View Full Version : Forming press

02-18-2015, 04:17 PM
I'm using a LEE Classic cast for forming.
Seems strong enough, but I do notice some flex while forming.
I have some old Herters and a RCBS JR3(?)single stage presses that I don't use.
Might those have less flex in them????

02-18-2015, 04:39 PM
If the Herters Is a Model 3, 81, Or 9 use them instead. . it also depends what your Forming. the lee cast is cast "WHAT". the herters is cast iron Or cast steel.

02-18-2015, 04:41 PM
There are several things that will give you the sensation of the press flexing.
1. The table top may bend under a very heavy load. This makes it feel like it is not solid when the press is ok. It is just the table.

2. Your handle might be bending under the load. The Classic Cast frame looks heavy enough to do most forming with ease but I do not know how solid the handle is. The handle on my old model Rockchucker is about 5/8" cold drawn steel and the entire setup seems very solid as long as it is on a good solid table top.

3. Some Herter's seem solid and some are huge C presses that will spring open like a cheap C clamp. You can check the amount of spring with a dial test indicator or dial travel indicator. Mount the mag base at the bottom of the frame opening and put the indicator contact on top of the frame. Then FL size a case for grins. My old Bair C press would spring open .007 to .008 when resizing commercial 30-06 brass.

4. The top of the frame of the RCBS JR3 is very nearly the equal of the top of a Rock Chucker frame. However the press linkage is the same as the wimpy non-compound C presses. It would work for light forming which uses about as much force as FL resizing of a 30-06 case. I would not use it for heavy duty forming since the linkage is not that strong. It does not have much mechanical advantage causing the operator to do a lot of physical work. When the operator has to use a cheater or hang his body weight on the handle that same load is transfered to your work bench. What you pull down on the handle goes to your bench. With a big honking press the internal mechanical advantage of the press makes it seem like you are doing less work because you are expending less peak force on the tool handle. What you are really doing with the big press with the compound linkage is moving the end of the press handle through a much longer arc. This generates much more force at the ram than the little presses can generate with the same arm force.

02-18-2015, 10:05 PM
I use a Lyman Orange Crusher press to form brass.
And the LEE press made from recycled rail's.

02-18-2015, 10:53 PM
What EDG said.

Le Loup Solitaire
02-18-2015, 11:09 PM
Generally speaking flex...(we used to call it "spring") is encountered in older style presses that were/are of a "C" design or anything similar.
Presses that are of the so-called "O" design can't/don't flex. A press such as a Hornady, RCBS Rockchucker, Lyman Crusher, etc; the O-type configuration simply cannot "give". It is unlikely that the linkage will flex, but the handle might especially if it is a long one. LLS

Lee S. Forsberg
02-20-2015, 01:21 AM
RCBS A-2 or Big Max.

02-20-2015, 09:42 AM
The lubricant will make a huge difference in the amount of force needed. The lee in the tube works well. The spray lubes I have used are not that good. It sounds to me like you need tochange to a better lubricant.

Lee S. Forsberg
02-20-2015, 04:47 PM
Flounderman is right lubricant does make a difference in the force needed to form cases. Use good lube but don't over-do it. Too much will produce dents in shoulders.

02-21-2015, 05:18 AM
It feels like the handle part is flexing.
Not sure what model the Herters is. I'll dig them out and check.
For lube, I use Kiwi Mink oil. Same as Imperial.

02-21-2015, 09:43 AM
Get a Redding Ultra Mag - note where the upper links are positioned.

02-21-2015, 11:02 AM
I have a Herter's press like this one: (Big picture in middle of page)


I've never checked it for spring but don't see how it could move very much. I also don't use it much since my RockChucker seems to work for all sizing chores.

OOPS! Sorry! It is 1st picture on first row. and last picture on 2nd row.

02-21-2015, 03:36 PM
I once measured the deflection in my old Bair C press at .006 to .008 when resizing machine gun fired 30-06 GI cases.
Not long after that I bought a 1971 original pattern Rockchucker.
After reading some of the comments here I knew the frame even on the Rockchucker would stretch some under load.
Elasticity is a normal property of the cast iron or steel. Design can help eliminate stretching as well as having a massive amount of material taking the load or having a very short non cantilevered design.
You would recognize this a front locking bolt action rifle. The front locking design has very short members to stretch and compress. An even more massive lock up is the Ruger #1 and Browning 1885. They don't look massive? Well the load path is very short and the breechblock and receiver loaded members are massive compared to many bolt guns.
On the other end you have the #1 MK III Lee-Enfield. The members under load are very long (just like a long rubber band) and especially the right receiver wall is not very massive resulting in a lot of spring in the system.

I just checked my old Rock Chucker with a dial indicator.
The sizing force that I would estimate it would take to size a 5.56 case or 30-30 case deflected the press frame about .001.
The force required to size a 30-06 that was swelled deflected the frame .0025 to .003.
I would expect that a belted magnum would spring it maybe .004 depending on how small the FL die is and how large the chamber of the rifle the case was fired in.

No back to the designs. Even though the Herter's press is massive it is open on one side so it will not be as rigid as you would think with all that metal.
Because of extra mass and design the A2 and A4 RCBS and similar tools would have less deflection than my press.
The Redding Ultra Mag is a pretty special design. The only part of the press in the load path is the top bridge of the casting and the long links. The rest of the casting looks nice but it mainly keeps the ram and die aligned. This design would show very little deflection - probably less than .0005.

A hybrid design that would be even less springy would be long links attached to the top of an A2 press.
That would be super rigid except - you would have no place for your hands to access the ram.

All of this begs a study on forming and FL sizing precision. Using my Stoney/Point case "headspace" gauge I found that there were a number of factors that affected the forming of a case to an exact head to shoulder dimension. Any variable that affects the time and the amount of friction and force in the process will affect the head to shoulder length of the resized or formed case.
1. Hardness of the brass
2. Surface texture or polish of the case
3. How much oversize is the case swelled if it is a fired case.
4. If the case is new - how large was it manufactured compared to the dies
5. Type of lube, amount of lube, how well the lube is distributed. The first few cases will have a different lube distribution after starting with a dry die.
6. Speed of the press stroke
7. Dwell of the press at max. stroke. (if you give the brass time to flow and take a set at the top of the stroke the results are more uniform)
8. Number of sizing strokes (if you want each case exactly the same you can cycle the ram multiple times)

If you just jam a full size case (Mauser size head) into a press with some lube and slam it in the die and retract you may be happy with the results because you have the case being sized more than necessary. You will never notice the variation.
If you check these cases 100% through a large lot you will find the head to shoulder dimension varies .001 to .002.
If you maintain good lube technique, run the ram into full stroke slowly and then permit it to dwell 3 or 4 seconds, then retract the ram spin the case 120 degrees and resize twice more slowly with the dwell you will find no measurable variations in the head to shoulder length.
Cases sized in this fashion for a bolt gun can be set right on .0000 clearance for range use and it will minimize stretching of your cases. Your accuracy will improve too.

Just like my old Bair. Notice the Cobra web or flare on each side of the frame.
A press without the cobra hood would be even worse.

02-23-2015, 09:13 PM
I form/size in my Rockchucker ("O" style press). I have only used it to form .300 BO out of 5.56/223 cases. My dad used it to form .44 AutoMag cases from 7.62 NATO cases and maybe a few other conversions.

02-25-2015, 07:23 PM
After I broke the pins of my Rockchucker a couple times, I bought an Ultra Mag. I told RCBS I was doing a bit of swagging, I only got free pins once.

02-26-2015, 04:29 AM
I use this


look at this mother