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  • DRO install question

    I'm nervous about installing a new DRO system on my RF-31 benchtop mill, particularly with getting the alignment right, so there is no adverse drag or binding between the scale and the read head. Just final torquing bolts after careful alignment can screw up alignment if all surfaces are not flat and square, etc.

    It seems to me that if some "off-axis compliance" were integrated into the mounting system it could alleviate alignment error, without introducing any significant measurement error.

    On an x-axis scale install, for instance, if a vertical slot through which a "post" were inserted vs a bolt, it would provide some vertical compliance between the read head and the "hard-mount", alleviating the required critical alignment.

    Is this a valid approach?

  • #2
    All the DRO's I have installed come with the head locked in place, in this way after mounting the scale and head onto the machine at this spacing, the head locks are removed.
    Most have a form of automatic tensioning to keep the head at the right position on the scale anyway in order to allow for minor misalignment?
    Max..

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    • #3
      I installed a Mitutoyu unit on my RF Taiwan mill drill with no problems. I had to shorten th X scale to match the bed length, but that too went well.Just take your time and use care to keep the scales parallel in both aves and you should have no problems. I used a dial indicator on a purpose made slide to maintain some sense of parallelism. Bob.

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      • #4
        If your talking about glass scales.
        To give some adjustment I use the next size under bolt. Most have room for a M6 but it wont allow for any movement, so use M5 and it will give you some movement to adjust it.

        If your worried about drilling the holes, clamp a piece of predrilled flat bar over the hole to be drilled and then drill it. This way it wont run off on you.

        And as for it moving when tightening, use washers under all your bolt heads, this will stop it moving when tightening. I have done 4 systems this way with no troubles and can adjust them spot on.

        The reader head doesn't like being off vertical, but the spring takes up a bit for side to side movement.

        Dave

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        • #5
          Hi jmark:

          I too was concerned about critical alignment and stressing the parts.
          I was very careful about all that and now that it's done, I think I overthought the entire process.
          Do the best you can and it will probably be far more than enough.
          Mike

          My Dad always said, "If you want people to do things for you on the farm, you have to buy a machine they can sit on that does most of the work."

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          • #6
            When I mounted mine on the 3 axis of my RF45 clone I was married to the dial indicator. Also I didn't use the mounting bolts/screws as the point of adjustment. For instance, the glass scale mounts on a piece of aluminum bar that's probably 3/8" thick by 1-1/4" wide and so long. In the 4 corners of that bar I put 4 'jacking screws' that rested against the mill surface. I used those to move the bar into alignment. The bar was held to the machine with one bigger cap screw in each end.

            I also found that those universal brackets with all the slots in them were about useless. Good in theory but impractical. Just got some aluminum angle off eBay once I had my mounting design firmly in my mind.

            I also had to modify the mounting arrangement for the long scale so it didn't interfere with the table locks or the limit switches. Took some redneck engineering to get it to all work in harmony. I was also able to incorporate a rubber cover over the long axis scale to keep scarf off of it and protect it from my clumsiness. Lastly all the mounting surfaces on the mills castings weren't square, parallel, or in alignment with each other or anything else for that matter. Hence the use of the jacking screws.

            I strived to have everything .001" parallel/square over the length of travel. I came very close (within .0005") of meeting that goal.

            Just take your time. Probably took me at least a week part time. If I ran into a snag I just went and had a beer and thought about it the rest of the day.

            Comment


            • #7
              Originally posted by MotorradMike View Post
              Hi jmark:

              I too was concerned about critical alignment and stressing the parts.
              I was very careful about all that and now that it's done, I think I overthought the entire process.
              Do the best you can and it will probably be far more than enough.
              You bring up a good point there.
              One my first install I was the same with stressing over the accuracy of the install, but after that you realize the reader heads are pretty forgiving as they are spring loaded. It doesn't mean you can just throw it on, but as long as you dial in the scale body and leave the plastic reader head spacers in place until you do up the bolts you will be right.

              I posted up my install of the X axis scale on the front of the table, it's a bigger machine but might give you some ideas.

              http://www.metalworkingfun.com/showthread.php?tid=386

              Dave

              Comment


              • #8
                Originally posted by dave5605 View Post
                When I mounted mine on the 3 axis of my RF45 clone I was married to the dial indicator. Also I didn't use the mounting bolts/screws as the point of adjustment. For instance, the glass scale mounts on a piece of aluminum bar that's probably 3/8" thick by 1-1/4" wide and so long. In the 4 corners of that bar I put 4 'jacking screws' that rested against the mill surface. I used those to move the bar into alignment. The bar was held to the machine with one bigger cap screw in each end.

                I also found that those universal brackets with all the slots in them were about useless. Good in theory but impractical. Just got some aluminum angle off eBay once I had my mounting design firmly in my mind.

                I also had to modify the mounting arrangement for the long scale so it didn't interfere with the table locks or the limit switches. Took some redneck engineering to get it to all work in harmony. I was also able to incorporate a rubber cover over the long axis scale to keep scarf off of it and protect it from my clumsiness. Lastly all the mounting surfaces on the mills castings weren't square, parallel, or in alignment with each other or anything else for that matter. Hence the use of the jacking screws.

                I strived to have everything .001" parallel/square over the length of travel. I came very close (within .0005") of meeting that goal.

                Just take your time. Probably took me at least a week part time. If I ran into a snag I just went and had a beer and thought about it the rest of the day.

                By any chance did you document your DRO installation on the RF-45 clone with photos online? If so, I'd appreciate a link to it.

                Comment


                • #9
                  Decent scales have a floating head internally that runs on either bearings or plastic bushings. Dont worry about it.

                  Comment


                  • #10
                    Originally posted by macona View Post
                    Decent scales have a floating head internally that runs on either bearings or plastic bushings. Dont worry about it.
                    I would've assumed this to be the case but that's the first I've actually heard of this! Glad to hear it!

                    Another question:

                    Is there a "rule-of-thumb" regarding the mounting of the read head vs the scale to the stationary part of the tool vs the moving part?

                    The factory installed Accurite system on the mill/drill at work is quite the Rube Goldberg machine, and does it both ways.
                    Last edited by jmarkwolf; 11-26-2012, 06:52 PM.

                    Comment


                    • #11
                      Just be willing to take as long as it take to make sure it's right. It took me a week to mount the scales on my milling machine. That included a lot of time making a custom mounting bracket for the Y axis. I also made some alignment fixtures to help make sure things were where they were supposed to be, and I checked and re-checked alignment as I went along. I probably didn't need to be as fanatical about it as I was, but it's one of those things that if done right you will never have to touch it again. Make it a Zen meditation.
                      ----------
                      Try to make a living, not a killing. -- Utah Phillips
                      Don't believe everything you know. -- Bumper sticker
                      Everybody is ignorant, only on different subjects. -- Will Rogers
                      There are lots of people who mistake their imagination for their memory. - Josh Billings
                      Law of Logical Argument - Anything is possible if you don't know what you are talking about.
                      Don't own anything you have to feed or paint. - Hood River Blackie

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                      • #12
                        Originally posted by doorknob View Post
                        By any chance did you document your DRO installation on the RF-45 clone with photos online? If so, I'd appreciate a link to it.
                        Lets see if this works. Any questions, just ask. This was done a few years ago but its still doing the job. Not 100% happy with the Z axis setup but it works. Would have liked it a little more ridged.

                        http://s180.beta.photobucket.com/use.../DRO%20Install

                        One thing on the aluminum angle material. I found the inside angle was typically tapered a few degrees so I had to always mill it flat where other mating surfaces were going to mount or the fastening hardware was going to go.
                        Last edited by dave5605; 11-27-2012, 01:15 PM. Reason: Add info on tapered aluminum angle

                        Comment


                        • #13
                          Originally posted by jmarkwolf View Post
                          Is there a "rule-of-thumb" regarding the mounting of the read head vs the scale to the stationary part of the tool vs the moving part?
                          I think I answered my own question:

                          If the read head is on the "moving side", the armored cable will continually be trying to sweep the "area".

                          If the read head is on the "stationary side", you can lash the armored cable down.

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                          • #14
                            Originally posted by dave5605 View Post
                            Lets see if this works. Any questions, just ask. This was done a few years ago but its still doing the job. Not 100% happy with the Z axis setup but it works. Would have liked it a little more ridged.

                            http://s180.beta.photobucket.com/use.../DRO%20Install
                            Thanks... I'll take a close look at the photos...

                            Comment


                            • #15
                              Update:

                              I succesfully installed a 2-axis Dro Pros Electronica system with magnetic scales.

                              Had to fabricate nearly all the mounting hardware since the supplied hardware didn't match up with how I wanted to mount everything.

                              Took about 4 man days, with the most tedious part being the alignment.

                              I had not used dial indicators much in the past, but got a good workout with this project.

                              So far I am very pleased with the quality of the product and support from Dro Pros.

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