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Thread: Compound linkage single stage presses

  1. #21
    Boolit Master
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    You are kidding right? That RCBS JR2 not a compound linkage. That is the only linkage that the RCBS JR ever had.
    Apparently you need to learn what a compound linkage looks like so you can identify one when you see it.
    I have to ask what do you think a SIMPLE LINKAGE looks like if you think the RCBS JR is a compound linkage?
    How about you show us a photo of what you think is a simple linkage is? What you are calling a compound linkage is the simplest linkage.



    Elements of a compound linkage
    1. Ram
    2. Swing arms (the long links) Without swing arms you cannot have the compound swing motion and the RCBS JR does not have them.
    3. Toggle block connected to the ram and the swing arms or long links.

    The RCBS JR just has a pivot block that only pivots it does not swing and rotate at the same time like a toggle block.




    Quote Originally Posted by jmorris View Post
    Have any photos of them?

    I found some RCBS JR2 photos but I guess they already went to compound linkage.

    EDG

  2. #22
    Boolit Grand Master jmorris's Avatar
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    I was going by the definition of compound lever.

    http://wiki.dtonline.org/index.php/Compound_Lever

    This would be a class 2 1 lever machine or a 2 bar linkage.



    This is a 5 bar linkage that applies force from one lever to another to increase force.



    This is also a compound lever.


  3. #23
    Boolit Master

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    The JR handle and pivot block act as a single piece and the link just transfers motion from the pivot block to the ram. I would call it a simple, non compound leverage.

    Compare the effort of full length sizing large rifle brass in the JR versus the RC with the same lot of brass and dies, and the difference will be clear.

  4. #24
    Boolit Grand Master

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    The JR series of presses suck for FL sizing of bottleneck rifle cases. Tried it once to see what it would take and it's significantly more force.

  5. #25
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    Compound implies multiple force multiplying features. A plier effectively has only a single movable lever attached to an identical handle which could be called a static member. There is nothing multiple or compound about it. It is no more compound than a seesaw.

    I am not sure why you picked vice grip pliers when they are not a reloading press.

    Why are you are dodging the photos of a compound linkage reloading press?
    Note the long links that allow the toggle block to rotate under the ram as the handle is lowered.
    Ultramag press

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    Lee presses with swing links -
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    RCBS A4 Big Max

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    [QUOTE=jmorris;4158033]I was going by the definition of compound lever.
    Last edited by EDG; 09-21-2017 at 11:38 PM.
    EDG

  6. #26
    Boolit Grand Master jmorris's Avatar
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    A lever arm that has a fixed pivot and one that rotates in an arc, a link that connects to the moving pivot at one end and converts the rotational movement into a linear movement at the pivot on the other end.

    Is that what I am seeing on the JR2?

    That would be the same description for how this one operates as well.



    http://rcbs.com/RCBS/media/RCBSMedia...ding_Press.pdf
    Last edited by jmorris; 09-22-2017 at 12:22 AM.

  7. #27
    Boolit Mold
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    I think the new MEC metallic press offers a lot of good features.

    https://www.gun-tests.com/issues/29_...l#.WcUF97pFwqQ

    Joe

  8. #28
    Boolit Grand Master jmorris's Avatar
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    I guess sometime in the middle of the night I thought was thinking about the OP's question and how to put qualitative numbers to the various presses.

    The idea of a hydraulic compression force transducer came to mind so I got up this morning and threw one together.

    The idea is pretty simple need a bore and piston with a diameter of 1.1276 or so to have 1 square inch of surface area, a gauge that reads in pounds per square inch and some fluid. Then I could pull on the handle with a scale and read the gauge for an input/output force comparison.

    It works as I intended, however the area I can measure with it now is of little concern because nothing needs force at that height. In any case I don't seem to have any 7/8-14 bolts or die just a tap and didn't feel like single point cutting the threads but I'll make an adapter so it can sit where the die goes and I can adjust it up or down and measure the last 0.000-.100 of travel the ram has because that's where most of the mechanical advantage is. Then we can have some numbers to play with.

    FWIW the little Lee there, at that ram height, was 8:1 or 40 psi for 5lb of pull on the handle.
    Last edited by jmorris; 09-22-2017 at 10:01 AM.

  9. #29
    Boolit Grand Master

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    I'm not sure that we are all on the same page here. There seems to be some confusion in defining "compound linkage". My first press, an old Herters "C" frame press, had a much simpler linkage than my Rockchucker has. You had to stand up and seriously lean on it to size a properly lubed 30-06 case. To the point that you moved the whole bench, even with several hundred pounds of lead stacked on back of it. I do this same job with my Rockchucker with one arm while sitting at the bench.

    Back to the original post, I expect any of the major brands "O" frame presses will be easy enough for the OP to use. Sure, we all have our favorites. But truthfully, there is probably not a wrong answer. If I were to buy another press it would be a toss up between a Co-Ax or that big C-H press. What a Hoss!

  10. #30
    Boolit Grand Master

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    Quote Originally Posted by jmorris View Post
    I guess sometime in the middle of the night I thought was thinking about the OP's question and how to put qualitative numbers to the various presses.

    The idea of a hydraulic compression force transducer came to mind so I got up this morning and threw one together.

    The idea is pretty simple need a bore and piston with a diameter of 1.1276 or so to have 1 square inch of surface area, a gauge that reads in pounds per square inch and some fluid. Then I could pull on the handle with a scale and read the gauge for an input/output force comparison.

    It works as I intended, however the area I can measure with it now is of little concern because nothing needs force at that height. In any case I don't seem to have any 7/8-14 bolts or die just a tap and didn't feel like single point cutting the threads but I'll make an adapter so it can sit where the die goes and I can adjust it up or down and measure the last 0.000-.100 of travel the ram has because that's where most of the mechanical advantage is. Then we can have some numbers to play with.

    FWIW the little Lee there, at that ram height, was 8:1 or 40 psi for 5lb of pull on the handle.
    Looking forward to seeing more on this. I always enjoy seeing your projects and admire the workmanship that you put into them.

  11. #31
    Boolit Man LittleLebowski's Avatar
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    Well, OP has a gunshot strong right arm and a circa 1967 RCBS Jr press he would like to trade into a press with more leverage however anyone wants to define it.

  12. #32
    Boolit Grand Master Artful's Avatar
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    Hang in there LittleLebowski - this is where it gets interesting - some of us have tried various presses but I have yet to see a scientific chart of the mechanical advantage listed for each reloading press. This is what your quest boils down too. you want the greatest work done with the least pressure applied to you damaged flipper. That is what this will tell us.

    Found this,
    calculating mechanical advantage of a press, measure the distance of the arc when you cycle the handle the end of the handle divided by the distance the ram moves at the same time ie; 30" divided by 3.5" of ram movement = 8.57 to 1 ratio?
    As the leverage is a variable the mechanical advantage changes constantly through the swing of the arc of the handle movement, I think their formula is too simplistic. That's where the actual measurement of force applied to the handle in correlation to force applied by the ram comes into it's own.



    I mean if your feeling flush you can buy one of these


    http://www.ch4d.com/products/equipment/presses/RC000

    Rock Crusher Press
    2 3/4"-12 top thread.
    1 5/8" ram diameter.
    Accepts 7/8"-14 threaded shank shell holders.
    8 1/4" stroke.
    27 1/4" overall length.
    Shipping weight: 103lbs
    Item #:RC000 $1,583.40
    740-397-7214
    Monday - Friday
    10am - 6pm EST
    Made in USA
    Which I bet probably beats the ultra mag, A2, Co-ax and anything else "normal" but I doubt I'll ever own one.

    Oh, a little googlage found this link
    http://reloadingtips.com/pages/reloa...comparison.htm
    Hornady Classic Single Stage Reloading Press

    Weight 9.6 lb
    Max opening height 3.875
    Ram 7/8"
    Max mechanical advantage approx 28:1
    ( Last 1/2 inch of ram travel)
    Primer catcher grade B+

    Hornady LnL AP Progressive

    Weight 29 lb
    Max Opening 4.75
    Ram 2"
    Mechanical Advantage 18:1
    Primer catcher grade A+


    Lyman Crusher
    Weight 16.2 lb
    Max opening height 4.25
    Ram 1"
    Max mechanical advantage approx 18:1
    ( Last 1/2 inch of ram travel)
    Primer catcher grade F


    RCBS Rock Chucker Supreme
    Weight N/A
    Max opening 4 3/8
    Ram 1"
    Mechanical Advantage 24:1
    Primer catcher grade B

    Forster CO-AX
    Weight N/A
    Max opening 4.0"
    Ram 2 at 5/8" each
    Mechanical Advantage 30:1
    ( This press has so much leverage that the manufacturer offers a "Short throw" arm to reduce the leverage.
    Primer catcher grade A
    found this as well
    http://castboolits.gunloads.com/show...ical-advantage
    Last edited by Artful; 09-24-2017 at 03:01 AM.
    je suis charlie

    It is better to live one day as a LION than a dozen days as a Sheep.

    Thomas Jefferson Quotations:
    "The strongest reason for the people to retain the right to keep and bear arms is, as a last resort, to protect themselves against tyranny in government."

  13. #33
    Boolit Grand Master jmorris's Avatar
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    Quote Originally Posted by LittleLebowski View Post
    Well, OP has a gunshot strong right arm and a circa 1967 RCBS Jr press he would like to trade into a press with more leverage however anyone wants to define it.
    I understand and will have some numbers on some of them this next week. I even have a co-ax to test.

    This is the easiest one on my arm.



    I also understand you are looking for a single stage but progressives reduce the repetitive motion that you have on single stages by quite a bit. Just how much depends on how many dies you are using but 3:1 wouldn't be overstating things.

    Case lube will also ease sizing, no matter how much leverage.
    Last edited by jmorris; 09-24-2017 at 10:15 AM.

  14. #34
    Boolit Grand Master

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    The Co-Ax can have all the mechanical advantage in the world. I hate it's operation. I find pulling down on the handle to be more stressful on my elbows. It's one thing to consider when choosing a press such as that.

  15. #35
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    Also the coax takes more pounds applied than a rock chucker not much but enough to make a difference with injured arm plus reaching up verses pushing down from normal position.

  16. #36
    Boolit Man LittleLebowski's Avatar
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    Appreciate the input gents, definitely not feeling flush with money, got a family to support on one income.

  17. #37
    Boolit Man LittleLebowski's Avatar
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    Quote Originally Posted by jmorris View Post
    Case lube will also ease sizing, no matter how much leverage.
    Yup, got several different varieties.

  18. #38
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    As far as case lube is concerned, I picked up some Imperial Die Wax at the suggestion of a friend many years ago and have not used anything else since. It is smooth and slick and seems to ease the amount of pressure needed to size cases. I wipe it on with my fingers and wipe is off with an old bath towel. works for me, james

  19. #39
    Boolit Master
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    Dollar for Dollar I don't think you can do better than the Lee Classic Cast press, many may have a bit more leverage but for the additional cost I see no advantage, heck for the price of the CH rock crusher you could have a bionic arm built, LOL!

    I have a Lee Classic Cast and can generate a bunch of leverage with it and if I need more the press lends itself to creative use of pretty much as long a handle as you want to put on it!

    Hunting the auction sites can find you a used one for reasonable money, heck I just bought a Lee Classic Cast turret press on this site for a C note plus shipping a great deal for sure.

    Imperial sizing die wax is the way to go if you can find some original green stuff that is, all I've seen since redding took over is a white colored wax and it does not work as well as the green!

    HM

  20. #40
    Boolit Grand Master Artful's Avatar
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    Hmm, I bought Imperial sizing wax before anyone bought the company and it wasn't green.
    je suis charlie

    It is better to live one day as a LION than a dozen days as a Sheep.

    Thomas Jefferson Quotations:
    "The strongest reason for the people to retain the right to keep and bear arms is, as a last resort, to protect themselves against tyranny in government."

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Abbreviations used in Reloading

BP Bronze Point IMR Improved Military Rifle PTD Pointed
BR Bench Rest M Magnum RN Round Nose
BT Boat Tail PL Power-Lokt SP Soft Point
C Compressed Charge PR Primer SPCL Soft Point "Core-Lokt"
HP Hollow Point PSPCL Pointed Soft Point "Core Lokt" C.O.L. Cartridge Overall Length
PSP Pointed Soft Point Spz Spitzer Point SBT Spitzer Boat Tail
LRN Lead Round Nose LWC Lead Wad Cutter LSWC Lead Semi Wad Cutter
GC Gas Check