Though the ink drum drive chain and gear seem to be operating normally when powered on, the ink drum itself is not spinning. The ink drum does move freely when manually manipulated.
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The pieces circled in my picture wouldn’t budge, even after multiple treatments with penetrating oil. However, the round bearer/stop piece that I point to was relatively easy to remove with vise-grip pliers and a socket. With that out of the way the drum easily fit back into place. The press is now reassembled and functioning properly. Thanks again for all your help!
You’re awesome! Thanks again, I’ll update when I get it resolved.
As I said previously, they’re not threaded (or at least not on #26078). I had to spray Liquid Wrench at the base, lock a pair of vice grips on them and walk them out.
To balance, place a spirit level on the bed, note the bubble position then set it on the drum and compare with the bed. (I travel with a 9″ level with a magnetic strip.) The larger set screw on top adjusts the height: right lowers and left raises (the opposite of roller height) because it pushes the drum arm down. Set the roller height with your setting gauge for a light contact. Just enough to bump the form rollers. Not ink required at this point. Return carriage to feed board. Disengage rollers, turn motor on, then engage rollers. The drum should contact the rear form roller. If it doesn’t not adjust each side to raise. Check the level again. This assumes that the rollers are in spec (3″ diameter for the SP20).
Thanks for the reply, Paul. Are the pieces circled in my pic threaded? I don’t see any evidence that they are removable. Also, how do they adjust the drum balance?
I just removed an SP20 drum last week. You will need to remove the part circled in your photo on both sides. They adjust the drum balance and are not threaded into the side on the set. Spray some penetrating fluid and push pull them out. It will probably that some rocking back and forth.
You will also need to remove the nut highlighted in my photo below (from manual sheet 244-A). The head of the bolt is on the outside. Please note that there is a spacer under the head to allow the trip arm to slide. Over-tightening when reassembling will make it harder to shift the print/trip lever.
We took apart the drum, cleaned it. A machinist extracted the broken bolts and gave us new bolts and bushings. The drum, arms, and sprocket have been reassembled, but we can’t get it back into position. The two highlighted pieces in the photo prevent the sprocket side drum arm from sliding into place. Please advise.
You could tap new holes, but you may be able to use a screw extractor to back out the broken ends in the drum. The smaller the screw the more difficult it can be to do this. No big deal for a machinist. But I wonder if the shaft that runs through the drum is bent and perhaps the bore for the bearing is reamed out.
Yep, I managed to get the drum out and saw that the three screws had sheared off. Not sure how to proceed. Do I need to tap new holes?
Fritz said there are three screws that passes through a hub on the sprocket. So either the screws fell out or sheared off. Not a daunting project. Don’t forget to tell us how it goes. And send photos too.
Based on my experience with other models, there should be two screws in the sprocket that fastens it to the end of the drum (SP15, No. 4) or a collar and a locking key (Universal I).
The SP20 manual doesn’t show the sprocket or provide a part number. To be sure, I asked Fritz to look up the drawing for the drum. Stay tuned.
I don’t doubt that the drum is going to need to come out, but I should clarify. The drum turns freely, though independently from the chain sprocket. With the drum out, will it be obvious how to tighten the sprocket to the drum?
The chain sprocket has become loose from the drum. An abundance of ink build-up (and possibly other materials) around the drum bearings is likely inhibiting what would otherwise be a free turning drum. Repair will require removing the drum from the bed. See manual sheet 244-A.
1) unhook the drum springs (X-20563)
2) disconnect the chain (there is probably enough slack that you wont have to move the motor forward)
3) lift the drum out of its arms (X-20998). Using straps should make this easier