3046Re: [PPLetterpress] Windmill Registration Problem
- Oct 4, 2004Wow, you all made for a good Monday!!! Although I didn't ink up, I did
watch the card in slow-mo and I did notice the tail end of the card was
going over top of the [ fly wheel side] pin. So I put a longer pin in
the guide and it looks to be better. Tomorrow I will ink up and see if
it PRINTS better, that will be the real test.
I will keep you posted.
On Oct 4, 2004, at 3:03 PM, Printer wrote:
> Every-other-sheet misregistration is a common scenario. When I can't
> fix something by adjusting this or that, I go back to Square One, so
> to speak, by running a sheet through in slow motion. That is, I turn
> on the press, and have the sucker bar pick up a sheet and let the
> gripper bar grab it. Stop the press right at the point where the
> gripper bar has grabbed the sheet, but before it has started to swing
> in to the platen. Now shut off the motor and let the flywheel stop
> spinning. Now you can open the hatch on the flywheel's safety cover,
> engage the clutch, and start turning the press by hand. Watch the
> sheet carefully as it is being brought in to the side guides, and look
> for places where the sheet is getting hung up or misaligned. What I
> would look for is:
> Is the sheet too close to/too far from the bottom guides?
> Is one end of the sheet slipping off the bottom guide?
> Are the bottom guides aligned well with the bottom of the platen?
> Does the front of the sheet get pulled against the front guide before
> the gripper releases it, or is it released just a little in front of
> that guide?
> Does each gripper arm grab the same amount of paper, or is there a
> big difference? This would indicate that one arm is way out of
> Because you are getting crookedness, I would suspect that one end of
> the sheet isn't landing on the side guide, and maybe is slipping
> between the guide and the platen. There is a little widget that
> slides onto the track under the bottom edge of the platen that is made
> for this kind of situation- it keeps the sheet a little off the platen
> until the side guides are up and in position. Alternatively, you can
> cut a little triangle flap in the tympan and curl the point up a bit,
> at the end where the sheet is slipping down. This pushes it off the
> platen just enough to catch the side guide.
> Good luck with this. These things can be really frustrating and each
> windmill has it's peculiarities, in my experience. But you can figure
> out a lot when you turn it by hand and look at what is going on
> carefully. It may not be the gripper arms causing your problem, in
> the end. Cast out all preconceptions and put your trust in empirical
> observation!! ;^)
> Joel Benson
> Dependable Letterpress
> San Francisco
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