Thread: Workbench Structural Anatomy

Myth 1: Perhaps, although if the material is heavier, it is probably denser and therefore potentially stronger. If all other things were equal, it seems a heavier bench should be stronger but I can't prove it. A bench carved from solid stone would be very heavy indeed but probably overkill for most work.

Myth 2: I made a bench for my lathe with the same construction that I will ultimately use for a workbench. It uses no fastners and no glue. It is held together with wedged tenons, wedged dovetail tenons, sliding dovetails and bridle joints. It might possibly need some dowel pins through the bridles but I've found that they are tight enough to not work loose. If any of the wedged joints become loose, they are easily tightened up again with a bit of thumping. Having heavy construction helps here because it gives a bit of dead weight against which to thump.

Originally Posted by silentC

Myth 1: Perhaps, although if the material is heavier, it is probably denser and therefore potentially stronger.

Isn't this a case of if it doesn't break/bend/move it's strong enough??? What I am getting at is if a bench of (say) 200kg is completely imovable in all respects, then 210kg is a waste of 10 kg of timber (and so on.)

Myth 2:It uses no fastners and no glue. It is held together with wedged tenons, wedged dovetail tenons, sliding dovetails and bridle joints. It might possibly need some dowel pins through the bridles but I've found that they are tight enough to not work loose. If any of the wedged joints become loose, they are easily tightened up again with a bit of thumping.

Apart from the joy of making the joints, WHY? if you had used glue they would not come loose, no thumping required, and no eventual breakdown of the joint. (I presume you have built it to be dismantled for moving?? and therefore gluing won't help!).

It is the working of the joint that causes the long term rickets, so I am postulating (I must stop eating so much fruit) that dismantling should be done somewhere other than at the right angled joints, contrary to historical logical tradition!

Cheers,

P

I suppose there is a break-even point where extra weight yields no benefit. I think this would depend upon the individual using the bench. Have you seen that bloke who can pull a semitrailer plus prime mover? I bet he would need a VERY heavy bench. If he was a woodworker, which he probably isn't.

Whether extra weight would actually turn out to be detrimental to the strength of the joints is another issue and, like I said, I don't think it would be - but have no way of proving it.

I got the idea for the joinery from Scott Landis's workbench book. I thought it would be fun, yes, but I also believe that a strong joint is a strong joint and doesn't need any glue. If you rely upon the glue alone, then you are stuffed if it fails. I suppose you could make a wedged joint stronger and unlikely to work lose if you glued it. I was really just agreeing that you don't need mechanical fasteners to make a strong bench and adding that you don't need glue for that either.

I'm also too cheap to spend money on bolts and fancy glue. The whole thing is made from a tree, except for the 4 screws which hold the lathe in place.

Originally Posted by silentC

Have you seen that bloke who can pull a semitrailer plus prime mover? I bet he would need a VERY heavy bench.

Depends on how blunt his plane/chisel is.

I don't know what the ideal weight for a workbench is, I suppose you'd have to ask Jenny Craig about that, but I do know that it has to be heavy enough to be "dead". By that I mean when you are pounding something or chiseling, with a suitable block to save the surface of course, you don't get any "boing", all the force is absorbed by the bench. I dont think weight is a factor in the structural integrity of the bench but it is certainly a factor in the boing in the bench.

As for how the bench is held together, thats up to the individual. If rubber bands work for you then go for it.

Interesting Thread Midge.

I think work benches need to be immovable and stiff.

Imovable so when you are chiseling horizontally or handsawing you don't have to chase the bench around your shed. My bench is not bolted to the floor but has sufficient mass so it's intertia resists any horizontal forces.

The stiffness is so the bench doesn't flex even if it stays in the one place on the floor.

It turns out that the materials we use add mass to achieve the above two requirements. So a heavy bench is not necessarily a good bench unless it is immovable and stiff.

If a new super light material was discovered that achieved my two requiements, was soft enough not to damage sharp edges on tools or timber then I would probably consider using it for a workbench.

BTW, consideration should also be given to where the mass is located so the workbench is stable even when overhanging large heavy projects are attached to the bench. I suggest a fair bit of the weight being down low.

I dont think weight is a factor in the structural integrity of the bench but it is certainly a factor in the boing in the bench.

I have this mental picture of a bench that makes one of those Looney Tunes type 'boing' sounds when you hit it. My kid has a toy workbench that makes a noise like that.

Originally Posted by silentC

I have this mental picture of a bench that makes one of those Looney Tunes type 'boing' sounds when you hit it. My kid has a toy workbench that makes a noise like that.

If that tickles your imagination then you should be around when I hit my finger. :eek:

Originally Posted by silentC

It is held together with wedged tenons, wedged dovetail tenons, sliding dovetails and bridle joints.

Any pics of the joinery Silent? I cant think how a wedged dovetail tenon would look like.

The ends of the mortice are cut on an angle, then one side of the tenon is cut on the same angle with the other side straight. The wedge locks the tenon in place. See attached pic. It's good for stretchers.

sitting on the fence :

the bench should suit its desired design purpose.

it should go "boing" if required, it should not move unless you want it too, if you move house a bit it should knowck down unless you are superman, another outside underpant wearing superhero or his homosexual sidekick.

with my work bench I wanted a nice long bench that was massy enough not to move but wasnt so hard to move if I decided to move it. therefore the drawers are removable as is the bench top. thus in a pinch I will whip out the drawers, unbolt the top from the stretchers and move the whole lot myself in 6 phases (4 x drawer, top then carcase). altogether I reckon the sucker weighs in at close to 200kg. What I like about the carcase is that the hardwood construction means its strong enough for me to lift it in the middle and as long as its balanced 9which it is) I can move it without anything breaking - albeit slowy - it is very heavy after all....

I havnt whacked it with anything yet so cant comment on the "boing-ability".

another thing since its so heavy I can use it as a stable table for my machinary (such as the 12' disc sander) and grinder.

I will finish it one day and post the last entry on the relevant thread - I promise!

Sounds like a good idea Zed - the removable mass.

I once cleaned out the scraps from the shelf under my bench, I put them back immediately after the bench realised it could escape. I realised just how important the mass was even though I hadn't intentionally placed it there in the first place.

As far as bonking on your workbench, I wonder how many people would own up to such a seemingly interesting activity.

Originally Posted by Wood Borer

I think work benches need to be immovable and stiff.

It turns out that the materials we use add mass to achieve the above two requirements.

If a new super light material was discovered that achieved my two requiements, was soft enough not to damage sharp edges on tools or timber then I would probably consider using it for a workbench.

Well the good news is that super light material has been discovered and it's actually been well tested: plywood.

Immovable is as easy to achieve as a couple of screws in the wall or floor. (Holes aren't that hard to repair when you move house). I have used the screw into the wall trick to stabliize the fumping bench, which is very stiff, but proportionally able to be toppled by me bending a bit of pipe in the vice.

Failing convincing anyone about the floor screws, fill the base with sandbags to your own specifications.

A plywood box frame with modern adhesives and minimal structure would give a very stiff structure. (Refer the tea-chest, which has semi flexible joints yet still remained in shape despite copping a pounding in transit).

The top would only need to be a torsion structure with maybe a 12mm upper skin, if stringers were also of 12mm and say 300 mm max in each direction, apart from the sound I doubt whether you'd feel the difference.

I have a feeling that the next round of responses is going to lead us back in a circle!

P

Yes, it sounds like a light-weight bench for light-weights. Probably the type of person who would drink light beer and caffeine-free coffee. Nah, I'll take my thumping great solid b@stard of a bench any day

What is it with arty architect types that they want to make things that are stronger than they look? They seem to have this obsession with making people feel uneasy

Yours in solidarity, brothers.