Wearing through Worm Crescents SP15

Hello out there! It seems that my SP15 (50081) has been wearing through worm crescents very quickly lately. Aside from a thorough cleaning, proper lubrication of crescent shaft (with powdered graphite) and worm gear (with Vaseline), is there anything else I should be looking out for? Or maybe I’m doing the aforementioned incorrectly…

I replaced the worm crescent in February when the oscillating roller started to get stuck at times, and again in February along with the worm gear (DR-338, used from NA Graphics), and AGAIN today! I don’t print often enough, or big enough print runs, for this to be normal. Before February, I hadn’t replaced the worm crescent for 3.5 years and it showed less wear. One thing that changed since 3.5 years ago is that I actually had powdered graphite on hand. Maybe I’m using it wrong?!

I appreciate any insight, thanks in advance – Melanie

PS – Thanks Paul, I’m certainly taking advantage of the Moxon special these days ;)

4 thoughts on “Wearing through Worm Crescents SP15

  1. Paul Moxon, Moderator - October 9, 2022

    So you’ve cleaned, lubricated and replaced the crescent, holder and worm. Here’s more ideas:

    Can you back out the crescent holder to let the crescent float a little bit more? Too much and the holder will damage the rubber.

    Does the oscillator intermittently contact the rider? More likely if the rubber diameter is too small and when the bronze journals (ends) are worn. The diameter should be 3/8″

    Worm gear shaft may be bent. Roll it on a flat surface.

    Oscillator frame may be twisted.

  2. Melanie Kohler - October 7, 2022

    It’s been a while but I’ve had no success troubleshooting this problem. I’ve worked with Fritz and different replacement parts, and I’ve worked with smoothing out the inside shaft of the oscillating roller as it showed some grooves from metal bits (probably from damage to the previous worm gear). The whole oscillating roller/worm gear/crescent system moves freely when it’s not on press, but when I place it back on press I hear the metal on metal grinding as the rollers spin. I checked the diameters of the form rollers and, while they are maybe 5 years old at this point, they are on spec. What other piece of the puzzle am I missing?

  3. Paul Moxon, Moderator - April 1, 2022

    Thanks for the update. Good sleuthing. Yes, crescent holders do wear on the inside causing the crescents to wobble. I have alerted Fritz to your post.

  4. Melanie Kohler - April 1, 2022

    Update – with a little more patience and troubleshooting I’m exploring the possibility that the shaft of the crescent holder (M-184) is damaged or grooved and therefore not allowing the crescent to move freely. In the process of ordering one (or more) from NA Grapics and will try to remember to post an update here in case this helps someone else down the road.

Leave a Reply

Copyright © 2022 vandercookpress.infoTheme by SiteOrigin
Scroll to top