How worn can be a tailstock be before problems begin to arise, such as a drill wandering off center (despite a center drill hole)? My 1946 vintage Southbend 9A tailstock shows some slop. Enough to cause some problems I think. With the spindle extended enough for me to measure lateral spindle movement at a point that is 1.5" out from the tailstock casting, I get the following.
Horizontal movement: .003"
Verical movement: .004"
Add an arbor to the tailstock spindle, plus a keyless chuck, and a drill bit, that long assembly multiplies the few thousandths substantially.
Near the drill chuck face, the vertical movement is .010", with only modest pressure on the chuck. You can see oil being squeezed out between the tailstock spindle and casting. The same thing happens when drilling starts. Despite a pilot hole, the drill bit tries to walk around and the tailstock spindle moves a bit under this force.
I have tried to make sure the drill trying to run around with the spinning stock is not due to tailstock misalignment, but maybe it is still off.
If the tailstock is worn, I may be in a bad spot, as I see no good way to fix this, and any replacement tail stock may be as worn as this one.
- Phil
Horizontal movement: .003"
Verical movement: .004"
Add an arbor to the tailstock spindle, plus a keyless chuck, and a drill bit, that long assembly multiplies the few thousandths substantially.
Near the drill chuck face, the vertical movement is .010", with only modest pressure on the chuck. You can see oil being squeezed out between the tailstock spindle and casting. The same thing happens when drilling starts. Despite a pilot hole, the drill bit tries to walk around and the tailstock spindle moves a bit under this force.
I have tried to make sure the drill trying to run around with the spinning stock is not due to tailstock misalignment, but maybe it is still off.
If the tailstock is worn, I may be in a bad spot, as I see no good way to fix this, and any replacement tail stock may be as worn as this one.
- Phil