Roast My Workbench Design

[Joshua Lucas]

I'm getting to the point in my workbench build where I need to stop overanalyzing everything and commit to a design. So, I'm submitting it to you all for a final sanity check.

The overall design is Moravian, with an angled leg vise and traditional tail vise.

The top is currently a single 3.5-4" slab of white oak that I am going to saw into a split top because it's too cupped to practically flatten in one piece. Splitting the top will also improve its stability because it will create two rift-sawn slabs instead of one flat-sawn one.

The leg vise chop and parallel guide will be hickory. I'm not 100% decided on the tail vise materials, but it will have at least the important structural components made out of hickory.

The long stretchers are joined to the legs with a Shitage Kama joint. I have used this joint before and I feel that it is more robust and more attractive than the standard tusk tenon on the Moravian bench.

Right Quarter View
Workbench_2019-Dec-31_05-40-37AM-000_CustomizedView26343280371_png.jpg

Left Quarter View
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Front View
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Close-up of parallel guide with leg vise chop hidden. It will be an all-wood version of Will Myers' ratcheting parallel guide. Edit: obviously the ratchet isn't going to balance as rendered. There will be a spring to hold it against the parallel guide.
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Underside of tail vise. There may be a few more guide blocks in here but I'm not 100% sure where they need to go and I didn't feel like rendering them. It shouldn't be a problem to figure that out as I build it.
Workbench_2019-Dec-31_05-42-44AM-000_CustomizedView2148606299_png.jpg

I may add a narrower version of the upper stretcher/apron on the "21st Century" bench here. The dog holes in my design are close enough to the front edge that they will interfere with a sliding deadman. I also feel that this design is more robust than a deadman.

[Jim Koepke]

Joshua, The only thing looking a bit off to me is the over hang for the tail vise end of the bench.

Your Shitage Kama joint seems like a great solution to making a joint for the ability to knock the bench down if needed.

Wedges are a great way to hold things:

Clamp & Wedges.jpg

Clamps help when something is going to have forces working against it.

jtk

[Derek Cohen]

Hi Joshua

I agree with Jim that there is too much overhang at the tail vise. I am not sure whether a Morovian bench is intended to work with the tail vise you have chosen? Ideally, the work piece gets clamped over a leg. This is where a vertical leg scores for stability. The Morovian triangulated legs should be strong, but I imagine that they will flex more than a vertical leg when working over it.

Regards from Prague

Derek

[William Fretwell]

Joshua, over a third of your bench hangs over the leg. This will make your bench unstable and wobble in use. Moravians generally are smaller with much thinner tops. The weight ratio of top to bottom is out of balance. The wedge joint for the stretchers sacrifices a shoulder, bad idea on a bench stretcher, you need BIG shoulders and bigger stretchers.
A clamping ledge under the front of the bench helps, the split top may provide that. Your dog holes should be oblong and angled in 3 degrees.
There is a reason big benches have straight legs and big stretchers, just look at historical benches!

[ken hatch]

A good rule for bench building is pick a classic design and build it with no changes. Then work on it, if something about the design drives you to barking at the moon, change it by modding the bench or if unable to mod it build another then work on it until you either love the change or return to barking at the moon.

After working on a bench you may be surprised at your insights as to the reason for the design elements that have survived over years and many bench builds. If you make changes willy nilly you may never arrive at those insights, most design elements that have survived over the years are there for a reason and have been proved and improved over time.

I'm a fan of the Moravian style bench for the modern woodworker and his shop but it took several builds and working on it for some time before developing an understanding of the wisdom of the original builders. If I had made change to the first build I doubt I would have ever understood why the bench works and would have gone on to another style bench with most likely the same result, a less than optimum bench.

Of course YMMV,

ken

[Jim Koepke]

The wedge joint for the stretchers sacrifices a shoulder, bad idea on a bench stretcher, you need BIG shoulders and bigger stretchers.

Little bits of wisdom such as this are one of my favorite parts about reading bench build threads. The reinforcement of basic building rules helps others with their projects be they making cabinets, tables, chairs or a bench.

The individual style isn't as important as what holds it all together.

jtk

[Andrew Seemann]

It's your bench, so build it however you want. That said, there is some wisdom to staying close to traditional designs for a hand tool bench. Hand tool benches are a mature technology. Most of the details were worked out hundreds of years ago by thousands of craftsmen trying thousands of designs.

Since you asked here is my take. I'm not as worried about the overhang on the tail vise. It is pretty typical of what Roubo calls German benches and most here call Scandinavian/Frid/Klaus benches. No pounding takes place on the vise or behind it. The tapered legs make sense for a bench that is going to take a lot of pushing down its length, e.g. planing, as they will resist racking well. As commented above though, they aren't ideal for pounding. Since straight legs are perfectly adequate for planing, and tapered legs not ideal for pounding, why go to the extra effort and taper them?

Overall observation: You seem to have a combination of a Scandinavian bench with a leg vise. Given that the tail vise is the hard part of a Scandinavian bench and the part that scares most people away from them (not sure why, they aren't that difficult to make), why not lose the clumsy leg vise and put on a proper shoulder vise? They are much more useful for dovetailing and edge jointing and hold work more securely. You're two-thirds the way to a Scandinavian bench; just add a shoulder vise and straighten the legs. Roubos, Nicholsons, and Moravian benches are trendy now, but Scandinavian style benches were/are the choice for cabinet makers for hundreds of years. There are plans out there for both Frid's and Klaus's bench.

Disclosure: My hand tool bench is a Frid bench and I love it.

Frid Bench.jpg

[Will Blick]

"Roast" your design?
I applaud it !
I am impressed with your CAD skills...what program are you using?
Effective use of CAD is so helpful in perfecting a design. I keep trying to get better at it.
Sanity checks are humbling, but mandatory IMO, others see what one pair of eyes often misses.
I too immediatley thought, too much unsupported bench over the legs. Otherwise, it looks like a great build, and something u will use and take pride in for years!! Nice design!

[Joshua Lucas]

Thanks for your input, everybody!

One thing to note is that this isn't my first rodeo: this will be my second bench (not counting doors on sawhorses); the current one is similar to Chris Schwarz's $175/$280 workbench (from the red workbench book). So, I have a general idea of how I work and what I want my bench to be able to do.

My attractions to the Moravian design are twofold: one, the angled leg vise. This strikes me as the best all-around front vise design, with its huge capacity and the ability to clamp boards vertically without racking. No offense to the shoulder vise fans, but I don't think there's anything it can do that the angled leg vise can't do at least as well.

The second is the ability to knock the bench down. This won't be a portable bench by any means, but even though I don't have any plans to relocate in the near future, at my age (29) it's a near-certainty I have at least a few moves in my future. A bench that can be moved by two people is a big plus.

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A lot of you are concerned about the overhang. I agree that it does look like a lot. One important thing to note though is that from a stability standpoint, the overhang isn't measured from the leg joint but from the base of the leg, which decreases the overhang by about 5 inches, from about 24 inches to 19. This is basically the same overhang used by most end vises, including the Benchcrafted wagon vise and the Frank Klausz tail vise. It's also less than a quarter of the total length (80 inches).

Also adding to the stability is that this is a very heavy version of the Moravian: my CAD software is estimating 270 pounds for the total weight. That's assuming dry wood too, which this is most certainly not!

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As for the Shitage Kama joint, I'm not concerned about its strength. It's very strong and derives most of its strength not from the shoulder like a normal tenon but from the fact that it's essentially a dovetail. The wedge drives the angled bottom face of the tenon against the mortise wall and very effectively prevents racking. Here's an x-ray view of one of the joints:
Shitage Kama.jpg
Note: as modeled here the wide part of the tenon does not actually fit through the narrow part of the mortise. I realized this today when cutting the first of these joints. It's easy to correct by just making a bigger wedge as it should have been in the first place.

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Wil, thanks for believing in me, haha!

I'm using Autodesk Fusion360. The learning curve is probably pretty steep if you haven't done parametric CAD before, but it's way more powerful than SketchUp and the like. And it's free for hobbyists!

[William Fretwell]

OK Joshua lets do some simple maths. Your tenon slope, all one of them is at about 15 degrees, as you increase the angle, say to 45 degrees the longitudinal force from wedging increases; would you agree with that? You have essentially a slope and a wedge, as you continue to increase the slope, say to 90 degrees you have a through tenon with a 90 degree wedge. For the same size, the force along the stretcher is given by the Sine of the angle. The Sine of 15 degrees is 0.259, the Sine of 90 degrees is 1.

So essentially you will achieve a quarter of the longitudinal force given by a through tenon of similar dimensions. In reality it will be much worse than a traditional bench as the tenons are larger and the wedge of a through tenon can be driven far tighter.

Keep thinking: The angled wedge of a through tenon is in an angled hole, it is exactly the same thing as you are building just at 100% efficiency instead of 26%. Now if the 26% is enough for your design please let us know in a few years.

Yes the longitudinal pivot point is in line with the bottom of the leg, however the lateral wobble is in line with the top of the leg. It is the lateral wobble that bothered me when using a bench with overhang. My bench is traditional with essentially zero overhang.

Ken’s insight into appreciation by doing what many lifetimes have taught us is most profound.

I have not even touched on racking forces in a frame, shoulder size and separation. Have fun with your half a dovetail!

You did say ROAST!

[Frederick Skelly]

Josh, it's your money and time. And chances are, even if your design is all wrong - which it probably isnt - nobody will get hurt. So go for it. FYI, I built my bench out of dimensional lumber and deck screws, long before I found SMC. The bench works very well. Probably because I spent 2-3 trips to woodworking stores studying how high end benches were constructed and used a lot of that. I also built a half scale mockup before the final bench.

You might consider doing a mockup of some or all of that bench (using cheap dimensional lumber), to test your designs. Several people here have built more than one bench. For example, Ken Hatch in post #5 has built probably six or more, and IMO, he is our resident expert. He has studied them and tried different classic designs to understand their workings. His advice on a bench is worth it's weight in gold, as is that of several others who have responded.

I'm not trying to tell you to always do what our forefathers did - if that was so, we'd all be working in Parthenon-style buildings and driving ox carts to work. But there's some kernels of wisdom here.

Look forward to seeing pictures of your bench build, regardless of what design you ultimately choose.
Fred

[Jim Koepke]

My attractions to the Moravian design are twofold: one, the angled leg vise. This strikes me as the best all-around front vise design, with its huge capacity and the ability to clamp boards vertically without racking. No offense to the shoulder vise fans, but I don't think there's anything it can do that the angled leg vise can't do at least as well.

An angled leg vise can still be subject to racking. The workpiece has to pass through the centerline of the vise screw to lessen racking.

There are many ways to counter racking in various kinds of vises. In my case a stack of shims has actually made it possible to use racking to advantage, especially with holding thin work:

Planing Thin Stock.jpg

Here having shims in the vise to counter racking also works to regulate the vise's pressure on the workpiece.

jtk

[Joshua Lucas]

In that comment I was contrasting the angled leg vise's vertical clamping ability to a normal leg vise more than anything. A standard leg vise can't clamp a board vertically without being subject to racking, while an angled vise can put the workpiece on the centerline of the vise and so avoid racking.

Of course any vise design can rack and the angled leg vise is no exception. It's more that some vises do so in more annoying ways than others. My current bench has a metal/wood hybrid wood face vise like I believe yours does, Jim. That vise may possibly be the worst possible design when it comes to racking since the only thing preventing it are a few little screws (six #12 wood screws on mine I think) holding the vise to the underside of the bench top. My current bench has a Douglas fir top so those little screws are now quite loose in their holes. Obviously you've made lemonade out of lemons but it's still not an arrangement I'd knowingly choose.

[Alan Schwabacher]

The dovetail wedged tenons will work fine. Paul Hasluck, Scott Landis, David Charlesworth have described them in their books, and from the name you gave them, it seems there may be an eastern tradition as well. My bench made with them decades ago is solid as a rock.

The flaw in the analysis above is that the critical force is the pull out force, not the force pulling shoulders in under no applied force. Before building my bench I tested smaller dovetail wedged tenons to destruction: the tenons do not slip. Failure is by pulling off the tenon itself. This breaks far more wood than is present holding in a tusk tenon, but I'll just say that both types appear sufficiently strong.

You are right that in terms of balance, overhang beyond the foot is critical. But rigidity of the top would be higher with less overhang. Note that many benches with large overhangs also have a 5th leg to stabilize the end.

A slanted leg vice does allow unimpeded vertical clamping, but note that it does not require the leg itself to be slanted. Slanted legs are generally used to help a lightweight bench to resist planing forces. Yours sounds heavy enough to not need this.

[William Fretwell]

My analysis compares force vectors in similar set ups. Testing the pull out force to destruction is pointless as in the real world resisting wracking is the goal, the force applied to the shoulders at rest must be greater than the wracking force when in use. With Large wide wide shoulders this is easily achieved.
The splayed legs of the Moravian design mitigate some of the wracking but two shoulders still help. If your roof caves in on a Moravian design then the pull out force may be of some interest if you seek refuge under it.