Installing a DRO Digital Read Out on a Lathe

[henryarnold]

I just bought a Meister DRO for my Grizzly 10x22 Lathe. Meister DROs are similar to Sino which are made in Asia. Meister is based in Singapore and has a storefront on EBay which is where I bought my setup. Three years ago I bought a Meister 3 axis DRO for my milling machine. Its been a great unit so I decided to go with Meister again.

The base price of the unit I'm going to show photos of was $468 including shipping from Singapore. There are cheaper setups but not much cheaper for a setup with glass scales. I also paid extra to get the smaller cross slide scale.

I have no affiliation with Meister but if you want to check them out, here's where I bought my setup:
http://www.ebay.com/itm/Meister-ARC2-dig...1e604706ed
When you comparison shop, be sure to note the shipping cost. There are a few EBay vendors with similar setups for $320 but their shipping is $125!!

I'll be documenting my installation with photos and text. There are many ways to install a DRO and there are a variety of DRO types so this is just one example. I found that looking at how someone else tackled installation issues was helpful to me so I hope this post will be helpful to the group.

The shipping took only 6 days which is very fast. Sometimes it can take longer. The shipment came in 2 boxes. Meister ships your display in one box and the custom scales you select in a second box. They are very helpful in making sure you pick the correct scale size.
   
Here's everything unpacked. Everything made it without damage. The kit includes the display which has all kinds of layout calculations and aids, mounting brackets, hardware, and a manual.
   
I selected a 570 mm scale for my carriage and a 170 mm scale for my cross slide. These are well made units. They have double rubber lips to keep oil and debris out of the scale. There are no plastic parts and the cable is armoured for protection.
   
In this closeup you can see that my cross slide scale is much smaller than the carriage scale. For larger lathes, it is not necessary to order the small scale. The normal size scale will usually fit on most lathes. My lathe is small so I decided it would be easier with the small scale.
   

[henryarnold]

I decided to start with the most difficult part of the installation which is mounting the cross slide scale. Its mostly difficult because I have a small lathe and the scale seems to be in the way one thing or another. Usually the cross slide scale is mounted on the right side of the carriage but I also explored mounting it on the left side. I tried this because my carriage lock and gib screws are on the right side.

Here's a photo showing the scale laying down with the pickup facing the chuck. I quickly realized that if I made a mistake and crashed my carriage into the chuck that instead of a scuffed up carriage top, I would have a destroyed scale. The scales are not cheap.
   

I also tried the left side with the scale upright but the pickup is too big to fit between the ways so the top of the scale is higher than the top of the cross slide. Again, this would make it vulnerable to anything large spinning on my spindle.
   

I concluded that there is a reason why most people mount their scales on the right side. It has the best protection there and although in my case it conflicts with the gib screws, I found that I can clear my carriage lock. Here's a photo showing how I intend to mount the scale. My plan is to make a mounting bracket where the scale can be easily removed so that if I need to access the gib screws, it will not be too difficult.
   

This photo shows the supplied cover laying over the scale. It will not overlap the cross slide. The cover will be cut down so it meets flush with the cross slide top.
   

During the next few days I'll post photos of my progress. I don't claim to be an expert. This is my second DRO installation. Be sure to warn me if you think I'm making a mistake or if you think you can suggest a better way to mount the scales. My carriage scale will be easy to mount. It will use the standard behind the bed mount with an arm that connects to the back of the carriage.

[ETC57]

Neatly done Henry,

Thanks for the pics.

Jerry.

[TomG]

Looks like a nice readout Henry, I'll need to start saving my pennies.

Thanks for posting the pics.

Tom

[DaveH]

Henry,

Looking good

DaveH

[EdK]

Henry,

That looks like a very nice kit of parts you got there. The price was very reasonable also. As usual, your posts are always top notch so thanks for posting this thread.

Ed

[PixMan]

You're on the right track with that Henry. You may consider moving it a little further back toward the rear. I don't know what that round thing is on the carriage, under the scale toward the operator side but perhaps you don't need to cover it. Here's the way the scales came installed on my dad's lathe. Note that the reader head on the X axis is mounted not between the ways but aft of them. It only took a simple angle iron bracket to get it there.





It's a very old installation, dating back to probably the 1980's. I did have to move the Z axis scale after it failed though. Apparently when the long scale was installed the lathe had a 10" 3-jaw chuck on it and never anything else. When I added a 5C collet closer, the carriage could now move a few inches closer toward the spindle. In doing so, the reader head got knocked out of alignment and stated rubbing against the housing. I could see none of this without crawling over the machine.

One day the readout just stopped. I thought a cable had come loose, but was horrified to find:




I bought a short 150mm unit (new old stock) off Ebay and put the new head in the 800mm scale housing. I moved the whole housing 4" closer to the spindle, and still have enough travel to put the carriage from mechanical stop-to-stop. Why they didn't do it right the first time is beyond me. I used an indicator to get the scale housing level and parallel within a "couple thousandths".




I'm sure your installation will be fine. I posted this just to give you a little more info and help you avoid the issues I hit in the long term.

[EdK]

(07-01-2012, 05:46 AM)PixMan Wrote: I don't know what that round thing is on the carriage, under the scale toward the operator side but perhaps you don't need to cover it.

Ken,

Those are just stacked washers he's using to space the scale temporarily at the correct height.

Ed

[henryarnold]

(07-01-2012, 05:46 AM)PixMan Wrote: You're on the right track with that Henry. You may consider moving it a little further back toward the rear. I don't know what that round thing is on the carriage, under the scale toward the operator side but perhaps you don't need to cover it. Here's the way the scales came installed on my dad's lathe. Note that the reader head on the X axis is mounted not between the ways but aft of them. It only took a simple angle iron bracket to get it there.



I'm sure your installation will be fine. I posted this just to give you a little more info and help you avoid the issues I hit in the long term.

Ken,
THANK YOU! This is the kind of advice I was looking for. I don't understand how your scale got damaged but that is what I was concerned about. I will not be able to mount my scale as far back as your dad mounted his because of my splash guard. I found a mounting position that gives me full travel and does not conflict with my carriage lock. With my planned installation I will have to remove the scale to adjust the gib screws but I don't do that very often so I guess it will be OK.

Ed is correct. I used a stack a washers to support my scale to see where it would mount. They are not part of the installation. I neglected to mention this.

Today I'm going to make my cross slide scale bracket and should have some photos soon.

[PixMan]

Henry,

The reader head (not the scale) on the Z axis (longitudinal) got knocked out of position when the carriage pushed the reader head to the end of the scale housing and moved the bracket. It was apparently enough movement to cause the thin cast aluminum "stalk" of the reader head (extending up into the scale housing) to rub against the scale housing seal and wear right though the aluminum casting, seen as the crusty-looking "T"-shaped thing and the now-separated base it used to be attached to.

In looking at the bottom photo, just imagine running that reader head into the end of the scale. It easily moved the bracket at those two long slots, and neither I nor my dad ever "felt" any problem. It took perhaps a year or less to wear right through as you see it.

Sorry about my optical delusion in not realizing that I was looking at just a stack of fender washers there.

I suggest you run the cross-slide all the way in to the stop, then place the scale housing as far back as is practical. The goal is to get the reader head itself far from being struck by the tailstock being slid forward, or anything else for that matter. I sense that's how the one on my dad's lathe was done, but we'll never know. The installation was already done when I got the machine for him.