Registration Failing, Plate Moving?

joshua, you first run must be registered to itself,The transparency method I’m not understanding? Back in the day we used to call whats happened to you”operator error”
Check to see if you first run is consistant register.That may be your problem.best james

I would put a piece of tape or a pencil line at the edge of your plate on the mounting base and see if it is indeed the plate that is moving or your gage pins. I have also seen tympan paper move if not securely held in the platen bails.

There are certainly several places that could be at issue. By putting a line around your plate position on the base, and along the gage pin position, you can easily see which is your culprit. If both stay the same and still you creep, it may be the tympan sheet itself moving, or you are getting slightly different placement of the sheets at the gage pins.

James, thanks for trying to be helpful, but I find little use in the advice of it being operator error. I know it’s operator error, which is why I’m posting here to figure out what I could be doing wrong. Let me be more precise in my explanation:

I started out by registering the first impression (the blind impression) to a test sheet of the stock. I pressed 125 of these blind impressions.

I then put the 2nd plate on the base, tape (outside the printing area) a transparency to my tympan, then ink and press into the transparency. I then slide a piece of the stock (that now has a blind impression) under the transparency for registration - this just gets me VERY close to perfect registration. I register the stock, according to where the plate is pressing. I print a test run, and make the minor adjustments necessary to have perfect registration (by sliding the guide pins). Once I have a perfect registration, I start pressing. After I’ve pressed about 10-15, I start noticing the registration is veering off. If I don’t stop, and re-adjust the guide pins, the registrations gets worse and worse. If I stop, and adjust the guide pins, it doesn’t remedy the problem. It keeps happening.

Then, obviously, this adjustment screws up the rest of the job, because then I have to make multiple adjustments on the last run (3rd impression), and end up wasting a lot of stock.

I thought at first it could be the guide pins, but they are the Kort Adjustable Quad Guides, and don’t appear to be slipping.

So, I know it’s user error. I know I must be doing something wrong. I get that. I have been racking my brain, and have printed this job 3 times, trying to be as careful as possible to make sure the runs are registered perfectly before I start…with no visible increase in successful printing.

jhenry,

Awesome advice! Thank you. I’ll definitely try both of those things. And just so I’m ready for the outcome, what do I do in each situation?

If it’s the plate moving, how do I fix that?

If it’s the tympan moving, how do I fix that? My bails seem to be pretty tight, but I think that’s the likely problem. Is there a way to tighten the bails on a C&P 10x15?

Thanks so much!
Joshua

joshua, You are hand feeding? You are using the grippers
and gripper fingers? And you are certain your first run was registered to itself? Did you run the blind impression
on top of itself to verify registration? You are certain your gauge pins did not migrate on the first run, james

I have had experience with tympan paper moving. On very old presses with worn, loose bales, the more you move them to adjust for registration, moving quads, etc., the looser they get. On our press, the bales are kinda tight on the corners but loose in the middle. We put two or three pieces of cardboard or thick paper cut to 1/2” by 9” inch strips ( for a 10” x 15”) under the tympan at the fold when we close the bales. It seem to help a lot.

James, I am hand feeding. I am not completely certain it was registered to itself, but I do know that I double impressed a few times, and it was spot on. However, I did not double impress every plate, so that could be an issue. How would it NOT register to itself? If I’m putting the paper in the same spot each time, and the plate/tympan/pins haven’t moved, wouldn’t it automatically register to itself?

londaypress, Thank you for this advice. I’ll start with making sure the plate is registering to itself, then check the bales.

when i print with dies, after i mount them i use masking tape all around the die to help hold it in place, if you print a few sheets, run them back again and that should tell you if the die moves. so many things could cause this problem, if the tympan moves you could wrap tape around it , also when i get position i tape the gauge pins down, this helps too. good luck dick g.

What kind of gauge pins are you using? I am assuming this is a platen press? Are your gauge pins properly secured?

Daniel Morris
The Arm Letterpress
Brooklyn, NY

Hi, Joshua—

In my experience, steel-backed plates will creep on the magnetic base during the run. I always tape the plate to the base with a 3M double-sided cello tape applied to the back of the plate. I trim the plate as close to the type as I dare with an ordinary hand paper cutter, and cover the entire back of the plate with tape, sometimes using two strips of tape under a heavy part of the plate for added impression. I’ve had no movement problems this way.

The plate must be gently pried up with an ink knife to remove it, and the tape stripped off and the residue removed with typewash when done.

This method makes the magnet something of a nuisance. If the magnetic surface is vinyl, it can be damaged by the prying-up action of the ink knife. I had a block of steel machined for a base. Perhaps you could turn the base with the magnet towards the bed of the press, and mount the plate to the back side with tape. Of course, you might have to pry the chase out of the press if the magnet is holding it in…

Good luck, Brian

Don’t do what Brian has said! You’ll never get that base off your press!

Dan

Graytin

If you are using a manufactured Bunting Base or similar you should not be experiencing plate travel. If you are using a Patmag, travel is to be expected. The rubber magnetic material, MagBack, was never intended for this purpose, that being letterpress printing.

Nevertheless, the Patmag can be used successfully if you treat the plate with a spray adhesive such as Scotch 77. Lightly spray the back of the plate and allow the adhesive to tack a bit before positioning the plate on the base. Note that you should outline the plate with tape to discern movement, that or use some form of device to prevent the plate from moving, such as surrounding it with used plate stock or using a butt bar on the side of the base in the direction the plate would normally travel (on a Vandercook, toward the cylinder).

Good luck

Gerald
http://BielerPress.blogspot.com

Gerald,

I bought a used bunting base am experiencing plate travel. Is it possible that older bunting bases were not made to be as strong as the newer ones? Or can they lose their magnetic strength over time? Even the plate does not seem to snap on as strong as with my new base.

Are there any solutions for this other than using an adhesive?

Thanks and sorry if I’ve hijacked the thread.
Carrie

Hi Carrie

Bunting guaranties the magnetism for life, or at least they do since I have been involved with them. This would be for the Cerface model (1994-). Not sure about the earlier bases (1985-93).

I’m not sure I would use an adhesive with the Bunting. They don’t even recommend underlays. I guess they don’t want to be blamed for shoddy printing. But… whatever works…

Any oddities with solvents you are using, oils, etc, that might cause a problem? Surface obstruction, accumulated ink? etc.

Not exactly sure how to deal with this but if you have the serial number you might want to contact Bunting. Not sure what they will do in this regard, since you are not the original buyer.

Note though, that the aluminum part of the base is not magnetized in regard to plate snap. The pre-Cerface model was a bit less thorough in its grid design in this regard, you sort of had to be aware of where you were placing your plate for maximum magnetism. I’ve never used one though, so that is just a surmise. I suspect plate uses in the more commercial years had a different intention than that which is common practice today.

Gerald
http://BielerPress.blogspot.com

I’ve used pin mount devices with both Bunting and PatMag bases, and this eliminates creep entirely; by the way, I have seen creep go in either direction on cylinder presses. Using adhesives with the PatMag will degrade the magnet (which fortunately can be replaced) since particles will stick to the plate when it is lifted.
The pins made for the Bunting bases were based on 5mm holes made with an eyelet punch, those for the PatMag based on a 1/16” drill. Pins are mounted in a block the same height as the base: the Bunting pin blocks were made of aluminum at a machine shop, the PatMag pins I make from .854” Elrod strip high base and 1/16’ brads, and wood is another possibility.
Another point of abuse with the PatMag is gouging the magnet when trying to lift the plate. File the corners to a bevel from the underside, and it will be easier to get a bite.

Thanks, Gerald.

I guess I will contact Bunting Monday to see what they say. It’s at the shop now, but I think the serial is #55xx. As far as I can tell, the base is in really good physical condition.

I have not noticed the problem on my Heidelberg, only my Vandercook, for what it’s worth.

Thanks again,
Carrie

HI Joshua,
I had a similar problem with my bunting base and the culprit seemed that my platen was out of alignment - even though the prints seemed to show even impression. This forces the plate to migrate during printing. I was shown that you can check this by closing the press, no chase inserted, using a roller gage much like you would to check the roller height.
Smiles and Happy Printing,
Michelle

Joshua,
I may be late to the discussion with this but no one has aksed about the paper being cut. You said you cut the sheets two out. Two out of what size and what equipment did you use to cut them. Even a guillotine cutter can be out of square. If the sheets have been cut out of square you can easily have a series (lift of 10-20) that are similar and than the next lift off slightly. Any shuffling (sequence) after cutting will disrupt the continuity of the cut set. If the sheets came from the mill square you should use their precut edges as you guide and gripper over any thing you cut by hand. (I am assuming you did not cut these on a hand trimmer, which will never be square)
If they are out of square everyone you checked with its own impression (double hit with same pin location) will be in register with itself. However the very next piece could be printed in a differenct location relative to the one before.

A good way to check for square is to turn one piece face to face with the next. If they are not square you will see an angled piece of one or the other sticking up higher on one side or the other. This should help.
Steve Varvaro
Southpaw Printers- Scarborough, NY

I didn’t see what type of press you are using….there is a possibility that the chase can move, especially if the lock up isn’t completely flat (old warped chase or furniture or locking up on a bad surface, or the chase is loose in the press side to side.