What Rule Perf to Select

We want to perf a sheet but need the sheet to be difficult to tear apart. They are having problems with the card stock coming aprt to easily at the perf. What is the courses rule perf we can use or any other ideas.

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Using 4tti and a ‘kiss’ hit is a good approach. Too, a simple crease will do the job as well. The crease guides the separation plus there is no danger of the piece falling apart in the handling. In my opinion.

One of the keys is to have sufficient gap between the teeth of the perf rule. A technique I use when I find the perf too aggresive for the stock is to use a small triangular file (a saw sharpening file works well) and run the file perpendicular to the rule face to open up the gap between the teeth. Take a few passes on each gap and then progress to the next gap. The process goes quickly if you don’t lose track of where you are.

I do a lot of perfing - perf and number, most often, in my commercial work, generally on carbonless sets, but often on tickets or covers as well.

Another issue to consider in selecting the best tpi perf would be the weight and the grain of the paper. If you will be cutting cross-grain, a rule with more cut than gap would be better; if you are cutting with the grain, you will need more gap than cut. The only way to really answer this question is to get a selection of different tpi rules and do some test cuts on the paper you will be using.

Also - be sure to cut against some steel perf base. Do not attempt to cut against regular tympan sheets or you will be in for a lot of headaches. NA Graphics has perf base, or you can use strips of steel strapping, Cut it down to length with your slug cutter and apply double-stick tape to mount it on top of your packing. sliding the ends under slits at either end and covering the slits with some scotch magic tape is a good idea as well.

If you will be printing and perfing in one pass, use only .909 perf rule. If you will be running dry, you can use .918. I stock and use .909 only, myself.

And make absolutely sure that you don’t have any type hitting the perf base… That would cause a serious problem. And, be sure to lock up some short pieces of regular rule at 90 degrees across the ends of the perf rule to protect you rollers from being slit open if you will be inking the form.

If you are cutting ‘card stock’ you will want to make sure that the gap is rather large compared to the cut. I’d suggest a call to your supplier and a brief discussion. Then stock up with a few pieces of 3 or 4 different tpi rules and do final testing on your press.