Workbench: Slabs or boards?

[Joe Fabbri]

Zach,

It's interesting that you would say sapwood side up. Maybe Schwarz (from pictures, that what it looks like he did) and some others were thinking what you're thinking--rather than trying to hide defects as I thought. As far as the strength of the heartwood, that's a minor issue, granted, particularly when you're dealing with a hardwood anyway. But, I think my greater concern is that when it cups up, the slabs will be essentially lifting off the leg joints, don't you think (instead of bearing down even more tightly)? I'm not too concerned about having some more work flattening the top, so if we took that out of the equation, do you still think that cupping up is more beneficial?

Joe

[Sean Richards]

That is a neat idea. I was planning for a solid top - but will consider the split top design with a tool tray/shavings collector in the middle.rick

When I put a new top on my bench a while back - I used a split top with an 1 3/4" gap down the middle. This is a large enough so you can fit a big F-clamp bar in the gap and clamp stuff - that plus some holdfasts covers most clamping needs. I also have a batten that sits in the gap that is about 3/8" higher than the bench top and acts as a planing stop - this is a real good feature of a split top.

[Jim Kirkpatrick]

Don't take any short cuts. Glued up 2 x 4" sized boards will be much more stable than a slab and will dry faster too. You're building a bench that could last generations. Take your time.

[Zach Dillinger]

Funny you mention that Jim... there's lot of benches made from slabs that have lasted generations. Using a slab is far from a shortcut, and gluing the top together is far from traditional. Not a bad way to go, but most definitely not the only "right" way.

Joe, it certainly is possible that the bench will cup up away from the legs. Depending on the style of joint used, it might cause a gap. Perhaps thats the reason for the Roubo rising dovetail that's been so popular lately. I'm not sure I see it as a problem. If we take flattening out of the equation, I'm not sure I see the cupping as any more beneficial than crowning.

[Joe Fabbri]

Zach, I agree. I'd say slab benches are very prevalent in antique workbenches. If you look at antique French workbenches, I don't think I've seen any that aren't slabs, and practically all single slabs--they often made pretty narrow tops, with 18-20" being the norm. These benches are often from the 1800s. Sure they have their checks and crowning issues, but I'm sure they're still very sturdy. I suspect with many of these benches they didn't fuss too much about being dead flat.

Anyway, Zach, I plan on using the Roubo dovetail and tenon (I'm not sure if that's what you're referring to, or if you're referring to what some call the impossible joint). I'm not sure, but with traditional dovetail and tenon joint, I don't see much keeping the top from separating, and I wasn't planning on gluing the joint. For me, I'm in the habit of orienting boards bark side down, or against a joint/surface. I'm interested in hearing what others have to say, though.

Joe

[Justin Green]

If it cups, your round tools roll to the center of the workbench. If it crowns, they roll off the edge. Just kidding.

[Aaron Rappaport]

Say Zahid,

Did you flatten the 4 x 4 s for your workbench by hand or machine? I find it is taking me well over an hour per 4 x 4 as I work on mine by hand.

Thanks, Aaron

[Russell Sansom]

You ask a good question. I've always been a slab guy. So was my grandfather and his father. I think they were because they could be with the availability of big lumber in their times. The laminated pine concept makes it possible for almost anybody to own a big, beefy bench these days. That's really cool. But I just have to have my slab.
A couple points to consider if you haven't:

Big slabs are tedious to work on and dangerous to handle. Really dangerous. If you have two or three in your shop at once, it's a recipe for disaster with all that potential energy.

Trying to run a 12/4 slab of maple 8" wide through a home woodworking machine is an adventure. When I didn't have those machines, I did it all by hand. Now that I do have an 8" jointer and a 12" planer I still do it by hand.
Flattening has never been a huge issue for me except once when the bench sat idle for a couple years. I count on my bench as The primary flatness reference in my shop so I tend to be finicky about how flat it is. I check it every other month or so. These touch ups only take a few minutes.

[Zahid Naqvi]

All hand planes. I was very diligent with the glue up and used alignment sticks to make sure the top was as flat as possible while clamped. I also jointed three sides of the 2x4s before the glue up (didn't care about the bottom). As a result I had to do very little flattening after the glue up. The first thing I did was, using two winding sticks, found and marked all the humps and hollows on the top. The first round was with a scrub plane to get everything flat, after that I went through a jack and then to a jointer. I didn't want a slick top so didn't follow up the jointer with a smoother.
Post glue up I got all the planing done in one weekend. I think the biggest time/effort saver was using the scrub to remove the bulk of the material, the rest was just getting rid of the ridges. If you include the time spent on getting the 4x4s prepped pre-glueup then I spent a couple of days on that too. These two weekends I probably got about 6/7 hours of shop time each day. Also try to do the flattening from 2-3 different angles, i.e. plane in an X pattern (45 degree from each side of the bench) on the top and then at the end plane in line with the length. But if you start with a jointer it is certainly going to take a long time, you need a rough to gradually smooth process.

Say Zahid,

Did you flatten the 4 x 4 s for your workbench by hand or machine? I find it is taking me well over an hour per 4 x 4 as I work on mine by hand.

Thanks, Aaron

[Joe Fabbri]

Hi Russell,

I'm glad you mentioned the jointer and planer. I have these slabs which are 3.5-4" thick, and 10-11" wide. They're over 8 feet long. Well, I'm trying to decide the best way to mill them. I figured I could get one side flat and buy a planer to get them even thickness. But I can't figure out how the heck I'd run them through it without a whole team of people! So I'm also thinking doing it by hand might be best. I'm still undecided, though.

Anyway, this is a point to keep in mind when deciding slab vs lamination. If you want a big slab, I guess, you have to make sure you either have heavy duty equipment, or don't mind doing it by hand. With a laminated top, everything could be done, it seems, on light-duty machines (lunchbox planers, etc.). Although I think I still prefer slabs if you have them, this is worth considering nevertheless.

Joe

[Zach Dillinger]

Joe, I don't think I'd worry about making them an even thickness. Far too much work. The only concern in this regard is that the area where the legs will rest are all in the same plane. Easy way to do that is to flatten the top, then use a sash filletster or similar tool to describe the plane referenced from the flat top only in the areas where the legs will meet the bottom of the top. After that, you can chisel / plane / adze / whatever the wood out to fit the legs in all four spots. Any more than this is wasted effort. In fact, leaving the bottom rough will add thickness to the bench in the areas that need it most.

Working with hand tools on such a project is, to me, the far better option. I don't like planers / etc. but I can't imagine using one on a piece of wood this heavy. With hand tools, you could even flatten the top while it is sitting on the floor. Don't do any more heavy lifting than is absolutely necessary.

With regards to the dovetail joint, I was talking about the impossitail version that Roy used on his Roubo.

[Joe Fabbri]

Thanks for the information, Zach. The wood I'm using (black birch) planes very nicely anyway. In particular, roughing down across the grain with my 5 1/4 jack is pretty easy, with the tight grain. So, I'll probably use all hand tools on it, and save the money anyway.

I'm making some heavy duty (hopefully heavy-duty enough) sawhorses right now, in order to get the pieces up to a better height. I've done quite a bit of work on the floor already, but it's a little annoying to do, and I think it's roughed out enough to move them onto horses. (I actually did quite a bit of roughing down with a skil saw- to kerf down to a certain depth and avoid tearing out- and chipped away with an simple adze I made from an old pick axe. It worked pretty well, though my wrists were killing me. That might be due to the bad ergonomics of the straight handle.)

Anyway, I like the idea of only squaring/flattening the areas for the legs. I wasn't going to try to get all of the rough hewing out of the bottoms anyway, just a rough flattening, but maybe like you say, I will barely do that. I suppose it really is better to treat it like a timber framing project, where only the joints are squared and true.

One place I figured a planer would be particularly helpful was in getting the legs equal thickness. Since these would only be at most 3' pieces, it wouldn't be too hard. But maybe that's not too important either, if they're a little off in thickness, so so long as they're square.

I guess with slabs, you simply have to prepare yourself for a good deal of handwork. That or bring it to some larger machinery with a bunch of people. On a boat project I was volunteering on, we were beveling big pieces (16 plus inches wide by up to probably 7, 8 feet) of 12/4 White Oak on an 18 Rikon bandsaw for the boat's frames. That was quite a job, even with a team of 3-4 people. It was interesting when we had to put pretty steep bevels on some.

[Jim Neeley]

I work in a large engineering office (Electrical Engineer) and took the issue of creep to a series of structural engineers. We talked about how the laminates run lengthwise and are supported by cross-supports towards each end. They explained that creep, if any, would be negligible in that configuration however they explained that creep is a real phenomena in wood, of you are looking for a *precisely* flat surface. Again, not a biggie in a benchtop but that it may at least be a measureable phemonema.

Glue creep, they explained, *might* be an issue if you were to cantelever the bench from a wall with no legs, such that the glue joint nearest the wall must take the full weight and torsion of the slab. Even then, they said it may not be an issue.

FWIW.. This was "water cooler" conversation, so your mileage may vary.

Jim

[Zach Dillinger]

Jim,

I agree that creep would be negligible if you have cross supports. But for a Roubo, without such supports, I can assure you its quite real and measurable. Lacking proper slabs, I built my Roubo by laminating a large number of scrap birch drawer sides (cost me $45 to buy a pallet load, which was more than enough). They are 3/4" thick, 4" wide and 16 1/2" long. I lface-laminated enough of these together to make a 24" wide, 4" thick, 8 foot long bench. It took me the better part of a summer and a gallon or so of Titebond. In the years since I've made it, the center of the bench (between the legs where there is no support) has crept downwards about 3/16". I've flattened it out but the problem has made me consider putting a secondary brace in place to shore up the center. This is an extreme example, of course, given my choice of material, but any large glue-up without support will suffer a similar fate. It's just too heavy, with too little support. Its like an overloaded bookshelf. Nothing can be done unless the shelf is stiffer or you add a central support.

My next bench will be rather more rustic in composition and will be made from two large slabs of 16/4 beech that were still dead green when I made my current Roubo.

[Joe Fabbri]

Zach, with two large slabs, do you think you would put a stretcher between the legs also? Or is it supported enough, to prevent the creeping you describe, since each slab is resting on a leg?

I wondered about people building unsupported Roubo benches with laminated (2x, etc.) tops, and whether it was necessary to add a stretcher. I recall some saying it would be overkill, but with lamination, you are straying from the original design of Roubo's (with the single slab). There seems to be a lot of laminated top Roubo's out there, so I wonder if other have had similar issues

Joe