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Best practice: vertical axis DRO scale on a surface grinder

We have used readouts on grinders for 30+ years, but never on the longitudinal (long table) axis. I can't think of a single time I would need it. What am I missing? We set a mechanical hard stop if we need to repeat to a certain position to grind something in a spinning fixture, but I don't need a readout for that. Use readouts daily for cross (saddle) and down feed.

Guilty as charged.

As you say, the vertical (Y) and cross (Z) DROs are useful. I don't yet know if the long (X) DRO is going to be helpful, but since I was adding a readout on this machine, I thought it made sense to do that axis as well.

My surface grinder (this is a J&S 540) doesn't have a hard and/or adjustable stop on the long axis. (I'll ask about that in the Abrasive Machining forum, don't think I have seen them on these machines.) So I thought one place that an X axis DRO might be useful is if I have a dresser set on the chuck, and want to come back to do a cross dress repeatedly. The X DRO will let me come across the diamond at exactly the same location.


PS: I have DROs on my other machines (mill, lathe, cylindrical grinder). The first of these is a factory Heidenhain installation, the others I did myself. All of these are reliable and accurate, and I depend upon that. If they didn't work correctly, I'd be lost. So when I do a DRO install, I don't cut corners, and make my best effort to ensure that they will work right every time.
IMG_20220128_090938699_MP.jpgYour Installation is top notch. 40 years ago I worked for Anilam for a few years, so I've seen plenty of DRO installations. Done right with proper guarding they are very reliable. Here are 2 examples of movable table stops, 1 Okamaoto, 1 Harig
It's a Sino SDS6-3V. It's not quite generic because the scale inputs are EIA-422 (balanced differential) rather than RS-232 (often called "TTL") which is unbalanced/single-ended.

I like Sino DROs and scales, because I've corresponded for many years with the main guy behind Sino, Peter Wendlandt. He really knows his stuff. Note that Peter has cautioned me against buying gray-market versions direct from China, and so I purchase scales and display stuff from authorized German resellers.

That's right, both the X and Y axis scales came with "flying leads" (meaning, no connector).

The Z (cross) axis uses an out-of-the-box Sino KA-200 scale, which already has the correct connector but has an RS-232 output. So for that, a small RS-232 to EIA-422 converter box is needed. It hangs out the back of the DRO. It's hard to see in this photo:

but is plugged into the Z connection between the scale connector and the DRO itself.

The vertical (Y) axis uses a Renishaw interpolator which has a native EIA-422 output. Here, I just had to compare the Renishaw datasheet connection diagram with the Sino one, and solder the leads in the correct order to a DB9 connector.

The long (X) axis was the same story, because again the readhead has an EIA-422 balanced interface. Again, I needed to compare the RLS datasheet to the Sino one, and solder the leads in the correct order to the DB9 connector.

Good to hear that!

I haven't had enough experience yet using the DRO to see the degree to which it will help me. But I have already discovered that the backlash in the vertical axis doesn't behave quite like I thought it would. So it should be easier to shift height settings if for example there are steps and then get back to where I was.


Thanks for the detailed and informative reply! I have some similar projects, so your DRO implementation details are particularly helpful. I aspire to the level of quality you demonstrate here.

When chasing micron-scale adjustments on my B&S, I found it was easier to back off 20-100um rather than trying to execute a small move and deal with the associated stick-slip. But I'm sure you're already well along in figuring out the quirks of your machine.

I found the long-axis DRO would've been useful when using the grinder for spin-fixture or OD grinding, since it makes it easier to get the work clear for a measurement, then return to the same position to take the next pass. Of course if you have an OD grinder, this may not be a common need for you. I got by on my B&S with a dial indicator and mag base.