I've always been lead to believe that floating dies produce better reloads because they allow calculated "slop" to cover for imperfections in the threads of the press and die, and for any unevenness in the press ram. As such I have a Forester Co-Ax and have free floated all my die sets for my 550B.

However, I was thinking about this today, and wondering how this is so. The floating dies allow the case to center properly, but as soon as you raise the ram, all the slack is taken up and now the die is "hard mounted" to the top of the threads, essentially negating any effect of free floating dies.

For example, as many of you know, with the Co-Ax, the dies are "free floated" by sliding the locking ring into a slightly oversized channel. This allows the die to move in all three directions, and also allows it to pitch and yaw. Theoretically this covers for any imperfections in the threads on the die or on the lock ring that cause the die to be out of alignment with the press ram and case. However, once you put upward pressure on the die by raising the press ram, the top of the lock ring is forced against the top of the oversized channel, meaning the die is now "hard mounted" just as if it were screwed tightly to the press. If the top and bottom of the lock ring are not perfectly parallel (meaning from the side the ring looks more like a trapezoid than a rectangle), the die will still be out of alignment, even though it is "free floated". Am I wrong in my thinking or is this really what happens?

I don't own this kind of equipment but I have an idea how it is supposed to work and your tought seems to me really reasonable.

Forster had the solution to a non-existant problem.

It's not just Forester as I know that David Tubb floats his dies as well. He doesn't seem to do something unless it's proven to make him shoot better. That's why I'm wondering if maybe I'm missing something here.

Something has to restrain the die. No matter what DT says he is losing a degree of freedom somewhere. Just like with your Coax press, the lock ring makes the die stop. If the ring is not square to the die body then guess what, the case gets forced into the die at an angle leaving the case head out of square.

I have two co-ax presses and their isn't any "slop" in my dies.The die slides front to back as designed to center over the round, but does not tilt on the horizontal enough to be anymore problem than any press with its shell holder. Make sue you use their die collars
Dan

quote:

Originally posted by ireload2:
Something has to restrain the die. No matter what DT says he is losing a degree of freedom somewhere. Just like with your Coax press, the lock ring makes the die stop. If the ring is not square to the die body then guess what, the case gets forced into the die at an angle leaving the case head out of square.

A RCBS bulletin said the shell holder must touch the bottom of the die to square the FLRS die with the shell holder. If you PFLRS as i do, then you will need a shim between the shell holder and the bottom of the die. When the shell holder and die are making contact, this is when you tighten the lock ring.

quote:

Originally posted by DannyH:
I have two co-ax presses and their isn't any "slop" in my dies.The die slides front to back as designed to center over the round, but does not tilt on the horizontal enough to be anymore problem than any press with its shell holder. Make sue you use their die collars
Dan

I do use the Forester lock rings. I'm not saying "slop" as in poorly machined parts. I'm saying that the channel was deliberately machined to be larger than a lock ring.

I also assure you that your die can pitch and yaw in Co-Ax. It's not much, maybe a few tenths of a degree, but it's still there. You dont' get all that much pitch and yaw from free floating a normal thread in die either, but it's all you need.

quote:

Originally posted by 243winxb:
A RCBS bulletin said the shell holder must touch the bottom of the die to square the FLRS die with the shell holder. If you PFLRS as i do, then you will need a shim between the shell holder and the bottom of the die. When the shell holder and die are making contact, this is when you tighten the lock ring.

This is why Redding Competition Shellholders are worth the price!

I have used a Forster for many years and here is what I have reached for conclusions:

The head of the press allows for fore-and-aft movement along that axis, with only a little movement in other directions. This movement is possible up to the time that the bottom of the press stops its movement.

The shellholder(s) allow for side-to-side movement up to the time that the bottom of the press stops its movement.

Between the two of the above, there is an infinite number of combinations available to follow crooked brass or to not induce a built-in misalignment.

In a regular press with screw-in dies, the threads always induce a small amount of crookedness and/or wobble in the dies. However, most of this is corrected for by tightening the lock-ring with the shell holder touching the bottom of the die under pressure.

The amount of tilt induced in the Forster by the lock-ring setup is no worse than the amount induced in a usual press with a threaded die arrangement and it may be better. Forster lock-rings are a tad better than others, being made with this in mind; hence, thier higher price.

The straightest ammo that I load on a conventional press is with my Forster, but the others are not bad and I do allow my dies to float. I use an arbor press for my benchrest rifle, along with L.E. Wilson dies. That, theoretically, is the best of what I have.

The co-ax allows the dies to float horizontally to self align with the cartridge during use. It has very little room for floating angularly, and any such float is certainly resisted when the lock ring presses against the top or bottom of the slot. That's the value of the co-ax mechanical design that avoids torque moments between the shell holder/"ram" and the die holder, rather than allowing them and trying to resist them, as conventional presses do.

The co-ax shell holder is perfect for precision loading, since the flatness and thickness of the jaws is very easy to control during manufacture.

How does one go about "floating" the dies in a 550?

Andy

I am not happy with the die system.

Fire formed concentric cases go into a die concentric and come out of good dies still concentric.

But bent brass comes out of good dies still bent.

The problem is that the necks gets sized first, and the brass is floating at that time.

quote:

Originally posted by BigJakeJ1s:

...

How does one go about "floating" the dies in a 550?

Andy

David Tubb goes over in The Rifle Shooter, but essentially you drill a hole into the tool head into which you secure a roll pin. You then drill a hole in your lock ring slightly larger than the diameter of your roll pin. Place the lock ring such that the roll pin you installed into the press head slides through the hole in the lock ring. Hold the lock ring just slightly off the top of the press head. Now screw the die into both the lock ring and the press head. Keep in mind that the lock ring can't rotate because it now has a pin in it connecting it to the press. Tighten the lock ring when the die is at the appropriate depth.

It's hard to explain online, but if you can find a copy of Tubb's book it'll become clear in a second.

Bully, you touch on a subject little known and rarely understood; we can't force a die-to-case alignment with hard mounted dies/etc. But we CAN force a curve into it if everything is hard mounted but off center!

I know of people who tossed a press because the ram had a little slop at full elevation, thinking it was too poorly fitted to make good ammo anymore. I tried to explain that all the ram does is push the case into the die and that ram slop only allowed the tapered case to slide into the tapered die with a precision fit but to no avail!

Anyway, a loose ram will allow the brass to align perfectly but you are right, the friction under load may prevent a misaligned die from moving quite as much as it may need for perfection. It will still be plenty good tho!

Bullydog,

Thanks for the explanation, I understand it perfectly.

quote:

Originally posted by Jim C. <><:

I know of people who tossed a press because the ram had a little slop at full elevation, thinking it was too poorly fitted to make good ammo anymore. I tried to explain that all the ram does is push the case into the die and that ram slop only allowed the tapered case to slide into the tapered die with a precision fit but to no avail!

Anyway, a loose ram will allow the brass to align perfectly but you are right, the friction under load may prevent a misaligned die from moving quite as much as it may need for perfection. It will still be plenty good tho!

Well, yes and no...

On a traditional press, the linkage exerts a sideways force on the bottom of the ram. If there is slop in the ram fit in the press, this will result in the top of the ram traveling in an arc from the bottom to the top of the stroke, rather than in a straight line. Combined with the friction resisting the free-sliding movement of the case in the shell holder (or shell holder in ram), this arched path tends to force an arched entry of the case into the die.

One way to get around this problem in a conventional press would be to have some sort of crossed roller bearing arrangement that would allow the shell holder to float horizontally, and virtually frictionlessly, over the top of the ram. Technically, there would still be a slight angular misalignment during the arched travel, but I doubt that would be enough to worry about.

Andy

quote:

Originally posted by Bullydog:


David Tubb goes over in The Rifle Shooter, but essentially you drill a hole into the tool head into which you secure a roll pin. You then drill a hole in your lock ring slightly larger than the diameter of your roll pin. Place the lock ring such that the roll pin you installed into the press head slides through the hole in the lock ring. Hold the lock ring just slightly off the top of the press head. Now screw the die into both the lock ring and the press head. Keep in mind that the lock ring can't rotate because it now has a pin in it connecting it to the press. Tighten the lock ring when the die is at the appropriate depth.

It's hard to explain online, but if you can find a copy of Tubb's book it'll become clear in a second.

Wait a minute... That sounded good the first time I read it, but on second thought...

Given that die threads are not acme (square), but triangular in cross section, merely loosening the die will still have the tendency of the die to seek the same center, just as if it were a flat-head screw in a conical countersink. Thus I'm not sure how much the die is going to seek alignment with the cartridge/ram vs the alignment with the male-female thread interface.

Andy

Bullet seating, do you really want a ram or die floating around when using standard RCBS type bullet seating dies? I dont think so, as the case body is not supported by anything. A custom bullet seating die with a inter sleeve to guide the case should work ok. Lets face it, factory dies are not bench rest dies, they are hit and miss at best as to quality. They are mass produced.

quote:

merely loosening the die will still have the tendency of the die to seek the same center, just as if it were a flat-head screw in a conical countersink.

Exactly!!!
And if the lock ring is not square on the die threads it will jack the die off center and hold it there.

bIG Jake -

quote:

On a traditional press, the linkage exerts a sideways force on the bottom of the ram. If there is slop in the ram fit in the press, this will result in the top of the ram traveling in an arc from the bottom to the top of the stroke, rather than in a straight line. Combined with the friction resisting the free-sliding movement of the case in the shell holder (or shell holder in ram), this arched path tends to force an arched entry of the case into the die.

Welll... to use your terms, Yes and No.

Yes. the wear pattern is greatest as you describe. But most rams wear all around due to the collection of primer grit they eventually gather. This usually allows the raised ram to be rotated in a small circle by hand. BUT --

Ram float, or "slop", doesn't matter because the case slips straight into the die and properly aligns the ram as it enters. Thus the die to case fit is as precise as it can be! On the other hand, if the ram fit is tight AND misaligned the case must bend as it enters the die, damaging the potential accuracy.

ALL custom rifle smiths use a floating chamber reamer when fitting a new barrel for the same reason, the float allows for a precise chamber.

BR hand dies align precisely because they totally "float" and are not locked into a massive chunk of potentially imperfect iron (that is, a common press).

(Another factor usually ignored in presses is the shell holder. There is a degree of slop in a shell holder's fit in the ram AND in the extractor groove's fit inside the shell holder. Thus, no matter how tight someone locks down his dies it won't improve the loose fit of the press' shell holder system!)

Bottom line; No, because a loosly fitting ram in a press does absolutely no harm and it can do great good.

A couple of observations on the analogy to floating reamer holders used in machining:

1. Floating reamer holders use ball bearings and/or polished mating surfaces to minimize lateral friction so that they pull off the alignment of the reamer as little as possible during use. Such is not the case with any ram/shellholder/case arrangement I've ever seen. Interestingly, about a year ago, Hornady announced a floating "shell holder holder" described as similar to floating reamer holders, for just this purpose. They pulled the announcement from their website shortly thereafter, and I never heard anything more about it.

2. Good machinists will be the first to tell you that a floating reamer holder is no substitute for an accurate alignment in the first place. They are usually considered insurance for that last little bit of accuracy. Typical range of operation for them is under 0.01", but quality of results is generally proportional to the amount of initial misalignment. I've seen much more slop, and/or "hard" misalignment than that in many press rams.

So what does all this mean towards sloppy and/or misaligned rams in reloading presses? Generally the less of both, the better.

Andy

Jake, your observations on a chamber reamer are correct but have only a casual application to a reloaders press and dies, I only used that illustration to show that floating fits can have a precision effect on some things. So, OK, IF the press and ram and die and shell holder are all in perfect alignment then no float is required for a precision fit. But that rarely, if ever, happens in our world, no matter what brand of tools we use.

In practice, the top of the ram is well stabilized by the case going into the die, at what ever position it needs to travel. All of the ram force is applied from us to a slopply fitted handle, toggle linkage and cross pins but the force on the ram is applied vertually straight up. This means that unless there is a misaligned but tightly fitted hole in the middle the rising ram will guide straight into the die while it's firmly supported at top and bottom.

That's why a tightly fitted ram can't help case alignment and will actually hurt unless EVERYTHING is nearly perfect. I say "everything" because the case's extractor groove, the shell holder's top slot and also its fit into the ram, the toggle linkage and both the press's and die's threads all come into play for final alignment. These factors can easily negate a precise but rigidly fitted press and ram.

A bit of side play in a ram is good.

quote:

Originally posted by Jim C. <><:
In practice, the top of the ram is well stabilized by the case going into the die, at what ever position it needs to travel. All of the ram force is applied from us to a slopply fitted handle, toggle linkage and cross pins but the force on the ram is applied vertually straight up. This means that unless there is a misaligned but tightly fitted hole in the middle the rising ram will guide straight into the die while it's firmly supported at top and bottom.

Take a look at a traditional reloading press (like a rock chucker or Lee Classic cast). When you start pulling on the top of the handle (with the handle at the top and the ram at the bottom of the stroke), which direction are you pulling?

I'll bet it's mostly towards you.

Now look at the bottom of the press. What's there to resist that forward force, to act as a fulcrum to turn that force into vertical force on the ram? The linkage arms can't provide it, they're hinged at top and bottom. The toggle is only constrained by the linkage arms and the ram, so all it can do is transfer that forward force to the ram (remember the linkage arms can't resist it). So that leaves the bottom of the ram having to resist your forward force, providing the fulcrum to rotate the force to upward pressure on the ram. Now, if the ram fit is sloppy, particularly fore and aft, that forward force on the ram will translate into fore and aft tilt on the ram, in addition to the vertical force moving the ram up.

Now, when you get to the bottom of the handle stroke (top of ram stroke), what direction are you pushing now? I'll bet it is at least partly to the rear (away from you, towards the bench).

For the same reasons your forward force on the handle translated into forward force on the bottom of the ram, your rearward force also translates into a rearward force on the bottom of the ram. This induces a fore and aft tilt in the opposite direction from the beginning of the stroke.

So during the stroke, you transition from a forward to rearward force on the bottom of the ram (in addition to the upward force). That causes the top of the ram to travel in a slight arc (depending on the amount of slop in the ram to press fit), not a straight vertical line.

Andy

Jake, I guess we've hijacked Bully's thread but we are both addressing a core side issue of his floating die question.

Anyway, all of your progression thru lever-toggle-ram travel is true but most of it is inoffensive to ram travel because there is virtually no resistance to the ram's rising until we approach full extension. Then, when we first begin to actually apply sone real pressure on the lever, the toggle and the swingling link's pins are very nearly in the same plain. Thus the vectored forces on the ram during those last few degrees of toggle rotation and link swing, almost all of the driving ram's force is carefully designed to be straight up. So at the point of maximum hand force there is virtually no front-to-rear pressure on the ram!

The ram's initial side loading forces are so low they are trivial until about the point case to die contact occurs. So the applied angles of hand pressure really have no significant effect on the ram's travel nor, especially, on the final case-to-die alignment.

Of course it is good that a press be well made and the various holes in good alignment. All of that is just as you cite in the example of barrel chambering, mechanical things should be close before starting. BUT, for the final case and die alignment to accomidate all of the variables listed in my previous post, it remains helpful for the ram to be slightly undersized, or a bit sloppy. Only then can things precisely "float" together without mechanical binding, no matter what or where any slight misalignments may be.

Jim, I think we both agree on the value of a small amount of slop somewhere in the process, we just disagree about where it is best located.

I believe it is best located in either the die mounting itself (as in the co-ax press), or in the shell holder, since there are no external lateral forces (other than friction) trying to push the die/brass anywhere but centered on each other if everything else is "tight".

I also believe your mechanical analysis of forces on the ram at the end (ram at top) of the stroke is flawed. Most traditional presses have a handle angle approaching 45 degrees below horizontal when the ram is at top of stroke. Since most people tend to apply force to the handle at a right angle to the handle, this means that approximately as much force is put on the handle towards the bench as downward. All of that horizontal pressure is resisted by the ram fit in its bore. The relationship of the pivots on the toggle to those on the links is irrelevant since the links are not resisting the horizontal force at that point in the stroke, the ram is. In fact, the vertical orientation of the links is what dictates that they can only assert (or resist) vertical force in that position.

You are correct in that the horizontal force on the ram is proportional to the vertical force, and that neither reaches maximum until near the end of the stroke when resizing tapered cases. Unfortunately, this is exactly where most of the resizing happens, and having the brass centered in the die, with minimum off-axis force, is most critical.

Incidentally, we should also look at what happens during the return stroke, when the neck is expanded. Most dies are designed such that the case fits rather loosely in the die (thus not held centered) by the time the expander button is pulled into the bottom of the neck. Note also that opposite horizontal force is operating on the ram, pushing it in the opposite direction as during the up stroke of the ram. Some dies are designed with the expander button located near the top of the stem so that the top of the neck is still held centered as the button is pulled into the bottom of the neck. I would suspect that these dies would have the most benefit on presses with a sloppy fit between the ram and its bore.

Most mechanical engineering statics textbooks are full of examples of similar mechanisms, and provide useful insight into the interactions of forces in such systems.

Andy

Okay. But are we both talking about presses with compound toggles or single toggles? (I have been addressing compound systems.)

I like the Forster size dies too! I adjust mine to start expanding almost as soon as the case starts down to maintain neck alignment as much as possible. Wish they made the buttons from carbide for a slick and easy removal.

quote:

Originally posted by Jim C. <><:
Okay. But are we both talking about presses with compound toggles or single toggles? (I have been addressing compound systems.)

I like the Forster size dies too! I adjust mine to start expanding almost as soon as the case starts down to maintain neck alignment as much as possible. Wish they made the buttons from carbide for a slick and easy removal.

The compound system, where the handle is attached to the toggle, which floats between the linkage arms and the ram.

Regarding the Forster Sizing die, I've always wondered what happens if the case gets stuck? With traditional dies, there is room enough to withdraw the spindle far enough to allow drilling/tapping the primer pocket. Can you withdraw it far enough with the raised expander ball?

Andy

quote:

..what happens if the case gets stuck? ... Can you withdraw it far enough with the raised expander ball?

It's not a problem with my routine. I use a universal decapper. None of my sizers have decap pins and the center rods are already pretty high so I could use a case puller easily, I think.

(Actually, I've never stuck a case in a Forster die! Stuck a lot of 'em in my life tho, especially when forming 22-250 from 30-06! But I don't stick many since I learned to lube the bases very well AND not to put overly much pressure on a nearly dry case as it enters. That "feel" took some hard-learned practice tho!)

Thanks for the info. I've never stuck a case yet, but I don't doubt I eventually will!

Andy