Okay, so it a simple 2 color business cards. A newbie could do this is an hour. But Nooooo. Using polymer plates, we ran the black, then matched up the red plate PERFECTLY on the Boxcar Press base. And guess what? Nothing lines up. So we adjust the plate on the base and run another test. Not consistent and worse than before. After pulling what is left of my hair out, I notice that the carriage “racks” a little bit left and right while it is in the middle of the bed. I never noticed this before so I think this “racking motion” is causing the misalignment of the plates or the “inconsistency”. How can I determine if this is it and if it is “racking” how do I fix it?
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It may never be too late to comment for a reader in the future with a similar problem. We seem to have a consensus, and confirmation, that it’s misfeeding. Once understood it can be rectified. Initial information, including private emails, lead me to believe that this wasn’t a variable. So down the rabbit hole I went.
Paul
Been off list for a bit so sorry for the delay in response. I don’t think that this is a press related problem re the registration concern. “We ran the black…”, etc. Maybe too many hands? A Vandercook is a slave to one master, especially when it comes to registration.
Gerald
http://BielerPress.blogspot.com
If the grippers are bending the sheet, the cylinder may be overpacked. When the tympan level is noticeably higher than the lever of the gripper bar, the paper gets contorted.
I took Frtiz’s advice. I hate to admit it but I think I had gripper trouble. By that I mean, I may not have had enough bite on the paper from the grippers. When I follow the carriage in print, holding the paper against the drum, I think I’ve been “pulling” it out of place.
I ran a simple black job and I printed over it again and again (with more gripper bite) and it seems fine. I recall that putting too much gripper can leave a moon shaped circle on the top of the paper. That is probably why I backed off…I thank all of you huge amounts!
I would like to see a picture of the base, plate, and lockup, and how the sheet is being fed. The lateral movement of the cylinder does not alarm me at this point until I can see these other things. One way to check your press register is to feed 10 or 20 of the same image back through the press for a second impression and see if maybe it is your feeding, or doing a “dip” sheet instead of a portrait feed–long edge of sheet against the rippers. Rather than repositioning plate on base, shifting base may solve the problem–side to side or position of base from print edge depending on how the misregister is happening.
In the video, the press is in print mode, correct? The clanking sounds like a cylinder that’s tripped. (The Universal, like most models before the SP series, are technically in trip when at the feed board.)
Given that the play is all lateral and none vertical, it’s not the carriage bearings, but it could be that the tie rods holding the two side plates together are not tight enough. Or, perhaps the cylinder guide plate (the flange again) on the opposite side is missing, although this is unlikely.
Thanks very much for your comments. And maybe Paul has answered it but I am not sure I described it properly. I fed the sheets consistently and my lock-up (using a Boxcar Base) was simple. So I prepared a short YouTube video. If you watch it (and I hope you do) keep an eye out for the relationship between the carriage and the press. It is slight but enough to make the clunk you hear when I PUSH and PULL on the carriage.
http://youtu.be/Li6BfoOmtAA
Michael
Universals do have the cylinder guide plates (flange), so I wouldn’t guess lateral play, either Eric. But this is what Michael wrote, hence my diagnosis. Otherwise, I’d suspect inconsistent feeding or poor lockup, too.
Getting lateral play on a Universal wouldn’t be easy. Doesn’t it have the flange between cylinder bearer and gear that mates with the recess between bed bearer and gear rack?
Register is affected by the feeder’s motion, and by sag as the sheet approaches the printing nip (especially true when there is a gap between head and tail printing areas, unless the sheet is supported by high furniture or plate base). And things have to be consistant on each run to get register.
If there’s lateral play in the carriage, then the bearings may need adjustment. This may be the result of over-packing the cylinder to achieve deep impression and/or locking up forms that are over type high. The stress from either can cause the position of the bearings to shift— or worse grind into the under rails.
After removing the covers, you’ll see that a Universal has two pairs of carriage bearings on each side: the upper pair (bearings 1 and 3) rolls against the under rail and the lower pair (bearings 2 and 4) roll on the lower rail.
To adjust bearings 1 and 3, roll the carriage (in print mode) to the middle of the bed. Loosen the small lock screw and large nut. Place a .003” feeler gauge between bearing and the rail. Use a mallet and wood block to tap the left side of the triangular adjusting plate. This causes the eccentric to raise the bearing. Tap until bearing is snug against feeler gauge. Retighten nut and lock screw. Roll carriage off feeler gauge. Adjust bearings corresponding bearings on opposite side of carriage, then adjust bearings 2 and 4 in trip mode and proceed as previously described.
While feeling some resistance, you should be able to turn bearings in place by hand. Bearings 1 and 3 will feel loose in trip mode, but tight in print mode. Conversely, bearings 2 and 4 will feel loose in print mode, but tight in trip mode.
For more detailed instructions read Gerald Lange’s article “Adjusting Cylinder Carriage Bearings Vandercook SP-15, SP-20, SP-25, Universal Models” available on this site at https://vandercookpress.info/vanderblog/articles/lange-adj/
I highly encourage Gerald as well as Fritz, Eric, and Dan to comment with their experience. Anyone else?