Sorbothane record weight?

I have an older b&o rx2 turntable that I am not comfortable putting much weight on, the spindle will probably not work with a clamp, and the tone arm is not adjustable so I am not interested in adding a mat.  It occurred to me that maybe a "puck" that doesn't weigh much could be made out of layers of sorbothane sheets and used as a low mass "weight" to damp record vibrations.  I have googled and searched forums and haven't found any hint that anyone has tried this. 

Is this a really bad idea for some reason I cannot think of?  I am certainly no expert.

Why don't you try it yourself? Worst it can do is slow it down if the platter drive is too weak. If it sounds better, then use it. I don't think it will though.
Reflex record clamps are universal. They use a collet that holds the spindle whether threaded spindle or smooth. You have a spindle? You can use a record clamp.
True mc, but some guys here have a very short spindle. 
I think 350g weight is perfect for any turntable, it's not heavy, most of the record weight are about 350g or less. 
Assuming your records are flat just a puck of any weight is pretty worthless. The rim still can vibrate just as much. You have to use either vacuum or a system like SME, Kuzma and Michell Engineering.
The Michell clamp is very light and works great. You can buy one online.
Using these versions of the same idea flexes the record into the mat and the rim no longer vibrates. It will also flex out small warps, a puck will not.
Hey Mike, check out my system Check out the turntable. Check out the clamp. DIY clamp btw. DIY clamping system. Look real close at the platter. See that little black washer around the spindle? Its just thick enough to hold the center of the record very slightly higher than the platter. The clamp is dished out. So when the clamp is tightened it pushes the record down onto the platter outer edge first.

Even somewhat warped records lay completely flat. The record is so tight and secure on the platter that when I get done with a side and remove the clamp the record sometimes sticks a second or two and then pops up. Why? Clearly the atmospheric pressure was holding it down. Yeah. I know. Miller built a freaking vacuum hold down without the freaking vacuum. Pretty amazing. Even for me.
A few record weight i've been using long time ago are on this image
The one on my SP-10mkII is a German Made for 30 Euro, the grey one on the left side designed not only for LP, but also for 45s (also nice and cheap). They are lightweight under 300g each. 

If you want the original look for Orsonic clamp that you can lock to your spindle. 

That Orosonic the collet style and will work on a smooth spindle.
Both Mitchell and Record Doctor make very simple and successful record clamps that really do push down and help flatten the edge.
Nothing new really however that's not really what the OP was asking.
But I have found that the Mitchell clamp requires more of a spindle standing proud of the album than the Record Doctor one does so at just $29.95 from Audio Advisor it might be worth a trial.
Also handily happens to weigh 350g....
Thanks for all of the input.  Unfortunately, It’s not as simple as buying a weight or clamp.  My spindle has a pop up plastic collar around it that drops down when an album is on the platter, leaving only the metal center of spindle above the label.  It is less than half the diameter of a normal spindle, and very short.  Without a record on the platter to hold the collar down, the platter will not turn.  (Cartridge safety feature). The platter and tone arm assembly are suspended from the underside of the plinth by three springs, now 30 something years old, and the recessed platter surface is only barely above flush with the plinth.  A 200 gram LP plus 300 grams and the platter IS flush (I checked) with the plinth as the springs stretch, and the very outer edge of of the album can make contact with the plinth.  That’s why I was looking for and trying to find something light other than the clamps I see to damp vibrations on the vinyl.  I’ll try the sorbothane and let you know if it makes any noticeable difference.  I’m using a SoundSmith SMMC 1 cartridge.

Mitchell clamp requires more of a spindle standing proud of the album than the Record Doctor one does

Michell actually makes 2 clamps for that reason. One for their own tables and one for Rega with the shorter spindle.
Google "Michael Lim light weight record clamp"...

It's a 45 adapter that can be used as a 58 gram weight (not really a clamp) and it's under $15.

I use a  DIY 150 gram weight on my suspended deck (Thorens) and suspect that going even lighter would be just fine.

Now you have described the workings of your table and add into it the fact that the springs have compressed with age a little it makes more sense.

Certainly try the sorbothane and let us know the results.

Has2be, I was not aware that Mitchell made two distinct different clamps, mine is obviously the regular tall spindle variety.
However I am using the Record Doctor one majority of the time now as it is also a decent weight to boot so combines two functions in one and seems to sound a little better on my Garrard.
Sorbothane keeps energy from escaping, what is need is something that allows rapid evacuation of energy from the system. Something like say Shun Mook Mpingo record clamp, at least they had the right idea. Has anyone thought to use an acoustic resonator? Viscoelastic materials like Sorbothane, not a very good one, requires a constraining layer to act as a damper. When Sorbothane is used as a record mat, there is no constraining layer.
Sorbothane is not optimum material for a record weight.
Thanks delay.  I will look into that, and as I pictured it in my mind, I thought of a golf club swing/warmup weight buried in my bag.  It’s like a little plastic covered donut.  I wonder what that weighs?

and thanks to the last two posts explaining that sorbothane is not a good idea for a record weight.

sr, it sounds like you are better off without a weight or get a new turn table.