Windmill impression question

You are discussion two completely different adjustments when you talk about impression and roller height. The Heidelberg operation manual does a good job of instructing you to make both of these adjustments, but you can’t adjust the ink rollers to make a change in impression. A change in packing and subsequent adjustment of the impression knob will equalize the impression from top to bottom of the platen. Side-to-side is a bit more complex, and might be accomplished with simple makeready under the tympan sheet.

John Henry
Cedar Creek Press

Thanks for the response John. Much appreciated.

Just to clarify, I initially set out to adjust the rollers, and once I pulled a few proofs it became apparent that something was up with the evenness of the impression. Perhaps the roller point was unnecessary info! Apologies for the confusion.

I had a good read of the manual and my next step is to attempt to normalise the top/bottom variation using the impression knob.

I could adjust the whole form with make-ready to even everything out, that would be fine, but I’m also wondering if the variation I’m seeing is due to a larger problem, which if addressed would result in a better alignment of the platen in general?

Or, conversely, how much variation across the print area would generally be considered acceptable or ‘normal’?

Is it not also curious (or maybe it isn’t at all, I’m not terribly familiar with the press, much more at home with my Korrex) that the heavier impression is in one corner, top-left, rather the right across the horizontal or vertical axis?

Cheers again
Dave

move or exchange your images (type) to different positions on the corners to see if the impression problems follow the images. adjust as needed.
roller height should be done with the gauge.
i can make one for you if you don’t have one. Or, you can buy one i’m sure.

As J.H. above rightly implies there is NO correlation between Roller Height and Impression. !
Generally accepted and usually published that on the Heidelberg Platen the Roller Height(s) are set and governed with and by the 4 adjusters ( 2 per side) that raise and lower the rollers as required, via the Roller Height gauge, normally comes with the machine, to produce the desired stripe/strip..
The adjusters (X 4) normally display and set, at ZERO and give options for +/- but very rarely required.

Again as J. H. implies, the overall Impression is governed with a fine balancing act between the packing and the (limited) amount of control from the impression handle, this maybe best explained by the fact that the Impression handle can and does ONLY alter the Axis & Fulcrum of the Platen face up to a point, - implying the Balancing Act,! because *Clamshell* is the governing factor,
PARALLEL Approach solves this. ? ?
When You have set Your Impression Handle to the required point, do You always bring the locking ring down fairly securely.

Good Luck. Mick. U.K.

Thanks Eric, the variation was noticeable on two different forms, but I’ll try your tip today to check like-with-like, it’ll either rule it out, or confirm the issue. Thanks for that.

Thanks Mick. I’m fairly sure I did both, but I’ll pay attention to the impression handle and the locking ring and try again. Cheers.

Any other thoughts/advice would be great - put simply; with even packing across the entire platen the top left impression is noticeably heavier.

Dave, re Your heavier top left etc., (if at all) more like, light on the right - into the grip etc., but that would be almost impossible, unless the M/c. had been battered over many Yrs without adequate lubrication.
The bearings involved with the Axis and Fulcrum for the Platen and the associated crank pins and connecting rod(s) are massively over engineered, to deal with the rated thrust and impressional strength of the Platen, - upwards of 30 tons.

One important point to check out, (if You have not done so already) via the oil reservoir and the associated ball ended lever seen under the Ink Duct at the rear, top up the sight glass to the datum mark with any good quality machine oil 30 W. is a good starting point, with the machine just *ticking over* and with safety, slowly pump/pull upwards of 30 shots around the central oiling pipes.

Seeing oil weeping from the Ink Drum bearings (highest point) is a good sign, but bear in mind that on the Crank Pin and associated parts (seen through the drop down inspection hatch at the rear) some of the moving parts and bearings are lubricated with flexible (plastic) piping, but ALSO involves *flip top* catch-pots, M/c. stationary, of course.

Again with the m/c., just ticking over, and whilst Pumping Oiling, and with safety in mind, should be seen, oil leeching from the outer exposed edges of the bearings.

You should be able to see a Fine Brass Gauze *thimble* on the Oil reservoir which can be flipped out and cleaned in spirit if needed.!

Perhaps your (stateside) Wittenberg/burgh, Printers Graphics Engineers can help, our U.K.
[email protected]
are very helpful as well.
Good Luck - Mick U.K.