Hi,
I would recommend you go strait to a glass scale DRO package from ebay or similar.
I have heard of many guys over the years fitting the cheap Chinese scales and having problems and glitches(even in a good environment), then they buy a glass scale DRO and wonder why they mucked around with the cheap scales for so long. Glass scales don't have any problems and work flawlessly every time you turn the system on.
If you do go to the Shumatech readout and cheap Chinese scales, it wont be long before you find the cheap scales not reliable or not accurate enough for what your doing, so then you will be looking for glass scales. It is not much more to buy a complete DRO package than it is to buy the glass scales separately.
Going by DRO pros site it will cost $150+ (depending on size) for each scale plus postage on top, when a 2 axis package posted to you will only cost around $420 and $550 for a 3 axis off ebay.
I just had a look around to show you a comparison of the scales in accuracy and resolution, and this is if there are no problems and they are working fine.
Below is from Wikipedia
Ordinary 6-in/150-mm digital calipers are made of stainless steel, have a rated accuracy of 0.001 in (0.02mm) and resolution of 0.0005 in (0.01 mm). The same technology is used to make longer 8-in and 12-in calipers; the accuracy for bigger measurements declines to 0.001 in (0.03 mm) for 100-200 mm and 0.0015 in (0.04 mm) for 200-300 mm.
http://en.wikipedia.org/wiki/Caliper
Standard glass scales have a rated accuracy of +/-0.0002 in (0.005mm) at 20 degrees, and a resolution of 0.0002 in (0.005mm) or upgrade to 1um scales (Sino $20-25 each axis extra with the kit) and they have a accuracy/resolution of 0.00004 (0.001mm)
When you look at the Shumatech cost wise, you will be up for
Shumatech read out $159.95
All of the parts in the link below for the through hole components and enclosure parts, looks to be around $50 worth
http://www.shumatech.com/web/products/dro-550/bom
Chinese Scales $50+ each maybe?
Change over to glass scales latter $300+
(And this is if you can buy one as they are unavailable at the moment by the looks of it.)
So as you can see it looks cheap to begin with, but it's just because you can buy each piece one at the time, instead of buying it all together.
I gave David my opinion on DRO's the other day, and it might interest you.
http://www.hobby-machinist.com/show...s-for-Bridgeport&p=33701&highlight=#post33701
Dave