Is this common or what? A little over a year ago my crackberry phone cratered, locked up, and upset me so greatly with RIM and all its offering that I predicted its demise because of the way they treated me. I’ve got a pretty good track record. Piss me off and your company is likely to suffer greatly or cease to exist. In any case, one of the good things about the crackberry was the vault for storing various passwords. So I lost all of it. And a bad thing about WordPress is that it uses your email address to track access to your blog. Having experimented a bit with various formats I forgot about an older blog that I had started – and now by some computing magic my access was always redirected to the old blog. Hopeless to get help with it from WordPress. Their support is a black hole of silence. That is why I went with the Thesis theme for my art web site, http://byhugo.com rather than straight WordPress. I can only recommend Thesis, they have good support!
Long story short, after some lengthy wrangling I seem to have killed off the old blog, and now finally have a way of updating this effort.
So what is left to do on the press? The platen is back on the press, just needs calibrating. In January I’m buying the motor and drive controller for the C&P press.
The first of my engravings has arrived, and I am anxious to get printing the fist limited edition!
With temperatures outside in the -20 degrees C range, I also need to arrange for heat in the garage.
Pictures to come…
After quite a delay (somehow you have to get the mortgage paid) I finally am getting back to the press. I had a plank of oak lying around from way back (sailboat building days) and decided to do something with it. From some inquiries with other printer/bloggers, I discovered that the feed and delivery table on my press was not the original, and I searched out the info about what size the original might have been. There is a fair bit of conflicting info about the tables out there.
In the end, that was not the most important anyway. I only had the one oak plank, and whatever I was going to make would be from it. A friend helped me out with biscuit cutting the two places where the boards that I had cut out would have to be joined to make the working surfaces. Using some 30 year old Industrial Formulators epoxy I glued the pieces together.
After some tiring sanding, first with 120 grit and then with 220 grit I got the boards into shape. Next I thought I’d try something I had never done, cover the working surfaces with clear epoxy finish. That worked out very well, only one little tiny fly lost its life in the final coat. If you plan on doing this sort of thing I can only recommend doing what I did – make it in two coats! The first coat will seal the surface and even if you get bubbles in it (you will because the open grain areas of the wood spawn bubbles like crazy) – you can sand them out. Then for the second coat you only have to watch for flies and bugs.
And then earlier in the week I removed the platen, just about too heavy for me to move by myself. The reason I removed it was because I discovered the platen needed to be moved closer to the press bed by about 1/8 inch. Once I tried making the adjustment I found that the mounting studs were really binding. Also it makes it a lot easier to clean under the center part of the press.
After considerable back and forth I am back to where I started. When I got the press there were only two of the three ink rollers present. Since I am going to use the press to print from engravings rather than from movable type (individually placed lead letter forms), the inking procedure is maybe a bit more critical. The rollers are built on a steel core of 9/16″ diameter, with the center 20″ covered with rubber to a two inch diameter. The roller trucks are slightly smaller in diameter, the idea being that the rollers are moved along by the trucks rolling on the rail until the part of the form that needs to be coated with ink is contacted by the rubber roller and sightly lifted, with the roller now rolling along the surface of the engraving (inking it).
Due to a chance encounter with a structural engineer in a coffee shop I got an education in the deflection/deformation experienced by the rollers as they move over the form (the parts of the engraving that gets coated with ink). Dave is his name, and after I asked about the workability of higher quality steel versus the original mild steel rods, he told me that I was addressing the wrong valiable. With a solid rod the strength of the steel has only a minor effect on deflection. He then explained the equations behind the resistance to deflection in a rod versus a tube, that is where the improvement can be had – making the portion under the rubber a tube would make it a lot more rigid.
Great, now I had a mission. I determined that a one inch OD tube would be ideal, would result in a half inch coating of rubber to get to the original two inch roller OD. Now I just had to figure out a way to insert the 9/16″ rods in both ends of the 20″ long tube and then everything in the roller saddle areas would be back to the original version. My approach to this is to get the tube line drilled at the ends, for say 3″ and to – with a slight interference fit – hammer in the shaft stubs for each end. About one inch from the end of the tube a 1/8″ hole can then be drilled perpendicular through the tube and shaft, and a spring pin hammered in to hold things together. Another set of spring pins can be used to hold the delrin trucks in place, and since they are made to specifications I can get them made the same diameter as the roller OD.
And then I had the great epiphany, what if the original roller cores were made of such small diameter steel in case the rollers came off the saddles during printing? I have heard of that happening. That would be a mess, if the rollers fell between bed and platen while the press was closing! So now I have another mission – is that a valid concern? Onward…
The first bit of new progress after a long cold winter. I’ve cut the pieces of Canstrut (or Unistrut whichever name you like best) and test assembled them. I’m guessing a bit for the motor size, but the Canstrut design I came up with is quite adjustable. The short sections with the hinges attached will get positioned between the press frame side panel castings. Once mounted, the motor will by its own weight keep the belt tight. Now I’m just waiting for the motor, and waiting for the last bit of snow to disappear.
This picture is from the corner of the platform that will hold the motor (where the four bolts are sticking up).
Motor Mount from Motor Location
It’s been more than a month since my last post. Not that I have been lazy about this, but making a living comes first, and so the work increments on the press have been smaller – with several weeks of interruptions. Then there was the gib-key fiasco for the pinion gear that I ordered wrong, and had to re-order. Then there was the straight edge that I ordered – and that somewhere during shipment punched a hole through the packaging and escaped into the wild (likely in the back of a UPS truck). That too had to be re-ordered, but now I got it and can finally get to work checking the press bed for straightness.
The last week has been like Christmas. I got packages from the seller of the press, with the feed table (with the cast bracket) and the all important chase. Then I received the mini-furniture cabinet that I bought via Briarpress from a printer in Florida, with a bunch of metal furniture (still waiting on the wood furniture). Ah, and I got an impression counter, not really needed, but why not.
And then there was a two week holiday in the sun and several weeks away up north.
A new resolution to throw out more stuff from the garage, so that I can fit the new stuff in place and make more room for working the press.
A list of what is required to complete the reworking of the press and make it ready to print:
- Finish cleaning and painting
- Polish / straighten press bed
- Check & correct side-rail elevation to press bed
- Check & correct/adjust platen to press-bed distance
- Define motor size and purchase
- Buy and install VFD
- Buy ink rollers & trucks
- Order the first zinc plate with backing
- Buy tympan & pressboard
- Buy cotton paper
- Buy ink
Well that’s it for now…
Press Free of Chains and Tiedowns
Interesting encounter today at the farmers market. When I was looking to sit down to enjoy my danish and espresso, there was no table free. So I shared a table with an older couple. We got to talking about things and surprise, surprise the gentlemen used to feed a C&P letterpress many years ago in a little town west of Red Deer. I asked about the speed, and he insisted that they were doing about a hundred pieces a minute top speed. Hm, that seems a pretty fast! The other production number I have heard a few times is about 2000 impressions per hour (iph), that comes to 33 pieces a minute.
I am going to aim for half of that, 1000 iph. My press has a 24″ diameter drive pulley. The smallest I am likely to get for the motor shaft pulley is 2″ diameter. So that works out to a 12 to 1 speed ratio.
With 7 turns per impression on my press, that is 7000 rotations per hour, or 116.7RPM.
On the motor side that is 116.7 times 12 = 1400RPM. For an 1800RMP motor, operating at 1400/1800 = 78% of maximum speed is not that bad.
But there is something else I have not mentioned before. I would like to increase the time available for the paper removal and placing task (while the platen is open) by manipulating (reducing) the drive speed depending on the press position (when the platen is open). During the three truns of the drive wheel while the platen is open I’d like to reduce the drive speed to about 40% (for a 1800RPM motor that would be 720 RPM). And during the four turns while the platen is closing/opening I’d like to run it at full speed. My plan right now is to use an inverter duty 3/4 HP motor driven by a VFD to be able to handle the cyclic acceleration/deceleration.
An 1800RPM motor actually runs at about 1750RPM at full load. Assuming that it will take half a turn (on the press) to accelerate from 720RPM to 1750RPM, and half a trun to decelerate back to 720, that makes one turn at an average speed of (720 + 1750) / 2 = 1235RPM.
So here is what my prediction is for overall rate:
3.5 turns at 1750RPM (at the press that is like running at 1250iph)
2.5 turns at 720RPM (at the press that is like running at 514iph)
1 turn at 1235RPM (at the press that is like running at 882iph)
Working out the average speed for the time weighting that each speed applies:
(3.5/7) * 1250 + (2.5/7) * 514 + (1/7) * 882 = 934.6 iph average speed, pretty close to the 1000 iph I was aiming at, and I gain a safety advantage with longer platen opening time. Let’s see what that would actually work out to: 720RPM / 12 is 60RPM at the press, that is 1 rotation per second, so for the 2.5 turns the platen is open – that makes it 2.5 seconds. Plus the bit of time the drive is speeding up and slowing down. So maybe close to three seconds time for the paper shuffle. That seems lots. We’ll see! One other feature I have been thinking about is to have two buttons on the feed table that have to be depressed before the press will return into the high-speed mode (or possibly if they are not pressed bring the press to an emergency stop via dynamic breaking). If you can think of holes in this reasoning, I’d like to hear what you are thinking.
Friend Tom with Press at Rogers Pass
Today was another day of rust removal. Now my order at Acklands came in and I have better emery-cloth and some rust remover to try out. Had bought a new set of wrenches at Home Depot, an open end – close end ratchet combination set in the typical heavy plastic packaging that you need a set of shears to open. When I came to use the 9/16″ wrench I find the ratchet did not work, and looking at it closer it was a used wrench of a sightly different style (still a Husky though). Back to Home Depot for a refund, but that was not so easy. Even though the packaging claims lifetime warranty there was a lot of waffling going on, I felt they were of the opinion that they were letting me get away with something. Frustrating.
Then a slight, could have been bad mishap. I had attached the throw-off lever linkage and left the lever pushed forward. Then I worked on cleaning rust off the platen and the tympan bale areas. I left the top bale folded down while I got busy with something else. As I turned the flywheel cleaning the main rocker shaft I felt a bit of resistance on the flywheel. Hm that’s not right. As it turns out there is just the right amount of extra space left in the throw-off position so that the bale just gets squeezed a bit – without damage.
Note to self:
1. Never leave anything on the platen that could cause damage.
2. Always turn over the press for a full cycle by hand, and check if anything seems to take too much force!
3. Never leave the platen bales open!
Filed under C&P, Letterpress