After inking up, here was what I worked through today:
1. Problem: Too much ink on the plates.
Solution: You guessed it...taping the rails. I started with many, MANY layers of Scotch before I found some of that nifty strapping tape like the guy uses in the Boxcar video. I was being super anal about making sure I had the same number of layers on each side, until I realized it was OK that the right rail was more worn down than the left one. Must...learn...to be OK with unevenness. It's not like I give away my last one in a handful of M&Ms if it turns out to be an odd number. What??
2. Problem: Rollers popping out due to the grabber shaft sticking.
Solution: OK, "grabber shaft" isn't really the technical term...but I've searched the C&P parts diagram and can't find the piece I'm talking about. It may be the roller frame or roller arm. Here's the wonkiness that was occurring:
Basically, the sliding shaft that allows the roller frame to go up and down as the rollers make their way across the ink disc and down over the plate was getting stuck in the up position. This led to rollers flying everywhere and totally bizarre ink patterns. I oiled every conceivable hole to no avail...then finally realized that the large spring under the shaft had a piece of metal sticking out of the end that was getting caught. A little twist, and all was well again.
3. Problem: Throw-off arm stops the machine dead in its tracks, instead of switching from "trip" to "print."
Solution: This one stumped me. Once again, this probably shows my lack of experience with platen presses...but I was pretty sure that pulling the throw-off arm towards me was what was supposed to make it print instead of just inking the plates with no platen contact. Instead, pulling the arm towards me caused the press to stop being able to move all together. Since it's a little noisy in the warehouse with the heater going, please enjoy my Marcel Marceau demonstration of the problem:
It doesn't seem like a part is sticky or not sliding properly - it really seems like pulling the throw-off lever is supposed to put the brakes on the machine instead of allow it to print. Do I have the wrong idea here? What am I doing wrong? How do I switch from "trip" to "print"?
In better news, a friend commented that I looked like a mechanic with shop rags and WD-40 in my hands. Hot.
Pulp & Press Soundtrack 4/3/09: Sadly, Jizz In My Pants (The Lonely Island) was the only thing trapped in my head all day. Next time I'm bringing my Tivoli and iPod.
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ReplyDeleteum. i just posted a comment and it came up as alsace. oops!
ReplyDelete"you are so butch. and nerdy. love."
C&P presses (and some others such as by Golding), at least older ones, were made with the rails below type high. As pointed out by George Mills in the book Platen Press Operation, "the correct diameter for a roller is one-sixteenth of an inch larger than the diameter of the roller truck." Since the correct roller diameter for an 8x12 press is 1 1/2" the trucks should actually be 1 7/16".
ReplyDeleteBecause most people today are told to buy their rollers and trucks the same diameter, and usually new trucks today are only available for sale the same diameter as the standard roller diameters, the only way to get the rollers to the correct height is to tape the rails so that the rollers are 1/32" below type high which, as per Mill's, is the correct relationship.
Presses, rollers, trucks, etc. have variations so it's perfectly possible and OK that more tape might be needed on one side than another, as long as the height of the rollers is consistent along their length.
The throw off lever is only for throwing off the impression, not for slowing or stopping the press.
- Does it stop the press only when there is a form in the press? The platen may not be adjusted properly and/or for the packing your're using. It's not uncommon when first getting a new press that the packing you will use will be different from the last printer and the platen may need to be adjusted accordingly. It's also not impossible that the last printer didn't have the platen adjusted properly no matter what the packing. This is often the cause of the problem you are encountering.
- With the press idle, does the lever move back and forth and engage and disengage smoothly and without stiffness, or must you pull or push hard? The bolt attaching the throw off lever may be too tight. Or the throw off mechanism may be gummed up, misadjusted, or both. Also, there are two retainling collars on the large shaft on which the roller arms pivot, located to the inside where they pass through the bed casting. If too tight against the bed casting they will hinder the operation of the throw off lever. This is unlikely to cause the press to stop, but it may not be helping either.
Rich
Rich,
ReplyDeleteWow - thanks!! I wish I could hire you to come live in the warehouse and be my personal letterpress troubleshooter. :) I haven't measured the rollers in comparison to the trucks, but from what I can see in my mind I would guess the rollers are about the correct diameter. I'm getting used to taping the rails - yet another way letterpress if helping me to overcome some of my perfectionism.
As for the throw-off arm, thanks for confirming what it is to be used for! Next week I'll try what you've suggested and see if the press will still go without the form in there. Platen adjustment seems like a real possibility here, as the press stops when the form is right against the platen and feels like that may be what's holding it up. If I need to adjust it, do I just go for the bolts on the back of the platen?
Also, the throw-off arm is REALLY stiff moving, even when the press is idle. I oiled every conceivable spot where I saw parts moving against each other. I'll try the bolt attaching the throw off lever first. As far as parts being "gummed up," do you have a cleaning solvent that you'd reccommend for giving the press a little scrub down?
:)
Nina
BFF - thanks! I feel a little like I'm working on a classic car...though I'm hoping the end result will be a little greater than just being able to drive around the block. :)
ReplyDeleteAs long as your rollers are 1 1/2" you'll be fine just tapng the rails. A simple and inexpensive way to set them to the proper height is to take a short length of 18 point rule and file it down from .918 to .886, using a micrometer to verify the measurement. Of course, an even easier way is to have a woodworker or machinist friend make either a wood or metal block to this dimension. The rule or metal would be better as it's more stable, but a small piece of wood will not alter that much and would work. Use this as a gauge across the length of each roller adding or removing tape until the roller just barely touches it. The measurement .886 is of course 1/32" below type high which is what you want.
ReplyDeleteI use WD-40 and 3M green pads to clean machinery. If there is built up ink, as there was on both my presses, I scrape the bulk of it off with a putty knife and then use acetone to get rid of the rest. This will also remove paint but if needed that spot can be touched up. On my first press the ink was so thick on the chase locking arm I had to remove it and soak it overnight in a coffee can of acetone. But snce I had disassembed the entire press for cleaning anyway it was no trouble. Your press doesn't look that bad though, from what I can see.
One place that gunk can build up in the throw off mechanism is in the groove of the casting on the throw off shaft at the lower rear of the press. There are two castings mounted on seperate shafts, one casting engages the other by means of a steel pin on one that rides in a groove in the other. It's also possible these are not adjustd correctly in relation to one another. There are locking bolts holding them in place on the shaft and they can be rotated on the shafts by loosening the bolts.
Also, the arm that connects one of those castings to the large shaft that the roller arms rotate on at the top rear of the bed casting might be on uside down.
BUT! It's much more likely that the bolt holding the throw off lever to its mounting bracket is just too tight or the mechanism is gunked up, or both. The bolt that holds the throw off lever to its mounting bracket should have a nut on the threaded end that comes through the bracket. This is so you can screw the bolt in to a point that leaves a little play for the lever and then tighten the nut against the bracket to keep the bolt in place which would otherwise work its way out. So if the nut is missing someone probably just tightened the bolt too much.
Rich