Decorative end-vise joinery - bolts vs breadboarding?

[Hasin Haroon]

Hi everyone. I am nearing completion on my mutant-Roubo workbench build and have a question regarding attaching the end cap to the top. The end cap will be purely decorative and on the left side of the bench (the side with the leg vise). The reason for this is that I will not be attaching a tail vise, and will have a quick release vise mortised into the right end of the top.

Seeing as how the end caps will be decorative and not face the stresses of a tail vise, would it be sufficient to breadboard it to the top? I will have a dovetail attaching the front and mortise and tenon joinery for the rest of the cap. I was picturing two oak pegs, one in the middle and one in an oversize hole on the back. I would prefer to avoid using bolts if possible.

Also, is wood movement likely to be an issue for a QR vise mortised into the end of the top? The bench is built out of pine.

Thanks in advance!

[Jim Koepke]

Seeing as how the end caps will be decorative and not face the stresses of a tail vise, would it be sufficient to breadboard it to the top? I will have a dovetail attaching the front and mortise and tenon joinery for the rest of the cap. I was picturing two oak pegs, one in the middle and one in an oversize hole on the back. I would prefer to avoid using bolts if possible.

This is often done with at least a dovetail on the front side of the bench for a reason. When planing full length on a piece to get the most from a bench the planing stop can be clamped on the end. With a breadboard end it is possible to knock the end off the bench.

IMO, I do not think seasonal movement of the wood will be that much of a problem.

Just my 333961333962

jtk

[Hasin Haroon]

Thanks Jim, that didn't cross my mind.

[Stephen Clement]

Just my personal preference, but Ibwouldn't waste my time on decorative bench features. You'll need to flatten your bench every year or two as you selectively wear it an it finds its equilibrium point, and adding an unnessessary bit of crossed grain sounds annoying. Any sort of end cap has no power to resist the movement of a 3+" thick top, so it won't do you any good in keeping the bench flat.

[Stanley Covington]

I have never built a Roubo bench, so my opinion may not be worth much, but I have built other benches. The Roubo's top has no cross-supports to keep it flat. If you want to help the top move less (impossible to stop all seasonal cupping), install large, thick, deep floating dovetailed cleats made of strong wood at three locations (ends and middle) to help. But then it would not be a Roubo.

I have done breadboards on a benchtop before. Not a good idea. Even if everything works fine, and they don't need to actually keep the top flat, with humidity changes, they are a discontinuity in the top and form a small step at the end of the bench that messes up planing efforts at the ends. A straight shot without decorative ends will make for a more useful bench.

A vise installed at endgrain is very likely to cause the top to crack with seasonal movement depending on the humidity changes where it will be located. The steel vise will restrain the wood from moving, and the lag bolts ( or whatever metal fasteners you use to install it) will initiate the failure. After it cracks the top, it ill work itself loose in 10 years. I imagine Alberta gets pretty dry in the winter months. I wouldn't do it.

Stan

[Patrick Walsh]

Stanley,

So what style bench would you build and with what type work holding apparatus would you use taking into consideration the above mentioned.

I just took delivery of 330 BF of 12/4x6"x12' ash. To date the plan is to build a greatly enlarged split top Roubo per the BenchCrafted plans but with all mortise and tennon draw bore joinery vrs the draw bolts.

I considered a classic roubo with only a leg vise and and dog holes for a hold fast. To be honest i much prefer the astetic of the classic Roubo design. However the bench is for using so that factored into my final decision. At the end of the day i decided on the split top as it is my belief that it will give me the most options with regard to ease of use.

Am i wrong in my thinking or do you see potential for regret with regard to durability amd longevity of such a design?

[Stephen Clement]

Stanley,

Am i wrong in my thinking or do you see potential for regret with regard to durability amd longevity of such a design?

Patrick,

You should be just fine. No bench will stay perfectly flat, and one as thick as a Roubo will move where it wants to. No reasonable amount of cross cleats will be able to resist the force of a thick top like that. The good news is that a glued up Roubo will want to move in many countering directions and should't move too far. Also, the thicker the bench, the less seasonal change matters. Chris Schwarz posted a blog a little while ago about his 6" oak roubo that doesn't move at all. It took like 6 years to get there, but now it is at equilibrium and the piece is so thick that the seasonal change can't penetrate all the way through before the next seasonal change.

The discontinuity for the tail vise end board is insignificant because nothing should every cross it. Your work is almost always to the right (assuming you are a righty) of the tail vise wagon. For the end vise cracking the bench, I think Stanley is referring to installing what would normally be a front vise at the end. Such that you bolt the base plate across the grain and restrain the wood from moving. A well designed wagon vise will have no problem. The traditional large sliding dovetail just let the bench move as it pleased. For benchcrafted's bolted end cap, you should make the four bolts around the wagon slot fit pretty tightly and leave some slop in the end cap pilot holes for the rest. This will keep the end vise area pretty solid and dimensionally stable, but let the rest of the bench move.

Personally, I prefer the solid vs split top, but thats just me. I suppose if you do a takedown design split top, you could use a jointer/planer to periodically flatten instead of handplanes. Otherwise, I imagine the split top may be annoying to flatten. I've never flattened one though, so thats all guesswork.

[Stanley Covington]

Stanley,

So what style bench would you build and with what type work holding apparatus would you use taking into consideration the above mentioned.

I just took delivery of 330 BF of 12/4x6"x12' ash. To date the plan is to build a greatly enlarged split top Roubo per the BenchCrafted plans but with all mortise and tennon draw bore joinery vrs the draw bolts.

I considered a classic roubo with only a leg vise and and dog holes for a hold fast. To be honest i much prefer the astetic of the classic Roubo design. However the bench is for using so that factored into my final decision. At the end of the day i decided on the split top as it is my belief that it will give me the most options with regard to ease of use.

Am i wrong in my thinking or do you see potential for regret with regard to durability and longevity of such a design?

Patrick:

I am not a workbench expert, but I have built four for my personal use over the years, and learned a little more each time.

Mass determines stability as a work surface, but mass can be had several ways. Laminated is more stable than, although not as attractive or as durable as, wider boards. Thicker is more stable and durable than thinner. Harder wood is better than softer wood. Ash should work just fine.

The top of my current bench (7' x 2' x 3") is made from keruing, a hardwood from Indonesia used for flooring. I bought it on Guam as T&G semi-trailer bed boards. Heavier and stronger than maple, but doesn't glue as well. Lots of silica which was hell on my plane's blades and soles. Its the best I could get at the Armpit of the Pacific.

The joint decisions must be driven by your needs for portability and storage. In other words, if it needs to knock-down for flat storage or shipping, or to get around corners or up stairs, or because the top and legs assembled are just too damn heavy to move without hurting something, then tusk tenons, or bolts, or other such joinery is needed. If portability or flat storage are not important, then long tenons glued and pinned (or glued and draw bored and pinned) would be more than strong enough.

The front and back legs on each end of my bench are joined together as two assemblies with spreaders top and bottom glued and pinned in place. The front and back long spreaders (skirts) (7"x1.5") are attached to the legs (6.25"x5.5") with shallow mortises (.75" deep) and 2- 12" x .75" bolts at each end connecting to captured nuts. Very rigid, but easily disassembled.

When I designed my last and current bench, I looked very hard at the details of the Roubo design, especially the signature leg joints. I am structural engineer by training, if no longer by vocation. The unusual dovetail through-tenons the Roubo bench's legs employs are interesting, and perhaps attractive, but clearly not as structurally effective as an ordinary mortise and tenon. Indeed, the benefit of the dovetail's classic wedging effect is not useful at the edge in any structural way, but significantly weakens the top at the edges as it tends to split off the edge. In fact, this mode of failure has caused the edge to break off towards the top's ends in some Roubo benches.

In addition, the mix of vertical leg surface and horizontal benchtop surface exposed to the leg-vise's pressure is counter-productive when using the vise, and in some circumstances, could cause the wedge effect of the tenon to overstress the top's edge. I'm not saying the design won't work, because it clearly does. I am saying the exposed dovetail through tenon at the leg-to-top joint is a decoration that does not improve the function of the workbench. I used twin through-tenons instead, without pins or glue, so I can disassemble it. It works fine and is very rigid. In fact, removing the legs is not an easy task but requires some serious prying and hammering.

In the case of my bench, in addition to the twin through tenons at each leg, the top is attached to the legs via two lag bolts through the top spreaders between the front and back legs of the leg assembly. The front lag bolt is a tight fit to the spreader, and the back lag bolt fits through an elongated hole in the spreader allowing the top to expand and contract in width without being restrained in the horizontal direction, while the lags and leg assemblies help (I think) to keep the top a bit flatter. Is this necessary? Perhaps not, but the Roubo does not have this feature and relies solely on the top agreeing to behave itself. It doesn't hurt in any case. Belt, suspenders, and full-pen welds wherever possible is my motto.

I used a leg vise with a very thick jaw (t4.25" x w6.5") that is flush with the top and extends down to about .75" above the floor. It tapers down in thickness, and at bottom end is supported on a big 2" wide urethane ball-bearing skateboard wheel which rides on the floor. The vise is driven by a 1.25" diameter steel German screw. Very rigid so I can bang away on stuff held in the jaws without stressing the screw since the forces transmit directly into the floor. The jaws open up about 16", so when extended, the flat top of the vise jaw will support work, effectively expanding the benchtop to an L shape for some projects.

I have found I don't miss a QR vise, but love the leg vise. The power, grip, rigidity, and stability are awesome.

I have a lot of dogholes, more than I need, in fact.

I would post pics, but don't have any on hand.

To answer your question directly, Patrick, I think the Roubo design will probably work just fine for you. But I think you can do better. Regret, you say? Regret is unavoidable. I like this quote; "A man has cause for regret only when he sows and no one reaps." (Charles Goodyear) To this I might add: "Each lesson learned is a harvest." Mistakes, more than education or training, teach us to try to think things through carefully and ask frequently "what might happen if..."

I am not fond of the split top, Patrick, since I want the top's full width and mass to work as a unit for me. Remember, your most important jig is your benchtop. it doesn't matter so much how sharp or true your planes are, or how accurate your straightedge is, you can plane and cut joints no more accurately than your workbench's top is flat and free of wind. So if your benchtop's flat and wind-free width is 10" of a 20" wide split top benchtop, then the widest board you can plane or join precisely, quickly and with confidence is 10".

I think the split top style is a an economic compromise, fine if you do mostly small stuff, but too small for cabinet and casework. That said, I have used but never made a split-top bench.

2d