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Thread: Leg vise experiences?

  1. #1
    Join Date
    Jan 2019
    Location
    Fairbanks AK
    Posts
    553

    Leg vise experiences?

    I just ordered from Lake Erie and Anchora Yacht Services, have a couple or four weeks to get my act together.

    My main questions regard the chop.

    I am seeing a lot of folks using 12/4 stock, but then trimming the top of the chop back to half an inch or so so they can get at the workpiece. Is 12/4 really neccessary? If I really need 12/4 I will probably have to glue it up. One 8/4 glued to one 4/4 should put me in the ballpark. Is there a compelling reason I couldn't or shouldn't build the chop up to 12/4 thickness to match the thickness or depth of my benchtop, about the top 4 inches of the chop, and then run 8/4 down to the floor?

    Is maple just traditional, or does it have a specific advantage over white oak or hickory? Weight maybe? I have been buying 8/4 in all three species lately for turning projects, I am leaning towards finding a piece of 8/4 that I can get some turning pieces out of and then use the not suitable for turning remainder as the chop.

    I can visulaize the install, I feel darn good about it; but I would like to hear from folks that have been using them a while.

    "I made my chop out of 8/4 butternut/white pine / figured walnut 25 years ago and it is great" is a valid data point. If I really need to glue up 12/4 from floor to bench top I would rather do it right the first time. "I started with an 8/4 chop but it flexed when I did ___ so I had to make a new 12/4 chop" also valid data point.

    The other thing is I am old enough and wise enough to ask all y'all, what am I not asking that I should be asking? I recognize I don't know what I don't know.

    Thanks in advance.

  2. #2
    Join Date
    Sep 2008
    Location
    N. Idaho
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    1,116
    Hi Scott,

    I have an elm chop that's probably 12/4, but that's because I got it from a friend, along with the wood for the base of my bench for the best price (free). I also have the Anchora chain and think it works great (there are some picks of the install in a thread I did of the bench build started nearly 10 years ago). From a structural standpoint 2x pine would probably be sufficient because the lever arms in the vice are short. So I would say pick anything that will suit your eye and wallet. I'm not sure what I would have done if paying for wood...

    Best of luck!
    "You can observe a lot just by watching."
    --Yogi Berra

  3. #3
    Join Date
    Jan 2019
    Location
    Fairbanks AK
    Posts
    553
    Thanks Chris, I am leaning towards 12/4 because I ass/u/me the ones before us needed it for something; but I will have to special order it and count on the order filler in the lower 48 to send me a good piece. My local guy carries 8/4 and under, he has a little bit of Brazilian something in 16/4 but it is more than $25/ bf. I will go look for your bench build.

  4. #4
    Join Date
    Apr 2019
    Location
    Madison, Wisconsin
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    145
    Hi Scott,

    While I donít have any experience with a leg vise to offer, I can tell you the following. All else about the geometry and materials being equal, the stiffness will go as thickness cubed, so 3 inches thickness will be over 3 times as stiff as 2 inches. The experience of others, as you indicate, seems to suggest the extra stiffness is a good thing.

    I donít see any reason you couldnít laminate pieces together to get the greater thickness if you go that route.

  5. #5
    My chop is 8/4 walnut and works fine.

    The leg vise works best when the fulcrum is slightly wider than the thickness of the held piece. So taper your chop or plan your chain install accordingly.

    Leg vise handles are lower than other vise types. While a lower handle implies greater holding power and leverage and depth capacity, it means more stooping. As I am getting older, the stooping is really wearing on me. The vise is plenty strong and I could have gone a couple inches higher with my handle without sacrificing power noticeably.

    If you are planning to use it to edge plane, a makeshift deadman on the other front leg is a godsend.

  6. #6
    Join Date
    Mar 2015
    Location
    SE Michigan
    Posts
    2,918
    My leg vise chop is 6/4 hard maple, which is 1/4Ē thicker than what Chris Schwarz shows in his Roubo bench plans. If itís ever flexed, I havenít noticed. It has plenty of holding power.

  7. #7
    Join Date
    Feb 2004
    Location
    Perth, Australia
    Posts
    7,856
    Hi Scott

    If you have not read the review of the chain adjuster on my website, here is a link: http://www.inthewoodshop.com/ToolRev...nAdjuster.html

    I have the very first AYS adjuster, which Jim entrusted to me for evaluation. It have remained on my leg vise for over 8 years.It works exactly as designed, and has been completely reliable.





    My leg vise is also a wooden thread, although not the quality of a Lake Erie, about which I have heard excellent reports.

    There is also an anti-racking mechanism I built for use with the leg vise: http://www.inthewoodshop.com/ShopMad...tiRacking.html





    You do need a deadman ...



    Regards from Perth

    Derek

  8. #8
    Join Date
    Apr 2019
    Location
    Madison, Wisconsin
    Posts
    145
    Quote Originally Posted by Prashun Patel View Post
    While a lower handle implies greater holding power and leverage and depth capacity, it means more stooping. As I am getting older, the stooping is really wearing on me. The vise is plenty strong and I could have gone a couple inches higher with my handle without sacrificing power noticeably.
    Hi Prashun,

    You have part of that backwards.

    In any statics situation (i.e. when things arenít moving, such as when you have something clamped in the vise) the sum of all forces and the sum of all torques must be zero.

    This indicates that the total force applied by the screw is shared between your workpiece and the base, with the sharing determined by how far each is from the screw. Force times distance for each (the work and the base) must be equal, so if the screw is closer to the work the force on the work must be greater because the distance is smaller.

    Therefore, a higher screw increases the clamping power but reduces the capacity.

  9. #9
    Scott,

    I've used chops made of 12/4 and ones made of 8/4 with a 4/4 lamination, functionally there is no difference. At that thickness wood used makes almost no never mind, pick something cheep and/or looks good.

    ken

    P.S. On the portable benches I've used 8/4 Red Oak or Beech chops with no problem.
    Last edited by ken hatch; 01-15-2021 at 11:40 AM.

  10. #10
    Join Date
    Apr 2008
    Location
    Provo, UT
    Posts
    396
    I laminated two 8/4 pieces and ended up with a chop that was about 3.25" by the time I was done. I cut the top of the chop at something in the neighborhood of 60 deg. rather than the 45 deg. I have seen others do. I like the look better and I can bring my saw to a steeper angle when needed. I used maple because I like the look, not because I was worried about any strength issues.

    I can't figure out why the photo is rotated. It shows fine in my desktop. Sorry.



  11. #11
    Michael, then I've had it wrong all this time. The screw should be as high as one can stomach in terms of sacrificing depth.

  12. #12
    I used 8/4 Hickory and it has absolutely no flex. 12/4 might be necessary if you're using pine but for most hardwoods it's pretty overkill.

  13. #13
    Be aware that you may have to adhere a non-slip material on the jaw(s) of your leg vise to secure the work piece. I probably erred in building my leg vise using only 6/4 material. I am considering adding stiffeners as a result.

  14. #14
    Join Date
    Jan 2019
    Location
    Fairbanks AK
    Posts
    553
    Yay!! Data! Appreciate it.

    I did find my c.2010 Chris Schrawz workbench book last night. In 2010 he used one piece of 8/4 maple for the chop with no objective reasons provided. Same author, c2020 workbench book he laminated two pieces of 8/4 maple face to face for a finished chop ' about 3 1/4 inch thick', again with no objective data or rationale.

    I guess I should pencil up a drawing and figure out how much force can be applied by the screw to the chop before the chop begins to flex. That's the fundamental reason for a thick chop, yes? Crank it down hard enough the chop flexes the the jaw face goes out of parallel with the bench face and then the work slips.

    That is exactly the problem with my current vise that is going away. When I crank it down hard enough the moving jaw pivots on the low edge of the clamped work piece, the mouth opens and my workpiece slithers away.

  15. #15
    Join Date
    Jan 2019
    Location
    Fairbanks AK
    Posts
    553
    I think we can model a vise chop as a simple beam with a point load. The screw ought to be able to generate enough force to ignore gravity. Simple drawing attached. The beam calculators I have access to on a timber framing website only have design values for structural beams 5x5 inches and up for floor joists and top plates and etc.

    I am going to have to dig a little bit for design values to plug in to the calculator, fiber stress in bending, modulus of elasticity, that sort of thing. Once I have those I can plug and chug with the data points in this thread to see if there is any consistency, I should be able to say something like "folks who can generate 12 psi on each sqin of the clamping face with no deflection of the chop have no comlaints. Folks who can only generate 8 psi per sqin..."

    I do need the width of your chop top and bottom. If you have 2" thick chop that is 2 inches wide at the stop block at the bottom and 12 inches wide at the bench top, on the beam calculator your beam is 2x2 inch section width. I'll run everything on 36" tall chops (36" long beams) for apples to apples, shorter beams with the same section width will be stronger.

    Do not despair, I actually enjoy math problems like this because there is an actual good reason to solve the problem. A needlessly thick chop means we are limiting our maximum jaw opening.


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