Re: [CAD_CAM_EDM_DRO] Al Extrusion Vibration Damping

A series of tests:


I did some testing a while back when I was building my combo frame.
It wasn't totally scientific but I did keep a test control. I used
several pieces (five I think) of 2"x18" pipe capped on one end and
gathered various materials to try. As I recall, I had;

Oil dampened patio sand (one ounce per quart of sand)
Dry patio sand
Dry play sand
Gravel (pea size)
Concrete (Ready-mix)
Steel screws, nuts and bolts (Mixed sizes)
Rolled rubber mat (tight fit)
Rolled foam padding
Hollow (empty)

This list is significant as I've listed them in the order of Best to
Worst for sound and vibration dampening. A special note being that
the last four had almost no detectable difference between them in a
"ring test". I used these materials based on suggestions at the time.

I suspect that the insulating foam would come near the bottom too. To
suppress the vibrations, you need heavy particles that will still
move. I didn't have any lead shot at the time or I would have tried
that. I'm sure that lead shot would come out at or near the top.

As far as weight, damp sand (unpacked) wouldn't add that much weight
to a small tool. I used one 50lb. bag to fill the frame below.
There's probably 250lbs of steel.


Ken Kopsky
Custom Car Works
Lytle, Texas

how much differnce do you think it made ?

10% - 20% or ????

The damp sand trial was probably 80-90% effective in reducing
vibrations. There was NO ring sound. The suspended steel ball I used
to strike the tubes made more "bang" sound. You could also see a
difference in the ball rebound between the various materials.

I'm using the frame in the picture above. The hammer is still Loud
because of the air motor (piston striking the die) but the frame
doesn't jump around. One of these days, I'm going to try and wrap the
hammer with something or develope a muffler.

This wasn't done by me
-- someplace else I saw another series of tests that used oil damped
sand to eliminate any moisture corrosion possibility.. same type
result.

jesse