SP-15 rear trip pin wearing ink drum belt?

SP-15 rear trip pin

My SP-15 is showing wear on the rear trip pin from the ink drum belt. Photo shows wear from both trip and print positions. The belt touches the trip pin. Is this expected? And if not, what’s the best way to adjust this?

Additionally the trip arm had been touching the ink drum (wear from that is also shown in this photo on the drum – vertical line of wear on ink drum). There is now daylight between the two as I was able to slightly adjust the bracket under the plate the motor sits on (bracket accessible on upper left of first shelf). However, belt is still touching pin.  Is there a better way to adjust both of these? Any thoughts appreciated. Video


11 thoughts on “SP-15 rear trip pin wearing ink drum belt?

  1. Pinwheel - January 20, 2016

    Success! In the end the SP-15 had two problems. The first was that the motor cradle bracket was misaligned causing the motor cradle to be misaligned; this solution outlined in the update on Jan 15th.

    The second was that the v-belt that was installed was too large. It had a 3L-190, but needed a 3L-180. With a 3L-180 v-belt the motor can move in the mounting slots toward the ink drum (it had been in the farthest position in the slots with the 3L-190) which puts the belt at a different angle where it does not rub on the rear trip pin.

    Re: changing v-belt on on SP-15 (in case anyone, including my future self, finds this helpful). Safety first: unplug. I found it easiest to first loosen motor bolts, then to remove ink drum. For reinstalling I first reinstalled ink drum (with new belt in place), slid belt over motor pulley, and then slid motor into position. Note, it was tougher than I expected to move the motor back into position. With a friend holding motor against tension of new belt I was able to get three bolts in. We tightened nuts, replugged, and ran motor with new belt for 10 min. Unplug. And now with new belt stretched (warmed?) we could slightly loosen the installed 3 bolts, tug on the motor a tad more, and then get all four bolts installed. Perhaps someone who’s done this before might have a better way, but this worked for us.

  2. Pinwheel - January 16, 2016

    I’m actually now thinking that I can move the motor slightly closer to the ink drum. I’ve confirmed that it’s in the farthest away position in the mounting slots. Moving it closer will change the angle of the belt to the pulley, and I think will clear the pin. I also reviewed my photos of the other SP-15s and their motor pulleys are more to the right relative to the trip pin.

    Although moving the motor a bit to the right will mean I will need a new belt. Is there specifications of a recommended replacement belt?

  3. Pinwheel - January 15, 2016

    Update: with help of a friend I was able to successfully move the cradle bracket back into a level position. This puts the cradle in a much better position. I’m happy to see better spacing between the rear trip arm and the ink drum, and the ink drum closer to the bed of the press.

    I then adjusted the motor plate rest so that drum is (as best I can tell) within the tolerances that Fritz specified relative to the bearing rail. Ink drum does turn form rollers when rollers are down (although if plate rest is moved higher, they will not turn). Cradle now rocks what seems a normal amount.

    So, lots of things now in proper place.
    However, the belt is still rubbing on the trip pin/plunger. Here is a better photo of the belt and the ink drum pulley. Both pulleys are metal. The v-belt is thick enough to stick up slightly higher higher than the groove. Make/model shown in photo.

    Should I need a thinner belt that sits in the groove more?

  4. Pinwheel - January 14, 2016

    I think I may have figured out the culprit after comparing my press to two other SP-15s in the area (thank you Paul for that idea).

    As previously mentioned the SP-15 motor and ink drum are mounted to a cradle that rocks down to move the drum out of the way of the impression cylinder. While the amount of rocking is limited by motor plate rest and the drum springs, the weight of the cradle is supported by a bracket (with arrow in photo – does this bracket have a name?). I believe this bracket is tilted in my SP-15, causing the cradle to be tilted away from the press bed. Also can see a small unpainted mark indicating the bracket used to be in a more level position. Both front and rear brackets are in this slightly tilted away position.

    I’ve also noted that the space between the ink drum and the edge of the press bed is too much – currently more than a half inch (3.5 picas). This was the other observable difference from other SP-15s. I think the whole cradle is slightly shifted to the left due to the bracket being angled left instead of level.

    OK, that said, loosening the locknut to adjust the brackets is another story. I can’t budge it with my combination wrench. It is heavily painted. I think my next steps are to strip the paint off and after an application of liquid wrench give it another try.

    Any thoughts on my assessment or next steps appreciated.

    (Lastly, photo shows trip pin in print position. Fritz will be relieved that the side of the pin that moves in the hole is not painted. Some small good news!)

  5. Fritz Klinke - January 9, 2016

    Additionally, the X-20805 plunger should not be painted as it slides back and forth to act as the cylinder trip. Parts that aren’t supposed to be painted are a sure sign of a rebuild. I would have to pull the print, but that sort of looks like a home-made replacement. Don’t forget the ink drum motor and ink drum are attached to the ink drum cradle so the motor moves as the ink drum is depressed by the rear ink roller.

  6. Pinwheel - January 9, 2016

    Thanks Fritz. The press was completely restored in 2012 and only lightly used by one operator before my purchase, so that’s why it looks so clean. I’ll get right on adding ink, grease, and lint after I get this fixed! While I suppose I could print with this going on, seems like it would be best to fix first and not operate knowing that this wear is happening.

    If the present configuration was altered from post-1962 specs it’s hard to say whether it was done at time of manufacture, during the 2012 restoration, or since. Either way I’m collecting ideas of how alter the present situation.

    And thanks for technical measurements. I’ll take a look, and also compare to other SP-15s of that era.

  7. Fritz Klinke - January 9, 2016

    The change from the V belt and pulley was made on 2/1/62 to the timing belt arrangement. I wonder that the ink drum drive on this press is original but rather a retrofit based on the engineering change date and date of press manufacture. The ink drum spring is X-20772 for the SP-15 and though very close in appearance to the similar SP-20 spring X-20563, it is a lighter weight spring material. I can’t tell from the pictures, but I don’t think it is a spring issue. The timing belt arrangement used a cheezy plastic pulley on the ink drum and these regularly break with age and use and the replacement is a cast iron pulley we have to have modified to fit the ink drum, and it is costly. What I am thinking is this press was retrofitted back to a V-belt arrangement rather than sticking with the newer timing belt arrangement to cut costs. My initial reaction at looking at the photos was that the problem was not enough dirt and grease, lint, etc.

    And on a technical note, the ink drum was specified to be “Ink drum to be .030 to .050 above bearing rail” and parallel with the bed. If not parallel, then shims were required.

  8. Pinwheel - January 9, 2016

    And is this the “drum spring” you mention? Checking, because none of the manuals I have seem to list a part X-20771.

    If after looking at other SP-15s I decide that the drum springs are too tight, what’s the best route for a proper replacement? Should I be able to replace hardware store stock, or should I be pursuing a proper Vandercook X-20771.


  9. Pinwheel - January 8, 2016

    Here’s a photo of the motor plate rest (I believe). This is what I moved up to get the trip arm to stop touching the ink drum.

    At this point there is little play in the up and down movement of the motor plate. I have video, but not sure if I can upload. If motor plate rest can’t be raised much more perhaps that points to the springs.

  10. Pinwheel - January 8, 2016

    Thanks Paul for your thoughtful reply. Will look into shoe and drum springs.

    Additionally, it sounds like you are saying that I could look at other pre-1969 SP-15s in my area to assess what the proper/operational spacing for the drum should look like. Yes? And yes I do know several on the list that have presses in that range, so I will contact them.

  11. Paul Moxon, Moderator - January 8, 2016

    Revised: The pin (X-20805 Plunger) position is fixed, so it can only be that the position of the drum is too high. Knowing that this press has been refurbished, it could be for a couple of reasons. There should be a rubber shoe on the motor plate rest that prevents the motor plate rising too high. Perhaps the replacement shoe is too thick. Another possibility is that the drum springs (X-20771) were replaced with one’s that are too short.

    There were several engineering changes for the SP15 during its production run. The serial number table says that #23700 was built in 1964. Sheet 248 of the manual shows an ink drum driven by a v-belt (X-21050) and pulley (X-21051). This appears to be correct in your photo.

    Sheet 282-A was added to the manual in February 1969. It shows an ink drum driven by a thinner, toothed timing belt (X-21723) and pulley (X-21724). This change could have been made earlier and may be recorded in the engineers’ assembly drawings.

    The census lists seven other SP15s (three with lower s/ns) in Seattle proper that you could visit. If you don’t know the operators, I’d be happy to email them on your behalf.

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