Setting Up My PM935 Mill

[DaveH]

On first sight increasing the base size is a good idea to increase the stabilization and it always is.  
However it is how the base size is increased that can cause problems and how the base fits in with the overall structure.

With the same size of object - the heavier one is more stable than a light one, coupled to this is where the majority of the weight is (at the top, middle or bottom)

eg. An empty 3'x3'x3' cardboard box is easy to tip over, fill it with sand ..............   Weight is important.

Coupled to the weight of the object is the strength of the material the object is made from eg the cardboard box will 'rip' before it is tipped (pulled) over.

The strength of the material of your mill can be visualized by having a 1/2" thick lip around the base of the machine - say 2" wide and a hole at each corner for the support pads. This would be easy for the manufacturer to cast and the extra width will increase the stability. On a light weight machine all is fine not too sure on a mill your weight.

Cast iron is great in compression nearly in destructible, in tension quite bad - tends to crack and break.

This is my thoughts regards your mill.
The 1/2" steel needs to be a whole plate (or at least behave as) and solidily fixed to the underside of the mill base. The 4 bolts holes I feel are not enough 8 would be better, but it must be fixed solidly. The steel base could be 4" larger than the mill base 2" all round.

There we have it - with a feet pad at each corner. The machine is switched on and the vibration goes down to floor via the steel plate which vibrates like a drum. Just bluudy great. We need to increase the thickness of the steel plate - more mass = more damping, go for 2" thick plate.

Now with the 2" thick plate should be better than the 1/2" plate except it is only going to be fixed at 4 points - that is just not sufficient.

That's my 2cents  
 
DaveH