Over or under packing 8X12 C&P
On my 8X12 C&P regardless of the amount of packing, the impression of the type from the Gauge Pins to the middle of the sheets is heavy and the type above the middle of the sheets has less impression.
I played with the amount of packing and it doesn’t change the out come.
Sometimes I use one sheets of press board and an extra sheets of paper and sometimes, two sheets of paper.
Sounds as though your platen and bed are not meeting up square when the impression occurs. Try running a test proof with a larger sort (18 - 24 point) in each of the four corners of the chase and check the quality of the impression. The deboss and ink saturation should be equal on all four sorts. If it is not, then you will need to adjust the platen bolts. When doing this, work carefully and use too-light-of-an-amount of packing, building slowly so that you do not accidentally smash any type. Good luck and keep us all posted on how things work out!
Jim
It’s also important to remember that as you add packing to an otherwise parallel platen/bed they get out of parallel. Think about closing a book without anything in it between the middle pages, then open it again and add several sheets of cardboard and close it again — but don’t do it with a valuable book! So to adjust for parallelism pack the press for kiss impression plus a little and adjust as Jim suggests. For deep impression it also helps to use a softer packing, to punch into the paper deeper — and out the back as well.
Bob
We have a new style C&P 10x15 which has a mechanism for dealing with this issue. I don’t know what version of C&P you have but check for these platen adjusting hand wheels
The new style C&P has a hand wheel in back just under the ink disk which adjusts the platen, increasing or decreasing impression as a whole. The hand wheel at the bottom left of the press will adjust the impression increasing or decreasing at the top versus the bottom.
The .pdf of the manual is available online. I could email to you if you can’t find it.
That platen adjustment is only on the Craftsman model of the C&P.
Has been posted many times in the past on B.P.!!
The vagaries of Genuine Parallel Approach versus Clamshell.
I.E. with all the will in the world and all the adjuster bolts available, it was is and always will be a fine balancing act with Clamshell action, especially and for instance having the M/c. set well, for normally used thiner stock, and then the one off Card/Board job.
O.K. altering all the adjuster bolts to achieve final parallel Yes possible, but not quick or easy and frustrating.! + usually the adjuster bolts tend to be coarse thread, strong, but finnicky when advancing or retarding, i.e. one flat produces a lot of advance/retard x 4?? … 3 Adjuster bolts (seen occasionally on Table Top,s) as in a three legged milking stool, partially solves the problem, (the Platen, has by default, to find a positive level) but is harder to achieve horizontal and vertical over all impression.
We have tried replacing worn adjuster bolts and re-tapping thread holes in the main frame, with fine thread,s gives good 4 point adjustment, especially when we marked the impression screws on every other flat 3 from 6 etc, But because the main frames on most of our table tops were crap monkey metal/diecast zinc etc. in the end not too successful, so we eventually drilled out the failed efforts, and reverted to standard/original threads with *Heli-coils* probably available Stateside.
Genuine Parallel Approach (Colt Armory, Vickobold, Kobold, Victoria Art Platen, etc.etc.) are the *Bees Knees* by comparison, it is quite normal and possible/practical to go from Air Mail, Onion Skin, Bible Paper type stock, to thick card, with just a tweek of the impression screw/ramp with very fine calibrations, often marked by the regular operator,s so that not even one sheet was wasted in *Run Up*
Don’t adjust the bolts.
Make a progressive packing which is a paper wedge that is thinnest at the bottom and thickest at the top.
Reduce your packing to get the correct impression at the bottom.
Then remove one of the packing sheets and glue tissue over it from a quarter of the way up to the top, then another from half way and then the final from three quarters.
Turn the sheet over and bury it under the other packing.
If it is still light at the top make your progressive as sixths instead of quarters.