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servo powerfeed on rockwell mill ??

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  • servo powerfeed on rockwell mill ??

    Hey Folks,
    wondering if anybody has mod'd a Servo brand powerfeed unit to mount to and work with a Rockwell model 21-100 mill, (as I'm planning to do)...just curious as to any potential "traps" to watch out for....seems fairly straightforward but better to ask now.



  • #2
    Here are a couple of pictures of the one I mounted to my Rockwell. It is a chicom, but installation is the same as a Servo;

    It was a build as you go and draw it on a scratch pad as most of my projects are. It was not too difficult.

    The mounting bracket is a piece of 1" aluminum plate bored to retain the bearing. This moves the bearing closer to the mill table, and the only modification to the machine is to move the shoulder on the feedscrew back to accomodate the new bearing location.

    I found a dial from a Bridgeport to retain the graduations, both machines use the same thread count so that works well. I had made a spacer to take up the space and was going to graduate that until the B'port part came into my life.

    I did do something creative in adapting the small leadscrew to the large bore of the bevel gear, but can't remember all the details. When you get to that point, let me know & I'll take it apart for more photos.
    Jim H.


    • #3
      Well, we're working all around your question, cause I did a leeetle bit different mod also...tho it should be real close. I've got one of the 6x26 import mills that seem? to be real close to the Rockwell and Clausing. I went at similar to J C in that I used one of the import "Bridgeport style" units, but I can see that we went at it in totally different ways. I'm afraid my memory is fuzzy on details of the construct, been some time ago, and like J C, I just start putting stuff together and dont have drawings. But obviously, it can be done---jump in and if you get in trouble, holler, and maybe one of us can help

      If everything seems to be going well, you have obviously overlooked something........


      • #4
        Originally posted by chkz
        just curious as to any potential "traps" to watch out for...
        One warning about the Servo feed itself: I have an original Servo Type 70 power feed that came on my Burke Millrite, and it's a bitch to re-assemble. The spring-loaded control arm for the feed shifter has to coerced into the back side of the power feed case and guided up behind the speed control potentiometer.

        At one point I called the Servo repair tech to ask if I was doing something wrong, and he started laughing -- there just isn't any easy way to do it...
        Other than that, the Servo tech support is spectacular.

        The Servo Type 140's, on which I think the Chinese power feeds are based, are much simpler to re-assemble.

        "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."


        • #5
          That must be why I got a Servo 90 so cheap. It's a basket case in a box. Someone took it apart and It's still that way.


          • #6

            I am no help in how to do it, but I do have lots of questions, some of which may even shed light on the process for chkz.
            I have a Supermax mill with 16mm diameter end on the lead screw that I would like to add a power feed to. Now my problem is that all of these retrofits seem to be for 5/8 ends on the lead screw. As near as I can tell from the pics on ebay, the units have a needle bearing which fits the shaft. The measley .005 isn't much but I bet it won't do the bearing any good! It also looks like the needle bearing is mounted in the housing for the feed unit.
            JCHannum, am I understanding that you moved the bearing to your new end cap? That would solve my problem as I could just get a 16mm bearing and put it in a new end cap. My concern would then be, if I understand what you did, how the extra shaft length and flexing affect the drive gears? I would, I believe, have to alter the gear to fit my shaft, as well.

            Stu Miller


            • #7
              I adapted one 15 or20 years ago You have to do away with the original end plate and machine up something to mount to the Rockwell and connect the servo to the other side . I seem to remenber makeing a stub shaft to extend the end of the Rockwell screw to get the needle bearing and servo parts to fit .I also used a Bp dial. unit was a servo 140 I thank. sold mill about 1990 but still going strong.
              Every Mans Work Is A Portrait of Him Self


              • #8
                I made a stubshaft to fit the the bevel gear to the Rockwell shaft. I might have adjusted some diameters to make it all fit. I bored out the handwheel bore to fit the stub shaft. This makes a sort of cartridge assembly the length of the bevel gear that bottoms out on the inner race of the bearing.

                I tapped the end of the Rockwell feedscrew and retain the whole works with a heavy washer and Allen screw.

                When you have the feedscrew assembly apart, it is a good time to adjust the backlash. There are sleeves on either end of the screw between the shoulder of the feedscrew and the inner race of the bearing. I made new ones and adjusted them for a tighter fit than they originally had. If your Rockwell mill seems to have a lot of backlash, take a look here first.
                Jim H.


                • #9
                  Mounted One on old Bport

                  I swapped some cat 40 holders for a servo feed that didnt work. (yeah im a scrounger) Got my friend(electro geek) to fix it. It sat for years on the shelf over my lathe. Other day 20 inch long aluminumn blocs with lots of long angled slots. I decided to mount the drive unit. It seemed like my mill leadscrew which always was screwy to start with was too long?? for the servo feed to fit correctly. I ended up shimming out the end bearing plates and commenced running the job. WOW what a nice option i got quite impaired drinking beer and just moving the mill and hitting the feed lever. I really enjoyed running that job with the fedd unit what a difference. Even in the die shop we didnt use fed on our first toolroom mills. Im spoiled now i want a cnc.


                  • #10
                    I hear you Mike! I have power on the X and Z(power down) axis on my little mill. Wish I had it on Y also. I had to do a bunch of pieces on the Y axis the other day and it near bored me to death....cranking on that wheel instead of flippin the lever.
                    I have tools I don't even know I own...


                    • #11
                      Thanks !

                      Thanks for the great input & photos guys! Much appreciated. I'll "plug away" at this and let you know how it goes!

                      Take care,



                      • #12
                        Question for those using Servo on Rockwell.......

                        Understand the Bridgeport and Rockwell use different pitch feedscrews:
                        10 (.100 per rev) on the BP and 5 (.200 per rev) on the RW. Read on another list that this caused problems with a very short adj. band on the speed control.
                        Did anyone have this problem?
                        I don't do drugs.
                        At my age, I can get the same effect if I stand up too quick!


                        • #13
                          As far as I know, they both use the same 5 pitch on the feedscrews on the table feed. As I mentioned, I am using the graduated dial from a Bridgeport, and Lane Sissons did the same.

                          There is no speed problem with the powerfeed I am using.
                          Jim H.


                          • #14
                            Originally posted by JCHannum
                            As far as I know, they both use the same 5 pitch on the feedscrews on the table feed....
                            There is no speed problem with the powerfeed I am using.
                            Thanks for the reply! I haven't yet started to adapt mine, but had seen a post on another list and had no reason to question it........oh, well, live and learn!
                            I don't do drugs.
                            At my age, I can get the same effect if I stand up too quick!