My windmill platen has me stumped

Our platen totally has us confused today. We had a red handle windmill T Platen which has totally gone crazy - I couldnt even think of an accurate description for the subject line for this discussion.

We are a printing a two colour job. The size of each job is slightly under half the width of a 8.5x11” sheet. We are printing the first colour to one half of the sheet, then turning the sheet around and printing that colour and impression again to the second half of the sheet. Then repeating the process for the second colour.

The first impression prints brilliantly, we then turn the sheet around to print that same impression to the second half of the card and every time without fail the impression comes out very crooked and half off the page. This happens every time.

We are only using the one arm of our windmill so its not an arm issue.

What could cause such a drama? Printing to the first half of the page is always perfect, turn it around and print to the other half - wham it has a heart attack?

Any ideas at all? When we print the second colour its the exact same thing, one of of the page is brilliant, second pass of the paper through the press its crooked???

Totally confused.

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You’re not dropping the sheet to brass guides are you?

Hi RedHeadedMatt - we havent had our platen for that long so still learning the ropes. How do we tell if the sheet is dropping?

sounds like the sheet might be curling after the first impression, then on the second impression it misses the gauges, hard to say thats the problem, but a good place to start. good luck dick g.

Thanks Dickg, we had wondered if the area of impression from the first print could effect the arms ability to hold the sheet correctly the second time around?

Are you using the sheet steadier as circled in red on the attached image?
This prevents the sheet from dropping below the lay gauges.
You need to determine if the sheet is dropping under or over the lays.
When you say you are only using one arm, do you mean you are only printing on alternate machine cycles? If so, why?

image: HAP_1.jpg


Preventing misfeeds
I posted some pictures March 09 that can help with getting sheets into guides

your first pass impression is causing a curl in the sheet so that when you turn it around the sheet is jumping over the left bottom guide.
While the press is running kneel down on the delivery side and look in to watch what is happening with the sheet and bottom guides.
Remedy use a longer guide pin to catch the sheet.