Bed wear

Hi



First post. I have recently aquired a Hercus model AR. I've had a Sheraton Model C for 20 years and I thought it was about time I had power cross feed and a gearbox!



I mounted a dial gauge on the Hercus tailstock's foot and had it bear against the front saddle way about 3" in front of the tailstock. Sliding this up and down the bed shows a difference of 7 thou between the bed center and the end. I guess thats a combination of both tailstock way and saddle way wear.



I tried the same test on the Sheraton; it has less than 3 thou difference over the bed length. It woud appear to be much less worn.



So, the question is: how much wear is acceptable? The Sheraton has a bit of a taper but thats very rarely a problem for the type of work I'm doing. I suspect the worn Hercus will frustrate me more though. Perhaps there is a better way to measure the bed?



There is an option to fit the Hercus A apron to the Sheraton - I'd need to source a Sheraton A leadscrew; the bed is 2" longer than the Hercus. I can feel the purists shaking.... well, these are 50 year old worn machines, I'm trying to be pragmatic.



Thanks

Murray