Harig 612 DRO Install

Earlier I'd made a post looking for the components to add the "fine feed" option to a Super 612 I'd just finished getting back into action( it had been involved in a tip over long ago, and sat unused, until the last guy to own it kindly gave it to me ). Anyway, finding the parts wasn't looking good, and CarbideBob had commented why not just stick a DRO on it instead? Seemed like a good idea, and I had already started watching ebay for components. Wound up finding a NOS Acu-Rite ENC150 1uM encoder, still in the factory box. Followed by an old but in good shape Quikcount display. All in for a little over $200 with shipping. The shocker came when I thought I'd just order the factory Harig mounting kit that Acu-Rite still offers, then saw the price. Depending on the vendor, retail is $400-$500 for a glorified V block and hose clamp! I needed an excuse to learn how to use a rotary table, and wound up making my own mount.

I had concerns that having the reader head mount attached to the motor housing, was going to transfer vibration and cause the least significant digit ( half tenth increments in this case ) to jitter but its rock solid. There's a little blip when you turn on the spindle, but it immediately settles back to where it started, and then never varies. The dust collector running has no effect either. Big relief there. Used a 6" Jo block to set the error compensation in the Quikcount, and it measured the 6" gauge to within a tenth and a half. Pretty good for 20+ year old instruments.

Pretty slick. At some point I want to add a DRO to my 6-12 also.

Nice rotary table work, that mount looks nice!

gwilley said:

Nice rotary table work, that mount looks nice!

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Damn nice!

I have that exact grinder , so this is a beneficial post. Where does the DRO display hinge mount to? I can't tell from the pic.If I am going to steal an idea, I want to do it correctly

Way nice work. OMG nice.
No disrespect but why did you decide to mount the reader on back of the spindle housing?
Ideally one would want the reader head in line with the wheel. That is just about impossible here.
There is some small twist up/down on this axis. I know it gravity loaded.
There is the whole abbe error and shit. Always wanted to do a dual encoder front and back side to nail it.

Make no mistake I do not mean to whine. File this under wow and great job done.
Bob

daryl bane said:

I have that exact grinder , so this is a beneficial post. Where does the DRO display hinge mount to? I can't tell from the pic.If I am going to steal an idea, I want to do it correctly

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Pretty much just bolted about an 18" long piece of scrap aluminum 1-1/2" square tube to the base/dust collector cabinet. Welded a solid plug in the end and tapped it for a 3/8-16 stud to secure the arm that supports the DRO display.

CarbideBob said:

Way nice work. OMG nice.
No disrespect but why did you decide to mount the reader on back of the spindle housing?
Ideally one would want the reader head in line with the wheel. That is just about impossible here.
There is some small twist up/down on this axis. I know it gravity loaded.
There is the whole abbe error and shit. Always wanted to do a dual encoder front and back side to nail it.

Make no mistake I do not mean to whine. File this under wow and great job done.
Bob

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Thanks Bob, and no disrespect taken at all, you make very good points, and some I pondered; particularly in regards to the Abbe error issue. I essentially stole the mount idea from Acu-Rite, as that is where they secure the reader via their $400 hose clamp. When thinking about the Abbe error issue, I figured that since virtually every measurement will be a relative one, whatever error is there, will hopefully always be there, and of a fairly consistent magnitude. In the end, I decided that having the scale around the corner, and pointed away from the dust source, outweighed any benefit from locating the read head as close to the point where the wheel contacts the work( which would be most ideal). I'd actually considered trying to figure out a way to install the scale and reader inside the column, but with the Harigs oil system, it's pretty much raining oil constantly in there. The other option was mounting it at the top of the column, and have the elevation screw( which doesn't rotate ) drive the reader up and down, and have the scale poking up in the air where the lead screw dust cover tube is. In the end said the hell with it, and mounted it the way Acu-Rite suggested. Again, appreciate the kind words. First time I've actually bolted the rotary table on my mill and used it, so it was a little slow going. Damn air compressor came on while I was really concentrating, and thank goodness it wasn't at a critical point! Turned that sucker off for the rest of the job!
I'm super impressed with the balance job that the folks at Harig did, when they made this machine! With the grinder and dust collector running, the least significant digit on the DRO( which is half a tenth ) is dead stable. I can just put light pressure on the spindle with my finger and cause that digit to toggle back and forth. There is virtually no vibration to speak of in the grinder. Considering it's relatively light weight, compared to other grinders, its pretty amazing.

Nice work, looks great!