A couple of months back, I took off the gear racks, one side at a time and cleaned off 40 years of ink, grime and paper dust. All are back on in exactly the same position and tightened down with hex head screws. Nothing was dis-assembled from the roller carriage. Now, when the carriage in on impression and not tripped off impression, (the other lever), there is an space of 1/8″ between impression cylinder and type-high. Anyone have any ideas what may be wrong? This press is in a college setting and has been used since I worked on it.
Mystery solved. I was afraid I had put something out of alignment when I took off the rails & tracks to clean and put them back on.
Tried printing yesterday with same packing as above. It took 3 sheets at the same time of 100# cover, .010 thickness, so the total was .030. That gave me a clue. Today I went back and checked for a cylinder undercut number somewhere. Remember the photo of the end of the impression cylinder with the number 5 68 5. The 68 stands for .968. The product sheet list the No. 2 Reprex Proof Press as having a .968″ bed and a bed plate. We don’t have the bed plate. The students have been packing the cylinders with many layers every since I have been at Foothill. Now I know why.
Thanks for helping me work this out.
Perhaps there is too much packing on the cylinder. I tallied what you told us:
.024 four sheets of tympan
.006 one top sheet
.005 mylar draw sheet
.030 Red board
.065 Total packing
Plus the thickness of paperstock
The Reprex manual (page 2) says the cylinder undercut is normally .040″, but could it be .070″? (You should be able to see the number stamped into the cylinder when the carriage is at the feed board.)
Too much packing would cause the cylinder to shift into trip when contacting a type-high form. See the 3rd paragraph of Scott Fisk’s post about his Reprex:
I don’t think the students took out any packing. It has 4 sheets of oil tympan, one top sheet and a top sheet of .005 mylar and one layer of Red board.
I took off the throw off lever, and the gear on the shaft of the eccentric. Bearing under neath. It looks as if all three large Allen bolts are not seated. They are not centered on the holes. I also took out the two very small Allen bolts that I guess line up the eccentric Plate? Could not get it completely off. However, I did discover the oil holes at the very top of the carraige assembly that go directly to the two bearing holding the cylinder. I doubt if anyone has oiled them for who knows how long. I did though. I put everything back together. Ran the carriage up and down the track and levered it on and off impression several times. When I left, the cylinder seemed to be lower. I will try an impression the next time up. Here is a picture that isn’t very good at showing the gap, at least a 6pt rule. I also discovered another eplace with the dates or what ever the numbers are. The 5 is also stamped on many of the bearing and gears.
Did the students remove 1/8″ of packing? Or remove a galley-height plate?
By “end” I assume that you mean the cover plate? This merely protects the carriage mechanisms from damage and dirt. It will be useful for you to remove it and see how the trip mechanism works, or in this case how it doesn’t. Please take a photo of this area and we’ll go from there.
Sorry, I misunderstood. Yes, the smooth part is right down on the rails.
If I take off the end with impression lever to see inside, is that likely to
surprise me with a spring popping out or something falling out?
Interesting, the trip lever on the lower right when facing the handle side of the press, has always given us problems. Maybe it is worn enough that it needs a few turns on the bolt at the end of the rod on the other side. I am going up today and will report back.
I’m not referring to the four carriage bearings, bur rather the smooth ends of the cylinder that contact the smooth rails above the bed. Technically, a flat bed press is only in print when these two surfaces contact. Any gap between a type high form resting on a type high bed is then derived from the cylinder undercut and is made up by packing.
I suspect that there is something loose in the linkage of the trip lever and the eccentric that raises and lowers the cylinder.
Yes, all four are riding right down on the rail. As nearly as I can tell the gear on the carriage goes all the way to the last tooth on impression. I don’t believe anyone has changed that. I am stumped. Can the gears inside the carriage get so gucked up that they would not go all the way up and down? Thanks for anyhelp.
Are the cylinder bearers are contacting the bed bearers in print mode?