Potter #2 proof press info

Hi everyone,

I managed to get my hands on a Potter #2 proof press and was wondering if anyone has any manuals. Seems unlikely, but I thought i’ll ask.

i am trying to figure out how to install the packing and the type of material i should used to print linocuts, poly plates and woodcuts. I have been printing on platen presses for a while but this is my first cylinder press. What sort of adjustments should I look for? does it have impression screws likes platens?

the press seems to have had an inking system at some point in time. its a pity it is lost. anyone know of a spare one?

thanks,
Leo

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Leo,

Congrats on your Potter. There are several slight variations on the same design depending on which manufacturer made your machine. From my own experience on my #2 made by Hacker, the packing/make ready is the only way to adjust the printing height. They do take quite a bit of packing as they seem to have been designed to print with a rubber or leather blanket near the cylinder.

Unfortunately, the inking systems are pretty tough to come by. I have just settled for inking by hand.

Good luck and happy printing!
Steve

thanks Steve, i thought as much with the inking system.

Do you use a rubber blanket? do you then put paper packing over that? how do you attach the blanket and the rest of the packing?

My rubber blanket was too beat up and cracked, so I do not use it. I would have used it if it were in better shape, and would have gone rubber and then tympan on top. I think they might have gone canvas and then rubber blanket on the top initially, or at least that was what came with my press when I got it.

Mine has two bars on one side of the impression cylinder and four pins and corresponding piece of metal with holes in it to clamp the other end of the tympan into. Because of the poor quality of my blankets, I used several sheets of tympan to get it up. Here is a good explanation of how to pack a cylinder press: https://bigjumppress.wordpress.com/2013/03/11/how-to-adjust-the-packing-...

It is not the same press, but it is pretty similar process. Let me know if you need pictures of the process on the Potter. I can send some later.

Thanks Steve. The link was very helpful to get the basics.

So, here is my first attempt to put a sheet of tympan. It is pretty rough and by no means near ready to print. I am only trying to work out how to attach the sheets and how the press works.

In the pictures you can see that i put the sheet under the gripper bar (or are they tympan grips?). Is that how it is done?

What is a good size of rubber blanket to purchase for this press?

I also need to figure out how do you register on this press?

Cheers,
leo

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Register was not designed into this press: grippers over the topsheet, but no pads or guides or feed table.
My old Hacker lacked guides also but there were tympan clamps where I could insert a 36 point brass as a head stop, with some tympan taped to the feed table and a platen-style gauge pin became a side guide.
Here, I think you would need to consider something like this:
https://sites.google.com/site/pocoproofpress/tym

“the packing/makeready is the only way to adjust the printing height”!!!!!!!!! Not so grasshopper. Most of the proof presses where designed to either have a base-plate in the bed of the press OR have the type/form on a galley. The bottom of the galley should be the same thickness as the plate. That is basic.

BUT, instead of adding packing on the cylinder to increase overall pressure, one can also more easily start adding sheets of paper under the galley or plate. Much easier to remove or adjust than taping on and taking off packing on the cylinder.

Also, mic the thickness of that crumbling old blanket and then find a fairly decent-sized commercial offset printer in your area. Introduce yourself, tell them you are a letterpress printer and wondered if they could give you one of their used offset press blankets. It should be larger than what you need, but you simply cut it to size. I used to assume that all offset blankets were the same thickness - NOT SO. That is why you want to know the approximate thickness on your original rubber blanket.

I have been doing great printing on a Poco proof press for forty years. I started by putting a used offset blanket against the cylinder and HAVE NOT HAD TO CHANGE IT in 40 years of use.

These offset blankets are usually chucked in the garbage when they need to be replaced, so don’t feel shy about asking for one. Well worth having.

Rick

Raising or lowering your form to meet the pack
can work if the adjustment isn’t excessive.
Ideally the face of the form should be
the same height as the rails.

The ink roller height can be adjusted & in this case
there is no automatic inking system to raise.

However, as the height of the inked surface increases
past the height of the rails along which the cylinder rolls,
the practical circumference of the cylinder decreases.
The rail circumference remains the same
as does the length of the bed but the difference
between the circumference at the point
where the cylinder meets the rails &
the circumference where it meets the ink,
drags the paper forward
across the surface of the form.
Raising the form height beyond some point,
leads to ink skidding.

Lowering the form and increasing the pack to meet it,
causes skidding in the opposite direction.

Both extremes put additional stresses
on the rack and pinions.

In 40 years I don’t think I have ever had much of a problem with ink skidding (a new terminology to me). The basic trick is to keep the sheet your are imprinting snug against the cylinder.

Since my Poco has absolutely no gripper or registration system, I had to make up something for myself. My solution was to pre-punch oversized stock and simply trim off the edge with the holes when I was finished. The main part of the scheme was to have two or three registration pins taped onto the cylinder. The pins allowed me to attached the pre-punched stock onto them and they then served as BOTH the gripper and registration as the sheets passed over the form locked into the bed. The other part was to tape the tail end of the sheet down with a piece of masking tape and this prevented any slurring or ink skidding. The piece of tape on the tail end could simply be lifted off the edge and reused for dozens of impressions before it finally lost its ‘strength.’ This also allows the sheet to be pulled through the press in both directions, because the tail end becomes the leading edge when returning to the original position.

Interestingly enough, there is a little “slippage” in the gears when the bed of the Poco goes back and forth in both directions. I do lift the ink-plate out of the way and print in both directions by simply braying my ink out on a glass covered table next too the press. This slight slippage does change the relationship of where the form contacts the cylinder, depending on which direction your are going.

So….. I also have drying racks next to the press and always have a habit to start my printing from right to left and I always put my printed sheets in the racks in a specific order. This way, when I need to register a second or other successive colors, I am sure that the sheet always travels in the same direction for impression. If the sequence gets “off” for some reason or another, the registration will be slightly off and I can quickly adjust and get back in sequence. I can do extremely tight registration if I need to.

Of course this is a very slow process, but speed has never been my aim and my runs are usually never more than a few hundred copies.

In recent years, I have wandered away from the punched-stock/registration pin system and simply use a folded and taped clip system. Much easier to set up on the press.

The process is very simple and I always try to keep it that way.

Rick

Thanks so much folks!

such a different ball game to printing on a platen.

Parallel_imp, what great link. I have been exploring that site a lot.

Rick, I was just going to get a new blanket but i think i will do a trip to local print shops first now! i would love to see a photo of your taped clip system, only if you get a chance.

Ragpicker press, thanks for explaining the causes of ink skidding. I will avoid excessive pressure.

One thing that i still think is odd is that when the press bed is in the center, the opening in the cylinder is what is giving contact to the bed. let me rephrase that in the form of a question: should the edge of the cylinder (where the opening star/end) match the beginning of the press bed? i think the cylinder is not in the right position.

When I lock my form into the press, I carefully lay my sheet over the top of it, trying to come as close as possible to the position it should be in at impression. Once I am satisfied that I am close and parallel, I then pull the bed under the cylinder so that the stock is squeezed between the form and the cylinder. This serves to “hold” the sheet in position and this is when I attach my folded tabs to the cylinder. These v-shaped wedges are plastic strips that were put into a vice and left there to gradually adjust to the folded-over shape. You want to change the ‘memory’ in the material. The finished v-shaped piece in about 1/2” square when folded shut. I open it slightly and put a piece of masking tape on one inside side, with some tape hanging out both sides. I then lift the edge of the stock and snug this wedge against the edge and then press it down on the cylinder so that the wedge is now attached in position to hold the stock in place. You need to do this at least twice on the same edge, sometimes three times for very large stock.

I then finish pulling the stock through and take it off. This allows me to burnish the masking tape to the cylinder and maybe reinforce the position with additional tape.

I am then ready to ink the form, place a sheet against the tabs, and tape down the tail end. I then pull an impression. Usually I am pretty much on the money and don’t need to make adjustments. If the position is “off” I simply adjust the position of the form in the bed and do another impression until I am on the money.

I should mention that the tabs only position the stock for going back and forth in each direction. For the side-to-side position I simply take a pencil or pen and draw a line against the edge of the stock onto my packing material on the cylinder. So….when I insert and butt my stock up against the taped tabs, I then just move the stock to butt up to the drawn line and voila - I am in business.

I hope all of this makes sense to everyone.

I also have methods to deal with registration on showcard presses with smaller diameter cylinders that roll several times over a form. I am always happy to demonstrate and talk about my techniques. I am usually always at the annual APA Wayzgoose (in St. Louis in June this year), The Annual Midwest & Great Northern Printer’s Fair (in September in Mt. Pleasant, IA) and the annual Hamilton Wayzgoose (in Two Rivers, WI in early November) so I can demonstrate various techniques at those venues for anyone interested.

Rick

I’m not surprised you are unfamiliar w/this
phenomena, Rick. It sounds to me like you
know what you are doing. It only occurs w/
under-packed or over-packed cylinders &
forms that are too high or too low. The cor-
rect term is “ink slur”. I use “ink-skid” only
because it does a better job of describing
the effect. It is a homemade term & I don’t
care if anyone else adopts it. “Slur” often
requires explanation. “Skid” is understood
immediately. I should point out that skidding
is more likely to occur when the printed
sheet is attached to the cylinder than when
it is attached to registration pins on the
press bed. Mechanical stresses still occur
but if the pin holes hold the paper without
tearing, slurring may be avoided.

Good to know. When I employ the pin registration system I use the registration pins that the litho film strippers used to employ on their light tables. They are short, have a slight lip on the bottom and are perfectly 1/4” in diameter.Most 3-hole punches (or paper drills) can produce a perfect 1/4” hole, so the “fit” is snug and not sloppy. The nice thing about them is that I also punched my masking tape to slip the pins through and the little lip at the bottom held them to the cylinder just fine.

On only one occasion years ago did I come across a three-hole punch and the holes were actually slightly bigger than 1/4” and made for sloppy registration.

I should also mention that the old registration pins had an almost microscopic bevel on the top rim. This allowed film (or in my case paper) to slide on without tearing or being hard to get on and off.

I readily admit that I am self-taught and just came up with a system that worked for me. I’ve been using it for 40 years so
I must be doing something right.

I have absolutely no clue where anyone would go to find registration pins any more. Remember the days when there would be rows of light tables in printing plants with strippers registering the film used to burn offset plates? Everything seems to be digital nowadays.

Rick