Thursday, January 9, 2014

Leterpress Printing Process

So, as threatened, here's the post with even more pictures going through the printing process. Click pictures to embiggen.

Here is my press. To the left is a piece of almost-white tile where I've been mixing up orange ink. The semi-circular part of the press disappearing off the top of the picture is the ink disk. In front of the tile is the end of a slinky-board. And in front of the press to the left is a small stack of coasters.
My press is a 6x9, which means that the chase, where the type, etc. goes has an inside dimension of 6" by 9". Here's the chase, locked up with my aluminum base plate for sticking photopolymer plates to, with the smaller of our two MuseCon logo plates:
The dark metal blocks, two along the top and one on the right side, are quoins - you put a key in the holes and they spread open to lock things in. Ron's chase uses a different system, which I could use on mine, but don't. More on that below. The white tape on the sides of my chase are holding thin wood on, so that it can't wiggle from side to side in the press. 
Here's a closer shot of the plate and base, in the press. That shiny thing down on the bottom is one of the rollers.
 Here's a better idea of what it looks like in the press: On the opposite side is the platen, where I've mounted a frame made out of heavy cardstock, with a cutout for a coaster and a notch. Don't worry, the masking tape is augmented with double-sided tape. I've also augmented the bottom edge of the frame with another layer of cardstock to help the coaster stay in:
 A blank coaster in the frame. I've skipped the boring bits of setup, which involve getting enough layers of paper underneath so that you get a good print, and getting ink spread out on the ink disk.
 As you pull down on the handle, the rollers roll up across the chase, inking the type/plate, and the platen closes toward the chase:
The press in the closed position. No, the rollers don't go all the way to the top of the disk, but the disk rotates with each cycle, so the ink stays evenly spread. I have to use both hands to run my press, as it is all cast iron, heavy heavy heavy.
4 of the 5 bolts you can see in the back of the platen are so that you can adjust it so that its parallel to the chase bed. The center one holds it to the rest of the press. The rails that the rollers ride on as they pass over the chase have been built up with strapping tape, so that they don't apply too much tape. Another fiddly adjustment job that had to be done (Ron's press was less worn, so didn't need the rails taped).
One coaster printed. Take it out with one hand while the other puts a new one in:
 Except when the coaster falls out of the frame:
 Retrieving the fallen coaster; carefully, so you don't bump the inky rollers:

On Wednesday I finally added a strip across the bottom quarter-inch or so of the frame opening, to prevent this. Even if you see something shift while you're closing the press, you DO NOT reach in. Metal hard. Fingers squishy. Guess which is going to win?  Fortunately, I only had one coaster get mangled, the rest fell out when the press was opening, with only a few stray ink speckles resulting.

Ron's press is a 3x5. Here's his chase locked up with the text for the coasters:
Ron's chase uses screws that go through the chase frame, two the top and two on the left. I can tell which sides, because that's where the chase irons are - you could screw against the wood furniture, but that would leave divots in the furniture. 

The little things holding the coaster in place are gage pins. These are new-fangled foam and plastic ones.
 Older style gage pins are metal, and can damage type or be smashed against the chase or the metal base for polymer plate. We have some, but haven't used them yet, because the foam ones have been working just fine, despite statements by some people that they should only be used in blah blah blah situations.

A finished coaster:
 The metal bar on the right side is a gripper arm. We have pairs of them for each press, and when printing on larger pieces of paper you position them so that they catch the paper and help peel it off the type, as the ink is sticky. 

But gripper arms are another thing that you have to worry about smashing or being smashed - You don't want to catch them between the chase and platen  or the aluminum base for photopolymer plates and the platen (would damage the gripper arm and/or the aluminum base), or between the type and the platen (damage the type).

I've posted this picture before, on one of the blogs, but I'll post it again so you can see the relative sizes of the two presses. Ron's press I can run one-handed:

I can do a lot more with Ron's press before getting tired, but mine has a bigger print area. The aluminum base we have doesn't fit in his chase, but we did buy some scrap, which we can put some of the smaller photopolymer plates on, so we can use them in Ron's press, or in either press in combination with type.

No comments:

Post a Comment