Shaky workbench

[Tiger]

Dear all,

I have made a workbench which is solid as it consists of double up 2 x 4s with several shelves. I have attached heavy duty castors on it so that it is mobile. The problem is that it rocks when you try to plane something on it. It rocked even before I put the castors on it. The original plans for the workbench did not include any bracing which was odd but I suppose the weight should keep it from rocking.

My question is will a brace (and what sort of brace) along one long side be enough to stop it from rocking? Should I look at putting a back on the bench?

Any thoughts welcome?

[savage]

G'Day Tiger,
I have made a similar bench with castors and the like, I braced mine by making a frame to join the legs (front to back and side to side) just above floor hight and put a sheet of 20mm ply onto this all screwed to gether with "tek" wood screws this gives me somewhere to put tins and jigs and the like, stiffened it up nicely.
But I would try and look at why it's wobbly in the first place (are the legs of even length/ is the bench flat or does it have a slight twist) and sort it out first.
Hope it helps.
savage.:)

[Cliff Rogers]

A sheet of ply as a back will act as a brace & stop the racking. (woodie techo term for bench wobble, similar to ar5e wobble)

[JDarvall]

Could brace it against the wall ? Screw bracket it to a couple of studs. But,, then maybe you like to use both sides of bench. I don't know.....

[seanr]

Not sure if this will help . I make benches for a living . I dont use bolts only screws but i do glue every join and put a bottom shelf that acts as a brace . The shelf uses only a little more timber than braces would . Now you may find that your bench has a twist in it . Just look down it from end to end, a twist will stick out like dogs balls. Even if your frame was perfectly square, when you put the timbers to the top ,unless they are dead square, your top right hand corner will lift (looking at it from end to end). Post a pic of your bench so that we can see where the problem is!

[Cliff Rogers]

I think he means racks, not rocks, that's why he asked about the bracing.

[Tiger]

Legs are same length, racking is probably a better word to describe what the bench does. It's fine for all purposes except when I try to plane something. There are cross members from side to side.

[Bodgy]

Once again, I've got similar problems. We must be in some weirdo parallel universe.

My bench also racks when planing. It has no castors. It does have a large horizontal brace. The solution is diagonal bracing, which is obvious when you think about it. What I mean is an X configuration. Thats fine for the back but will destroy shelf access and knee room if put on front.

I just grin and bear it and keep the planes sharp.

Adding mass to the bench may help. If you've got bags of cement etc, drape one over each lower end brace.

[growl]

Tiger,

IMHO I don't think the extra mass ideas will help if the bench is racking.

IF the feet are staying in the one position and the top is moving from planning back and forwards, what you need is diagonal bracing. Extra mass will only hold it to the floor better and stop it sliding.

What happens when the bench "racks" is like a square frame being held along the bottom and the top moved to form a parrallel-o-gram. Diamond shape. What you need to do in this case is stop the diagonal lengths from changing by bracing. Put a diagonal brace on the diagonal that is getting longer to stop it racking or cover in the side closest to where you are planing to stop it racking with builders ply bracing. If your bench joints are too loose putting the bracing on the opposite side of the bench to the planning side may not be enough. What you are trying to do is stiffen the benches joints by adding strength to them.

Builders use ply bracing and gal straps to stop house frames from doing the same thing with the loads placed on the frame from winds and the weigths of a house.

Hope this helps.

Greg ;)