Question about leg vises.

[Luke Dupont]

Hi guys.

For fun, to see if I like a leg vise or not, I made a crude one with a screw and a 2x4 which clamps on to my work bench's leg.

One thing that I noticed is that the slot for the "runner" (which has peg holes drilled in it) at the bottom, if cut perfectly straight, doesn't allow the vise jaw very much rotation and needs to constantly be adjusted and pushed / pulled in and out, or else it will cock in the mortise and lock up similar to a hold fast.

Do you normally cut this mortise with a taper, widening towards the back? Or perhaps do you just cut it larger by 1/4" or 3/8" or something?

[Phil Mueller]

Luke, mine is just cut square and slides in and out with ease. I suspect it’s just that your vise is “crude”? Don’t mean this as any sort of criticism, just that a properly made and aligned “parallel guide” works smoothly.

[steven c newman]

Most are cut a bit oversized....and rely on a pin to lock the slider in place.....
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Mine? Well...the "screw" is a short pipe clamp.....just needed a 1/2" hole drilled through the leg. Chop is a rived 2 x 6 Sycamore slab....there is a "step" at the bench's foot, that the chop rests on.
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There is a shelf underneath the bench's top..sticks out just far enough to rest larger panels on. I can add the clamp as needed.

Didn't have much use for a 24" long pipe clamp, anyway....so. Was cut to just touch the far leg....but, I can adjust the opening of the vise as needed....normally, I at most need 1-1/2" between the jaws.

[Luke Dupont]

Luke, mine is just cut square and slides in and out with ease. I suspect it’s just that your vise is “crude”? Don’t mean this as any sort of criticism, just that a properly made and aligned “parallel guide” works smoothly.


You bet it's crude!

I'm a huge believer in iterating, and getting the big mistakes out of the way first with the crude version :)

Of course, crudeness can introduce its own problems at times...

I'm guessing that depending on the construction of the screw, and the retention system, and how much it allows the vise to rack or not, you will have more or less of a smooth in and out versus "pivoting at the base" action, though I'm really just speculating here..

[James Pallas]

Loose slip fit. A nice tight mortise will only allow for seasonal use.🙂
Jim

[Tom Bussey]

Pictures of my original mock up. I liked the cris-cross the first time I saw it. The cris-cross takes all the weight of the chop and moves parallel to the bench leg. No racking or adjusting the lower pin.

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Some more pictures of another leg vise.

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And pictures of the leg in assembly

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[Tom Bussey]

The length of the cris-cross is not real critical. The easiest way is to drill the hole for the pin in a drill press so it goes in straight. I used a 5/16 drill bit. The pin is a 5/16 regular bolt from the hardware store. I cut the head and the threads off the bolt to fit the leg. The same goes for the cris-cross. I also bought a longer 5/16 drill bit to finish drilling the hole through the leg and the chop. Rout the cavity after drilling the holes it helps keep the hole straight. I used a forstner bit to remove most of the waist and then a router to finish it of.

If you look closely at the third picture in the second set of pictures you well se 3 wood screws holding all the pins in place. The pis tend to work them selves out.

The most important thing about the cris-cross is that it is I/2 inch wider at the bottom than the top of it. So the bottom of the leg should have about 1/4 if an inch cap showing when the top of the chop is shut. that allows the clamping force to be greater at the top than the bottom. It is clamping principals and you will have to trust me on this one .

I hop I have helped someone.

[chris carter]

The mortise for my pin board has a 1/16" gap on each side and 1/8" gap top and bottom. In other words, the mortise is 1/8" wider and 1/4" longer than the pin board, with the pin board smack in the center.

[Tom Bussey]

I am talking about the cris-cross itself. On the criss - cross pictures at the top where the pin goes through the wood the diameter is 1 1/2 inches or a 3/4 radius. However the diameter at the bottom is 2 inches or a 1 inch radius. Because the fulcrum point is the bench screw and the pinch point of the chop is at the top of the bench, the chop sticks out about 1/4 of an inch from the leg of the bench at the bottom when it is closed at the top. One would think it would be farther like a 1/2 inch because there is a difference of 1/4 of an inch on one piece and 1/4 if an inch on the other radiuses. Because there are two parts to the criss cross

Bench Crafted speaks to the issue but claims, and rightly so, that the gap on his Criss - Cross is engineered into his cris-cross. With Bench Crafted all you have to do is follow instructions when mounting

If you are spending less than a dollar for bolts and some scrap wood then there need to be a difference in radii. and the bottom needs the stick out a little bit.

[Scott Winners]

On my leg vise I had about 1/16 clearance all around between the parallel guide and the through mortise at the bottom of the leg. Once I got into the wet season it did start to bind up - exactly like a holdfast, good analogy. I worked with it for a few weeks, found the shiny areas on my parallel guide and took them down just a wee bit, problem solved.

[steven c newman]

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Ugly, but works....

[Paul Saffold]

thanks, Tom. Bookmarking this. How has your wood version held up?

[Tom Bussey]

Here are some pictures of my first leg vise. It is left handed and on the back side of my bench. I have been using it for 6 years now and haven't had a problem.
here are some pictures of it.

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Here is a picture of the front of my bench which sees more of the work load.

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[Tom Bussey]

And I wouldn't be planning on putting a leg vise on this one. I am going to use a cris-cross instead of the traditionally bottom bar with holes and a pin. I wouldn't do it if they didn't hold up. Please forgive the clutter this picture was taken in the winter with no heat. things just come in and find a flat spot to land

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