Questions on a Roubo bench

[Jim Leslie]

I'm planning a build of a roubo and looking for comments on the leg vise configuration using the Benchcrafted hardware. As far as I can determine there are really 2 options: One is the criss-cross hardware and the other is the supporting structure (the one with all the holes) at the bottom that glides on 2 rubber rollers. What are the pros/cons of each? And what is the purpose of the cross pin that goes through the holes? Logically, I believe it is to prevent racking (could be wrong) but if it is, wouldn't it need to have finer adjustment? And if it is there to prevent racking, is it a pain to use/adjust when clamping stock of various thickness?

[Jim Koepke]

The pin is there to prevent vertical racking.

The fineness of the adjustment isn't as critical over the longer distance. Usually the pin would be set so the bottom is just a hair bigger, big hair, than the work piece. This induces the top into a pinch hold. If the pin was set to a point less than the work piece it would have a splayed hold which would not be as secure.

My mind keeps playing with an idea of having pins with springs on them so they could be operated by a foot lever. This would keep the operator from having to bend over all the time to set the pin.

Recently there was a thread about another option of using a bicycle type chain in a leg vise:

http://www.sawmillcreek.org/showthread.php?222948-It-Spins!

It is downright impressive how well this vise is set up.

Here is another method:

https://www.youtube.com/watch?v=qI38vYEYOe0

jtk

[Marko Milisavljevic]

Aside from criss-cross and parallel glide with a pin, there are other options

- Chain, for which there is a kit by Jim Ritter, and I described my build (http://www.sawmillcreek.org/showthread.php?222948-It-Spins!) recently

- Spinning footplate (http://www.popularwoodworking.com/workbenches/schwarz-workbenches/erik-mortensens-awesome-english-workbench)

Chain and criss-cross are they only ones that are "automatic".

There have been attempts made with linear bearings, but I think other approaches are much more reliable.

[Augusto Orosco]

I'm planning a build of a roubo and looking for comments on the leg vise configuration using the Benchcrafted hardware. As far as I can determine there are really 2 options: One is the criss-cross hardware and the other is the supporting structure (the one with all the holes) at the bottom that glides on 2 rubber rollers. What are the pros/cons of each? And what is the purpose of the cross pin that goes through the holes? Logically, I believe it is to prevent racking (could be wrong) but if it is, wouldn't it need to have finer adjustment? And if it is there to prevent racking, is it a pain to use/adjust when clamping stock of various thickness?

As others have already mentioned, Benchrafted hardware is not the only option (Jim's chain mechanism is very clever, for instance). But between only those two Benchrafted options, and price differences aside, the only case I see where the criss-cross could be less desirable for some compared to the one with the rollers is in the chop thickness. Because of the need for a mortise to encase the cross, the chop must be thicker than otherwise necessary (I think 2.5" is the minimum). To achieve this thickness, you need either 12/4 stock or you can simply laminate a 8/4 and a 4/4. I personally don't mind a thicker chop and went with the criss-cross.

Besides that, I think the criss-cross is superior to the rollers in every way. Even the installation is easier, since there are less moving parts to make. Unfortunately, I am still in the process of building my own bench and haven't yet reached the point to install the vise, so I can't comment on how it works. I have installed the Benchcrafted tail vise already, though, and it's very nice. The fit and finish of all their products is top notch.

[Jim Leslie]

Thanks for all the replies! It confirmed how I was imagining it works having never seen a roubo close up. I don't like the bending over to set the pin. To me that will get old (as I do!). The chain idea is novel and looks clean, but I do like the criss-cross method. I really like the Benchcrafted hardware - I built a Moxon vise using their hardware and love it. I built my first bench in 1980 (European style) and it's time for upgrading.

[Jim Ritter]

Please don't use bicycle chain. It is not strong enough. If you are making your own use #35 roller chain. I measured upwards of 600 pounds tension depending on the distance from the screw. I've got 18" from the screw to the top of the beam and the force is 400 pounds. The jaws themselves exert 1600 pounds. Yours might be different, it is a lever and depending on the spacing of things like fulcrum, effort the force will change.
Thanks for the mention of the chain I appreciate it.
Jim

[Jim Matthews]

I've had a leg vise, and replaced it with a Patternmaker's vise
and permanently installed Moxxon (twin screw) vise.

Were I to return to a leg vise, I would emulate Paul Miller's (https://www.youtube.com/watch?v=liHVemMxGJQ) clever V8 degree design.

In practice; the chain adjuster, pins or wheel are not essential.
The same effect can be achieved with a series of spacer blocks,
shaped like an inverted U, to fit over the lower board.

Most of us work with stock that's two inches thick, or less.
Having all the travel of a leg vise is nice, but an expensive
consideration for surplus capacity.

You can make your own from the excellent Acme screw set available through Lee Valley.
There is no finer fit and finish than the Benchcrafted product, but it's significantly more money.

[Marko Milisavljevic]

My mind keeps playing with an idea of having pins with springs on them so they could be operated by a foot lever.
I had thought about large serrated teeth on bottom of parallel glide. Then, set up a spring-loaded hook that is mounted on the leg, and springs up to lock into serrated teeth. Design it so there is a pedal with which you can press the hook away from teeth with your foot, while you are adjusting the vise.

[Joe A Faulkner]

I built a traditional style leg vise with a wooden screw. In truth, typically when using the vise, I'm working material of the same thickness such that there is not a lot of bending over to set or reset the pin. If you are concerned with bending over, one thing to note about all leg vises, is that the screw is usually 7 - 10 inches lower than the bench top, so you will find your self bending some to operate the vise. I think this is one reason some folks who have tried leg vises have gone a different route. My first vise was quick release face vise. I do find the handle position to be slightly more convenient than the leg vise. It isn't so bad that I plan to abandon the leg vise, but since you mentioned not wanting to bend over, I thought the difference in handle height worth noting.

[ian maybury]

I've just started my Roubo, and also have plumped for the criss cross as i have a bad back. Can't comment on performance, but it looks excellent. (see videos below) Advantages of a leg vise include the lower placement of the screw compared to e.g. the twin screw types, and taking up less real estate. It seems like a Moxon will very nicely handle the tasks the twin screw might have - and it's removable when not needed, and doesn't have to be expensive to make either.

As Jim above it's worth bearing in mind that the X mechanism can be bought on its own for fairly reasonable money, and the other vise parts elsewhere. The BC stuff is lovely, but I had some Lee valley screws in stock. I've likewise milled up and bought the parts for my own variant of a handwheel equipped wagon vise - for the same reason.

There's a couple of very nice videos here of the Benchcrafted Roubo vise, and the installation of both a leg vise with one variant of the X and wagon vise mid way down the German distributor's page: http://www.fine-tools.com/roubo-hobelbank.html

[Jim Leslie]

The more I read here and on the net, the more I'm opting for the criss cross design. I have no issues bending over (well.. so far anyway) but it just seemed like something I would not have to do with the criss cross hardware. And one less step during clamping. Probably a minor issue to be sure.
Joe: you mentioned a wooden screw; since this morning, I have been reading a lot and now considering the Lake Erie vise hardware and the Benchcrafted crisscross h/w. As Ian mentioned it is a reasonable cost . I just downloaded the install instructions and it looks like it may be a good alternative. Must admit though, I'm really torn between the two.
Jim: I do have a BC Moxon but would like to reserve it for mounting on the bench for dovetailing. Quite a while ago I had pretty much the same thought, but was concerned I would not be able to clamp a wide board or panel due to it's depth restrictions. With the new build, I want to also add a sliding dutchman so I can clamp long items that may have substantial width to them. I couldn't imagine I could do that with the Moxon approach, but I may be been wrong there and missed something. One thing I *really* got to like about the bench mounted Moxon is the added height and not having to bend over.

[Christopher Charles]

I built a split top roubo and finished it about a year ago. I used the BC tail vise and rollers for the leg vise. The screw is a german one from woodcraft that I already had and added the hand wheel from a salvage yard (build photos here: http://www.sawmillcreek.org/showthread.php?169730-Is-the-Klausz-Frid-Scand-Bench-Dead). FYI, the hand wheel means no leaning over. The rollers worked well at first but are fiddly. I'm likely to replace with a criss cross at some point since the cost is not outrageous.

Good luck,
C

[ken hatch]

As you have not started your build I will add a thought on leg vises. BTDT and found the leg vise (with rollers, the crisscross was not out at the time) slow and fiddledy and after working with it for a couple of years I deinstalled the leg vise and went back to my Paramo #52. I've worked a little on other benches with non-BC leg vises and they were no better. For ease of install, cost, and function it is hard to beat an early, pre-war through the 70's, English QR vise for the face position. BTW, I don't like the face vise installed flush with the bench front either. BTDT as well, I'd much rather have it stand proud. Added that last to point out my preferences may not be shared by most woodworkers so.....

[Marko Milisavljevic]

I don't like the face vise installed flush with the bench front

Can you elaborate as to why? I put suede on bench face and now it is annoying me a bit when jointing thinner boards, as they flop around a bit since they are not flush with the rest of the bench. When it is flush, it is a little better suited for sliding a finger or two along the board to press it against the bench, as if my fingers were a fence on a rabbet plane.

[ken hatch]

Can you elaborate as to why? I put suede on bench face and now it is annoying me a bit when jointing thinner boards, as they flop around a bit since they are not flush with the rest of the bench. When it is flush, it is a little better suited for sliding a finger or two along the board to press it against the bench, as if my fingers were a fence on a rabbet plane.

Most of the reason is with the vise proud I find it easier to place work pieces in the vise. The photo is an early one and does not show the bench jack and the series of 3/4" holes in the side of the slab for holding the bench jack. The bench jack is the same thickness as the vise face so when supporting long boards they are supported as if the vise was flush. You mentioned one of the other reasons, with the vise proud it is no problem to have both faces lined with leather. Maybe a leg vise with a long arm can exert more effective holding power than my old Paramo #52 but I doubt it, I know from experience the set up I'm using now holds much better than the leg vise on the other bench.

A gratuitous bench photo :-) :

http://i257.photobucket.com/albums/hh222/VTXAZ/workbenchFinal_zpsbcafa141.jpg

The leg vise in action on the old bench:

http://i257.photobucket.com/albums/hh222/VTXAZ/moxon_zps4a025bdc.jpg

[John Sanford]

Please don't use bicycle chain. It is not strong enough.
Jim, I find myself skeptical of this concern. Having been part of 400lbs cranking uphill at 15mph on a bicycle, the amount of force that a quality bicycle chain can transfer is substantial. Furthermore, the conditions that most bicycle chains experience are far harsher than they'll ever see in a bench being used. Perhaps you have the force calculations or busted chains to support your concern.

[Jim Ritter]

John here are a couple of pics of my real life tests. Somewhat subjetiive because I didn't have a scale on the handle but these are as I would use the vise. When I read as above where some want the longer Tommy bar to be able to lean into it I can only wonder at the forces generated. This is what I measured.
At the top of the jaw.

http://i1135.photobucket.com/albums/m628/boatman53/a5ae9086.jpg

Twelve inches down from the screw.

http://i1135.photobucket.com/albums/m628/boatman53/c0ee8a0f.jpg

http://i1135.photobucket.com/albums/m628/boatman53/33462096.jpg

Eighteen inches down from the screw. In this case just above the parallel beam in my vise.

http://i1135.photobucket.com/albums/m628/boatman53/08084edf.jpg

Roller chain specs can be found on line, anyone can look them up. Will bicycle chain work, yes but there is very little safety margin. You don't have to buy parts from me, I just don't want anyone to get hurt if a chain breaks.
Jim

[Jim Koepke]

This may be where the misunderstanding started with my post:


another option of using a bicycle type chain

If my nomenclature was a bit better I would have said Roller chain or motorcycle chain.

Jim, thanks for showing the actual psi forces involved. This may save a few people from building something with less wood strength than is necessary.

jtk