Tear and Crushed Spine Trimming Perfect Bound Books

[VinnyPiazza]

Hello,

We are looking for advice on trimming perfect bound books on a guillotine. We have a table top Duplo perfect binder and after gluing the book we trim the three sides to make the book flush.
Unfortunately we continue to have a problem with a small tear appearing in the corner of the book on the bound side and spines getting crushed causing a wrinkle in the spine. We have tried many things to prevent or minimize both problems.

Job Specs: (For current problem job)
The book is a 6x9 71 sheet (142 page) book with 60# uncoated text for inside pages and 10pt c1s for the cover.
Grain is parallel the spine.
Cover is a full color image and UV coated.

Things Tried:
New Sharp Blade.
Cutting 1, 2, 3, and 5 at a time.
With and without chipboard.
Chipboard between covers and inside pages.
Chipboard and/or scrap paper between books and top and bottom of stack.
Foam pad on clamp.

Not Tried:
Sharpening the blade to a different angle. (Not feasible under deadline.)

Picture of Tear: (Also attached to thread)
https://www.dropbox.com/s/fdjo88lmn5jeo3t/2012-06-11 08.05.23.jpg


Any help would be appreciated.

Thanks,
Vinny

 

[jotterpinky]

We also do a fair number of perfect bound books and trim with our guillotine. We have been unable to get away from the small tear at the edge, the only thing that helps is to make sure the direction the blade is traveling when coming down (ours travels down and to the left) is moving into the spine, i.e. the spine is always to the right and making sure it's as sharp as possible.. To get around the crushed spine we cut smaller lifts and use a foam pad (sometimes have to tape two together). Make sure the foam pad is not over the spine area when the clamp comes down so the spine does not get clamped and crushed. We tend to move it to the left about 1/4" - 1/2" from the edge of the spine, you'll have to experiment to get it right. If you're already doing this then try adjusting the pressure on your clamp. Good luck.

 

[ondemandbindery]

You can build up pads to only put pressure on the center of the book and that may help. And the amount of material you are putting under the knife will greatly be the decision maker as to how much chipping you get. If you look at a true Trimmer for binding Perfect Bound books you will realize that a flatbed will never produce the quality of a true Perfect Bound Trimmer. The best case scenario I have found is to cut the books 1 at a time which is extremely time consuming.

Good luck,
JW

 

[VinnyPiazza]

We are using a type of foam pad for our clamp. We have adjusted the pads to not cover the spine and played with the pressure. We have had luck controlling the crushing of the spine but cannot get the tearing problem solved. We will continue to try different things and let everyone know if anything works.

Thanks,

Vinny

 

[Al Ferrari]

Does the tear occur at both the head and the foot cuts of the books?

At all books in a stack, or just the top one?

Are you turning and flipping the stack of books each time so that the blade always moves toward the spine?

Does it happen at the face trim? If not, then this makes it related to the spine.

Al

 

[KPetrochko]

Here is an answer.
We have seen this MANY times and the best workaround (shy of an angle regrind) is to 'relief cut' before the final trim.
In other words.... make one cut 1/8 inch out from your final trim on the head and foot. THEN make final head and foot trim. You should be able to stack books still (3/4/5) and in 5 cuts versus 3 have a nice product. Trust me. It works.

 

[Al Ferrari]

Is this necessary at the face cut also? If not, why not?

Al

 

[narseman]

There is no wrap around at the face. It's a flat sheet cut.
We have the same spine tear problem also but not as bad as yours seem to be. Usually it is the outer layer of the cover that comes away very slightly at the cut. Laminated covers pretty much eliminate it as the lamination holds the outer layer of the cover together at the spine wrap. We usually trim one at a time with a foam pad not covering the spine, (holds the clamp off the spine) Also reduce the clamp pressure to it's lowest setting, espcially if the paper seems soft or fluffy. (not sure how to say that) Another big help may be to clamp the spine as tight as possible during binding to get as square a spine as you can. A tight 90 deg angle will reduce the tendency to tear. It's mostly the curvature of the cover wrappping angle that will produce a tear like yours. tighten up the binding clamp. Hope this makes some sense.

 

[Al Ferrari]

The discussion so far has focussed on what is happening during the cutting event. But what is needed is to investigate how the particulars of the binding variables would impact this cutting event problem.

What I mean is this: can the thickness difference between the spine and the body of the book be lessened by either or both less adhesive, or less roughening of the sheets at the spine prior to applying the adhesive, because here is where the thickness difference is being created. Also, perhaps the clamp that holds the sheets during the roughening event needs to be moved closer to the roughening tool to better support those sheets, or that clamping pressure may need to be increased.

In other words try to fix the problem at the cause, not at the symptom.

Al

 

[Al Ferrari]

The suggestions made in my earlier post may be of little value to users whose perfect binding equipment does not have the ability to control those variables. For those situations, valuable suggestions have already been made by others in this thread. But it is instructive to learn what means are available in our industry to prevent or minimize the "Nail Head" appearance or profile of perfect bound books.

The following quote is from Perfect Binding - PrintWiki

<'Gluer'. While still clamped together, the book block is carried to the gluing station, where applicator wheels force the adhesive onto the spine, a back spinner metering the thickness of the adhesive (which is usually about 0.020 inch). Often, multiple glue pots are used to apply separate layers of different adhesives. Paperback books, for example, have one layer of a low-viscosity hot-melt adhesive applied to bind the pages together, while a layer of a high-viscosity hot-melt adhesive is used to adhere the book block to the cover. Thicker publications, such as metropolitan telephone books or heavy catalogs, use three different types of adhesives.>

Note that the adhesive requirements for binding the text sheets together can be addressed separately from the requirements of adhering the cover to the block of text sheets.

Al

 

[lfelton]

Vinny, all the discussion is very interesting, but in fact you got the answer you needed from Jotterpinky in answer 2. We trim 99% of the output from our 2 perfect binders (1 EVA, 1 PUR) on an automated 3K trimmer, but there are always some odd sizes that need finishing on one of the guillotines. Make a pad up of several sheets of grey board a bit smaller than your finished size and place that on top of the book to be trimmed making absolutely certain the spine is not covered. That takes care of not creasing the spine, but make sure your pad is thick enough. Then always remember to trim the block from the spine towards the open edge as Jotterpinky says. I get tired of saying this, but make sure your guilly blades are sharp (ours are replaced / reground weekly). Ever so many issues come down to blunt blades in the end.

Is it me, or does that PrintWiki article seem like it's written by somebody with not much experience of a 21st century bindery?

 

[Al Ferrari]

Have you read many Wikipedia articles? They are often written by more than one person. I actually found many parts of it informative.

Al

 

[Al Ferrari]

Can you suggest ways of fixing the problem at the cause, rather than at the symptom? That is, at the binding event, rather than at the cutting event.

Al

 

[ondemandbindery]

Vinny, all the discussion is very interesting, but in fact you got the answer you needed from Jotterpinky in answer 2. We trim 99% of the output from our 2 perfect binders (1 EVA, 1 PUR) on an automated 3K trimmer, but there are always some odd sizes that need finishing on one of the guillotines. Make a pad up of several sheets of grey board a bit smaller than your finished size and place that on top of the book to be trimmed making absolutely certain the spine is not covered. That takes care of not creasing the spine, but make sure your pad is thick enough. Then always remember to trim the block from the spine towards the open edge as Jotterpinky says. I get tired of saying this, but make sure your guilly blades are sharp (ours are replaced / reground weekly). Ever so many issues come down to blunt blades in the end.

Is it me, or does that PrintWiki article seem like it's written by somebody with not much experience of a 21st century bindery?

This was a good response and having 2 Binders in house you have certainly seen your share of books trimmed on the flatbed. You can also play with the clamp pressure on the knife. A trimmed both from a flatbed as apposed to a true PB trimmer is like comparing Apples to Oranges so keep that in mind also. A good sharp blade is always critical for Finishing as always.

Good luck,
JW

 

[VinnyPiazza]

Thank you everyone for the advice. The tearing was happening on all books not just top and/or bottom. We were able to successfully trim the books with minimal issues using the solution below.

Our Solution:
With a new blade cutting into the spine we positioned the pad just shy (1/8’’ - 1/16’’) of the spine. By having the pad offset put less pressure on the spine but still close enough to hold the book rigid preventing the tearing and crushing. We also added chipboard between books just smaller than the finished pieces for support. I’m sure this dulled the blade but it worked. We were able to cut 6 at a time using this method. For future orders we will try reducing the glue on the binder but there is no adjustment for pressure. Maybe the amount of glue on the spine was too much. We are also going to try reducing what is being trimmed off.

Thanks,
Vinny

 

[Al Ferrari]

Thank you for reporting back Vinny.

It would help all of us to better understand the cause f the problem if you could post a picture of the "end view" of the spine area of one or a small stack of the troublesome books, either before or after trimming.

Thanks,

Al

 

[VinnyPiazza]

Here are some shots of the books for reference.




Thanks,
Vinny

 

[narseman]

Well - A little late commentary.. Wish I had seen the pictures at the time. (Had I paid more attention) The tearing / cracking I see here is far worse than I had imagined and often the result of dull blades (duh) AND / OR a poorly fit cut stick. That is.. a height difference from the metal deck of the cutter and the plastic cut stick used to prevent blade damage. The cut stick maybe slightly lower than the deck plate. I would suggest padding under the cut stick with strips of paper (the same width) until it is level as possible. The less bounce (compressibility) the better. Also rotate and replace the stick often. Not sure who this helps now.. but my 2 cents.. deposited.

 

[jrsc]

There were some comments about regrind angles but nothing specific. We are getting some tearing/chipping on the spine (not on the front like the pic above). Our blades are currently 21 degrees. What would you recommend for book trimming? Books I'm noticing it most on are thick books 1.5 in +

 

[Mike C.]

Our cutting blades are at 24 degrees.....pad 1/2 inch off of the spine, clamp pressure turned down. we run our books with 1/4 head trim so the first cut we take 1/8" off and then cut the other 1/8" inch off, (less pressure on paper). Excess glue on spine will also cause chipping.