Metric vs Imperial lead screws

[Harley80915]

I think I have lathe on the brain today

opps

Hi all, in my continued search for a mill, I wonder how much the pitch type (I don't think that the right term) of the lead screw matters.
I know that some of the small mills have metric lead screws but dials in thousands with some weird fraction left over.
I would put a DRO on any mill I buy so I would think that it wouldn't matter whether the lead screws were metric or imperial.
Or am I missing something completely obvious?

Easy to do on the x, y and Z (verticle) lead screws. Just measure the travel of the lead screw one full crank on the handle and
that will tell you what your lead screws are. For example, if your table moves 0.1 inch cranking handle one turn, then your lead screw
is 10 tpi or 10 turns per inch. Many cheap Chinese ones have metric leads so measure those with metric units. I have a Precision Mathews and they have better 10 tpi lead screws. Those are made in Taiwan, better products than China.

 

[projectnut]

Thanks gents, agreed on the need to learn to use the machine before diving into a DRO. I have since learned that the dials are actually metric so that takes away the insanity of imperial dials on a metric lead screw.

I don't know if you're looking for a new or used mill. If you're considering a used one Bridgeport did make Series I mills with both imperial and metric dials. I have a 1972 Series I machine that came out of a local high school. It was ordered from the manufacturer with both sets of dials.

Before I installed a DRO about 8 years ago I did use either the metric or imperial dials depending on the job at hand. The metric dials were used far less than the imperials, but I never had a problem with poor measurements when I did use them.

As a side note when I brought the machine home the original invoice was still in the storage space in the column. The machine was purchased with the dual dial option, a 6 inch vise, and a set of Hardinge collets by 1/16". The total price was just a tad over $1,400.00. I paid a little more than that when the machine was 30 years old. Not to worry though, it came with several end mills. Over the years students had apparently damaged a few and hid in the column.

 

[macardoso]

I just did a DRO install on my lathe and found the carriage handwheel to accumulate 12 thou of additional travel per every 0.7" revolution (yes, it has a graduated handwheel). I couldn't figure out why my parts were coming out wrong until I saw that.