A while ago I bought a Viscount VivaX weighted piano keyboard. It's quite good for the price I paid but one problem is the sound of the hammers transmitting through the floor. The shared house I live in is lightly built and sound travels through the walls and floors like paper, I was going to have to do something if I wanted to be able to play my piano without annoying the rest of the house. I tried several layers of cut up foam from a camping mat but it soon compressed too much under the weight and was useless. A friend of mine had some sheet rubber which I think was originally used for tool drawer lining so I had the idea of making some sound insulating platforms to go between the keyboard and the stand. If you don't have sheet rubber drawer lining you could use bicycle or car inner tubes, or do something similar with bungee cord.
The keyboard stand is one of the 'X' Style double keyboard stands. I suppose the design could be modified to suit any construction.
The plan was to make a wooden 'inverted gutter' shape and stretch the rubber over the open side, creating a sort of upside down hammock for the rails of the stand to nest into. (reading over that description, it's a good thing I have a camera to describe it a bit better!)
I didn't want any solid path for sound to transmit from the body of the keyboard to the stand, so I would have to cut out gaps where the diagonal parts emerge from the round bar. I took some measurements and cut out a base piece and some wooden rails for each side. I've labelled up an image with the dimensions in mm.
The wood is used was 20x44mm Pine for the rails and 120x18mm for the base. The material isn't really important here but I originally wanted to make the base part out of something like 12mm ply, but b&q were short of plywood at the time. Notice how the two sides are different, this is because the diagonal bars on the stand emerge from each side at different places as they cross over in the middle.
Cut the wood to the dimensions shown (or whatever matches your stand)
I drew a line on each side of each base piece for the centre line of the screws. This will need to be half of the width of the rail wood. It's probably a good idea to mark right and left at this point to avoid mix ups.
Drill holes for the screws in the base pieces (these will be equal to the outer diameter of the screw thread) I also recommend drilling pilot holes for the screws or the wood will most likely split, these should be equal to or slightly smaller than the inner diameter of the screw. To keep things neat use the line drawn earlier for lining up. I spaced the screws about 30,40 mm apart, make sure there are at least two screws on the smallest parts.
Lay out the rubber sheet and mark it up, it's handy if you have a chinagraph pencil. There are 4 strips and they match the width of the smaller wood pieces, so they have widths of 75, 225, 110 and 190mm. I made them about 320mm long, which left a good bit of room for error.
Sandwich the rubber between the base piece and the longer 'uninterrupted' rail and insert the screws (leave a few hundred mm or rubber sticking out on the inside to allow for any slippage that might occur, if you don't leave enough the screws will be more likely to tear through the rubber) I didn't use glue and haven't had any problems with slippage, but I suppose it wouldn't hurt to use some. Fold the rubber around underneath and repeat for the other side. I didn't stretch the rubber at this point as it would've made it difficult to screw in the rails, but I didn't leave too much any slack. When you are finished you should be able to press hard into the rubber without slippage or the wood splitting. (yes this is PH bit with PZ screws, ah well)
If all went well, it should look like this:
Try the newly made dampers on your stand, I found it easier to put the piano on the stand first and slide them in afterwards as they tend not to rest in the right place without a keyboard to keep them horizontal.
When making these I thought bouncing and shaking of the keyboard during playing would be a problem, but they are actually quite stable. The weight of the keyboard keeps the rubber tight enough to avoid excessive movement. Now hardly any vibration goes through to the floor. Success!