Help C&P 12x18 impression problem

I have a C&P Old Style 12x18, with boxcar press base and photopolymer plates. Until recently I have only done projects that are 5x7 max, but have been working on a new project that is 4x18. During the process I noticed that its not giving an good even impression. I also have had to put almost 3-4 redboard for packing behind it to get certain areas to even ink up. I know there is process out there of adjusting the big bolts behind the platen, but I am unfamiliar with how to do it.

But it doesnt seem right that I would be packing so much redboard behind the tympan paper. And the areas that are bad, are the bottom and right corner of the platen.

Any help?

Thanks so much,

Miguel

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i would remove the packing and check to see if the bottom right of the platen has been welded at some point. it sounds like your plate is the wrong thickness for your base if your putting that much board behind the base to get it to ink up. Dick G.

You might have the boxcar press base not sitting level. You lockup might be pushing one end of the base up. You do not need to lock up the base as tight as you would hand set type.

Also, take out the packing and start with just a few paking sheets. See if one end of the image is darker than the other. This means your platen is not level or the basse is not level.

There is no welding marks at all on this press.

to level your platen you should lock a piece of type in the chase in each corner (at least 48 point type, like a w) then put in normal packing, one red pressboard and about 3 sheets of 20 lb. then pull an impression and make your adjustments until all four corners print evenly,make small adjustments it doesn’t take much. good luck Dick G.

@DickG

So I lock type right up to each corner? Not sure I have enough furniture to even do that, unfortunately. All I have is 2 boxcar bases 6x9.

On ebay you can pick up the space material and type you need.

thanks everyone, was able to lock type in each corner and adjust the platen.

Plyzo,
If you can get your hands on it, get four pieces of type-high rule, preferably 12 to 18 pt.
Lock these up in your chase, making sure that the whole lock up lies flat on your stone (level surface), with not ability to rock. Put in your normal packing, one piece of redboard and some other stock, bond or whatever. Then pull your first proof. You will see very clearly where your impression is heavy or light. Turning the screws under the bed, in very small increments, pull a series of proofs until you find the right balance, level. Then tighten the retaining nuts so that the bed does not move.
Once you’ve done this right, you should never have to do it again.
Feel free to call if you need info 917-509-4844
Steve

Check out the leveling the C&P 8 x 12 on the “troubleshooting the press” section of BriarPress.

So was able to lock some type in each corner and get a kiss impression on each corner that looks pretty damn close. Started to press some work with my boxcar base and still have areas like the middle that hardly get any impression. also have to put 3 red boards behind it to get an impression strong enough for the middle section. Then what happens is it super hard to even turn the press. This can’t be normal. I have never had an issue before on my smaller 5x7 projects. This project is 4x18, so never really ran into this problem. I don’t know what else to do. I did notice that my tape on the rails was even touching the platen, but needed that amount of tape or else ink would hit base. I am totally stumped.

Anyone have anything I should try next or check out?

Tnx

If the cut you’re trying to print is 18” long you’re beyond the practical limit of the size image you can print on your press. Presses can’t print well beyond an area about 2/3 the size of the chase.

Another issue might be where in the chase you have the cut positioned. Something long and narrow like that should be positioned slightly below the centerline in the chase as if you were printing a letterhead. You will get the best pressure at that position.

Also make sure that the chase is not warped and that the base is locked up flat. If you aren’t locking up on a dead-flat imposing surface you need to do so.

It may be that the platen is not adjusted properly and it wouldn’t hurt to check it but I’d check those other things as well.

Rich

Front Room Press
Milford, NJ
http://frontroompress.blogspot.com
http://thebittenline.blogspot.com

My chase is flat and so is it when it’s locked up on the stone. Currently using that exact position, and have tried positioning all the way at the top and bottom with no luck.

Plyzo,
Everything that has been said above is accurate and should be helpful. (At some point you should adjust the truck for your rollers. You shouldn’t have to add tape to the bearers to get even inking and roller rotation. I am sure you’ll find info on this some where on the Briarpress site.)
At this point you have not said what the image is or how dense the image is, solid, photo, heavy type, or large blocks of small time. As mentioned above you are pushing the limits of the press (which is always fun) but you may find it useful to break the job up into two or more parts and register them in-positon if possible. If no, find a friend with a Vanderkook.