Determined to get the Most from my Poco!

Hi Group,

I've had my Poco about two years. It took a while to sort out some missing bits (the stops) and get it working smoothly. Boy, it sure does love some lubrication on those gears. I wonder what product everyone likes best for that? My husband thinks I should switch from generic grease to his teflon bicycle chain lubricant.

I got a metal plate the thickness of a galley and the full size of the bed so it's now type high. I'm using Yupo as my tympan--it's durable and wipes clean. So far I've printed some book arts kinds of things with metal type and linoleum blocks and that worked pretty well but I realized registration was a big issue. A friend has a proof press and thinks I should just register on the cylinder but my experiments didn't seem to work. Since it prints from both directions I couldn't just rig up a registration device like a Vandercook would have.

I liked Neil Giroux's idea but didn't have the metal working skills to make that and didn't like the business of hanging it from the ceiling. I'm in a warehouse with a VERY high ceiling and I'm 4'11". After some thought, and looking at any other tympan/friskets I could find, I decided it would be good to have it open across the bed. Hinges need to be small and I thought of those piano hinges I saw at Home Depot. I do some bookmaking and have lots of binder board so I attached a piece to the piano hinge which can then be locked up in with the furniture. One minor drawback is that the piano hinge is a little too short but I can hold it at the right height for the hinge and if I tighten the quoins it will stay at the right height. There are two sizes of piano hinge and I used the narrower one. I make the holes with a Japanese hole punch.

The first prototype was without a frisket. I just cut a hole in the binder board where the type or image was and made registration stops on top of the binder board. I'm printing a wedding invitation right now using a boxcar base and polymer and realized the binder board alone wouldn't be a good idea. So I used some heavy mylar as an underlayer and added it to the hinge instead of making another hinge. It worked but it was a little awkward to use-kind of like opening a two page book. I cut out the print areas from the mylar and put register stops on the binder board.

I'm wondering if I can find a better material than the binder board because it's a little too thick. I like the piano hinge because it is very reliable in that is doesn't shift or wiggle. I use very short flat bolts/nuts. They are sold in the hardware store with a sort of matching sleeve and are what you might use on a photo album and I think it was called a "post". It has a very low profile head and I replaced the sleeve part with the thinnest nut I could find.

One thought I've had would be to use a some kind of sheet metal for the tympan frame/frisket frame with the center cut out so that it would not need corner hardware. I actually wondered if a hinge of duct tape would work. I really like those carbon fiber hinges I saw on the blog. Will the epoxy be strong enough to hold the frame together?

I should mention that my poco was sandblasted by the previous owner and used as a display piece.

Well, that quite enough for one post. I posted on Briar Press (Poco stops and other issues) and if you scroll down there are some more photos.

http://www.briarpress.org/15410

http://www.briarpress.org/17061

(Lynn Starun)

hinges

The problem of hinges for the tympan and frisket frames continues to bother me. There's just not a lot of room to work. But yesterday morning, I remembered that I had built the perfect hinges before. Even written up a web page on the subject. Behold!

I think these will solve most of my problems.

Preston

New tympan-frisket assembly, progress

The tympan framework is done and I built the frisket frame in exactly the same fashion, just a bit smaller so it nestles inside. Here are some pictures showing what tympan frame looks like, along with some details of the corners.

Here's the entire thing, upside down.

Here's a corner, from the bottom. The CF cloth makes it a little rippled on this side, but the other side (where it's glued) is quite smooth. Hmmm, that's wrong. I should have put glue on the rippled side and left the smooth side up.

And here's what it looks like from the top.

The bars are 1/8" thick and the L brackets are 1/8" thick, so the corners will fit between the cylinder and the 5/8" furniture.

Preston

New Tympan-Frisket Assembly

On my website, I write extensively about my 1st attempt. It turned out pretty well and Marya and I have been able to print all sorts of things with it, including multi-color and double-sided jobs. Nevertheless, I'm dissatisfied. The oak bars are 3/4" wide, so we end up losing 3" from the usable length and width of the bed, a pretty high percentage. It's also hard to duplicate, requiring some woodworking for the oak and metalwork for the hinges.

I had the idea of using carbon-fiber pulltrusions, since I knew they were quite stiff, available in convenient sizes, and pretty easy to glue together. I buy them from a company called CST.

My first attempt was unsuccessful. I built the tympan frame using bars 1/8" thick by 3/8" wide, using simple lap joints to fasten the corners together. The area for the glue joint (3/8" x 3/8") was too small and the glue (epoxy) joints broke.

While I could use wider bits of CF to increase the glueable area, one of my main motivations is to recover usable area in the bed of the press; wider bars would defeat that goal. I discussed the problem with a friend of mine, Howard Rush, who can build anything. He came up with the idea of using L brackets to hold the corners together. Not only that, he helped me build them!

First, we needed some raw material. We built a plate of CF-epoxy, 1/8" thick and about 5" square (a similar plate can be ordered from CST, but we wanted to get to work right away).

Next, we laid out the 8 required L brackets on a sheet of paper and glued it (with 3M 77 spray glue) onto the plate.

Following the outlines, we cut out the individual bits, sanding them to neaten up the edges. We used Howard's table saw with a diamond blade, but it would be possible to use a Dremel tool with an abrasive cutoff wheel (aka Dangerous Disk!). By the way, I also used the Dremel tool to cut the bar to length.

Here are the pieces of the tympan frame, ready to go together. Before glueing, we sanded all the mating surfaces, then cleaned them with MEK to remove and dust, oil, etc. that might interfere with the glue bond.

We layed it out on a slightly oversized scrap of shelving, then worked for a while to ensure all the corners were square before glueing.

We held the bars in place with hand clamps and remembered to add some teflon (wax paper would be ok) to prevent glue from sticking to the shelving.

Next we mixed up a batch of high-zoot epoxy (Loctite Hysol 9430), weighing the 2 parts carefully, and brushed a thin coat on the mating surfaces. Finally, we clamped the L brackets in place, lightly (too tightly will squeeze out the epoxy). A slippery job, but it turned out ok.

Finally, we let it dry for a week (until I had a chance to visit again).

Next, we need to build the frisket frame. Same process, just sized a bit smaller.

Preston

New tympan-frisket assembly

I've started building a new tympan-frisket assembly for our press. The basic idea is the same, but I'm using bars of carbon-fiber & epoxy instead of oak. The CF is very stiff, so I expect to be able to use narrower pieces (3/8" instead of 3/4"), wasting less of the bed area. It won't look as nice as the oak, but perhaps looks aren't everything.

Other parts, knife hinges and so forth, worked out well the first time and will be the same.

I'll add some pictures when I make enough progress to be interesting.

Preston