View Full Version : More ??? about DROs

05-17-2006, 02:40 PM
What a great site this is. I did a search and answered most of my questions about DROs - which is best, which are cheap, how flexible, etc. So far, these facts stand out:

Newall - The "Hardinge" of DROs. Widely felt to be the best. Scales (the DRO's sensors) are very robust, and aren't bothered by chips, coolant, oil, etc. Pretty easy to install, well supported. Requires [table travel] + about 10" of table length to properly mount.

Accurite - Strong competitor to Newall, different kind of scales (sensors), but have heard no complaints on robustness. Priced about the same as Newall.


and closer to the low-price end:

Shooting Star - Well regarded Canadian product. Priced pretty competitively, decent user base. Downside is the rack and pinion scales (sensors) - many feel that they would be quite vulnerable to contamination, but I haven't heard of problems from actual SS users.

Shumatech - A very inexpensive kit, uses scales from Chinese calipers as sensors. May not have enough travel for the average Bridgeport, but there are a variety of scales that can interface to a Shumatech, some making it as expensive as the "big boys". Definitely a DIY affair, but as an electro-computer geek, that doesn't bother me. Time would be a factor for me. Founder was badly hurt in an accident, and questions have arisen about support, however, there is some Yahoo group that supports it pretty well.

CheapassDRO - Mr Cofer's amazing contribution. Very inexpensive, based on Chinese scales, and appears to have a lot of smart folks supporting the effort. Interfaces easily to many CNC systems, very flexible, easy to improve, free open-source code.

Most DROs support tool offsets, bolt circles, inch/metric, and a few other basic functions. The high end probably features more accuracy and "gee whiz" features, but with a little additional code CheapassDRO can do anything they can do.

Now with the questions:

I've got one of those very prolific Bridgeport 9x42 mills, and I'm now shopping around for a DRO. The Newall makes me drool, of course, but there's one thing I don't see discussed much about DROs in general. Except for the CheapassDRO and possibly the Shumatech, I don't see any mention of being able to interface the DRO to a computer, for example, as the move toward CNC takes place. Does this mean that, when going CNC, the DRO head is just decommissioned? Maybe the DRO sensors are commandeered by the CNC controller, so the readout head is not needed?

Interfacing the DRO to a computer could have other uses as well. In conjunction with a touch probe, it would be the only way that I'd be able to measure something nearly 3' long to a resolution of (as little as) .001" at home. Also, how about using the data from a DRO to control a power feed? The unique sensors used by the Newall would be nice in a CNC environment, but they're not your normal Quadrature or "Chinese digital" in the interface to the reader head. (I've heard it's a tube full of steel balls, and by watching capacitance variations as the reader head travels down the tube, you can get position info. How many CNC systems can speak that language?)

So, except for the CheapassDRO, do any of the other well-known DROs have provision to export live data to a PC or other device? Or is this a silly idea that isn't needed for some other reasons?

Apologies if this has already been covered, but I tried to do my homework searching the archive first. I'd appreciate clarification from the gang here.