Close registration on a fast C&P

Hi everyone!
I’m having trouble with close registration jobs on my motorized C&P. I’m finding a couple points of play, which turns into major visual problems when I’m on a subsequent run. Assuming slowing down the press isn’t an option, what should I do? I’m using the megill spring tongues, so I know my pins are tight - must just be bounce.
I’ve googled and found elsewhere on this site mention of the flying dutchman but I’m not sure how easily that would work for handfeeding - simlarly with the double sided tape under the pin solution as well. I’ll try both come Monday but I was wondering if anyone had something more tailored to c&p handfeeding.

I should also add that we don’t use a typical tympan paper - we use a heavier slick coated card that’s left over from other processes.
Thanks!

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Just finished a run of 400 booklet covers of white on black using a double impression of silver as a base followed up with a single opaque white on top of that. Using Megill double grip gauge pins. Slowing down was the best for me. I tried the flying dutchman trick and that helped some with the double impression of the silver as the paper jumped less after the first impression. The second went all over the place. When adding the opaque white layer, accurate feeding was the main issue, so I slowed the press down and stopped it completely between impressions. Luckily that’s pretty easy as I treadle my press and the treadle is indexed so it is ready to go down when the press is completely open.

Even so I lost maybe 10% due to mis-registration.

@arie
I can definitely live with 10% loss, but i probably won’t be able to slow down my press due to time pressure. At run speed I’m making an impression roughly every 3 seconds, and that’s counting a trip each time too.
I learned on treadle so I yearn for one again but yeah speed is unfortunanetly the biggest problem atm. My print literally pops out of the pins on return.

On reading this I have a sharp pain in the back of my head (it may or may not be related to an old pressman and a line gauge). If we don’t have time to do it right the first time, when will we have time to do it over?

Hello. Registration can be a frustrating thing. But! The good news is that it is often an easy fix. if you have the bracket for the tongue, use it. A tongue can be made out of any thin metal. Skid “Banding Wire” (that flat blue/black steel that they band skids with) is a good choice. You can get, at the hardware store, a can of “dip” that is used to make plastic coatings on tools. Such a a pair of pliers. This can be used to rubber coat the end of your tongue as seen in the pic.
Check for side play in the gripper bar. The end castings can be moved in. You may need to take a round file and slot the mounting holes a bit. Also check the sideguide cam for any play. A bit up and down is ok. The spring is made to take that up. A light oil on these parts will help.
you can contact me if needed.

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KlugeTongue.jpg

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CheckPlay1.jpg

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@ericm

Unfortunately I don’t have the tongues (although maybe I could scrounge around for the brackets) on this press. I imagine they were taken off for interfering with the boxcar bases. I do like the “dip” idea though. My friend who runs a kluge will appreciate the tip!

You know…. running a press too fast almost never produces the best result, and leads to a lot of accidents. I run a lot slower, and consider 10% loss due to misregistration / mis-fed paper to be way too high.

Remember, the most time consuming part of printing is the set-up. If you slow down your feeding by 30%, and reduce your losses (and thus the total impressions required) you will find that the overall job takes very little more time, costs less in materials, and looks better. (and your fingers will not be in peril!)

Have you considered that the register built into your artwork might be too tight? It is not butt register I hope, where two adjoining colors just butt up against each other and there is no overlap, or “trap.”

Oftentimes you can build more trap into all or part of the job and not compromise its esthetic qualities. Even if you do something like put down a silver and then overprint a white, as Arie says above, you can make the silver plate slightly smaller so that if the white plate is slightly out of register, the silver will still be covered up and won’t stick out on one side.

You graphic designers, don’t take this the wrong way, but many graphic designers have little concept of how to prepare artwork for a job so that it can be economically and efficiently printed. They just worry about aesthetics, and if the job is made up of 11 colors and has no traps for adjoining colors, for instance, so be it. When receiving or preparing art, it is important to critique it and make changes if and where necessary. When I worked for a paper cup manufacturer, there were very few jobs that we could just make plates for and put on the press without changes. Almost all of them had to be modified to a greater or lesser degree, to make them economically printable.

Another trick, which works with McGill Double Grip or regular gauge pins: Cut a small wooden wedge from a matchstick and insert these so as to hold the tongue down so the sheet cannot ride up the pin.

Not sure how fast your press is running, but best to place the sheet against the front pins, before sliding to your side guide to ensure a more consistent register. Glycerin on the fingertips can also help with sheet control both for feeding and delivery.

I don’t know if you’re using a Boxcar base, and if you are what size it is but I would look into getting a set of grippers for your press. I don’t ever print photopolymer so I just have to worry about the gripper arms clearing the form, but there is a trick of running string/rubberband between the two of them if they can only clear the edges of your plate. I’ve done 3 or even 4 hits of the same color at a decent speed and it looks good even on detailed type.

The Megill spring tongue gauge pins seem like the most problematic choice for tight register. I prefer the Megill double grip gauge pins as the most versatile for making changes between different sized forms, but they can also be a little bouncy for tight register. Like Mike said, you can try to shim the tongue to hold it down for best results. As also noted it helps to use gripper fingers and/or rubber bands to help keep the paper in the same position against the tympan.

However I have found that the Kort Quad Guides are far superior to other gauge pins for tight register… there is little or no bounce or variation. Unfortunately they are not made anymore, but maybe you can find a used set, or American Printing Supply has something kinda similar that may work, no guarantees.

The Flying Dutchman definitely helps to keep the paper in place for tight register.

Matt

Why do you need to run the job fast?

Are you trying to show off to others?

If you wanting a first class finished job, just do it at a medium speed.

The press is very old, and running i fast will cause the press to walk. The press parts are old and going fast doesn’t make the press work better!

I think if you practice something a lot you will get better at it. I suggest you set up a job with just enough ink to make a light print. Get some old leftover stock and practice at the speed you want to get good at. Run 20 or 30 sheets and then run them through again. This way you will see immediately how well (or how far off) you are doing. By practicing this over and over you will be able to work out what small movements of your hand will make for a better register. A few weeks or months or years of practice and you’ll be speed racer.
I find that when running at a good clip I load the stock so that the paper hits the bottom right gauge and the side gauge on the left at the same time and then slide the stock down onto the left bottom gauge. If I can keep the it in contact with the side gauge as it slides down then I get very good register. I keep the side gauge very low, maybe a half inch above the bottom gauges. Maybe a little more for a larger sheet. I’m sure there are many other ways folks have as their style. That’s just mine.
Also, I handle the stock in such a way as to have a finger toward the center of the sheet and press the sheet down against the tympan for that moment as I release my other fingers. This helps to keep the sheet from bouncing once I have it in position.
One other thing that I do is to hold any fingers of both hands that I’m not using to handle the sheet, tucked under against my palm to keep them out of harms way. No sense in letting them flap about potentially getting caught somewhere when they are not even doing anything.
OK, one last thing. If I’m running the press fast for a job I start feeding before the press gets up to speed. That lets me get in the groove and work up to full speed. If I misfeed a sheet and need to get going again I can step on the brake a little and slow it down some if I feel like I need that to start up again.
If I repeated someone else’s comments please forgive me.

Here’s a couple more. When using grippers I sometimes remove the gripper closest to the feed table. That gives me all the time in the world to position the stock when running fast without having to time it to the gripper.
Sticking a piece of foam rubber to the underside of the gripper can help stop bounce.
One thing I do with a particularly difficult color registration job is to tilt the image about 30 degrees. If you have a boxcar base this should be easy and if you use wood mounting you can make it oversize and cut it down to the angle you want.
Set it up so that the side gauge pin is low not high on the platen, then the stock will tend to slide right down into position against the side pin. I use this method with excellent results but I’ve never tried it fast.

Update!

I tried the dutchman and found it lacking for my situation.
I got the chance to ask a former worker what the old pressman would do and inferred the rest.

With the mcgill pins, bend the tongues wayyyy down before setting the pins. This creates a situation where you have to fight past the tongues when you’re feeding, but once the stock is in, it’s in. Adjust the tongues up enough to make it safe enough to feed, and if it’s final trim, so the tongues dont damage the stock. It works great, although it’s now all on you to figure out how to adjust your feed- I’ve adjusted so that my elbow is out and I feed with my open palm over the stock, sort of like I’m ‘waving’ the paper in. Pins need to be rock solid so you can slam into them with your stock - I lock them down with strong tape ,although if it was a very long run I’d use sealing wax. Old pressguy just taped his pins on - must’ve worked out just the right feeding force, but I’m not there yet lol.

@geoffrey
Yeah I don’t make the artwork. Sometimes a job comes to me, super tight, multiple runs on letterpress and other processes, and I just shrug and get on with it. Challenges make the job more exciting,and it’d led me to this method that I’m happy to report can hold point perfect as long as I’m feeding well.

“Remember, the most time consuming part of printing is the set-up.”

Winking Cat: That has often been my experience as well, though I admit that my press runs are only 100 - 200 impressions. A possible corollary to this might be that taking a little more time in set-up/makeready will get better results.

Once I had managed to find a set of EIGHT Cornerstone brand twin plate register quoins - the ones with the scale marked around the centre drum - then my two-colour work register problems went right away. However for three and more colour fits I had to dream up quite a different system,