That would work
Established Member
Also, it looks like most of it is made from quick grown pine? that may well be a lot of the reason it feels like that.
Workbench Tension/Vibration
- Thread starter Osvaldd
- Start date
Help Support UKworkshop.co.uk:
You've done the obvious intuitive things. Did the soft mountings have any effect at all?
In dealing with vibration problems in engineering it is useful to analyse the directions and perhaps the frequency of vibration. So try to answer the following questions
- Is the main component of vibration along or across the bench? Does it vibrate as much when you plane across the bench as it does when you (as normally) plane along the bench?
- Is it the same on the been top and on the legs?
- Is the vibration mainly in the top, the apron, the legs or the stretchers of the bench?
- If you push the bench left to right or back to front do you feel any racking (motion of the top relative to the feet, making the structure into a parallelogram rather than a rectangle).
To answer these, whack it hard with a mallet in different directions (with a scarp pice of wood in the way to prevent damage) and use the fingertips of your free hand to sense the vibration on different parts of the bench. Fingertips are very sensitive to vibration, and you should be able to isolate any joints that are not rigid enough, since the vibration will be strongly damped across them.
As others have said, I think it is likely that there is some lack of rigidity in some part of the structure. Better to try to find out where before you go adding bracers everywhere.
If you can answer these questions, the solution may become obvious.
In dealing with vibration problems in engineering it is useful to analyse the directions and perhaps the frequency of vibration. So try to answer the following questions
- Is the main component of vibration along or across the bench? Does it vibrate as much when you plane across the bench as it does when you (as normally) plane along the bench?
- Is it the same on the been top and on the legs?
- Is the vibration mainly in the top, the apron, the legs or the stretchers of the bench?
- If you push the bench left to right or back to front do you feel any racking (motion of the top relative to the feet, making the structure into a parallelogram rather than a rectangle).
To answer these, whack it hard with a mallet in different directions (with a scarp pice of wood in the way to prevent damage) and use the fingertips of your free hand to sense the vibration on different parts of the bench. Fingertips are very sensitive to vibration, and you should be able to isolate any joints that are not rigid enough, since the vibration will be strongly damped across them.
As others have said, I think it is likely that there is some lack of rigidity in some part of the structure. Better to try to find out where before you go adding bracers everywhere.
If you can answer these questions, the solution may become obvious.
Phil Pascoe
Established Member
Mine is perfectly stable without any aprons.That would work":360rz2fo said:
One thing I did with mine was to put the (five inch) rails at different heights from front to back, with the shelf in a rebate on the top of the front rail to a quadrant fixed at the bottom of the back rail. Their being in different planes helps stop (to borrow Mike G's (iirc) word) parallelogramming.
Jacob
What goes around comes around.
Ditto B&D workmate, but it still vibrates if you saw/plane on it.Osvaldd":37xsxrw8 said:
Actually you get similar if you try to saw/plane on an ordinary lightweight table. It's not the mass it's the stiffness - if you brace it against a wall you can eliminate the problem.
Jacob, its not loose or rocking back and forth like a workmate, I know that feeling, I have a workmate, from LIDL . As I said, it's the opposite of loose, its too tight somewhere and it resonates like a drum skin or a guitar string when you strike it.
. As I said, it's the opposite of loose, its too tight somewhere and it resonates like a drum skin or a guitar string when you strike it.
Jacob
What goes around comes around.
Well I dunno!
Maybe you've just got to get used to it.
Planing endgrain is difficult if you aren't used to it. Try sharp blade very fine set, experiment on the end of wide board (6"+) but thin (10mm or less) to get the feel?
Maybe you've just got to get used to it.
Planing endgrain is difficult if you aren't used to it. Try sharp blade very fine set, experiment on the end of wide board (6"+) but thin (10mm or less) to get the feel?
I am listening to exactly what you are saying. It is surprising since looking at the bench it seems fine with no obvious thin joints. A simple way to see if frame stiffness is actually the problem, and where it might be, is to temporarily put diagonal bracers on the front/back/sides, held by clamps.
Can you temporarily take off the top and see if the fram has the same problem on its own?
If it is really a resonance problem then you may have accidentally hit a resonance mode of the structure when planing. But that would be a huge coincidence but doesn't square with the whole bench having a rubbery feel. That indicates a lack of stiffness in one or more joints, and you have to identify where this is. It is unlikely to be a leg or stretcher as these are pretty massive.
While you are testing for this, I suggest you remove the soft feet, but use wedges to ensure that all four feet have solid contact with the floor.
Keith
Can you temporarily take off the top and see if the fram has the same problem on its own?
If it is really a resonance problem then you may have accidentally hit a resonance mode of the structure when planing. But that would be a huge coincidence but doesn't square with the whole bench having a rubbery feel. That indicates a lack of stiffness in one or more joints, and you have to identify where this is. It is unlikely to be a leg or stretcher as these are pretty massive.
While you are testing for this, I suggest you remove the soft feet, but use wedges to ensure that all four feet have solid contact with the floor.
Keith
Bod
Established Member
Osvaldd":31ie1ifj said:
At the top of the legs, is there a top rail, that goes from front to back, supporting the top all the way across?
Bod
samhay
Established Member
How wet was the timber when you built it?
Or put differently, how long did you store it before you started building?
The reason I ask is that it may have shrunk considerably and the screws are now holding the joints fractionally apart. Can you reset these?
Or put differently, how long did you store it before you started building?
The reason I ask is that it may have shrunk considerably and the screws are now holding the joints fractionally apart. Can you reset these?
yes, there are bearers on each side.Bod":hycpsl66 said:
unfortunately the top is glued to the front apron, and the apron is glued to the legs. I will loosen the screws though.MusicMan":hycpsl66 said:
samhay":hycpsl66 said:
some of the timber was pretty damp when I got it,but It obviously wasn't green wood. I stored it in the shed for about 3-4 months before I started working with it.
profchris
Established Member
If this is a resonance problem you can check it out as we do in instrument building. Your workbench top is the resonating part, and if you add weight to it at a particular point you will change its resonant frequency. Obviously you'll need quite a bit of weight, a few grams won't do it. But something like half a dozen litre cartons of juice/long life milk should do it.
Stack them up in the middle of one half of the bench, then plane something. Does the resonance change? If so move the weight around until you find the spot where it produces the most beneficial effect. Add/subtract weight to see what that does. If this solves (or nearly solves) the problem then you can screw the equivalent weight to the underside of the top. Or add some bracing underneath (maybe two diagonal braces, 2 x 1" on edge), though you're back into experimenting here to find the sweet spots.
That said, this seems the most unlikely answer. If the bench feels rubbery and not solid, then it's probably moving somewhere.
Stack them up in the middle of one half of the bench, then plane something. Does the resonance change? If so move the weight around until you find the spot where it produces the most beneficial effect. Add/subtract weight to see what that does. If this solves (or nearly solves) the problem then you can screw the equivalent weight to the underside of the top. Or add some bracing underneath (maybe two diagonal braces, 2 x 1" on edge), though you're back into experimenting here to find the sweet spots.
That said, this seems the most unlikely answer. If the bench feels rubbery and not solid, then it's probably moving somewhere.
Bod
Established Member
Osvaldd":25twk8r6 said:
"unfortunately the top is glued to the front apron, and the apron is glued to the legs. I will loosen the screws though."
There it is..
I'll bet the top is not sitting firmly on the bearers at the top of the legs.
Try screwing up through the bearers into the top, with a heavy weight on the top to prevent any "jacking" apart then the screws start to bite into the top.
The top is glued to the apron, but not quite at right angles, now the apron is glued to the legs, the back of the top is slightly raised. Hence the bounce, had the apron/top joint been the other way up, then the top would be pressing down.
Bod
Bod, I have pre-drilled proper holes in the bearers, there should not be a problem there.
I have glued the aprons first then put some glue on the edge of the top and clamped it to the apron at the same time while the glue was still setting I have screwed it from the bottom.
One thing I just remembered when adding aprons to the frame there was a slight miscalculation where the slots in the aprons were too close to each other by a few mm so I used a ratchet strap to pull the top of the frame and then slide the aprons in, bad idea probably. So there might be some weird tension going on between aprons and the frame.. or maybe this has introduced a twist in the frame and its doing something weird now.… well I dunno…
I have glued the aprons first then put some glue on the edge of the top and clamped it to the apron at the same time while the glue was still setting I have screwed it from the bottom.
One thing I just remembered when adding aprons to the frame there was a slight miscalculation where the slots in the aprons were too close to each other by a few mm so I used a ratchet strap to pull the top of the frame and then slide the aprons in, bad idea probably. So there might be some weird tension going on between aprons and the frame.. or maybe this has introduced a twist in the frame and its doing something weird now.… well I dunno…
That would work
Established Member
I have found that the most effective stiffening are diagonals from the centre of the apron to the bottom of the legs. I have two full length braces on the back of my bench and to maintain acess at the front the diagonals come from under the apron (not the centre) to about half way down the front legs.
Bod
Established Member
Got me beat.
Let us know what you find...It's got to be interesting.
Bod
Let us know what you find...It's got to be interesting.
Bod
Woody2Shoes
Impressive Member
I notice that neither of your vices is aligned with a leg. The only place you ought to be sure of hitting the bench without a problem is directly above the top of a leg. If the vices were aligned with a leg you might be better set.
As others have said, the only way to reduce vibration is to add mass and/or stiffness (e.g. by diagonal/cross-bracing in more than one dimension) and/or damping (e.g. cork/rubber/etc pads under feet).
Are you sure it's not just a matter of getting used to your new bench - it's still early days I guess?
It looks nice anyway! Cheers, W2S
As others have said, the only way to reduce vibration is to add mass and/or stiffness (e.g. by diagonal/cross-bracing in more than one dimension) and/or damping (e.g. cork/rubber/etc pads under feet).
Are you sure it's not just a matter of getting used to your new bench - it's still early days I guess?
It looks nice anyway! Cheers, W2S
thetyreman
Established Member
looking at the bench the aprons are not as big as a traditional bench, you might have a case of the bench top being much heavier than the sides, does the bench actually move when you're planing in the vice? if so it's not heavy enough, one of the things I did was added a very heavy 30-40KG unused metal vice on the platform underneath, it made a big difference, also try some wedges, I need them under my legs to stop it moving on an uneven concrete floor.
thetyreman
Established Member
also I added this rubberised cork to the outside jaw, I'd highly recommend it: https://www.ebay.co.uk/itm/NITRILE-RUBB ... 2749.l2649
First, thanks for all your help.
I have tried many different things as suggested: added weight, loosened the top, removed the tool well, clamped a bunch of wood to different parts of the bench and found that, as you can see in the picture, a piece of wood between left side front and back legs and a piece of plywood across the bottom half of the back side have reduced ringing by about 80%. I’m happy now.
I have tried many different things as suggested: added weight, loosened the top, removed the tool well, clamped a bunch of wood to different parts of the bench and found that, as you can see in the picture, a piece of wood between left side front and back legs and a piece of plywood across the bottom half of the back side have reduced ringing by about 80%. I’m happy now.
Attachments
Similar threads
