Aluminum for wagon vise rails

[Marko Milisavljevic]

I'm building a wagon vise with rails based on Benchcrafted design. To replicate effect of vise block riding on rails, I'm considering using a plate of 1/2 hard maple riding inside a rail sandwich made of 1/8" aluminum bars, sandwiching a 1/2" MDF bar, and screwed underneath the bench top.

I'm selecting aluminum because it is readily available straight and smooth, unlike steel. I don't fully understand forces that rails have to take. When vise is tightened, vise block will want to turn clockwise (if you are right-handed, looking from bench front). I am not sure if this rotation will first be stopped by the nut, or if there is enough play in the nut so that it will be stopped by the rail. I am using LV screw, and there is very little play in the nut, but there would probably be very little play in rails too. If rails have to withstand this force, it seems it would be considerable. If there is roughly equal distance between top of bench dog and nut, and nut and end of rail plate, there would be as much force pushing down on back and of rail and up on front end of rail as there is clamping force. If this analysis is correct, 1/8" aluminum may be strong enough. I don't think it would break, but I don't want it to give, or vise will probably feel mushy when tightening. In addition to this twisting force, centred around the nut, the whole screw will want to rotate upward centered on collar, but this is not a concern since it will just be pushing aluminum up into the solid bench. Any thoughts? Should I find 1/4" aluminum?

[Greg Fletcher]

Maybe create your own based on Lake Erie Toolworks using UHMW runners. Here is their product and the installation video.

[Bill Houghton]

I'd consider 1/4" aluminum. 1/8" seems thin to me.

[allen long]

A second vote for the 1/4" minimum. At 1/8 inch, the aluminum can easily be bent by simply torqueing down screws (if, for instance there is a piece of stuff/contamination between the aluminum and the MDF substrate.)

[Marko Milisavljevic]

Thanks Greg, I considered that and a few other ideas, including various schemes for assembling rails using wood, aluminum bars, angle aluminum, UHMW, inside as well as outside the bench (and even linear bearings and shafts) and I think keeping rails below would be easiest to set up accurately (because I can flatten the top after bench is complete, then flatten the bottom accurately enough to be parallel to top, then install rails) and to maintain if need be, and it removes least material from the bench.

[Brian Ashton]

If it were me I'd avoid aluminum for anywhere where there is two surfaces rubbing together and/or wanting to bind or wrack do to forces being exerted. My experience is it's great to work with but too soft for tools. I'd be going with steel. If you do choose aluminum get the hardest grade you can find.

[Jim Matthews]

If the forces are entirely linear (no racking), then the bar stock should be entirely in tension.
The wedging force of the stock in the vise will have a reaction force away from the center of the bench.

I think the more important aspect would be the bending moment if there is any misalignment.
Would the rails be solid, or hollow box section?

How large a screw would be used?
The amount of material removed to bore the hole will focus stress at that tangent nearest the edge of the stock.

I dunno the metalurgy of Aluminum types, some are likely "tougher" and less prone to stress fractures.
I would imagine that if a bar fails in this application, it will be where one of the mounting holes are drilled.

[Richard Line]

I agree with Jim that the bending moment is the biggest concern. Your approach is putting the moment reaction surface (the lower rail) considerably lower or further away from where the moment is being generated (the top of the bench or a bit higher). Roughly speaking, I suspect your approach will about double the bending moment over the typical arrangement. Also, I would not count on the screw to resist the bending moment; it is helping to create it and it is not designed to resist bending moments.

The easiest way to reduce the moment's reaction forces is to make the maple plate as long as possible. I would also suggest using 1/4" (at least) steel plates for the rails. Flatten or straighten them as best as you can. They don't have to be as flat as a jointer plane, but they do need to be flat over distances as long as the maple plate, and smooth. Consider applying some UHMW to the running surface to reduce friction. I'm not sure if you were planning on putting metal rails against the bench's bottom; I don't think that is needed, flatten and wax (or UHMW) the bench bottom in that area. Fastening the metal plates will call for screws (lag bolts?) that do not use the mdf for part of their grip length; they need to have something like 2-1/2 inches in the bench top, more if possible; and the holes in the mdf need to be close fitting to resist bending of the screws.

Hope this helps a bit.

[Winton Applegate]

Yah, every time I look at the wagon vises available they sure look wimpy compared to the Klausz vise style of moving a dog.

You can buy smooth steel. Just look for "cold rolled".

Here is a link for the home shop dude (or dudet).

I didn't look to decipher the specifics of your design etc.
I left the wagon train long ago.
Alternatively you could make it from solid aluminum. You can even mill aluminum with your wood working table saw/blades if you really bolt everything down to the jigs to hold the parts to run over the saw.

. . . the Klausz is the stuff though.
Make the wagon to make the Klausz that's the way I would do it.

[Winton Applegate]

aluminum get the hardest grade you can find

That could be tough but I agree
Seriously. There is a monstrous difference in strength and resistance to "plastic" deformation (even elastic deformation) between the right alloy of alu for the job and the annealed cheep stuff from the Home Depot.
T-6 is one hardness spec to keep an eye out for.
Unless you are building an air craft, a race car or a fine bicycle where power to weight is an issue . . .
stick with steel
or
Klausz

[Winton Applegate]

How long until we see carbon fiber wagon vises for sale at Lee Valley.
ha, ha, ha, ha,
I hate carbon fiber bicycles.
Yah I know . . . all light and stiff.
I worked on a ten thousand dollar one yesterday.
They rattle
they creak
the internal cable routing does not work as well as the old external.
Any color you want as long as it's black . . . or so it seems.
Give me old school jewelry finish and quality silver brazed steel any day.
OK
I got it out.
I'm better now.
(Klausz)

[Roderick Gentry]

Carbon takes a long time to get the bugs out, but then it takes over. For 30 year in archery it saw minimal use in bows, and early controversial use in arrows. Today it owns the arrow market, even the traditional archery one, and only cost holds it back on the bows. It is actually a fairly cheap material at this point, only problem is the demand is moving faster than the production, or so it seems. It was really cheap then 9/11 and airbus created huge demand.

[Roderick Gentry]

If I was trying to make that out of aluminum, what I might try is to get some Al C channel, the square stuff, one side missing. I would notch a block of wood so that the c-channel would be flush to the adjacent planes of the block. I would screw and epoxy the C to the back of the channel so it would be firm to the block, then fix one of these composite blocks to either side of the channel. You would have built in alloy channels. I would probably try to rig some bearings to ride in the channel. You could use wood, but I would use something like diamondwood. MDF is pretty weak, though it might work. It shouldn't be a big deal swapping out the MDF if one had to.

All that said, we are woodworkers, and the original vise that moves on wooden contacts should be fine. Again, if it failed to work it would probably be an easy thing to add the hardware. Consider that the reason the BC hardware is metal is because it needs to be plug and play for people who want that kind of thing. If you are making it anyway, reproducing the commercial kludge isn't the only approach. It's kinda like I prefer wooden planes and wedges, but I fully get that others prefer the knobs and doo dahs. But if there was anyone out there skilled enough to use the wedged planes, it would probably be someone like Hotley. He makes great training wheels but is a good enough cyclist to ride without them, I am guessing. Likewise if you can cobble together metal vise hardware using woodworking techniques, you should be able to make the same thing beautifully in wood, and save a lot of time and money. I wouldn't assume the wooden solution would be worse.

[Roderick Gentry]

OK, another option might be linear motion parts for a CNC. Sounds expensive, might not be:

http://www.cncrouterparts.com/v-con-...s-c-47_50.html

So the key part are the bearings with the v groove to them. You can either buy the hardened rails and the clamps, mount those under, or partially in you bench. Then with 4 bearing on the underside of a plate mounted to your sliding jaw, you would have a solution. But cheaper still would be cold rolled plate with the edge ground to a 90, or alloy, so ground. These plates could then be bolted directly to the bottom of the bench, and the four bearings mounted as before.

You may be able to find cheaper parts on Ebay, which for you app might be quite sufficient.