Dang Forrest, you've hit upon my idea EXACTLY but put me off it. But I don't understand your answer!
In order to add density and vibration damping to my knee-mill I was thinking of filling it with sand AND soaking the mixture with oil, sort of a slurry. No good reason for this, it just seems like an approach that might work to me. The sand provides the weight, the oil-slurry effect adding to the vibration dampening.
Forrest, you sound like you've come across such a nutty thing. Can you tell me why it won't work well, and whether capping the bottom of the column and filling up with plain ol' sand will help keep down chatter? I'd like to maximize the ability of this mill and don't mind making a few modifications. Seems simply adding mass to the column might be a step forward.
By the way, I've stumbled across a source of anti-vibration mounting pads on eBay. They're made by Paulstra, the Stabiflex model 530622, hardness of 45.60.75. (Took a while to figure this out.) If you go to the Paulstra website and navigate through the 'flexible mountings' catalog you'll come across the Stabiflex mounts on page 40. Or, on the odd chance this link will work, you might go straight to it here:
http://www.paulstra-vibrachoc.com/Stabiflex_GB.pdf
The eBay link to these mounts is right here:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=3812310776
The seller has more of these.
This French company lists the nominal static load of the mount as 95-380 dekaNewtons. A whuuut? I tried to find a conversion table on the 'net and the best shot I've got is a conversion of 2.25 pounds per dekaNewton. If this is right, then each mount is suited to support ~200 to ~850 pounds. The mount is shown in the catalog as suitable for machine tool usage and the load range looks good. Somebody here might need a few of these, and at $10 for a set of 8 how can you go wrong?