flexible mounts for sanding table

I am trying to come up with some idea for mounting a 300mm x 300mm platform to use as a large orbital sander ( face up). My problem is I want it to move 1 to 2 cm at it's longest travel. It will be more elliptical than round movement. Will run at about 3 to 4 cycles per second. Only rubber mounts I can source won't handle the amount of movement. Any and all suggestions welcomed. I have considered suspending it. Using sets of ball sliders mounted at 90 deg to each other. Compression springs seems the more obvious but how.

Why not try something like this you could use extension springs to hold the table down or centered on the ball rollers you movement would be limited only to your imagination.
Attachment 22190
They are called ball bearing rollers

Interesting thought. Thanks Frank. I will check it out more.

I am going to experiment with some short lengths of silicone rubber round bar. Will have a cup top and bottom out of pipe then force the ends in to them. Drive will be from a cheap variable speed jigsaw. This will give me a recpricating table to clamp sandpaper to. The idea is, if using a disc sander, you only use about 65% of a sheet. This will use close to 100%

Giant upside down square sheet sander? Mmmmm... I like the sounds of that. Sounds like you are looking to make rubber torsion(?) Mounts? What about flexible (rubber) fuel line pieces clamped to opposing pins. The distance or space between the pins may be critical but would give a simple flexible "joint" for movement in two directions. Some other type of hose may work better, something like the silicone tubing used in coffee makers to join the plastic pipe to the aluminum pipe in the burner. There is an answer out there somewhere:headshake:

You could try what i did for vibrating concrete in small head-stone moulds. two platforms with a 2 " by 2" diameter spring mounted near each corner. Of course you dont want to use flat steel plate for construction and a whipper snipper just above idle to give the vibration. A later improved (no smoke) version saw one spring moved a bit and a steel bar set in its place and fixed to one surface. a small electric motor (like a washing machine) with its shaft ovaled ran touching the bar gave good vibration.

As you have sourced rubber feet you could try 2 feet with joining tubing between nearer the centre but still supporting the sander platform.

I like that idea too.

Version #1. Sort of works but main issue is the travel of the saw is too much. The overall action is too violent. I was going to add an image but looks like this stupid site requires some outdated format or something.

Version #1. Sort of works but main issue is the travel of the saw is too much. The overall action is too violent.Attachment 22338

Now that I see what you were making. many of the ideas for movement control that were published would have worked equally well.
As for being violent there are 2 ways to tone that down one being mass the other being variable speed
many saber saws have a high and low speed others are variable I have one that has both
you could use a link bar between the saw and the plate with a pivot being closer to the plate than the saw something like 1.5 to 1 or what ever it took to reduce the total movement

Or you might try attaching a stiff extension spring to the plate then attach the other end to the saber saw this might dampen the stroke and the violence.
If that is not enough then attach a second spring to the plate where the first spring is connected and attach the other end to the base mount
I built a small gold sluice several years back using a similar spring set up

I considered a lever action to reduce the travel but not worth all the trouble to make something reliable. I haven't dismissed the idea though.I was just trying to make one with out spending money. The best option is a crank but then I need to spend a fortune of belts and pulleys. I have more ideas up my sleeve. Just wish I had the time to try them.

You if you had an old cox 30 airplane engine you could cut it up attach the piston to he plate, chuck the crank in a drill and have the perfect amount of stroke and speed

I eventually decided to try reducing the travel with a lever but the whole lot is just too wishy washy. A rotating shaft with a wheel on it and a crank pin will give an elliptical motion. As the shaft is moved away from the centre, the travel will increase. I need to go back to the start. Might have triggered an idea for someone though.

I feel that this suggestion is a bit incomplete as i do not have a good feel for the srength of spring to use, but that said, a spring between the saw and the table (as part of the linkage connecting the saw to the table) will dampen the action. The spring would work in both compression and extension and should soften the motion. An adjustable preload on the spring may help with choosing the right spring rate or strength. More preload, stiffer action. Less preload softer action. Keep at it, I like your idea.
Eric