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Servo 140 vs Servo 200 knee power feed

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  • Servo 140 vs Servo 200 knee power feed

    Cranking the knee on my Acer 3VSII milling machine is getting old (as am I), so I'm seriously considering a knee power feed.

    I've had an Align X-axis unit working just fine on my Acer for about 4 years, transplanted from my old Bridgeport where the same unit ran for an additional year or two.

    Before the likelihood of hostilities between Communist China and Taiwan (and possibly us) I may just have gone with another Align unit. But I believe the afore mentioned hostilities will orphan all of our Asian tools, so I am now looking at only the USA made Servo brand.

    For the z-axis, Servo offers two models, the type 140 and the type 200. Servo customer service tells me the difference is only the strength of the motor, with the 200 having ample torque for heavier knees, whereas the type 140 may be "shy" in some circumstances. The Servo selection guide recommends either power feed for my specific mill.

    Can anyone advise having any torque issues lifting the knee with the type 140?

  • #2
    I have used a lot of Servo power feed on BPs, up to the 150. This is for x axis feeding. Personally, I would go with the 200. I think it will work better and last longer.
    Kansas City area

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    • #3
      I hear ya Toolguy.

      Since my original post, I found a Youtube video of "Old Iron Lover" (Installing a Power Knee Drive On a Bridgeport Mill - YouTube) installing a Servo 140 on the knee of his Bridgeport. It's obvious from the sound that it's struggling a bit to lift the knee, and he states in summary that the Servo "will trip out" sometimes. So, if I follow through with my threat to purchase a Servo it will be a 200.

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      • #4
        I think I have one setting on the shelf if you are interested.
        olf20 / Bob

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        • #5
          Well, The 140 means that is the torque it produces in Inch Pounds.
          So a simple test is to measure the force needed to raise your Knee
          A Bridgeport handle is 7 inches long, so if you need more than 20 # of force to turn the handle , the 140 will be too weak
          If less than 20 #, then it will work. And the 200 means 200 inch/Pounds of torque
          i would suggest you put a rotary table on the mill or your heaviest vise when testing

          Rich

          not sure what the Acer handle length is --measure accordingly
          Green Bay, WI

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          • #6
            Originally posted by olf20 View Post
            I think I have one setting on the shelf if you are interested.
            olf20 / Bob
            If he's not, I may be. Let's wait to hear from him first though.

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            • #7
              I'll be 80 this year so cranking is hard for me as well. The setup in the photo works fine.
              You may only view thumbnails in this gallery. This gallery has 1 photos.

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              • #8
                I have seen guys install 2 gas charged lift struts
                to "counterbalance" the knee, to make it easier
                to move. Might be helpful here.

                -D
                DZER

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                • #9
                  Originally posted by Doozer View Post
                  I have seen guys install 2 gas charged lift struts
                  to "counterbalance" the knee, to make it easier
                  to move. Might be helpful here.

                  -D
                  HMMMMM. Now there's a thought. Thanks, Doozer
                  I cut it off twice; it's still too short
                  Oregon, USA

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                  • #10
                    Personally I like dead weights, chains and pulleys,
                    but lift struts are a cleaner install.

                    -D
                    DZER

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                    • #11
                      While on the subject...
                      The new line of Dynamo from Servo is their imported line of feeds.
                      I have come to find that they are technically superior than the old
                      gear crasher design. They use a magnetic clutch rather than a
                      dog finger clutch. Much smoother engagements and reversals,
                      without the gnashing of teeth (clutch dogs).
                      Note the wing-shape knob on these in place of the lever and knob
                      of the classic Servo design. I have seen other brand (rip off) import
                      feeds with this wing-knob and they are of similar design, and might
                      be really good also. Better design, but quality in the build is always
                      tied to the brand name somewhat. I have bought a few Dynamo
                      feeds off ebay, and I really like them. Never an off brand variant.
                      So if you are wanting a power feed, be aware these exist.

                      --D

                      DZER

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                      • #12
                        Originally posted by olf20 View Post
                        I think I have one setting on the shelf if you are interested.
                        olf20 / Bob
                        Hi Bob. Questions. Send me a PM.

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                        • #13
                          Would adding a counterweight to take some of the load off be an option?
                          Chilliwack BC, Canada

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                          • #14
                            Hi BC.

                            I've seen that sort of thing done for drill press tables, but not for Bridgeport knees. I'll try to find examples on-line to acquaint myself.

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                            • #15
                              I would not add a counterbalance because one of the benefits of a knee mill is that the big, heavy knee sits very solidly on the two ways and the jackscrew. If you deload the jackscrew you stand a chance of making the knee more vulnerable to vibration caused by chatter. Of course, I could be wrong about this. Someone else brought it up on another forum.
                              At the end of the project, there is a profound difference between spare parts and left over parts.

                              Location: SF East Bay.

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