I've found the easiest way to check how much wear is on a lathe bed is to use the tail stock ways as the reference. Since the tail stock ways usually have minimal wear, those ways can be used as a reference for the carriage ways, which can have significant wear, usually over a span of a foot or so near the spindle. In the case of my '40's Wards lathe (made by Logan), the ways were not flame hardened, probably due to "value engineering" to keep the costs down, and had over 20 thousandths dip in both the V and flat ways. I eventually found an almost new bed ($90) which solved the problem.
To measure the wear, I move the carriage to the extreme left, fasten a 1/10th thousandth dial indicator base to the tail stock, put the indicator point on the way to be measured and slide the tail stock from end to end measuring how much dip is on the carriage way. There is usually minimal wear on the right side carriage ways and you can watch the needle dip right where you would expect the wear to be. It works well for both the flat way and the V way. I measure the V way at the 50% point. It is critical that the indicator base does not move while measuring the V way. As such, a magnetic base is not sufficient, mostly because of the thick paint used on castings, so the best method I found was to C-clamp the indicator base to the tail stock.
Last week I used this method to check the ways on a 12X36 Enco for a friend, which indicated about 6 thousandths max droop. As a result the dealer knocked $500 off the price while learning how to measure the wear on the ways.
My original intent, before I found the pristine base, was to set up a grinder to reshape the bed ways on the Wards lathe, (stripped down, of course) again using the tail stock base as a platform for the grinder, but I never got that far, so at this point it is just theory.
To measure the wear, I move the carriage to the extreme left, fasten a 1/10th thousandth dial indicator base to the tail stock, put the indicator point on the way to be measured and slide the tail stock from end to end measuring how much dip is on the carriage way. There is usually minimal wear on the right side carriage ways and you can watch the needle dip right where you would expect the wear to be. It works well for both the flat way and the V way. I measure the V way at the 50% point. It is critical that the indicator base does not move while measuring the V way. As such, a magnetic base is not sufficient, mostly because of the thick paint used on castings, so the best method I found was to C-clamp the indicator base to the tail stock.
Last week I used this method to check the ways on a 12X36 Enco for a friend, which indicated about 6 thousandths max droop. As a result the dealer knocked $500 off the price while learning how to measure the wear on the ways.
My original intent, before I found the pristine base, was to set up a grinder to reshape the bed ways on the Wards lathe, (stripped down, of course) again using the tail stock base as a platform for the grinder, but I never got that far, so at this point it is just theory.