Gripper height

Hi guys.

Very new to this. I have recently invested in a GTP platen although I am only die-cutting not foiling at this stage. I have managed to get a good even impression on my test die but now that I am ready to add the creasing matrix it looks like the grippers will hit the matrix once it is stuck to the cutting jacket.

My question is… is there a way to adjust the height of the grippers so there is more clearance and if so will this effect other parameters - mainly picking up the sheet - which it currently does cleanly.

Also the cutting jacket seems to bow in the middle by about 1mm. should I worry about this. It is the cutting jacket that has 3 holes on 3 o the 4 corners for the GTP and is 2.5mm in height. (not sure if this is a foiling jacket height or a cutting jacket height).

And lastly should you ever pack under the jacket / bed or only behind the chase?

Many thanks in advance!

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I don’t believe you can adjust the height of the grippers on your press….you can on a kluge. All of your packing should be under your jacket…you can spot patch under the die if needed. Use a low matrix. Sometimes the matrix will get ripped off by the grippers or worse. Try building a “ramp” to help lift your arms up and over the matrix. It might not work for all your jobs….depends on it you have the room….you don’t want the “ramp” in interfere with other rule, such as your cut rule. Please see this link for more information. Good luck and congratulations on your new press.

No, you can’t adjust the height of the grippers. Do not attempt to bend them so that you gain more room between the gripper and the jacket because registration will suffer by doing so. Whe the platen of the GTP is almost closed and the gripper starts to open, you need to check wether it is resting on a small pin. The very end of the gripper needs to touch it gently so that vibration of the gripper is killed. If there is room between the pin and the gripper, bend them carefully to have both grippers touch the pin - as said before: gently! In case you can’t lift it off the pin with a soft touch of a finger bend it into the opposite direction. Remember to do both grippers.
So, that’s for the grippers. There’s nothing else to check or adjust.

Regarding the jacket: replace it in case it has a bow. This is dangerous!!! Thickness of 2mm = foiling jacket / Thickness of 3mm = die cutting jacket.

Building a ramp for the gripper is the only solution to your initial problem. Be sure that it doesn’t make problems regarding registration by blocking the sheet on its upward travel. In some (very extreme) situations it can help to go without a jacket and build up your makeready directly on the platen.