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  • Variable speed questions

    You can see the pic of the drive about the third down:
    http://motorhead.iwarp.com/lathe/lathe.html
    When running down to the lowest speed it hangs up and the lever won't move anymore. I disassembled the whole thing and tightened the belt up with it on the lowest speed. After running up and down the speeds a few times it binds. The shaft and sheaves looked OK. I was afraid to grease the spindle for fear of slinging it all over the belts.
    Any advice on setting up this type of drive? The manual calls for 1/2 inch standard v belts and I installed one of those lawn and garden types.
    Just wanted to add that the middle sheave is the only one that moves.

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    Hoffman in Warner Robins Ga

    [This message has been edited by hoffman (edited 11-25-2004).]
    Techno-Anarchist

  • #2
    I have a Rockwell wood lathe that uses a very similar drive. On mine the cable is replaced with a rack.
    I bought it used from a tool dealer. He thought the spindle bearings were gone, it howled and vibrated bad. Brought it home cheap planning to replace the bearings. Loosened the belts and she ran like a charm. They had them too tight. That was probably 15 years ago. Have never touched it since, wouldn't want to guess the number of hours I have on it now. Seems to be a great drive system with an incredible speed range.
    How tight do you have the belts? Try running them fairly loose. I work the heck out of my wood lathe, cuts that should stall it but have never noticed the belts slipping.
    Let me know if I can help anymore.
    Greg

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    • #3
      What is the spindle speed range on an arrangement like that? Not including backgear.

      About the jamming... Maybe the V-belt goes too low into the groove and goes past the useable wedge part of the conical disc, due to being too tight.

      Anyway, Gates makes belts specifically for variable drives. They are very flexible lengthwise, but very stiff crosswise. They also are much thinner than the usual V-belt in a cross-section, height-vs-width-ratio sort of a way. Don't recall the model name, but sure someone else does. Maybe one of those would be the cat's pyjamas.

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      • #4
        Check the crossection height of the belt and make sure its the same as the A section belts,sometimes the lawnmower belts are thinner.
        Other than that I'm assuming you used the recomended length.
        I just need one more tool,just one!

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        • #5
          On my way home from work I got a good premium belt from a bearing and drive supplier that's made for variable drives.
          I may put it on tonight but I'm just dog tired. Of course If I get motivated enough to get a wrench in my hand I'll be up past midnight fooling with it...
          Anyone else like that?
          Oh yea, Rob. It goes from 250 - 1500. Back gear is from 50 - 250.
          ------------------
          Hoffman in Warner Robins Ga

          [This message has been edited by hoffman (edited 11-26-2004).]

          [This message has been edited by hoffman (edited 11-26-2004).]
          Techno-Anarchist

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          • #6
            The variable speed drive looks identical to the Rockwell/Delta wood lathes. I've seen a few problems which resulted in binding.

            1) A piece of the belt was stuck in the pulley and wouldn't allow it to collapse all the way.

            2) The cable tension spring was trying to wrap around the pulley for the cable.

            3) The shaft the variable speed pulley pivot is mounted to was rusted, this wouldn't allow the pivot to slide sideways as the speed is changed. When I find this I also find the shaft is allowed to slide sideways, it should be fixed in place with setscrews.

            I've found the easiest way to work on the drive is to remove it and do the work on the bench instead of crouched over inside the cabinet.

            Dan

            [This message has been edited by BFHAMR (edited 11-26-2004).]

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            • #7
              You know, I just gotta ask...

              The variable speed pulley seems like such a great method for machine transmissions. Few parts, quiet, relatively inexpensive, versatile, simple to operate, works on the fly... Great.

              Why then does it not appear on more machinery? Why do machine manufacturers insist on using four-step v-belt pulleys in triplicate with that handy stop -loosen tension- move belt- check diagram- tighten up- restart method, in myriad configurations? Or a boxful of gears and gear levers? Why are there reams of posts here about VFDs, but not variable pulleys? Cost could just not be an issue; not with all the other parts that go into a machine.

              What am I missing here? Is there too much friction? Too little power?

              Have a few conventional belt-drive machine tranny projects* on the stove and was all set to make chips today, but am seriously thinking about ditching it all in favor of a variable drive.


              *Long story. Maybe a new thread later.

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              • #8
                I got it after pulling the drive out and putting it on a bench. It's made with thin bronze bushings between the sliding sheave and the shaft. Seems that the bushing was loose in the bore and after a few cycles it worked it's way out and put the sheave in a bind. I staked them with a punch as sort of a knurl and pressed them back into the sheaves. It had 2 bushings so I put grease in the space between them. I think I got it whipped. I think it's gonna be a good system especially for centerdrilling/ drilling jobs where you have to crank the speed up for cdrill and then drop it down for drilling.

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                Hoffman in Warner Robins Ga
                Techno-Anarchist

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                • #9
                  <font face="Verdana, Arial" size="2">Originally posted by Dr. Rob:
                  You know, I just gotta ask...


                  Why then does it not appear on more machinery? Why do machine manufacturers insist on using four-step v-belt pulleys in triplicate with that handy stop -loosen tension- move belt- check diagram- tighten up- restart method, in myriad configurations? Or a boxful of gears and gear levers?

                  .
                  </font>
                  I have one on my big wood lathe,it's a Lovejoy unit very similar to the one on the Delta lathe,its about 6" od and has all the benifits mentioned above.
                  I wanted another one,found out it cost$375.00 new(choke).
                  But I was looking at it and figured all it really is ,is a stack of three aluminum discs grooved radially so they can close up tighter with the angle turned on the faces for the belt,a keyed mandrel and a bronze bushing,big deal.
                  This maybe one of my next casting projects.
                  I just need one more tool,just one!

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