Compound Leverage and Length of Linkage

[jimkim]

I am thinking about modifying a press. I want to build a new toggle, linkages, and if necessary a longer ram. How much effect would longer linkage bars have on the leverage? I want to increase the leverage without making the lever longer.

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[Ford SD]

I am thinking about modifying a press. I want to build a new toggle, linkages, and if necessary a longer ram. How much effect would longer linkage bars have on the leverage? I want to increase the leverage without making the lever longer.

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Physics Not my strong Point

Most presses change lever ratio at different points of arm travel

Cam over is the point were you get the most force with the shortest travel of the ram

the easy way to increase pressure is a longer leaver(arm)

if you increase linkage length you increase travel = less force

if you reduce linkage length you reduce travel = more force but also reduce length of travel

[EDG]

Increased multiplication of force requires a longer travel of the handle.
This assumes the travel of the ram stays the same.

But you can make the ram travel shorter and keep the same handle travel to get a higher force.

But you cannot get the increased force for free.

[jimkim]

Thanks. I found the formula. I guess I'll be plugging in some numbers.

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[kenton]

Would you mind sharing the formula?

[jimkim]

Two on top.

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[EDG]

For all sort of solutions to problems in mechanics take a look at "Machinery's Handbook".

[kevin c]

Modifying my presses so they can take chunks out of my fingers that much more easily doesn't strike me as something I wanna do...

[1/2 Yuman]

I am fairly new to reloading and still working up the nerv to start casting. However, as an engineer, I would hesitate to alter the the linkage or mechanics of a press. Somebody somewhere once said if you are pushing really hard on the lever arm you have something wrong. It would possibly make it easy to do damage without realizing it until it is too late. Just my 2 cents.

[jimkim]

For all sort of solutions to problems in mechanics take a look at "Machinery's Handbook".

I have my bible, next to my Bible. I love both books.

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[jimkim]

I am fairly new to reloading and still working up the nerv to start casting. However, as an engineer, I would hesitate to alter the the linkage or mechanics of a press. Somebody somewhere once said if you are pushing really hard on the lever arm you have something wrong. It would possibly make it easy to do damage without realizing it until it is too late. Just my 2 cents.

I've said that several times. I plan to swage bullets with this press(Lee Classic Cast), and I want more mechanical advantage. I've been wanting to do this since I saw the one Swagerman(RIP) had.

I am now on a fixed income, so instead of buying(with non-existent money) a swaging press, I'm going to borrow a shop and make the parts I need. I think it's the machinist/fab tech in me that makes me do these things. I've always loved doing R&D work.

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[cwlongshot]

Have you looked for a small arbor press on ebay? More power on tap means less work for the operator.
Trouble I see witj most of these reloading presses is the timy ram dia. Plea t strong for job at hand. But maybe not if your gonna alter things.

CW

[jimkim]

Have you looked for a small arbor press on ebay? More power on tap means less work for the operator.
Trouble I see witj most of these reloading presses is the timy ram dia. Plea t strong for job at hand. But maybe not if your gonna alter things.

CW

It has a 1 1/8" diameter ram.

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[john.k]

The leverage of Lee Cast presses is easily altered by drilling a second set of pivot holes in the rocker ,so as to increase the mechaincal advantage.............this has been done zillions of times since the presses came out........however if you increase the leverage,you reduce the ram travel,and in the simplest case ,it doesn t come up to the die............if you are swaging ,this doesnt matter,and might even be an advantage (as it puts the process down from the crossbar)............the whole beauty of the Lee press is ,if you stuff up the job,new bits are only $10 or so.

[john.k]

The other thing with Lee Cast presses is the ram pivot in the rocker..........there are two studs secured into the sintered material of the rocker..........which would seem to be a weak point....but in practice it isnt...............now ,if I was going to apply mega force to this assy,I would remove these studs and fit a HT through pin..........note that this pin has to clear the swing links,so you cant use a bolt and nut..........third point is the ram is soft steel,so at a certain loading,the slots for the shellholder will deform,close down ,as it were.....................however ,if I wanted big force,I would just build a hydraulic unit with bits from the scrap box.

[dragon813gt]

http://castboolits.gunloads.com/show...t-for-leverage

Not sure you’d want to do more than that.

[john.k]

Without consulting prior art on the press,If I wanted big force,I would just make a new rocker in one piece similar to the RCBS one,and replace the drop links with 4140 HT,and the ram with a material sufficient to sustain the load without deforming.The frames are allegedly unbreakable,which is impossible of course,but it would be interesting to see someone else test the limits.

[jimkim]

Swagerman shortened the ram. He also lengthened the toggle. The shorted ram allowed him to get the lever into a position in which the leverage was much higher, than at the bottom of the stroke.

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[EDG]

Long ago the RCBS A2 was designed for heavy duty use. The ram is much larger than most current presses plus the top of the ram is removable if you need to substitute a solid ram. Close inspection of the bottom end of the ram and the toggle block shows some thought to strengthening the weakest part of many presses. When you have a single cross pin and simple clevis type connection such as most presses have an overload has to shear the cross pin in 2 places. The RCBS A2 has two slots in the bottom of the ram for 2 lugs on the toggle block. This results in 4 points of shear for the larger cross pin. It appears that a very knowledgable engineer designed the linkage of the A2 for extra heavy duty use. You can modify existing presses for additional leverage and still not get the beefed up toggle block and ram like the A2 came from the factory with.

[Kenstone]

Swagerman shortened the ram. He also lengthened the toggle. The shorted ram allowed him to get the lever into a position in which the leverage was much higher, than at the bottom of the stroke.

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Yes, the mechanics of a reloading press is more "toggle" than "lever".