Crooked precut paper

Hi, all,

I currently buy my paper precut to size (already cut to A7, for example) because I don’t have a paper cutter, nor do I have room for one at the moment. Buying precut paper is convenient, but I often find that the paper is not cut perfectly straight. At least one edge is slightly off, which makes it hard to get registration and lineup right. So far, I’ve only used #110 and #300 Lettra for printing.

I’ve purchased Lettra from various sellers and run into this issue. Is this typical? Aside from cutting my own paper, is there anything I can do? I worry that having a slightly crooked edge compromises my product (and my sanity). Any advice would be greatly appreciated. I’m also very open to paper recommendations!

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I would talk to where you are getting your paper from and let them know your concerns and issues. A dull blade, to large a lift, to small a lift, out of square back guide, old blade - too short, lazy cutter operator. Cutting is harder than you might think, especially cotton. It takes effort to get it 100% perfect. It also can be a factor of how many sheets you are ordering. I was not sure if you are talking about a cut that is out of square or and a bullnosed edge. You might try Astro Paper in San Diego.

In theory crooked paper should not be a problem, if you are using 3 points of contact with your lays or pins and using the same points of contact on subsequent colours.
The problem arises if you have a wavey edge and use a full width lay so the sheet is unable to balance on 2 points and the side lay.

In theory crooked paper can actually cause all kinds of alignment issues if the angle of the gripper+guide edges are not aligned straight up and down the stack (stack twist during cut). If up and down the vertical/height of a pile, there was a twist along the edge due to clamp pressure or dull blade during cut, each sheet will have a slightly different angle.
Each angle will present a different position when ‘pinched’ by the windmill 3 point register, for example- or will present a different ‘lateral’ location when registering to the lay-stops and side-guide pull on a cylinder, such as a heidelberg etc….
leading to consistencies in registration on the same sheet, but differences in location sheet to sheet, and different final trim allowances.

There are many other cutting issues that can cause even more extended variables to come into play when one considers the engineering of consistency mechanisms are built to exact- just think through the problem like a simpleton though.

Evaluate each pile and find the most square cut edge, mark the sides of the paper if possible with a ‘guide’ and ‘gripper’ edge, and then load into machine for first run accordingly.

Personally, when I divided sheets for printing, I would always cut the stacks ‘rough’, then do a pair of final ‘shaves’, which means the stacks had a nice, sharp, consistently 90’ edge to them. This allowed me to then mark that edge with a red marker as the ‘gripper’ edge of the sheet, for loading into the feeder in the consistent direction required. I am guessing that your commercial paper supplier is not going into that kind of detail when dividing, but that is why a real process control freak like me has to have their own cutter.

Good luck!

In my days buying paper in bulk for the trade, both ex-mill and ex-stockists, I often found the larger sheets A1 and A2 to be definitely not squarely cut. In the best quality shop, this was normally rectified by guillotine skimming on issue from the printing houses’ paper store, the cost of doing so, being easily saved at the make-ready-on-press stages. Our guillotines were very tightly managed for squareness.
This is UK experience