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  1. #1
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    Default Sliding Leg Vice Wheel Redeisgn

    I'm in the slow process of installing a glide vice.


    I want the mechanism to exist entirely below the lower shelf. In order to do this I've re-designed the wheel support to be horizontal, making it wider (not a problem on a 130mm leg), but reducing the total height.



    Any thoughts before I put saw to wood?
    My blog: ~ for the love of wood ~ - http://theloveofwood.blogspot.com/

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  3. #2
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    Ok so you still have two bolts holding the wheel housing on the frame but you have not dealt with any bending/torque forces on the wheel housings. The original, I gather top picture, deals with this with the tall housing style and inline boltings.

    I may be wrong but to me you are loading the mounting plate of wheel housing badly. There is no vertical support for those bending forces.

    If you want to use this new design I suggest make it of steel, forget making it of wood.

  4. #3
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    it might be my tired brain but I don't follow.
    which forces are you worried about?
    ?down on the wheel causing downward rotation at the bolts?
    My blog: ~ for the love of wood ~ - http://theloveofwood.blogspot.com/

  5. #4
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    With the vice as you clamp a piece in the section above the screw you get forces in the lower horizontal support, which is passed through the two wheels into the bench frame.
    These forces are vertical not horizontal in nature. The two wheels are trying to hold the beam in a horizontal position but the vice action actually is trying to twist or rotate the beam. Hence the positioning of the wheels units.

    I will try to knock up a quick diagram sometime to day to help explain it.

  6. #5
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    With a piece in the leg vice you get two main forces generated, F1 caused by the piece on the vice and a second force, F2. The second one is mainly noticed by a swing of the foot of the vice toward the bench. These forces all pivots about the screw, the pivot point.

    To counter the effect of F2 a wheel is used and directs a force F2a down on the support beam. For this force to be effective in maintaining a vertical vice face it must act at a pivot point. The second wheel under the support beam is that pivot point. Thus the force F1a can exert a counter to the F1, F2 combination.
    This now mean that the top wheel is not just held in place but must be constructed so the forces it directs are down. To support this force it needs fixing behind the wheel. That is fixing method in line with eth wheel inline to the support beam. Hence the fixture points for this top wheel can not be effective in support of that wheel if on the side. Also if made of wood you may end up getting along grin separation/cracking.

    In a similar way the wheel under the beam has to have its support fixing method below the wheel not alongside.

    Using your design you are not providing sufficient support strength to the wheels and you may run into problems if made of timber.
    Steel may help but again there is no support for the wheels against the forces they are intended to hold.

  7. #6
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    I see where you're coming from.
    Two additional factors are
    1. the stress through the joint between the back piece and the wheel support. I thought a comb/box joint would work best here.
    2. the relative position of the bolts and the axis of the wheel. With the bolt as vulcrum now above the axis the top is unlikely to lift away from the leg.


    Additionally, I've allocated a place where a third bolt could be added if needed.

    (The sketch was prettier, but comp crashed and this is the quick remake.)
    My blog: ~ for the love of wood ~ - http://theloveofwood.blogspot.com/

  8. #7
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    Since the effective height has increased it has a better chance of doing the job.
    Also the relocation of the bolting will help, especially that new third bolt.

    Have you resolved the hand held router with the tongue and groove work?

  9. #8
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    Hi

    My vise follows Chris Schwartz's design with a slot through the bottom of the bench leg, a wooden beam and a wooden peg through one of the holes in the beam. The wooden peg has not broken yet and the vise can put a lot of force on wood in it. It is important to move the peg for different size wood in the vise so the vise leg remains vertical.

    My 2c worth

    Andrew

  10. #9
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    Well I'm trialling the design... slow progress but we'll get there. I guess we won't know until it's on the bench and operational.
    My blog: ~ for the love of wood ~ - http://theloveofwood.blogspot.com/

  11. #10
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    Look good from here.

    So when will these move to the bench and have the test run??

  12. #11
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    Bench is still under construction so it might a while...

    waiting on a vesper square before doing the joinery.
    My blog: ~ for the love of wood ~ - http://theloveofwood.blogspot.com/

  13. #12
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    I've posted further progress on the Bench Thread.
    My blog: ~ for the love of wood ~ - http://theloveofwood.blogspot.com/

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