Heidelberg Windmill picks too many sheets

Dear All

I just have cleaned the pump, fix the elevator mechanism and I am still having the same problem… double sheets!

I am trying to print Offset 300 gr/m2 stock.

I have tried with more and less angle for the bar 3-1, more and less height for the pile table, rubber suckers, I have placed the the accessory T2220 to hold the paper in the middle of the pile, and T1249F 2x to hold the second sheet after the first one sucked by the bar…

I am kind of frustrated, any tip, help, suggestion?



Log in to reply   9 replies so far

Manuel, looks as though you have tried all the normal operations, *bar one* perhaps!
When you knock your stock up to position it between your side standards, are the side standards perfectly vertical , to the platform?? in each case, even a tiny piece of paper under one can tip either in,!!! just enough to make the stock tight near the pick up position, possibly check with an accurate measure, slid from the bottom to the top, of your standards, with the table right down will show, AND (as shown to me on My Thompson Platen) when loading the pile, knocked up in smaller blocks, but also small blocks, rolled lightly, (like rolling up a newspaper) to give just a *tiny* negative upward tilt to each sheet, so that on pick up, the fingers have more chance to separate, sheet by sheet. Apologies for potential rubbish? Good Luck.

Try adjusting part T1654 – it’s a spring clamp on the left side of the sucker bar. If you rotate it, you’ll find a hole underneath it, which will let some of the air escape when it goes to suck up the next sheet. You can fully expose the hole or only partially. Sometimes this has helped when I get too many double feeds.

I personally find rubber suckers only valuable for really heavy stocks like Lettra 220. Anything lighter and it just pulls up way too many sheets.

There’s also a little spring finger on the back of the feedboard (can’t find the part # right now). You can adjust how far it protrudes above the stack of paper with a small turn knob and that has helped in the past as well.

Lastly, I try to let the suckers pull the sheet up to it, not have them contact the stack, so maybe try having the stack a little lower than you’ve had it.

On the base of the pump on my platen there is a pressure release valve run the press and unscrew it ‘til it makes a coughing sound then ten screw it back until it stops pulling doubles

Manuel podes poner una bandita elastica que cruze todo el ponepliego la sujetas de donde van las lenguetas separadoras generalmrnte funciona tb podes usar las lenguetas metalicas metidas unos 2 mm de costado podes tambien intercalar los chupetes cerrando y abriendo si usas los de goma capas no te conviene que esten en las puntas igualmente para papel 300 gr no creo que sea necesario usar chupetes cuales usas los que son de fuelle?

Lo otro que puede ser es que la pila de papel vaya subiendo demasiado rapido eso se regula con un mecanismo que podes ver si miras la maquina de frente sobre la izquierda abajo se afloja una tuerca ysemueve gralmente si no trabajas con papel’muy grueso va todo hacia el extremo izquierdo.

Quick fix works sometimes A strip of masking tape up and down the feed pile tail end of the sheets, suckers pick up the first but the tape creates enough resistance to prevent double feeding.

I often adjust the feed table blast cock to reduce the air blast, and make sure the blast holes are in their topmost position, or one click below, until I get one sheet to separate reliably. I agree with dropping the feed table and taking the suckers off. I find that the suckers work perfectly well for 300 gsm stocks without rubber suckers or sucker bar slides. Also, are you riffling the sheets before you stack them? Try shorter lifts… if it’s smoother paper, quite a bit of suction can build up low in the stack from the weight.

I also reduce suction and rarely use the plastic slides.

The lower the pile height, the less suction; so I’d also ensure the lift-rate is not raising the pile too fast. If you are feeding a few sheets ok, but shortly later pull doubles, the pile may be rising too fast.

Separator fingers on the front standard are very useful to keep the next sheet from picking up.

It is a balancing act with many variables, and no two operators will balance exactly the same way. Finding what works for you is always trial and error (hopefully before deadline).

In terms of suction, the greatest to least amounts are as follows: Bar mounted with suckers, bar without suckers, bar with yellow slide, bar with red slide and finally the bar with the pink slide (or a piece of tape over a red slide with pinholes punched through the tape.

I do most of my work with a yellow slide (from 20 lb to 100 lb cover). The slides act as a choke, which reduces having to fiddle with the general suction (the spring collar on the sucker bar. I will turn alternating suckers halfway off if I am having doubling problems—that and increasing the sucker bar angle. Lots of variables on a Heidelberg sucker bar feeder (Windmill/K line/S line/GTO etc).

I can’t recommend suckers at all—unless handling heavy coated stock (18 pt on up).