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Forum topic by andre_p posted 03-10-2016 02:28 PM 700 views 0 times favorited 14 replies Add to Favorites Watch
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andre_p

9 posts in 272 days


03-10-2016 02:28 PM

Topic tags/keywords: workbench black acacia slab

Long time lurker and admirer of so many of the great projects posted here! Excited to finally be getting into woodworking a bit more seriously.

I’m currently working on my first workbench and recently had the chance to buy a slab of local hardwood (Black Acacia, dried 2 years) that I’m hoping to use for the build. It measures 2” x 23” x 55”, which is about right given my space constraints in San Francisco, and I want to build a bench in the Roy Underhill “Little French Bench” style (https://dblaney.wordpress.com/2011/06/) but I have a few concerns:

- Is 2” too thin? I’ll be router planing it, so will probably lose another ~1/8”
- Is a slab a bad choice because of wood movement issues?
- Would it be difficult to install a wagon vise in a slab bench?
- Is a slab compatible with the style of legs used in Underhill’s bench?

I think some of my worry comes from the fact that I see so few slab workbench builds and so I’m uncertain about some of the pitfalls I might face. I appreciate any advice/input.

Here’s a picture of a slab very similar to the one I ended up with (mine has less cupping).


14 replies so far

View rwe2156's profile

rwe2156

2190 posts in 943 days


#1 posted 03-10-2016 02:53 PM

I’ll answer what I know about:

– Is 2” too thin? I ll be router planing it, so will probably lose another ~1/8”

IMO yes, especially if you want to use a bench hooks.

– Is a slab a bad choice because of wood movement issues?

It depends on whether the bench is located in a climate controlled shop or not. Definitely has to be taken in to account regardless. When anchoring to base fix the front and use a method to allow for expansion like slotted holes.

I think some of my worry comes from the fact that I see so few slab workbench builds and so I m uncertain about some of the pitfalls I might face. I appreciate any advice/input.

Here s a picture of a slab very similar to the one I ended up with (mine has less cupping).

- andre_p

-- Everything is a prototype thats why its one of a kind!!

View bondogaposis's profile

bondogaposis

4024 posts in 1813 days


#2 posted 03-10-2016 02:55 PM

I don’t see how you would install a wagon vise on a single slab with out a great deal of difficulty. The usual configuration includes a dog hole strip and an outer strip. You could still incorporate the the slab for the rest of the top. I think the first step in designing a bench is to acquire the vise hardware first, then work around that.

-- Bondo Gaposis

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JBrow

818 posts in 382 days


#3 posted 03-10-2016 05:20 PM

andrep,

Is 2” too thin? I’ll be router planing it, so will probably lose another ~1/8”

The closer to a finished thickness of 2” you can keep the top, the better. A couple important attributes of a good work bench are mass and flatness. Mass keeps the bench from scooting across the floor when applying lateral force, such as when planing. Flatness is a little easier to maintain with thicker lumber than thinner and offers a registration surface for flatness when building a project.

Is a slab a bad choice because of wood movement issues?

The worry with the slab is the same as with wide glued-up panels. Will moisture enter the slab more on one surface than on another and introduce a cup after the slab is flattened? When milling the slab, ensure both edges and the top and bottom surfaces are milled at least enough to expose fresh wood. Any sanding on one surface should like be done on the other three surfaces. The end grain should also be sanded to a fine grit.

While working on the slab, store it so air can get to all surfaces. This will help maintain moisture equilibrium in the slab. When the slab is complete, apply a film finish to all surfaces. Apply the finish to the end grain until the finish lies on top of rather than being sucked into the wood.

But if you are worried that you may experience some cupping later on, ensure the top can be easily removed from the legs. The open mortise and tenon joints can be mechanically fastened. Then if cupping occurs, the top can be removed, re-flattened, and a series of kerf cut made on the underside of the slab, like is seen on solid hardwood flooring. The kerf cuts can help relieve some wood stress.

Would it be difficult to install a wagon vise in a slab bench?

Even a two inch thick top may not be enough for the vice and dogs. This can be fixed by first flattening the top. Then face glue a piece or two on the underside of the slab along a long edge and dimensioned to accommodate the vice and dog holes. Thickness to accommodate the vice need only be where the vice and dog holes are located. The vice should be at hand before building up the edge.

Is a slab compatible with the style of legs used in Underhill’s bench?_

If the grain direction of the top and the legs run more or less in the same direction, it is unlikely wood movement will be noticed. Wood will move across the face and through its thickness of the top and the legs, more or less about the same.

If worried about whether the 2”- thick slab to leg joint is not strong enough, face gluing short pieces keeping the grain running the same direction, will give more surface to let in the leg tenons. This added wood should strengthen the connection.

Generally, the problem I see with the Underhill design is that the legs are located directly below the edge of the bench. I can see where from time to time your toe might catch a leg. Recessing the legs would avoid this problem.

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TheFridge

5765 posts in 948 days


#4 posted 03-10-2016 05:31 PM

I have a smaller bench (24×48) with the legs and aprons flush with the edge of the bench all around and I haven’t found it to be a problem at all.

-- Shooting down the walls of heartache. Bang bang. I am. The warrior.

View jdh122's profile

jdh122

879 posts in 2279 days


#5 posted 03-10-2016 05:42 PM

The main reason 2 inches might be insufficiently thick would be that holdfasts might not hold in it. But if you check out the Nicholson-style bench that Mike Siemsen makes (there is a great video of it floating around) all out of 2by construction lumber (so 1.5 inches thick) he solves the problem by adding blocking underneath the bench wherever he puts a hole for the holdfast. Since this in an easy retrofit you could make it and see, then add the thickness if required.

-- Jeremy, in the Acadian forests

View sepeck's profile

sepeck

314 posts in 1603 days


#6 posted 03-10-2016 05:50 PM

I am going to use a Douglas Fir 4×12 for my first homemade bench top. http://www.homedepot.com/p/4-in-x-12-in-x-8-ft-Prime-S4S-Douglas-Fir-Lumber-454511/202083094

Available materials, not all that expensive so I won’t be attached to banging on it. Pretty thick (3.5” before planning), Douglas Fir. If I mess it up, shrug. Use the cut off part as a base for my vice. Built it, beat it up. Learn from it. Then if you still want a pretty bench out of hardwood, you can roll in the lessons learned from that one.

-- -Steven Peck, http://www.blkmtn.org

View shampeon's profile

shampeon

1712 posts in 1645 days


#7 posted 03-10-2016 07:35 PM

I made this Roubo-style bench in SF with most of a slab of 12/4 red oak. It’s thicker than your 2” acacia, but it’s a smaller workbench.
Click for details

I’m no longer in the city, so I don’t have the same size constraints, but so far I’m still enjoying the size of the bench.

If you want a wagon vice, add a strip of another wood to the front of the slab. One complication is that Roubo-style front legs means your wagon vice and hardware need to be to the right of the leg. That means you’re going to need a little extra length on that side.

Do you know how dry the slab is? If it’s not completely dry, it’s going to be harder to anticipate movement. Since the slab is cupped, make sure you make the top the side that has the high point in the center. That way you can flatten it with a hand plane periodically, if it continues to cup.

As for the legs, sure, you can attach those legs to a slab. It’s just an angled mortise on the back and rising dovetail in the front. But, you should be aware that those joints are more advanced.

-- ian | "You can't stop what's coming. It ain't all waiting on you. That's vanity."

View andre_p's profile

andre_p

9 posts in 272 days


#8 posted 03-10-2016 09:46 PM

Wow – lots of amazing feedback. Thanks everyone for taking the time to respond. I’m realizing I should have done some more research before buying!

rwe2156: I’m not familiar with slotted holes. Could you point me to some explanatory material?

Bondo Gaposis: thanks for confirming my suspicions. Given that I might end up going with the Veritas Inset vise instead.

jdh122: I appreciate the tip about the holdfasts and will definitely seek out that video.

JBrow: Thanks a bunch for your response. Lots of helpful information in there, especially the tips about how to work the bench top! Veritas Bench Pups call for 2” thick bench tops; is there a significant disadvantage to using them?

sepeck: I may end up going that route after all, especially as I am realizing the complexity of what I’ve taken on…

shampeon: Thanks for your feedback and for sharing your bench. I really like the design and am glad to hear you’re satisfied with the size. The Little John Workbench (http://www.theenglishwoodworker.com/wp-content/uploads/2012/10/10.jpg) has been a big inspiration for me as well, and I think I may just use an inset vise as in that bench.

If I decide that I want a thicker bench, do y’all think it would make sense to rip the slab down into 3” strips and combine it with some additional wood to get back to the same approximate width?

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shampeon

1712 posts in 1645 days


#9 posted 03-10-2016 10:56 PM


If I decide that I want a thicker bench, do y all think it would make sense to rip the slab down into 3” strips and combine it with some additional wood to get back to the same approximate width?

Yeah, that’s definitely the best way of getting a thicker bench with your current wood. With a smaller bench, you will want as much weight as possible to prevent it from moving under heavy planing, though acacia is pretty heavy.

I don’t know how much you paid for your slab, but I personally love the look of acacia, and in some ways think your slab would be much more attractive as a coffee table than as a workbench. But it’s your bench, and I’m just some random dude on the internet.

FWIW, you shouldn’t have any problems with holdfasts with as long as it’s more than 1.5” or so. The wedging action of the holdfast is what gives it its strength, and it actually wedges better in a thinner top. See https://www.toolsforworkingwood.com/store/blog/251/Some%20Tips%20on%20Using%20Our%20Gramercy%20Holdfasts

-- ian | "You can't stop what's coming. It ain't all waiting on you. That's vanity."

View builtinbkyn's profile

builtinbkyn

651 posts in 402 days


#10 posted 03-10-2016 11:14 PM

Andre it appears the slab is cupped. You’ll obviously need to flatten it. Even if it’s not cupped or not as bad as it seems to be in the pic you’ll need to plane it flat at some point, to get a true surface. It’s unlikely there’s no twist in the slab. You’ll not end up with 2” if that’s what it is presently. However as has been mentioned, you can use blocking below the top where the dog holes are located to give holdfasts the bite they require.

There’s no reason I can see why you cannot install a wagon vise. If you’re making one from wood, it will need to be closer to 3” tall vs 2” or you may not engage the pitch of the wedge enough for it to properly engage and hold. But I’m no expert on that. I’ve only made one and at 2 3/4” tall, it works as intended. However there’s no reason it cannot extend below the surface of the top’s bottom. You could add a skirt to hide that if you don’t want to see it in profile.

-- Bill, Yo!......in Brooklyn :)

View andre_p's profile

andre_p

9 posts in 272 days


#11 posted 03-11-2016 12:13 AM

builtinbkyn – The slab was cupped; I actually traded it in for another one that is a lot flatter. I’ll still be router planing it but I only expect to lose 1/8” of thickness.

shampeon – I paid $110 for the slab (is that a good price?) and am definitely considering other uses for it. I might turn it into a side table or desk. At the same time, I’d really like to build a nice looking workbench and don’t mind investing in it. Seeing pictures of your workbench has tipped me towards sticking with the acacia :)

View shampeon's profile

shampeon

1712 posts in 1645 days


#12 posted 03-11-2016 12:57 AM

17 or so board feet of 8/4 acacia at $110 is around $6 a board foot. I’d say that’s pretty good. Less than 8/4 red oak at Bay Area hardwood dealer prices, and less than what I usually see acacia going for on Craigslist.

-- ian | "You can't stop what's coming. It ain't all waiting on you. That's vanity."

View JBrow's profile

JBrow

818 posts in 382 days


#13 posted 03-11-2016 02:38 AM

andre_p,

I see no reason the Veritas Bench Pups would not work for you so long as you retain close to 2” of top thickness.

I have metal square bench dogs and wish I had gone a different way. I think ¾” dowels, with a flatten notch would have been better for me. It would be easy to remake one if it got damaged. Being wood, there is less worry about nicking a blade. But I will live with what I have, since I rarely use bench dogs and do not know how to keep round wooden dogs from simply dropping out of the dog hole.

View kiefer's profile

kiefer

4881 posts in 2129 days


#14 posted 03-11-2016 02:47 PM

Just another small bench that may give you some ideas .
This is a workbench and not a show bench that is in daily use and shows the scars to prove it .
I have been working on this bench for some time and did changes to improve it along the journey that I thought would improve it .Watch the video and you will get a better view and understanding .

https://www.youtube.com/watch?v=bNr65p49Qso

Klaus

-- Kiefer https://www.youtube.com/user/woodkiefer1/videos

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