LETTERPRESS
Some essential tools you will need.
Original comments at the bottom.
Read and digest carefully. Sleep, then read again and tackle each issue one at a time.
Probably cheaper than having one made. Set rollers as instructions.
They have an instructions page How to... If you have soft, 'gel' like, rollers go for a lighter ink strip. Rubber ones a bit wider.
To check your Block heights you will need a Type High Gauge.
This one (left) is original but expensive and in USA. It's not a good one though. It's made of cast iron. They are usually made of Brass to minimise marking the block you are checking the height of.
This will show you what a traditional gauge, in brass Looks Like...
Type High Gauges are probably difficult to come by so what you could use is a Micrometer - measures mm and decimal inches. Either from eBay or your local hardware store.
"Packing - Happy Dragon style - Mylar on a blanket, I think they're are a couple of newsprint bits in as well. Changing the number of 90gsm sheets that I actually print on (ie in front of packing) seems to make very little difference to overall print."
Oiled Manilla Packing
Not sure what you are doing with Mylar and what kind of Blanket it is. A rubber Litho Blanket or something off your bed ? My choice would be Oiled Manila with Newsprint underneath. You can find the Manilla on eBay UK but this link is for stuff that's 273gsm which is a bit thick. 200gsm, or even thinner, would be best. You may have to go on the hunt for it locally or you could try the thicker stuff.
You could try using a cut up "Manilla Folder" from your local Stationery Shop. I'm sure this would do just as well. Failing that a bit of 200gsm card. Use your local newspaper for the under packing.
This is because they are not evenly type high across the face or not sitting squarely on the bed properly. Use the Type High Gauge / Micrometer to measure .918". Make sure it's the right height on all four edges. Use strips of tape to pack up the height or sandpaper to reduce, if necessary. You may have to apply tape just down one edge of the bottom to even the height up from this / to this ---
Related to this issue is getting your forme perfectly flat when you lock it up. Wood furniture is notoriously dimensionally unstable. Several pieces alongside each other can produce an effect like a bridge arch; bowing.
Insert narrow strips of card as indicated by the dots in fig. above. This will help flatten the forme out. Better still, use metal furniture but still test for forme bowing.
"Plane the Forme Down" is something the Compositor would do as he locked up the forme on the 'Stone'. The Printer would then take the forme and on a Cylinder machine, with a horizontal bed, would unlock the forme and plane it down again before locking up and beginning his "make-ready". The "Plane" is a block of hardwood perfectly flat and smooth on one face. For an Adana Plane make it about 100 x 70 mm and 25 mm thick.
How to:Lock the forme up and wipe the back of it. Unlock then very Lightly lock up the forme. Place the Planer block on the face of the forme and tap it with a lightweight mallet working it all over the forme. This ensures that type and blocks are on the same plane i.e. level with each other. Then finish locking up. This is why you need a flat metal plate to lock-up on. A piece of kitchen counter top would substitute.
"I don't understand when to change what (roller height, bed depth relative to roller, packing - all seem to be different ways to move the type closer/further away to the paper"
- Set your Rollers (this is NOT a frequent event)
- Remove packing and set Bed PARALLEL to platen (this is NOT a frequent event)
- Replace Packing, do not use obscure stuff that would make Caxton turn in his grave
- Make up Forme as suggested, ensure it's flat
- Do the impression test suggested below to achieve correct "weight"
- Experiment with packing thickness
- Then DO NOT touch the bed adjusting screws.
"When I have the bed much closer to the rollers it leaves a visible impression on the rollers - which feels 'bad' but may be normal."
What you are seeing here is the type and blocks in the forme removing ink from the rollers. If the roller height is set correctly this should not be an issue. If you have heaps of ink on the rollers it will show up more. On an Adana 8x5 the bed cannot be set closer to the rollers. You can only adjust the roller height by packing the roller bearers. I suspect you are running with too much ink.
"Finally - would a spirit level not speed things up, or am I missing the point *smile*"
A spirit level only respects gravity and does not respect an Adana 8 x 5.
ORIGINAL COMMENTS
Setting up a letterpress machine is an Art. There are those with a scientific bend of mind that say otherwise. These people are scientists not Master Printers. Your 'press room' should have a consistent temperature / humidity summer and winter. This is not only good for the press and operator but great for paper storage; although I have worked an Arab platen in a shed with snow coming in through holes in the roof !
On an Adana 8 x 5 the roller bearers move with the bed, so you cannot make the type 'stick out' to damage rollers. Bed to roller surface height should be a tiny bit under .918 of an inch. Using a roller gauge which is a short bar, say around 1" (25.4 mm) long, machined to .918" (23.3172 mm) in diameter, mounted at right angles to a handle in a T shape formation. Lightly ink up the rollers evenly and slide the gauge between the bed and a roller. This will leave a mark on the gauge that should be a bit less than a pica wide. The roller gauge will also have a 'feel' when you slide between roller and bed. You will learn to know what this should be, eventually. Check centre and ends of rollers, one at a time.
If the mark is too wide adjust the roller height by pasting paper or card to the bearers. If the mark on the gauge is too thin the bearers then are too high; you probably want to recover the rollers. There are 2 bolts in each bearer that attaches them to the bed. There may be some adjustment possible there. This will save recovering if it is. I never had to do that so cannot tell you if it's achievable. On an Arab platen there are leather bearer covers that could take under-packing. You could also put a bit of packing between forme and bed. This in effect 'lowers' the bearers.
Check that both rollers have the same diameter. You might find that the very ends of the rollers are greater than the centre. This is caused by absorption of wash-up spirits. Recover if you frequently print from full out formes.
On all the letterpress machines I've worked we used an 'oiled manilla' as the top layer of the platen / cylinder packing; a fairly hard material of maybe 200 gsm. Under this we had a number of sheets of newsprint at 45 or 48.8 gsm. For an Adana I would start with 3 or 4 sheets of under-packing.
The bed should be set parallel with the platen. Until you achieve this you will get nowhere. Once the bed is set you should not be using the bed adjusting screws to increase or decrease impression strength. If you want to tweak the overall impression then a sheet or two of fine tissue in the packing or even behind the forme will give it a bit extra oomph. You will, of course, being human, succumb to tweaking the screws.
It's a fine balance. Increase packing thickness for greater impression too much and you throw out the parallel kiss when paper meets type. Too much packing and you get over impression at the top of the platen; too little and the bottom is too strong.
The bed can be initially set by using the roller gauge in each of the corners. Check the centre too. If it's different from the corners then the platen may be warped. With a bare platen, screw the adjustment until the gauge contacts the platen very lightly and still be movable. Check all 5 positions; corners and centre. Back off all four of the screws one quarter turn or more, evenly. Pack the platen.
To fine tune the bed to parallel, and to get the right impression strength, lock up in the chase 5 letter M's, caps in 12pt, in a pattern the same as the number 5 face of a dice. One close to each corner and one in the centre. The corner one's about a pica away from chase edge. Move the bottom M's to a position where they will not smash the lay bar. When you lock up the forme make sure it's not bowed; nice and flat. Take off the frisket. You do not need ink on your rollers for this exercise. Ensure the bed is scrupulously clean, which it should be at all times. If it's oxidised at all, clean with very fine emery cloth and thinly wipe with a very, very, light oil. Oil diluted with kerosene (paraffin) is ok.
Having attended to your packing take an impression on a mid range paper, say 80 gsm. Look at the back of the sheet and hold it up to the light at an extreme angle so that you can see the bump the type makes through the back of the paper. If you see nothing then put on your glasses, otherwise increase your packing until you see some impression on the back of the sheet. Balance packing increase with bed screw adjustment. Always, of course, making exactly equal adjustment to each of the screws. Put a mark on the knurled end of the screws to monitor movement amount. When all 5 impressions of your letter M are even then you have reached nirvana. If you are still having difficulty with this then retire to the nearest Bar and begin again tomorrow.
What's next ? Start your first real job and construct a 'make-ready' sheet, peculiar to the job in hand, to put under the packing. But that's another story...
TIP: In the old-days a forme was locked up on a 'stone', a cast iron bench top that had been machined pan flat and had a recessed lip to accommodate the thickness of a galley. As a substitute get a small piece of very thick sheet steel, bigger than chase size, and use that as your 'stone'. If you are picky you will have it machined flat too.
Print Dictionary Google books will not show you all the pages but it's multi language including Spanish. Your local Library ought to be able to order up a physical copy. It's a mixture of stuff including modern digital.