Just when I thought my SP-15 problems were over, there’s another issue! I apologize for the length of this post, but I’m trying to be as thorough as possible.
I noticed that the press was inking rather lightly, but the impression was good and I had plenty of ink on the rollers. As I adjusted the form rollers I noticed that they were significantly higher towards the end of the bed (away from the feed board). Also, the gear that forces the geared form roller to roll was skipping in the track and would stop spinning shortly after engaging the teeth.
We started by trying to shim the track up. This kept the form roller spinning, but the height was still inconsistent front to rear. Next, we tried readjusting the side bearings – many times. This actually seemed to hurt rather than help. We adjusted the top bearings in trip and the bottom in print to a 0.004″ gap using an automotive feeler gauge, which I believe to be correct. We tried it the other way (adjust top in print and bottom in trip) and the press would no longer trip, leading me to believe that we were running into problems with interference due to the bearings being positioned incorrectly.
After we played with it for a while, we noticed that one of the form rollers sits too low on the gear side of the press and is unable to be adjusted any higher (there is a 1/4″+ ink strike on the roller setting gauge). The other side adjusted fine with a simple turn of the knob. We don’t think that the problem is with unevenness in the bed or bearers because a blind impression is consistently good no matter where we put the plate on the bed. This leads me to believe that the problem is isolated to the form rollers and the associated pieces.
Photos of the inking problem are here:
So, that’s my situation. Here are my questions:
1 – Is it possible that it’s a bearing adjustment issue?
2 – Is there any way to put spacers on the form rollers to bring the up to where they need to be?
3 – What else might cause the inconsistency in form roller height from side to side and from front to back?
4 – Could shimming the gear track have exacerbated the problem? Was it the correct fix given the problem of the gear skipping teeth?
5 – Is the bearing supposed to roll against the form roller on the geared side (photo at link above)?
6 – Is it possible that my bed or my bearers are uneven?
If you have any other ideas, that would help a lot. I’m fresh out and frustrated. Thanks.
I think that this press originally had roller supports that would have provided a rest for the cores and thus raise up the adjustment screws. This is probably noted in the model index card at NA Graphics. If you can’t get longer screw posts then do as John suggested and clean out the sockets for the adjustment screws and add nuts or washers.
We were able to re-adjust the bearings again this evening and the bearing no longer touches the form roller gear (we had to adjust them while in print). However, we are still having problems with the form rollers. As Paul said, the form rollers are new, so I don’t think this is the problem. The problems are:
1 – the height of the rollers change when the press switches between print and trip. My flickr link in the initial post shows the problem, although now the rollers lift at the end of the bed when they are tripped.
2 – The form rollers are also still too low and the screws don’t seem long enough to give us the correct clearance. The press has a galley bed and it’s possible these were not the original screws. We measured the length of the screws in the bearing blocks and they measure 2 5/16″. What should the length of the screws be?
As Rachael knows, I saw this press last week. I helped her reset the cylinder, free-up the trip arm and readjust the carriage bearings. (It was my recollection that the front bearing nearest the form roller had clearance, but it was a long and dreary day in Rochester.) The form rollers are new and the durometer spot on. It may be that the possible that the wrong bearing block adjusting screws were used. There are two different screw lengths. This press had some restoration work done on it and it’s possible that the screws were taken from another one, or the s/n wasn’t considered when the parts were ordered.
2/3 – are your form roller blocks in good shape and the form roller height adjusting knobs moving freely – ie. not overtightened or in need of lubrication.
5 – bearing adjustment should be performed on impression.
Firstly – don’t worry about the length of the post, you have given us plenty of information and have obviously tried to figure out the mechanics yourself which is always a good learning process.
1 – Given that you think you had even impression to start with, a problem with bearing adjustment was unlikely, but looking at your flickr photo it is now – the bearing shouldn’t be touching the form roller gear.
2/3 Forget spacers. You might want to look at the sockets in the side plates into which you insert the form rollers – if they are filled with debris/gunge then the form roller blocks may not be sitting at the correct height and therefore giving you no room for adjustment. I vaguely remember reading about someone inserting material into those sockets to raise their (shrunken) form rollers as a makeshift solution.
How old are your form rollers? – as rollers age they can be prone to overall shrinkage, overall swelling; or an uneven change in diameter. In a recent post Paul stated the diameter for sp-15 form rollers should be 2.5″.
4 – Don’t know about that one but a gut reaction is that altering the shimming on the gear track is not a good idea.
5 – No, definitely not, the bearing is on an eccentric which will move it not only up and down in relation to the bearers but backwards and forwards in relation to the gear when adjusted.
6 – Unlikely.