Why isn't my bench stable? advice needed

[Matthew N. Masail]

So I decided to make a new base from my benchtop, this base would allow me to place vises where I want them.

The previous base was rock stable, not a hint of movement, it had legs at the far corners of the bench. the new is base pictured here:
306181

the base is only 40" long, and the bottom bars about 23", which is the same as the benchtop. My issue is that the bench is highly unstable, it rattles, and the far right corner bounces when I use the face vise.

-The legs are flat and all for edges are co-planer.

I found that I would need about 30kg of mass on each side on the legs to keep the bench stable, and while that is kinda doable, I use thinking maybe there is a better solution.

also I'd like to know, did I make this with bad mechanics, or is it just not long enough at 40" to counter balance the cantilever effect from the top hanging over the edges?

I'm open to all Ideas besides building a new base.... I have no wood, or time for that anymore.

[Brian Holcombe]

All the weight is in the top. I'd make the floor stretchers much heavier.

[Matthew N. Masail]

Thanks Brian. I'm not sure how much heavier can they get? I needed 30kg of steel to keep the bench stable... or is stiffness in play here too?

how is what I did different to this? http://www.google.co.il/imgres?imgurl=http://www.finewoodworking.com/assets/images/pages/workbench/essential-workbench.jpg&imgrefurl=http://www.finewoodworking.com/workbench&h=300&w=330&tbnid=Zkd0ar-GFI-4JM:&zoom=1&docid=g2vxN6jeHWnG6M&ei=gOrTVJ-lMYGqU8GYg_AF&tbm=isch&ved=0CD0QMygUMBQ

[Chris Hachet]

I would push the legs back out to the corners, actually. The face vise could work inside the left front leg rather than outside of it. My MINI Cooper S is a great handling car, the wheels are pushed by the designer to the far outside corners. My bench is about the same size as yours, but the legs are near the edges of the bench...stable as a rock...like yours was....

And here is one area where I agree with Chris Schwartz. The legs really should be even with the front and back faces for clamping options. Much easier to work that way.

I know you said you had no time to fix this....in the mean time, add a shelf on the bottom and dump some sand bags on it perhaps.

Just my two cents.

Chris

[Chris Hachet]

Thanks Brian. I'm not sure how much heavier can they get? I needed 30kg of steel to keep the bench stable... or is stiffness in play here too?

how is what I did different to this? http://www.google.co.il/imgres?imgurl=http://www.finewoodworking.com/assets/images/pages/workbench/essential-workbench.jpg&imgrefurl=http://www.finewoodworking.com/workbench&h=300&w=330&tbnid=Zkd0ar-GFI-4JM:&zoom=1&docid=g2vxN6jeHWnG6M&ei=gOrTVJ-lMYGqU8GYg_AF&tbm=isch&ved=0CD0QMygUMBQ


I think its mostly physics rather than stiffness.

[Matthew N. Masail]

I would push the legs back out to the corners, actually. The face vise could work inside the left front leg rather than outside of it. My MINI Cooper S is a great handling car, the wheels are pushed by the designer to the far outside corners. My bench is about the same size as yours, but the legs are near the edges of the bench...stable as a rock...like yours was....

And here is one area where I agree with Chris Schwartz. The legs really should be even with the front and back faces for clamping options. Much easier to work that way.

I know you said you had no time to fix this....in the mean time, add a shelf on the bottom and dump some sand bags on it perhaps.

Just my two cents.

Chris

I think I will try tomorrow to push the base to the far right (as far as the side vise will let me) and maybe extend to base to have 2 extra legs on the left.... I'll end up with a 6 leg base ! lol, but I really prefer the face vise on the far end, because I found that any bench space to the left of it was pretty much wasted for me and my bench felt even smaller yet.

[Brian Holcombe]

I'd make them wide as well, that will help. If it's annoying off the front then I would make them wider toward the back to widen the footprint. That, in addition to making them from heavy stock should improve the stability.

You can beef up the stretchers too. I wouldnt be surprised if the stretchers on my bench weighed 2/3 as much as the top, they are 8/4 by 9" by 40"~, combine that with the heft of the feet and legs and the base is heavier than the top, lowering the center of gravity.

[Thomas Schneider]

Thanks Brian. I'm not sure how much heavier can they get? I needed 30kg of steel to keep the bench stable... or is stiffness in play here too?

how is what I did different to this? http://www.google.co.il/imgres?imgurl=http://www.finewoodworking.com/assets/images/pages/workbench/essential-workbench.jpg&imgrefurl=http://www.finewoodworking.com/workbench&h=300&w=330&tbnid=Zkd0ar-GFI-4JM:&zoom=1&docid=g2vxN6jeHWnG6M&ei=gOrTVJ-lMYGqU8GYg_AF&tbm=isch&ved=0CD0QMygUMBQ

The bench in the link you provided has toenail feet. On your bench the foot is a flat board. Not sure if that's part of your problem or not but worth a second look.

Tom.

[Maurice Ungaro]

Wider is better, as far as the base is concerned. Short of going BACK to what you had, you could take a tip from the lathe crowd: run a shelf between your two stretchers and add weight to the shelf. My first, and soon to be secondary bench kinda looks like yours, and it's tippy when planing across. I don't know why people enjoy an overhang of their benchtops.

[Tom Vanzant]

Before you reconfigure the base, try shimming under the leg that "bounces". It sounds like your bench feet do not meet the floor evenly. 4"x4"X1/8" pads under the ends of the feet will help bridge floor uneven-ness, but try the shim first.

[Prashun Patel]

I vote to check that your floor is flat first. Shim as necessary to sit flat.

Next I am troubled by your base. How are the legs attached to that base. Without a deep tenon into a base you may need a lower rail on each side of the base. You can half lap it now that it's built.

Last do you have an upper stretcher?

Reading it again if you are having rattle and bounce issues it points to an unlevel floor. Even a small bench can handle reasonable forces on a cantilevered vise.

[Charles Bjorgen]

My bench setup is similar to yours. I'd recommend installing pads under the four corners of the feet. I used pieces of 2x4 for that purpose. You can also make a shelf to span the stretchers for tool storage. Instant weight.

[Dan Clark]

The bench in the link you provided has toenail feet. On your bench the foot is a flat board. Not sure if that's part of your problem or not but worth a second look.

Tom.
I agree about the flat board. From what I can see, it looks like there is limited support for front to rear racking forces. As a test, the OP might want to consider vertically lag-screwing an 8/4 X 8" wide board on the outside edges of the legs to connect the bottom of the front and rear legs. It won't look pretty and it's probably not permanent, but it's a quick and dirty way to see if that is the cause of bench instability.

Regards,

Dan.

[Jim Matthews]

Prashun beat me to it.

Have you put a level on the bench?
I've got a more broadly cantilevered bench,
yet it's stable. The addition of a shelf
spanning the bottom stretchers will reduce
horizontal twist, but won't appreciably
reduce flex in the uprights.

Simple enough to build a shelf and put your planes on it for mass loading.

[Winton Applegate]

Here are some general observations about woodworking benches and how they compare to other general purpose work benches such as chest of drawer type benches and welding tables :

Many general purpose work benches are often "built in" to a wall; anchored to the floor and to the studs in the wall.

Woodworking benches in general lack angular cross bracing. Adding built in cabinets with drawers like the Shaker benches (http://stuartblanchard.com/2011/12/05/workbenches-and-work/) or Phillip Lowe’s bench (http://www.finewoodworking.com/woodworking-plans/article/a-workbench-that-works.aspx) tends to do the same thing as angle bracing.

Woodworkers avoid bolting the feet / legs to the floor because they don’t see anyone else do that. The pros don’t because they need to move the bench for various big projects but they tend to have full size benches that are massive enough to be free standing and stable. The home shop dude, or dudett consciously or unconsciously emulates this but tends to have a smaller / lighter / cheeper bench which should probably be bolted to the floor or a wall to stabilize it.

so the bench, if small may have a tendency to wiggle, teeter, slide across the floor or tip.

Weight is nice but without bracing you just get an immovable thing that wiggles.
Shimming the feet is a good diagnostic but at least one or two feet that adjust, like a washing machine or refrigerator base is the way to deal with an uneven floor or out of level bench.

Of course every body wants a woodworking bench they can move around.
Me . . . I want a bench that does not wiggle or slide across the floor or tip when I really get to cross grain scrub planing. So I am not above anchoring a bench to the floor or to a wall or running arms over to a wall or two.

For metal working it is kind of the same thing but I can not tolerate any wiggling at all when I am hacksawing. ( a small metal table can get to oscillating).
Running a brace to the wall and anchoring it has been the best solution.

[Matthew N. Masail]

Thanks everyone! the feet are not flat boards, I cut o curve out of the middle of each board, it just doesn't show in the picture. the bench top is attached with 4 lag bolt going through a short stretcher that is tenoned into the legs. My shop is tiny as you can see so the bench must be movable. I have shimmed the feet, no issue there. I will get to work on it and post the results... I guess angled legs might have been a good idea ! ?

[Pat Barry]

Before you reconfigure the base, try shimming under the leg that "bounces". It sounds like your bench feet do not meet the floor evenly. 4"x4"X1/8" pads under the ends of the feet will help bridge floor uneven-ness, but try the shim first.
This is pretty much what I was thinking as well. I do not think the cantilever is overly large and I do not think it is the reason for your problem

[Dave Anderson NH]

One thing that no one else has mentioned Matt is extending the stretchers and moving the right hand legs to the end of the bench which removes the cantilever from that end. This would have no impact on the location and use of your face vise. From your photo it appears you could pick up almost another 12" and thereby increase the stability. I also agree with Chris Hachet that the front legs should be flush with the front edge of the bench. You could either leave the rear legs recessed to allow full length clamping or make the rear legs flush too at your option. Between moving the right legs and making the front legs flush you would pick up quite a bit of stability.

[Richard Hutchings]

I think the OP mentioned that mounting to a wall was out but I just wanted to add my 2 cents. I love having my benches attached to my walls. I get zero movement and I can make my benches out of lighter/cheaper material. What's a couple of holes in the wall of a shop matter? It's also pretty easy to put lags in your floor. The only issue I see is that you can't rearrange it easily. Choose a good spot, bolt it in and enjoy a rock solid bench.

[Matthew Hills]

My initial thought was the physics -- base too short for the load applied across the top.
Might be able to keep things down with enough weight on a shelf.
Or maybe modify the base to provide a trapezoidal support. (e.g., have the back legs closer to the ends than the front legs)

Matt

[William Whitfield]

Not an expert by any means. Could the items you put in the vice have sufficient weight so as to be beyond the legs and start to tip the workbench?

[steven c newman]

#1: Instead of full length pieces for feet, just add a square to the bottom of the legs. One at each outside corner. Doesn't take a whole lot of wood. It can eliminate any rocking though. Then, you could add a 4x4 inbetween the legs above the cross piece, for added weight.

#2: add a false bottomed shelf. It will look like a thick shelf, but is hollow on the inside. About like a box. Fill the inside with dry sand. Now the bench will weigh MORE near the feet than the top does. Harder to tip over that way.

[Richard Hutchings]

I have never see a bench with a flat board between the legs like you have. This will never work in mind, no matter how flat you may think everything is. Four legs are hard enough to get perfect and your floor never is, if you move it you'll most likely need to change shims somewhere. You could try adding some levelers at the four corners right under the legs along with some sand bags. Seems like it's most likely a weight to length ratio problem.

Does the bench rack when you're planing? I don't see anything in the design to counter it. It looks like a very nice bench and with a little tweaking I'm sure your going to be very happy with it.




So I decided to make a new base from my benchtop, this base would allow me to place vises where I want them.

The previous base was rock stable, not a hint of movement, it had legs at the far corners of the bench. the new is base pictured here:
306181

the base is only 40" long, and the bottom bars about 23", which is the same as the benchtop. My issue is that the bench is highly unstable, it rattles, and the far right corner bounces when I use the face vise.

-The legs are flat and all for edges are co-planer.

I found that I would need about 30kg of mass on each side on the legs to keep the bench stable, and while that is kinda doable, I use thinking maybe there is a better solution.

also I'd like to know, did I make this with bad mechanics, or is it just not long enough at 40" to counter balance the cantilever effect from the top hanging over the edges?

I'm open to all Ideas besides building a new base.... I have no wood, or time for that anymore.

[steven c newman]

Oh, these type of legs do work, just need a set of "feet" added, is all
306217
This is my bench, note the feet? 5/4 "pads" were added. About all that was needed. Bench is quite stable.
306218
And my shop is even small thatn the OP's shop...

[Dan Clark]

Oh, these type of legs do work, just need a set of "feet" added, is all
306217
This is my bench, note the feet? 5/4 "pads" were added. About all that was needed. Bench is quite stable.
306218
And my shop is even small thatn the OP's shop...
Your bench has one major difference from the OPs bench - there is a brace between the front and back legs about a few inches above the bottom horizontal board. This should help eliminate front to back racking.

[Jim Koepke]

I am a little late to this thread.

Here is my solution and it still works:

http://www.sawmillcreek.org/showthread.php?119667-3-Bench-Hold-Steady

I have since used a small piece of rope to keep it from moving when the bench is moved.

jtk

[Curt Putnam]

I would put 4" x 4" x 1/2" pads under the 4 bottom corners as the first step (or just get a set of heavy duty levelers.) Then, once you've got it shimmed to level with only 16 sq" of bearing surface, if you still find it to be unstable - then: 1st I would assure myself that the top/leg connections are solid. If not, they need to be made tight and solid. Lastly, pretty much any bench can be stiffened by the application of plywood (or hardwood panels) around the bottom. Just some thoughts ....

[Richard Hutchings]

I agree but I don't see those pads on the OPs bench.

Oh, these type of legs do work, just need a set of "feet" added, is all
306217
This is my bench, note the feet? 5/4 "pads" were added. About all that was needed. Bench is quite stable.
306218
And my shop is even small thatn the OP's shop...

[steven c newman]

My suggestion to the OP was to add these pads to his bench's legs.

The stretcher between mine was merely to hold the legs still, until I got the feet done. I can also add a shelf between the ends.....someday....

[Richard Hutchings]

I always make my bottom boards out of 4x4s and cut a recess between the ends.

[Tom Scott]

I don't think anyone has said this, but the long stretchers are too low. It is physics in that...the stretcher is resisting the racking motion (not mass). When the stretcher is at the very bottom of the base, then it is the furthest away from the force being applied so it is acting like a flagpole. The higher up you can get it (mid-point or higher) the better.

[Matthew N. Masail]

I said it before, my bench feet only have 4 contact point - there is a curve cut into the bottom of that "flat board". you guys have been and great help and this has been a fairly interesting subject. I didn't think my over hang was too much at 25cm or 1\6 of the bench length, but combined with a high center of gravity from the heavy top is was indeed too much. also the face vise itself weighs 15kg. so the conclusion is that a "light" base cannot handle much of a Cantilever effect, and needs splayed legs on one side in order to mount the face vise on the far side. I didn't want legs flush with my bench top, personal choice, and the stretchers need to be low because I'm adding drawers and shelves, so what I think I'm going to do is move the base to the far right, leaving only 15cm of overhang for the end vise, and I will be adding another leg assembly to the far left, this will give me a nice leg to mount a height adjustable leg vise on the other side of the bench..... might work out quite nicely

[ian maybury]

Hi Matthew. Coming in late, but i'd add to the voices:

Flat feet won't easily rest in a stable manner - even on a seemingly flat floor. Aim for point/relatively small pad support at each corner.

Only a tripod with three contact points is always stable regardless of the flatness of the floor/surface. (almost the first principle taught in jig and fixture design on a mechanical engineering course) A tripod isn't an option on a bench, because it's not laterally stable enough - but the principle still applies. Three legs/points/pads will contact the ground simultaneously. Choose the three that best level the top, glue on packers if needed to achieve this. Then shim/adjust the fourth (short) leg so that all four are simultaneously in contact. (this principle beats trial and error every time when levelling machine tables and the like too - set one jacking screw/support point purposely low, then adjust the other three to level the table. Then ease up the fourth to just close the gap/prevent wobble.)

The legs look quite a bit inboard. Aim to get the points/pads contacting the floor spread as far apart in both directions as is reasonably possible without blocking access to work - by e.g. putting pads under the ends of your existing flat feet.

Deep cross stetchers well tenoned into the legs should stiffen the structure a lot. It may not be too bad lengthwise, but looks likely to be very flexible crosswise.

[Winton Applegate]

Could the items you put in the vice have sufficient weight so as to be beyond the legs and start to tip the workbench?
Yah Will's right I wouldn't clamp any brontosaurus bones (https://www.youtube.com/watch?v=GJu8RreAGnM) in that sucker.

[Winton Applegate]

Steve,

Bench is quite stable.
In the words of Ben in the movie Short Circuit (https://www.youtube.com/watch?v=K6TLYwelOPk) "I'm standing here beside my self".
Stable ?
My guess is you never scrub/jack plane cross grain.

[Derek Cohen]

So I decided to make a new base from my benchtop, this base would allow me to place vises where I want them.

The previous base was rock stable, not a hint of movement, it had legs at the far corners of the bench. the new is base pictured here:
306181

the base is only 40" long, and the bottom bars about 23", which is the same as the benchtop. My issue is that the bench is highly unstable, it rattles, and the far right corner bounces when I use the face vise.

-The legs are flat and all for edges are co-planer.

I found that I would need about 30kg of mass on each side on the legs to keep the bench stable, and while that is kinda doable, I use thinking maybe there is a better solution.

also I'd like to know, did I make this with bad mechanics, or is it just not long enough at 40" to counter balance the cantilever effect from the top hanging over the edges?

I'm open to all Ideas besides building a new base.... I have no wood, or time for that anymore.

Hi Matthew

My last bench, which was used over a period of about 18 years, was similar skinny and short base with a longer than stable top (it was not built for handtools when I started out). Yet it was rock steady - because the base was bolted to a wall. You have found that you can steady your bench by adding weighs to the legs. One simple solution is to bolt the bench to the floor (if possible of course). Another - better - alternative is to add a cabinet to the base and fill it will tools. That will add both bracing and mass. It is possibly the only reasonable solution you have other that rebuilding the base, but you will have to wait a while to know that it is successful. I bet it will be. Just leave space above the cabinet for holddowns.

Regards from Perth

Derek

[Tom M King]

I have gotten by for decades with a "portable" 5' bench by putting one corner against a wall-preferably under a North facing window. When I retire, I intend to build a heavy bench, and have been collecting the wood for it for the same decades I've been using the small one at work.

[Matthew N. Masail]

I decided to give myself another week or so to make a base similar to this one
https://dblaney.files.wordpress.com/2015/02/moravian_overall_img_3548.jpg

I think\hope that is a SMART design for stability in a small bench. I'd like to be able to easily move my bench around. I'll have to make it at work since my shop in non operational right now, I'll post the results. Thanks again for all the responses.

[Kent A Bathurst]

Hi Matthew. Coming in late, but i'd add to the voices:

Flat feet won't easily rest in a stable manner - even on a seemingly flat floor. Aim for point/relatively small pad support at each corner.

Only a tripod with three contact points is always stable regardless of the flatness of the floor/surface. (almost the first principle taught in jig and fixture design on a mechanical engineering course) A tripod isn't an option on a bench, because it's not laterally stable enough - but the principle still applies. Three legs/points/pads will contact the ground simultaneously. Choose the three that best level the top, glue on packers if needed to achieve this. Then shim/adjust the fourth (short) leg so that all four are simultaneously in contact.

Or - the method I used - I got 4 industrial swivel leveling mounts. They inset into holes drilled in the leg bottoms, through heavy-duty tee-nut type plates. Just use wrenches to adjust and lock all 4 until the top is level in all directions.

There is enough swivel in the assemblies to account for unevenness in the floor.

ALso - I have drawers on top of the stretchers - as you plan. I am willing to bet that if I weighed the contents and the drawer cabinet itself, it is greater than the weight of the bench itself. The drawers are full of screws, drill bits, hand tools, etc.


http://www.mcmaster.com/#standard-leveling-mounts/=vto5p4

[ian maybury]

I didn't like to mention engineered adjustable feet in the current (neanderthal) company Kent, but probably a very good idea on an uneven floor. Carefully selected to be really strong and firmly mounted as there could otherwise be problems if sliding the bench sideways.

On the sloping legs Matthew. I'm sure you're well aware, but it's the distance apart of the support pads that will determine the basic stability of the platform in any given direction - not the angle. The angle becomes relevant if it makes it possible to achieve a given (e.g. wide) foot placement without obstructing hardware, your feet or your access - but otherwise won't necessarily add anything much except a fair amount of complication...

[Winton Applegate]

On the sloping legs Matthew. I'm sure you're well aware, but it's the distance apart of the support pads that will determine the basic stability of the paltform in any given direction - not the angle. The angle becomes relevant if it makes it possible to achieve a given (e.g. wide) wide foot placement without obstructing hardware, your feet or your access - but otherwise won't necessarily add anything much except a fair amount of complication...

I hope I wasn't misleading when I mentioned "angle bracing".
I was thinking along the lines of this (http://myoutdoorplans.com/workshop/diy-workbench-plans/) but hopefully more elegant.

[Kent A Bathurst]

I didn't like to mention engineered adjustable feet in the current (neanderthal) company Kent, but probably a very good idea on an uneven floor. Carefully selected to be really strong and firmly mounted as there could otherwise be problems if sliding the bench sideways.

:D :D

Even Neanders buy hardware, hinges, etc. Except The Most Reverent George Wilson, who who I think casts his own metal, and goes from there. The Gandalf of the Neander Forum, methinks.

I mentioned "industrial" in my post - the link I provided aren't even the ones I got - there is another group that is seriously industrial - I had access via my work, and got that style at a stupid price because we built machinery.............but for normal use, that price is likely not required.

You can mount the ones I showed, and drag the bench as needed. But - once you do, you are now on a piece of real estate that is unlevel in different planes that the spot you left. The swivel feet will accommodate that change in planes, but the bench top may no longer be dead-nuts level.

[Matthew N. Masail]

I didn't like to mention engineered adjustable feet in the current (neanderthal) company Kent, but probably a very good idea on an uneven floor. Carefully selected to be really strong and firmly mounted as there could otherwise be problems if sliding the bench sideways.

On the sloping legs Matthew. I'm sure you're well aware, but it's the distance apart of the support pads that will determine the basic stability of the platform in any given direction - not the angle. The angle becomes relevant if it makes it possible to achieve a given (e.g. wide) foot placement without obstructing hardware, your feet or your access - but otherwise won't necessarily add anything much except a fair amount of complication...

Thanks Ian. of course I know it has to do with the footprint. I knew building this base that it would have a cantilever effect I just didn't think it would matter so much.

[steven c newman]

Rarely need to
306532
But sometimes I do..

[Pat Barry]

I decided to give myself another week or so to make a base similar to this one
https://dblaney.files.wordpress.com/2015/02/moravian_overall_img_3548.jpg

I think\hope that is a SMART design for stability in a small bench. I'd like to be able to easily move my bench around. I'll have to make it at work since my shop in non operational right now, I'll post the results. Thanks again for all the responses.
I don't know. Sure that new design might be nice but first is your bench racking or rocking. Rocking all you need is to shim it. Racking all you need is to crossbrace it. The way I understood it you just built the new legs. If it were me I'd fix the racking or rocking and be done with it.