Trimming Paper with Crop Marks

I would suggest you get your hands on an Alignmate to help establish alignment on the sheet.
http://www.printersparts-nc.com/alignmate.htm

Unless you are trimming the sheets individually on a cutting mat with a straightedge and x-acto knife, you will always want your printing to be square to the sheet’s edge.

DGM

An experienced cutter operator can do it, if it’s not a lot, maybe one or two lifts. It is far easier on a hydrolic cutter than one with a manual clamp.

You use the backguage and side to get the pile square/straight, then you have to twist the pile away from the backguage to line the crop marks up with the clamp edge. You have to be very careful not to twist the pile and keep it stacked very straight. We have to do this from time to time with work printed on digital printers.

Once the one edge is cut straight to the crop marks you can use that edge against the side to cut the next side giving you a new corner to place against the backguage to cut the remaining two sides.

It’s not the easiest or most precise, but with practice you can get good enough to save a job without rerunning it.

Like said above, it can be done, but is a pain in the ass and shouldn’t be part of anyone’s workflow.

We all learn these lessons at some point, next time we will measure extra carefully before running the job :)

I’ve saved many jobs, by adding a shim to the back gauge. Usually chipboard applied with double stick tape. Cut the chipboard to the width of a rib on the back gauge. You will only need it for two cuts, once you have a square corner (90 degrees)to work with, remove the shim and cut as normal, always placing the square side to the back gauge. The amount you’re off is roughly the thickness of the shim. Beats winging it by holding the stack square and in register.

As long as the crops align from front to back, it can be done as outlined above. If, for example, the print was rotated 1/2 degree to the right on the front and the same 1/2 degree to the right on the back, the total skew front-to-back will actually be 1 full degree, since to the right on the front is to the left on the back and vice versa. If that’s the case, you’re SOL. Even if you cut one side straight, the other side will be off. As The Arm suggested, an AlignMate or any other transparent grid will be invaluable.
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Michael Hurley
Titivilus Press
Memphis, TN

I have something called a copy-check – hard plastic with a grid and metal side guides.

http://theprintersshopper.com/index.php?main_page=product_info&cPath=0&p...

Nifty tool, Jonsel. Definitely useful if you’re in a high-speed production environment.
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Michael Hurley
Titivilus Press
Memphis, TN

Those of us who also do general printing see this all the time, especially with work that comes off of digital equipment. Shims on the backgauge are the way to go. I keep a few thicknesses handy, and just pop them on and off all day long as we trim.
Bill

Oh, yeah. The techs for the high-speed laser printers at my day job tell me a rotational or directional skew of up to 1.5mm is within design parameters. That can wind up making for a heck of a shift, front to back!
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Michael Hurley
Titivilus Press
Memphis, TN

Michael - its a joke to see whats become of acceptable parameters. Try printing something with borders on both sides. Technology certainly made things faster, but not better. I think that’s the reason many of us are here!
Bill

Oh, we just did. Wedding invitation package with about a 10 point black border around every piece. The invitations themselves were OK, thankfully, as they were single sided. We just cut them carefully in very small lifts. The double sided RSVP cards, however, were a total failure. Terrible front-to-back skew on many of them. The customer wound up taking the border off everything except the invitation itself. Granted, I think it actually looks better that way. It draws the eye to the invitation and not the other parts. Still, it’s not what the customer originally wanted.

As to technology, it certainly has made things different. Some things are certainly better, some are certainly worse. I’m sure in 50 years’ time, there will be those who look back on the heady days of the early 21st century with great nostalgia for “The Good Old Days.” Who knows?
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Michael Hurley
Titivilus Press
Memphis, TN

In the same way that a good designer knows how to design around letterpresses weaknesses, crafty designers should also be working around digital’s weaknesses, and skew is a biggie.

Yeah, technology is good, until it decides it doesn’t need you anymore! Much to Titivilus’ dismay…. ;)
Bill

Yeah, skew and lack of color fidelity are probably the biggest issues I have with laser printing. Even with daily machine calibration using an external spectrophotometer and use of digital calibration throughout the design, preflight and print process the color on a particular job might be totally different from one day to the next. It makes reprinting jobs a pain sometimes. Still, the speed, print detail and especially the variable data capabilities are very nice.

And I think a lot of that tech is in fact the creation of Titivillus himself! Automatic spellcheck and things like twitter and texting have to be some of the most devilish ways of getting people to write terribly ever invented. I expect he’s meeting his thousand pokes-full quota quite handily these days!
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Michael Hurley
Titivilus Press
Memphis, TN
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Thank you for all the great advice. I will definitely try out all the suggestions and tools!

I’m thankful for a community of help!!

Becky

Hey Gang,
A few thoughts from a paper guy.
First of all as Bill from Waldwick says, a good designer will design around the parameters or the weaknesses of the process.
Paper mill sheeting has become very good, using a few techniques that result in a more true sheet although it does not have that ice block look of guillotine cutting. However, guillotine cutting is almost never exact and will always have some variation. Even the newest and the best has some skew caused by the drag on the blade. This would be a particular challenge, no pun intended, on a older manual cutter. I know I’ll get some printers swearing they cut 99% of their work perfectly square and that there printing is absolutely square to the sheet, but I think they’d be fibbin.
One way to know how square your cutting was is to take the top sheet from the lift and place it face to face with the bottom sheet. More often then not on guillotine trimmed sheets you’ll find some variance.
One way to work with this is to always keep your lifts cut from the same position relative to the cutter backstop and side. Marking the edge of the lift helps, then make sure you feed the whole job using the same side guide relative to the lift as well as the same side of the sheet. If you inadvertently feed face up, then face down you using a different set of guides you could run into problems.
Best advice avoid tight rules or graphics that will be easily detectable if your printing or cutting is off.
Steve

Even suppliers can trim off-square. We check small size stock by flipping half the lift to see if the edges align.

Challenge service manuals describe a method to align the backgage by flipping a small lift.
Adjustment page:
https://www.dropbox.com/s/ov9evqwh5fmuexj/Challenge-CutterF-Align.pdf?dl...

(The dropbox login window can be skipped.)