RCBS Summit Press Flex (pictures)

[Project355]

I'm happy with my Summit press, does what I want it to do, and fits the limited space I've got.

You hear about "flex" but I can't find online where someone has documented the same. The RCBS manual has been changed from "adjust the sizer so that the press "cams over" at the end of its stroke, now includes an insert that says you may have to adjust your sizer up to 2 turns past "cam over" with no case in place. Flex-o-la.


So, here goes on the flex issue. The press column screws are tight, blue LocTite'd in place. I checked 'em, still nice and tight. Further tightening would most likely destroy screw heads by stripping the hex key fitting.

What you're seeing is the Summit press, with a Lee .45acp carbide sizing die and shell holder, and a 45acp case at full stroke of the press. The die was adjusted so that there was just a bit of resistance at "cam over" at full stroke. Yet... as you can see... a decent amount of flex.

More to come - got some chores to do, but I want to show a .233 case, and comparison to the cheapest press on the market - the Lee hand press. Just to let folks know, there is no flex with the same die/shellholder and 45acp brass on the $27 press! But I need to take pictures to show it.

 

[mdi]

Are you saying the gap between the die and ram when a case is being sized is indicative of flex? I have owned a few presses and the gap is from "slop", tolerances, in the linkage and associated moving parts. Put a dial indicator on the top of the frame, then run a case through, or "cam over" and see if there is movement, flex in the frame. Linkage "slop" is normally no real concern and dies can be adjusted to compensate, because the slop is the same every cycle...

 

[Bill M.]

I would not think that flex in itself would be an issue in sizing accuracy. The fit of the case in the die is. The case is loose in the shell holder. I would hate seeing or feeling flex but is it really a problem?

 

[Milt1]

I don't understand how one takes a picture of flex without some way of showing no flex and then showing flex? A better explanation is required in my opinion.

 

[Project355]

Aw hold yer horzes, I'll get some better pics. Wish I could post video. Can I? Its clear that with the press stressed already a bit, at full stroke, parts move more due to the added force needed to size even a minuscule case such as 45ACP

This is not slop. The die already had pre-stress on it with no casing in place. All "slop" was removed.

 

[Skgreen]

IMHO, the Summit was created more for it's compact design than being 'flex-less'.
My LNL AP flex's, but as long as I'm doing the same thing with the same stuff, the flex is consistent and can be compensated for.

 

[eyeshot]

I almost bought the Summit because it looks like a tank and I liked the die to case vs. the case to die. I went with a RC II, brother's estate, and it flexes. I assume they all flex to a degree and as mentioned above you adjust it out of the process as best you can. A press that doesn't flex would require new benches all around.

I still like the idea behind it. Nice closeup pic by the way. I can almost smell the green.

 

[berettaprofessor]

I still have to have explained to me why I care about press "flex"...whatever that is. All flex, as I understand it, accomplishes is to tell you, if it really ever occurs, that you are overworking your press. If you can flex a solid steel press, you're asking it to work and eventually break. Cartridges don't need that kind of force...at least not cartridges that I care to shoot.

 

[243winxb]

Lee .45acp carbide sizing die

Shell holder should not cam over on a RCBS carbide die. Light contact, just touching may be ok for Lee.

Carbide vs Steel die, very different.

https://support.leeprecision.net/en/knowledgebase/article/full-length-die-adjustment

 

[mdi]

Looking at the pic, the gap appears to be 1/32"-1/16". If a cast iron fixture, like a reloading press flexed that much, it would break after much use. Cast iron is not a very malleable metal, nor will hold up to much stress/flex, basically it is more brittle than wrought iron or steel...

 

[243winxb]

Adjustable linkage? WHAT?

3. The linkage is adjustable for resistance so I don't have to use a full stroke every time. It can be set to stop 2-3" above the shell holder or wherever you want it set. Great for seating bullets or sizing small cases.

RCBS instructions
BULLET SEATING
The Summit™ Reloading Press design is great for seating of bullets in the cartridge
case. The open frame design allows excellent accessibility. The optional Short Handle,
#09291, and ability to tighten the linkage to reduce the press stroke greatly aids in
seating bullets in cartridge cases. To tighten the linkage, insert a 3/16” hex key wrench
into the broached end of the toggle pin. Using a 9/16” open end wrench, slightly turn
the nyloc nut on the toggle pin from back to forward

Could be a problem??

 

[Project355]

The linkage can be tightened on its middle and lower pivots, against wavy washers. This allows you to release the handle mid stroke if need be, and the press will not "fall", possibly decapping your thumb. The up/down or camming action of the linkage is not adjustable. I keep mine set so that the handle will "just" fall. The adjustment also helps eliminate side-to-side movement of the die platform. There are two screws in the back that run in a slot, which more or less guide it, but with no side/side play in the linkage, you get less sideways jostling.

First a picture of the press, with Lee 45acp carbide sizer at "touching the shellholder


Next, the same setup, a moment later, with the arm and linkage fully "cammed over", which takes all play out of the linkage.



And finally, with a 45acp cartridge case being sized, at full press stroke. Note the gap, and note the _size_ of the gap.

So with all the play in the mechanism accounted for, operation against further resistance, even though the handle is fully down, something "gave way" a bit, resulting in a gap where previously there had been none. Please note, its quite easy to tighten the die a full four turns past "fully seated on the shellhoder" and still pull the handle easily down to full cammed over position. Why is that do you suppose? Because as resistance (due to the parts touching) increases, the press flexes.

Some sharp eye may have noticed the Lee decapper "not flush" with the top of the die. There's a reason for this. The Lee decapper is so damn long that decapping occurs at a point that is not optimal for the power delivered by the press's leverage. By raising the decapper a bit, it decapps with at a slightly lower die platform position, making decapping easier. Yes, that puts more stress all in one spot on the stroke, and I'm basically talking about stress and flexing, so that practice of raising the decapper doesn't help issues. But, neither do I get a "two stage" decapping process where the first stage, or resistance, is the decapping point.

Next post, .223 and a bit more revealing

 

[Project355]

In this set of pictures, I'm using an RCBS small base die for .223 and the same press setup as before in the previous post.

First the handle at a point where the die is fully touching the shell holder


Now with the handle fully "cammed over"



That camming is about 1-1/2 full turns on the die after "touching" with the handle fully down. So, you can see, the die is touching shell holder at some point before full handle lowering.

And now a sized .223 case


The telling and interesting point here, is the size of the gap. If just taking "more play" out of the mechanism, and not due to flex, the gap should have been the same as the .45acp. However, the gap is much larger, well over twice as much. Why is that? Because the greater resistance to sizing created more flex in the press.

As such.... Although I like my Summit press, and it fits my needs, I cant recommend that someone use this press for full length sizing of say... well... anything more substantial than pistol rounds. I'll see if I can get some pictures of the Lee hand press, which does not flex at all. Back to my Sunday honey-do's though for now.

 

[mdi]

Nice pic, but in my opinion, you won't be able to determine if the frame is flexing just by observing a gap. To find out for sure I think you need to mount a dial indicator and at full stroke measure, see any flex...

 

[Project355]

Shell holder should not cam over on a RCBS carbide die. Light contact, just touching may be ok for Lee.

Carbide vs Steel die, very different.

https://support.leeprecision.net/en/knowledgebase/article/full-length-die-adjustment

And that, Sir, is sort of where I was going with all this, but you beat me to it.

 

[Project355]

Nice pic, but in my opinion, you won't be able to determine if the frame is flexing just by observing a gap. To find out for sure I think you need to mount a dial indicator and at full stroke measure, see any flex...

There really isn't a "frame" on the Summit, just a vertical column. The column is held to the base by two machine screws on each side, left and right. There used to be... three on each side in previous versions of this press. Why did they go to two? The top screw would crack the casting. That is also why I suspect the rear, and front, have no fixing screws: That's where the most force on the column joint would be.

Got an explanation for the varying gap, besides parts flexing? Not trying to be argumentative, I just don't see it, because I know the "play" in the parts has been removed.

There are three points in which the mechanism can flex. First is the column itself can "bend", but I find this unlikely as its two inches of solid steel. The next is the joint at the bottom, where its held to the base, or the base fitting itself may flex. And last, the die platform can flex. My money is on the joint and/or base fitting, as the die platform is pretty stout.

I think the ex got my magnetic bases and such, because I didn't grab 'em soon enough, but I still have an Interrapid test indicator, which will do nicely. Gotta see if I can grab a magnetic base and long arm so I can mount the Interrapid on the base, and measure the top casting movement through the length of the stroke. Testing the flex in the die platform is going to be more tricky. Maybe mount to the back of the platform and come around front with the test indicator and see if the front moves in relation to the back. Something to think about.

 

[Skgreen]

From what little I've read, the Gen 1 Summit had the 2 screw base. The Gen 2 Summit had 3 screws.

https://www.thehighroad.org/index.php?threads/giving-up-rcbs-summit-press.794721/

Heck if I know.

 

[Project355]

Well, mine is two screw. The "book" is older and shows three screws. Why older? It has the old ATK web and email in it. I'm almost certain two is current.

 

[mdi]

I don't own a Summit, but I have been a machinist/mechanic all my life and can see how some mechanical things happen. Looking at a pic is see a slide moving up and down a tube. There has to be some sort of clearance between these two parts or there would be no movement possible, unless there are bearings that can be "pre loaded", adjusted for zero play. In the pic I see 6 pivot points in the linkage, and when I say "slop" I mean a workable tolerance between parts, common terminology. Again, if there is zero or too little tolerance between moving parts, movement wouldn't be possible. There is a phenomenon "tolerance stacking", where a few thousandths clearance here plus a few thousandths there, maybe in 3 or 4 different areas, add up to several thousandths at the end of the "chain".

I think a stand of sorts beside the press with a dial indicator attached accordingly could measure the difference between the slide movement of loaded (no case) vs. unloaded. Not impossible but a bunch of precision inspection tools would be needed...

I'm not knocking your press or your "testing" methods (when I first saw a Summit I was very interested and may have purchased one, but a Co-Ax on sale jumped in front of me so I bought it), just initially voicing my thoughts. Personally I have not read many (any?) complaints about the Summit other than it'd minor limitations (I did see someone complain he couldn't use his Lee bullet sizing kit on his Summit).

BTW; I have a C-H single stage press that was manufactured, as far as I can tell, in the '50s. It must have had many (hundreds) of thousands or rounds produced in it and while it looks like it was well taken care of there is nearly 3/64" movement in the ram at full stroke, but I did make some very accurate and consistent ammo on it, so I have no doubt your press with that gap can and will produce some premium ammo...

 

[LiveLife]

BTW; I have a C-H single stage press that was manufactured, as far as I can tell, in the '50s. It must have had many (hundreds) of thousands or rounds produced in it and while it looks like it was well taken care of there is nearly 3/64" movement in the ram at full stroke, but I did make some very accurate and consistent ammo on it, so I have no doubt your press with that gap can and will produce some premium ammo...

Another C-H single stage press user here (model 205) and it's seen a lot of use resizing military .308 brass but still able to full-length resize brass even with some "slack" in the press/linkages.

when I say "slop" I mean a workable tolerance between parts ... There is a phenomenon "tolerance stacking", where a few thousandths clearance here plus a few thousandths there, maybe in 3 or 4 different areas, add up to several thousandths at the end of the "chain" ... difference between ... movement of loaded (no case) vs. unloaded.

I have 14 presses and they all have some amount of "slack" in the press/linkages to an extent from almost none to noticeable. So I adjust my dies while resizing to compensate for any "slack" in the press/linkages.

First a picture of the press, with Lee 45acp carbide sizer at "touching the shellholder.

And finally, with a 45acp cartridge case being sized, at full press stroke. Note the gap, and note the size of the gap.

Gap you are seeing while resizing brass could be the sum of "tolerance stacking" mdi posted from inherent mechanical design, manufacturing process and/or wear.

What I usually do when I see daylight between bottom of die and top of shell holder/shell plate during resizing brass is adjust the die further down to compensate for the "slack". The picture you posted where bottom of die touching top of shell holder while not resizing brass is not factoring "slack" in the press/linkages. So while resizing brass with ram in uppermost position, adjust the die down so as to eliminate daylight you see.

 

[tightgroup tiger]

I don't know if the press frames are actually giving much, the gap would be lop sided if they were. They would be tipped back against themselves.
I would check the two U-shaped arms, I'll bet they are giving because the gap between the shell holder and the base looks fairly consistent, front to back.
Put a block of wood under the top ram and bring it down on the wood and put pressure on it. You should be able to see something flex.
Watch the U-shaped arms to see if they are trying to straighten out.

Edit: not straighten out, kink in.

 

[ZGunner]

https://ultimatereloader.com/2019/0...ng-presses-compared-single-stage-shootout/12/

I don’t know how much this helps, I’ve just been skimming the comments. Ultimate Reloader did a press shootout of 14 different single stage presses to include the Summit. I linked the Summit test results but you can go back to the beginning to see how he got there. He tested the slop and concentricity of loaded ammo. I feel like it was a pretty scientific approach to testing them.

 

[GW Staar]

I still like my 2 screw original, but I prefer the old Rock Chucker II for sizing rifle. I've said this before..... I bought the Lee APP originally because I was enamored with the concept of a single station Automatic Processing Press, with a case/bullet feeder. What I think is this: if I can modify the Summit to do what the APP can do, I will have something special, and unique. Imagine an APP with the mass, toughness,and smoothness of the Summit! That's the real reason I just bought a 3D printer.....give me time....I'll practice on the open bullet feeder from Ammo Mike.

One more thing. For my body (unfortunately on the old and creaky side), sizing with the Summit is hard on it, ergonomically, at my normal bench height of 42". My shoulder hates the exercise up there. (Also why I've never wanted a Forster) But, it's a totally new animal if you lower it to 24 to 30 inches high (I haven't, permanently, yet), where I can painlessly bear down on it with my weight. I have an old exercise tool of my wife's, a "step platform" that I stand on that makes a huge difference.....but it's in the way....I'd rather make lowered bench for it. Basket ball stars obviously won't have that problem.

 

[higgite]

Just for grins, make a thin horizontal mark on each of the two linkage bolts and measure between them with the handle “cammed over” and the die just touching the shell holder. Then resize a case and make the same measurement. If the linkage arms are flexing enough to cause the gap shown in the pictures, you’ll be able to measure it with a ruler.

 

[Project355]

I still like my 2 screw original,

The "originals", the first released design, had three screws. If you look at the RCBS introductory video for the Summit press, when it was first released as a product, that press has three screws. As far as I can tell, not too long afterward they went to two screws.