The top wheel of the motor assembly pulley on my Vandercook 4 (#12545) keeps loosening. The set screw tightens, but loosens after the motor runs for a bit. The wheel and the belt move on the post toward the operator, away from the motor. This is a recurring problem, but every once in a while I tighten it and it holds for months. There is a trench in the post that holds the pulley (see photo, visible just to the left of the set screw). Should the set screw be seated in/over that trench? (With the wheel pushed back on.) I replaced the 1/4 in. long set screw that was there; is that the correct length? Could this all be happening because I need a new belt? I’ve never replaced it (15 years), but it’s not frayed or showing variable wear.

Thanks …


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10 thoughts on “Vandercook 4, pulley set screw won’t stay tight”

  1. For the Vandercook 4 records: the apparent culprit in this year’s long problem was the lower pulley on the motor, pictured in its ‘before’ state. There was a slight slope to it, likely from wear, that moved the belt toward the operator and put stress on the upper pulley set screw so that it loosened. A machine shop evened the pulley surface, and the belt (and upper pulley and set screw) have been staying in place now for several weeks.

  2. Yes, we tried installing the new belt by putting it on the bottom pulley first. I worked on this with Sara Langworthy, who has a No. 4. It really wasn’t even close to fitting even with the motor raised. The old belt has the has the Vandercook MM-144 number on it.

  3. I’m back at this still unsolved problem. (Belt on pulley immediately travels to the outside of the top pulley and drags that top pulley with it (away from the motor), loosening the set screw and square key, which are both new.

    I raised the motor as high as the screws allow, and can’t get the new belt from NA Graphics on. I’m going to put this back together with the first belt, which is an original Vandercook belt. Should the belt be tight enough that it requires raising the motor to remove it? In other words, should I put the belt on and then lower the motor to tighten the belt?

    I have also moved the lower pulley out a bit, away from the motor to see if a better alignment with top and bottom pulleys is possible.

  4. Place the belt over the small pulley first, then set the over end against the left side of the large pulley and rotate the pulley to the right as you ease the belt onto it.

    If this doesn’t work, then the motor has to be raised. Loosen the nuts on top of the motor plate, raise the motor then raise the bottom nuts. The motor must be level.

  5. Update: I finally got the set screw to hold the new key by stacking two screws, a tip I got from a home machinist website. (One long one did not work.) So, a temporary fix and I can print.
    I got a new belt from NA Graphics, but neither I nor a stronger friend could get it on the pulley. It does not stretch AT ALL. See photo for the length I need to find; is this normal? Do I just need to hire some hand strength?

  6. You say that the pulley is very stable, but is set farther out from the motor more than the upper pulley. If you set the pulleycloser to the motor is it not stable? The key may be too small, though a larger key may need to be filed down.
    Unlikely, by theere may be wear between the motor shaft (center post) and the pulley.

    I checked my small pulley: it does not have a keyway just like yours. I don’t understand why since the motor shaft has one. Without a keyway on the pulley a key won;t work as intended. I don’t know why Vandercook would have done this. Thought I have not had trouble with my small pulley.

  7. Thanks, Paul. I got a new square key, and a new set screw and reassembled the pulley. It was all tight, but after running the motor a few minutes the key started moving out, and then the wheel moved. I re-tightened a few times, each time with the same result. I can see that the set screw is making contact with the key because of a circular imprint on it. The manual for the #4 isn’t good on the motor assembly (at least the one I have) so I took some pictures of the lower part of the pulley. It seems very stable, but it is set apart from the motor more than the upper pulley. I also see an open area in the center post; is there a key missing here?

  8. The trench is called a keyway. You’ll find a matching keyway on the pulley. Once the two keyways are aligned, slide in a square key. Keys are available at hardware stores. The key for my later model No. 4 is 316 × 1¼, long but confirm the specs as it may be different for your press. While you’re at it, replace the set screw as it may have become damaged.

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