or any strong use. That’s why you have hard contact between die and shell holders.

 

[STS]

All presses flex during sizing or any strong use. That’s why you have hard contact between die and shell holders.

I don't have hard contact between the die and shell holder. If there is, I machine a clearance between the two so I can control sizing.

 

[MagnumW]

I don't have hard contact between the die and shell holder. If there is, I machine a clearance between the two so I can control sizing.

You have to use a set of different thickness shellholders to get hard contact at your desired bump. Rcbs sells a set of 5 - .002 increments

 

[J.d. Popkes]

Oh shit, we’re steering towards shoulder bumps! I’m bailing out.

Everyone!!!!! YOU DO YOU, YOU ARE ALL CORRECT.

 

[MagnumW]

Don’t leave yet we move to neck sizing only next!

 

[STS]

You have to use a set of different thickness shellholders to get hard contact at your desired bump. Rcbs sells a set of 5 - .002 increments

OK

 

[J.d. Popkes]

 

[Hohn]

So no one gets their pants in a bunch I agree with murray - its not the press that makes good ammo. That said I’m used to an O-press with no flex yet I like the Zero turret concept so Im playing with it to make it meet MY expectations which are beyond its design expectations. With a locking plate on only one side of the turret it flexes on the non-locked side with my loads.

I’ve stiffened it to where it has near zero flex for my use which requires 35# force on the handle. Will it matter on sizing consistancy? I’ll test and find out. See mockup pic. Then to 3D print or mill a comparable strength bridge piece that fits look of the press.

Enjoy a laugh at my crude mockup done for testing - it did the job just fugly and I don’t want it to block more than 2 holes. Just fooling around in the reloading room. I can think of at least 3 more ways to do the same thing but this required no press modifications.

Your O press has flex. A Zero has flex. A PraziPress has flex. All presses flex and this is unavoidable.

Steel has a flexural modulus of 200GPa or 30MPsi. That’s it. It doesn’t matter how something it designed, you can’t possibly make it stiffer than the parent material and there’s no such thing as infinitely stiff.

The amount of deflection in any press is a function of sizing force. And sizing force is a function of 1) geometry and 2) metallurgy.

People get all bent out of shape that they see variables in their sizing when it’s the case themselves that are the source of variation. Minute variations in hardness and thickness (yes, even in AMP annealed brass) can easily account for 0.001 of shoulder variation.

Let’s do a tiny bit of math for an example. Steel’s modulus is 30MPsi, so a force of 30lb will deflect a length of solid steel (in tension/compression) by a millionth of an inch per inch of length and per sq inch of area. So if you are sizing a case with a mere 30# of force and your ram is 10” long and ~ a sq inch in cross section, you are compressing the ram by 0.00001”. This is the amount a substantial steel ram is being compressed in the direction in which it is very strong.

Now, what if I have bending loading? What if I have hard brass or I’m sizing brass a lot? If you’re putting 30# on the press handle, you’ll putting a LOT more force on the ram itself— 100# or more.

Presses will vary a bit in the degree of how sensitive they are to variation in the cases and sizing, but consider this: a press with more flex can actually improve the sensitivity of your ability to perceive case to case variation. Measure the shell holder to die clearance with your a feeler guage set at the top of your full sizing stroke. You’ll see the variation in cases that will be eye-opening. Even with annealed, trimmed and otherwise prepped brass, I can easily see 0.0015 or more of variation within a run of 10 cases. It’s probably 0.002” in a tray of 50. And it has nothing to do with the press, dies, or such. It’s entirely case variation.

 

[MagnumW]

Your O press has flex. A Zero has flex. A PraziPress has flex. All presses flex and this is unavoidable.

Steel has a flexural modulus of 200GPa or 30MPsi. That’s it. It doesn’t matter how something it designed, you can’t possibly make it stiffer than the parent material and there’s no such thing as infinitely stiff.

The amount of deflection in any press is a function of sizing force. And sizing force is a function of 1) geometry and 2) metallurgy.

People get all bent out of shape that they see variables in their sizing when it’s the case themselves that are the source of variation. Minute variations in hardness and thickness (yes, even in AMP annealed brass) can easily account for 0.001 of shoulder variation.

Let’s do a tiny bit of math for an example. Steel’s modulus is 30MPsi, so a force of 30lb will deflect a length of solid steel (in tension/compression) by a millionth of an inch per inch of length and per sq inch of area. So if you are sizing a case with a mere 30# of force and your ram is 10” long and ~ a sq inch in cross section, you are compressing the ram by 0.00001”. This is the amount a substantial steel ram is being compressed in the direction in which it is very strong.

Now, what if I have bending loading? What if I have hard brass or I’m sizing brass a lot? If you’re putting 30# on the press handle, you’ll putting a LOT more force on the ram itself— 100# or more.

Presses will vary a bit in the degree of how sensitive they are to variation in the cases and sizing, but consider this: a press with more flex can actually improve the sensitivity of your ability to perceive case to case variation. Measure the shell holder to die clearance with your a feeler guage set at the top of your full sizing stroke. You’ll see the variation in cases that will be eye-opening. Even with annealed, trimmed and otherwise prepped brass, I can easily see 0.0015 or more of variation within a run of 10 cases. It’s probably 0.002” in a tray of 50. And it has nothing to do with the press, dies, or such. It’s entirely case variation.

Note that with Redding shellholder sets you see zero clearance between shellholder and die everytime. Thats their purpose to maximize consistency.

But you suggest an interesting point - which is more consistent inserting brass into the die to the same depth or with the same force ? Those seeing a gap are sizing with a constant force and those using the shellholders are sizing to a constant length. Everyone using the shellholders does so because they perceive their results have gotten more consistent. Fwiw.

 

[big5ifty]

.. if you are sizing a case with a mere 30# of force and your ram is 10” long and ~ a sq inch in cross section, you are compressing the ram by 0.00001”.

Those numbers are just numbers, not a real world effect.

The expansion on the metal due to ambient conditions change is greater than that.

All presses certainly do not flex.

4 thou flex to me means it's broken, and I don't care how expensive it was.

 

[coldboreshot]

This is why I keep extra containers of Jiffy-Pop (popcorn), in the pantry.

 

[J.d. Popkes]

Those numbers are just numbers, not a real world effect.

The expansion on the metal due to ambient conditions change is greater than that.

All presses certainly do not flex.

4 thou flex to me means it's broken, and I don't care how expensive it was.

Show me

 

[big5ifty]

Show me

Really.

You actually need to be shown that a reloading press that flexes 4 thou is rubbish ?

 

[MagnumW]

Its not the 4 thou flex that irks me, its that with just a few tweaks on the design it could have been eliminated.
The simplest being an extra turret lockdown bolt for if and when you want near zero flex with magnum cases.

 

[J.d. Popkes]

Really.

You actually need to be shown that a reloading press that flexes 4 thou is rubbish ?

Show me one that doesn’t flex

If you’re making solid contact with die/shell holder press flex don’t matter.

So yes, show me a press, full length sizing that doesn’t flex, with an indicator.