Bench Plans/comments?

[alex grams]

This will probably be the millionth thread of bench design, but I just wanted to throw this out and get some feedback on the bench design. I am a hybrid hand/power tool guy. The main dimensions are 72"long x 30"wide x 34.24"high, with a 2.25" thick top.

I plan on adding cabinets on the underside, but with their top being about 6 inches below the underside of the benchtop so that i can get dogs/items that fall through the dogholes. I will build the top of 8/4 hard maple, and the base either out of maple or ash, with the posts being 3.75"x3.75".


I wanted to make the bench semi mobile, so am contemplating putting 2 of these on one end so I can prop one end on casters and move it from the other end:

http://www.rockler.com/product.cfm?p...=mobile%20base

I am going to make the two legs bolt to the cross beams, so that if ever need be it can be broken down, but the leg assemblies themselves will be permanent/glued.

I am still iffy on how to attach the top to the base, hence the multiple base designs in the picture. I am probably just going to but a lag bolt on each of the short cross beams at the top of each leg assembly. I wanted something more than the lower cross beams to help provide some rigidity to the base.

I am welcome to suggestions and any comments. For my uses the bench is in line with what i need, so I am mainly looking for design changes in terms of construction methods that may help make things stronger/easier to build, cheaper, etc...

Thanks in advance.

[Victor Stearns]

Maybe Something like this?
Did not intend to move this once it was finished. However I did make allowances in that it can be broken down easily. The cross beams are mortise and tenon, but held together with tee-nuts and 1/2" bolts. Top is lag bolted through the top of legs. Very solid and much nicer than the old B&D Workmate.
Good Luck
Victor

[Peter Gavin]

That is a nice design, but I have decided to make my next bench with the front legs in the same plane as the front of the top. I understand Christopher Schwartz advocate this (though I have not got around to reading his book yet) and it seems like it would be very handy to be able to use the legs as a support for long stock by using dogs etc. I would still leave the legs in the back under the top to leave a convenient palce for clamping etc.

Peter

[John Schreiber]

I think what you've got would work fine. These suggestions are based on my planning and building my bench.

Make sure the end boards allow for expansion and contraction of the bench top.

You may want to move the face vise so that it's left edge is flush with the left edge of the top.

Upper long stretchers are probably unnecessary if the top will be lag bolted securely to the short stretchers. The top actually serves as a long stretcher itself. The bottom stretchers could be a little taller to prevent wracking.

If the front legs are flush with the front of the bench, you can use them in clamping.

Aprons are a mixed blessing. I think they should either be eliminated or made thick enough and deep enough to allow easy clamping against the bottom. It's a real pain when you have to jigger the clamp to fit on a narrow apron. But they are nice when you can clamp against them from the front.

Think about how you will be using the vises and if there will be excessive wracking forces on the mechanism when you use them with one dog hole at a time or when holding wood. Not that I see a really good solution, but I wouldn't want to always be clamping against one of the extreme ends of the vise.

My 3 cents. Use as you see fit. If you haven't read the Chris Schwartz book on workbenches I'd recommend it.

[David Keller NC]

Alex - I'm just finishing up a bench that's based on the principles in Chris Schwarz' book. If you don't have this book, I'd highly suggest getting a copy and reading it before building a bench. The cost of the book is minimal, and will pay for itself many times over. The real difference with this book compared to other workbench books out there is that Chris explores the why about different bench designs, instead of just the "how".

Even if you choose not to buy the book, it would be worth downloading and reviewing the extra chapter he wrote on knock-down bench designs:

http://blog.woodworking-magazine.com...Book+Free.aspx

I used Veritas Bench Bolts for my latest workbench, and the jig Chris shows for getting the alignment right is very, very useful - all 8 holes that I drilled to receive the round nut and bolt length lined up perfectly.

Regarding your design - I'd suggest a few changes. One is that I'd consider making the top thicker. For both power tools and hand tools, having a top that's stiff is important, and over the span you're specifying, you might have flex issues with a 2-1/4" top, particularly if you use a softwood species like Douglas Fir. I'd also reduce the width - there's good reason to make the width no more than 24", as that allows clamping a standard cabinet depth on both the front and back sides. I'd also make the stretchers flush with the front legs, and make the front leg surface and feet in the same plane as the workbench top/aprons.

If you're interested I'll post a picture of my almost-completed bench a little later today.

[alex grams]

Thanks for the info. I do have Schwartz's book and it was a good help.

I see the point on moving the smaller face vise against the edge.

The skirts are going to be 1.75" thick, so should offer plenty of size to allow clamping on the bottom of them.

I am going to doghole the skirt also, so I can use the face vise with the dogholes to hold up longer stock.
I got some larger stock for the lower stretchers, so they are going to be about 6"x2" instead of the shorter 3"x2". I may actually double up the stretchers so they are 3"x4", and they are going to be lag bolted.

Thanks again for all the input. I've spent a few months just working the design out in my head.

Edit:
In regards to David, the top will be a little thicker since I was about to get some wider stock, I should be able to do 2.5".

I am a pretty tall guy, 6'4", so the depth of the bench will pose no problem. But I am aware of the reason for your comment, and gave it due consideration before finalizing at the width of 30".

Thanks for the info on the Veritas Bench Bolts, I may go that route, but that is more money to consider. I would prefer those over lag bolts, but 8$ per bolt is a pretty steep price.

I thought about making the legs flush, but that isn't something that would really add a lot of features I would use. Maybe I will learn otherwise and in the future next bench I will do that.

[David Keller NC]

Alex - If you decide to go the route of standard hex bolts, check out Chris' blog both at Woodworking Magazine and The Lost Art Press. I can't find it at the moment, but there was a blog entry regarding teaching a class on building a knock-down version of one of the benches in the book, and he describes a router jig made from plywood and off-cuts that allows perfectly routing the bolt shaft trench and the hole for the hex nut.

Personally, I'd rather pay the $24 bucks it takes to get 4 of the Veritas bench bolts (you only need one per stretcher end if you make a beefy Mortise and Tenon and fit the shoulders correctly) than build the more complicated router jig for doing standard hex bolts.

Regarding making the legs flush - one big advantage of doing this is that you can mount an extra 6" wide stretcher about 8" below the bench top on the front of the bench, drill this with a series of holes, and have instant support for holding a long board on edge (using the face vise and a dog in the extra stretcher). This idea was a feature of the knock-down bench that Bob Lang detailed one issue ago in Popular Woodworking. If you want to look at his design but don't have a subscription, he posted a sketch-up model in the Popular Woodworking Editor's blog. Moreover, it really doesn't take any extra effort nor more material to build them flush on the front, and as far as I can see, there is no downside.

[Johnny Kleso]

First I would not add face vise dog holes across the whole bench..

I would add a double/triple hole just in front of the face vise to use as a planing stop.. This is like the flip up end stop you see on some benchs.. You dont need to clamp evey piece of wood you plane in a vise, most of my planing is done with just a stop at one end...

If you add cabinets make sure you add room for clamps to hold stuff to bench top..

Also I like my thicker top (it moves less) if your using SYP I would make it a little thicker..

[alex grams]

David, i did some number crunching regarding the bending strength of the top and the thickness of the top for two scenarios:

-A 2.25" thick top that is a total of 33.5" wide, the width including 2 1.75" wide by 5" tall skirts at each end

-A top that has no skirts, but is 33.5" wide and 3" thick.

my 2.25" thick top with the skirt experiences about 21% less deflection than a flat 3" top with no skirting.

So while, a thicker top may sound like an nice solution, it is a diminishing return for the amount of wood it would take to achieve similar results a bench top that has a skirt extending below the sides of the primary slab.

Thanks for the comments though, because without it I wouldn't have calculated to check the bending resistance of the alternative top designs.
-Alex

[David Keller NC]

Well, there's a couple of other reasons why you might want to go with a thicker top, depending on your holding arrangements. No question though, that almost any design with elements of a torsion box (like aprons) are going to be really stiff.

The two other reasons besides stiffness are that holdfasts sometimes don't work so well on very thin or very thick tops, at least the forged kind that you would want to own (don't bother with the cast kind - they're complete junk that will break in two at the slightest provocation). "Very thin" in this case generally means less than 3", and "very thick" generally means 5" or more. The second reason is mass - you generally want a bench to be extremely heavy, though it can be designed to be dissassembled into manageable parts weight-wise. The top on a bench is the usual route to supply that mass, though using 4" square or larger legs helps out.

One other thought about the apron/no apron method of improving the stiffness of the bench - I wonder whether an apron design with a thin top would potentially result in a not-so-stiff center of the bench that would flex under load, though the overall bench would be quite stiff to deflection. In my particular case, that's a deal-killer, as I use benches extensively for handplaning. Might not matter too much if that's not something you see as a possible use, and you could potentially work around this by including a transverse brace mortised into the aprons, though that might intefere with some clamping operations.

And - this is just my opinion - Chris is right about aprons being a PITA. I've gone through 4 bench designs over the years (with #5 almost finished in the shop), the first 3 of which had aprons. I can see how the English bench with very wide aprons might serve to adequately support long boards on their edges, but my benches had a more usual apron dimension - about 5" or so, and that wasn't adequate for clamping one end in the face vice and supporting the other with a dog in a hole in the apron. Again, my opinions may be colored by how I work, but the problem with doing this is that on wide boards the board's edge that you want to work on is quite elevated off the floor, which makes using a jointer plane tiring, and using a router on the edge an exercise in awkward holding at mid-chest to shoulder height.

[Johnny Kleso]

If you run a skirt around the top it makes it very hard to clamp anything unless the skirt is 3" OR 4" Wide.

[David Keller NC]

By the way, Alex - I forgot about this when I posted my last message, but there's a way around bench holdfasts sometimes not working too well in thin or thick benchtops. The forged holdfasts that are available from either Galena Village Blacksmith (Phil Koontz - superb product and reasonable price) or from Tools for Working Wood are made from parallel, round bar stock. My experience is that they work or they don't, and it depends on the thickness of the top and what it's made of. Generally, the Phil Koontz holdfasts I have don't work too well in hard woods like maple that are less than 2.5" thick.

However, Colonial Williamsburg sells the ultra-traditional forged holdfasts with a tapered shank (they sell them through the Prentis store) - the tapered shank allows them to work well in stock as thin as 1.25". The Best Things (www.thebestthings.com) carries these, or you can order direct from Williamsburg.