1340gt surface finish problem

Once the motor and floor are eliminated, if the problem still exists, I would look at adding another set of vertical supports and feet to the stand at the area under the right side of the headstock. I think that may be where Sanddan is headed with his comment above.
 
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If the problem is the floor, not the stand, then putting the entire stand on a thick, wide metal sheet of perhaps half-inch thickness may help. This will spread the entire weight of the machine and stand across the area of the sheet, which will reduce pressure on the floor.
 
I was gonna chime in earlier about a statment from a brown and Sharpe cylindrical grinder owners manual.(I suspected the floor as the problem)
It is under the "work shows chatter finish" trouble shooting. It states as one cause "Machine located on insufficiently rigid floor, or floor transmits vibration to machine"

and then says see page 20...on page 20 is "isolation mountings" "these mountings eliminate the need for expensive machine foundations where external vibrations are a problem.

And it is a 2400 lb machine.
 
So many good replies here, lots of good information. I wonder how we ever made is through life before these forums existed internet ha ha. Im thinking that the 3 phase/VFD Will solve it. But that doesnt mean it was the motor, had the old motor come back here too, put it on my machine, and cuts just fine. (And while these arent Baldor motors, they are still pretty decent motors from Taiwan) What I believe is since the single phase motors are just not quite as smooth as the 3 phase w/VFD (Although in most cases smooth enough on this model for a good finish) and since its on the stud floor, its not absorbing that vibration, it might even be magnifying it. And the 3 phase will have less vibration, so not as critical what kind of floor its on, so hopefully that takes care of it.
 
Sorry,late to the party. There is a strap,or gib, on the back of the carriage which rubs under the back flat way of the bed. Hand lift up or gently pry up on the back of the carriage and indicator check to be sure the gib (strap) takes up all the play without causing a lot of drag.
 
sanddan said:
I have a question on the stand, are the uprights connected in the area marked in red? It looks like the frame is a "C" shape with that area an open span.

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Like many, I have been following this thread. I hoped the OP would answer Dan's query here.

If there are no tension/compression members in the stand's upper end where Dan marked the photo, this leaves the verticals without proper lateral support. In addition, the loading on the verticals appear to be eccentric. With this they will tend to deflect/bend inward. Without the support Dan marked, the system could vibrate and this could be the source of some of your vibratory problems.
 
I'm late to the party too.

I have a similar issue with my lathe. Mine is in the spindle. I have a threaded spindle nose, and none of my chucks seat properly. Additionally, the spindle is mounted on class 3 bearings which have an intrinsic .0003 run-out.

Have you compared chucked work to work run between centers, with the head center mounted directly in the spindle bore? Have you tested the fit on your camlock taper?

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I'm running a Clausing 111/4800. Date 1948. I'm right now making a D1-3 spindle for it.

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