Where possible a closed loop servo system is always the best. And in my opinion, feedback directly from the load (the table in the case of a mill) is the best way to go. Unless you are buying a 6 figure machine, relying on the encoder/leadscrew for positioning accuracy introduces too many variables into the equation. I use magnetic readers on my mill that replaced the original encoders.
Open loop stepper systems tend to loose pulses, especially at higher speeds and/or heavy loads. It is possible to close the loop with stepper systems by programming in on-the-fly error correction, if you have a feedback device on the axis.
Hi
Is this mill made in the USA. It looks like the one from Grizzly
Hi
Is this mill made in the USA.
It looks like the one from Grizzly
http://www.grizzly.com/products/Heavy-Duty-Mill-Drill-with-Stand-and-Power-Feed/G0755
or the one in the UK
http://www.amadeal.co.uk/acatalog/AMA45A.html
what is the difference in the mills, they all look the same, just the specifications,
in the speeds & motors. Is this one any better ????
The one in the UK look nearly the same.
ps
is tooling for the NT30 Spindle inexpensive and easily obtained in the UK
Both the Industrial Hobbies and the Grizzly mill are made in China. The UK mill you linked is probably made there too.
There is some variation between the mills, but they all started life as clones built following the pattern of the Rong Fu 45 (RF45) square column mill.
The Industrial Hobbies mill received quite a few upgrades over the last decade at the behest of IH, gaining larger table, larger base, thicker cooler on the head, etc.
I would look a little more carefully at the specs when you buy a mill; the UK mill comes with an MT4 taper, which I would rather not deal with in a mill. You should be able to look around and find an R8 RF45 square column mill from an importer in the UK. Try here:
http://www.axminster.co.uk/metal-working/milling