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Thread: New collaborative project: Bench top press

  1. #1
    Join Date
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    Default New collaborative project: Bench top press

    I am beginning the design of a unique bench top press with a capacity of up to ten tonnes as a target. It will be built from structural steel shorts and some small pieces of plate, require no welding, take up little space and may be operated by hand at reduced capacity like an arbour press or by inserting a hydraulic jack to provide maximum effort. The jack is not dedicated to the press, sits upright in the press at bench level and is merely placed in the right spot for operation.

    This press will utilize a 6 bar linkage to provide approximate straight line motion and direction inversion to make this possible.

    To this end I have designed a Sketchy Physics motion simulation of the 6 bar linkage. One of the bars is the background and is inferred as such. In the realization the linkage will not appear at all the same as this model. The purpose of the model is to optimize the straight line motion produced by the linkage. I have spent a number of hours and have the action good enough to proceed with the project but improvement is possible.

    There are two aspects to the linkage that operate dependently on each other. One is the travel of the ram in rectilinear motion for as long a distance as possible. The second is that the ram remain square to the work table as closely as possible throughout the range of motion.

    This is where any/all of you may help. Further optimization of the linkage is definitely possible. A 6 bar linkage may have a rigorous solution to the ratios of the lengths of the bars but I don't know how to derive it. Apparently neither do many others because there are current projects to discover other straight line linkages via brute force numerical methods.

    I could spend many hours adjusting the positions of the pivot points in very small increments to find a better configuration but I have other projects that I must do to get ready for winter. I thought I would instead make use of the considerable talent on this forum and distribute the computing workload to all that would like to contribute.

    Therefor I have made this simulator that can be easily modified moment by moment to try different configurations. You don't need to know how to design a Sketchy Physics model to use it. All that is necessary is to use the mover tool, the rotate tool and to know how to edit groups in order to apply these changes.

    Hinges that reside in a particular colour of link may not be moved to another colour. They may be moved anywhere within that colour of link. Collision detection is turned on so that impossible configurations cannot be constructed. If you manage to disable the simulator, a distinct possibility, make sure you have a working backup of your last/best configuration. I will use whatever configuration that is submitted/discovered that produces the best motion and of course that person will receive credit for assisting in the design. When a better configuration is found, as I am sure it will be, then make sure to save the workspace as an SKP file.

    The requirements are a computer capable of running SketchUp, the latest version of SketchUp, Ver 7.1, and the latest version of Sketchy Physics plugin Ver 3 RC1

    Link to the simulator file for SketchUp (1.6Mb)

    http://ixian.ca/video/slinkage_1c.skp

    This is what it looks like as an animation. In actual usage you have full control over the movement by simply dragging on a linkage part.

    Free software for calculating bolt circles and similar: Origin now settable to bottom left! All values positive. Click Here

  2. #2
    Join Date
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    Default

    What about using the parallel motion linkage that was used on some old steam engines.

    http://en.wikipedia.org/wiki/Parallel_motion

    This is only one example there are others, I believe, old model engineer mags. may have more info.

  3. #3
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    Default

    There are very few linkages that operate from one side only. Watt's linkage doesn't. Also, the linkage must provide for an easy reversal of effort to accomodate the hydraulic jack upright at bench level.

    I should point out that this linkage is not my invention, it was originally used on drill presses. I haven't been able to find any more information than that.
    Last edited by Evan; 10-03-2009 at 08:08 PM.
    Free software for calculating bolt circles and similar: Origin now settable to bottom left! All values positive. Click Here

  4. #4
    tattoomike68 Guest

    Default

    I dont see the point of making that. you can do better and dump the silly linkages.

    Make a strait hydrolic or air powered ram, there is nothing to gain with the linkages.

  5. #5
    Join Date
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    On the Oil Coast,USA
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    Default

    How much stroke? And what about a toggle linkage?

    http://www.iroquoisiron.com/b96100.html

    Checkout the rest of they're stuff,pretty neat.
    I just need one more tool,just one!

  6. #6
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    Air power isn't suitable for a press. Most hydraulic presses are fairly tall to accomodate the cylinder or jack mounted above the working area. This is intended to be perhaps no more than 24" tall with a 12" stroke. Think in terms of an arbour press with a lot more force capability.
    Free software for calculating bolt circles and similar: Origin now settable to bottom left! All values positive. Click Here

  7. #7
    Join Date
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    Palmer Alaska
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    Default OTC Push Pullers

    Not fast, but very easy to adapt for different jobs...

    With different length legs, and sizes of bearing separators, I have yet to find a normal (under 50 ton) job that these won't handle....

    http://www.otctools.com/products/17_...p._push-puller

    Mine I have in a single drawer in tool box (Both 17 ton and 30 ton models...)
    dissassembles into easy to fit in tool box pieces.

    A lever top unit could be made to fit existing legs and bearing seperators...

    The adjustable width/length, light weight/portability, and ability to assemble around an object to allow dissasembly, make it very handy...

    Nice made in US forged steel tools...

    I have pushed and pulled hundreds of pulleys, springs, Macpherson struts, Bearings, Press fit rifle barrels 16.25 inches long, pins....

    Does require 2 wrenches for pushing/pulling, but very smooth and controllable power... A hydraulic head is available as well.
    Last edited by Bguns; 10-03-2009 at 09:54 PM.

  8. #8
    Join Date
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    Toronto, Ontario
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    Default

    This may be closer to what you were thinking about........

    http://books.google.ca/books?id=R9QD...age&q=&f=false

    Early PROJECTS in METAL also had a couple of variations of this style.

  9. #9
    Join Date
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    Default

    Think in terms of an arbour press with a lot more force capability
    Could this linkage activated press create more force than a rack type arbor press using only hand power ?

    Steve

  10. #10
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    That is very similar to what I have in mind. However, if that lightweight design can actually withstand 11 tons of force at the press end then I am being much too conservative in what I intend. I haven't done any stress analysis yet but in that case I see no reason why what I have planned cannot go to 40 tons or more using a 20 ton jack.

    Thanks for the link, that is a nice design.

    Steve, yes, it should be possible. Right now I am fine tuning the linkage numbers and will shortly begin the design proper. I will design it entirely in Sketchup as a working model.
    Last edited by Evan; 10-04-2009 at 02:48 PM.
    Free software for calculating bolt circles and similar: Origin now settable to bottom left! All values positive. Click Here

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