Hi Bob;
Not to pop any ballons here but to get a stiffer machine you would need to step up to something like a Bridgeport clone. There may be other alternatives besides that, but a stiff machine will require mass and good design.
As to your issue first described in this thread, it is hard for me to grasp what you are describing. One thing to consider is attaching the indicator to the head in such a manner that you eliminate all other mechanical joints and see what you get. There are a few things to be concerned with when checking out a spindle.
First is radial run out followed by axial run out. Associated with the axial runout is the amount of deflection you get on axis when applying pressure to the spindle.
In essence if you can move the spindle up and down you have a set of poorly adjusted bearings or other mechanical problems leading to little preload. Lack of preload could also result in you seeing lateral deflection of the spindle. You could also have a tolerance problem leading to lateral deflection.
In any event if you have concerns about the spindle (or any element of a machine for that matter) you need to isolate your measurements to the area you thing the problem is. That is why I suggested repositioning the indicator. My gut feeling is that the bearings might be loose, followed closely by errors due to measurement techniques.
Dave  |