setting ink keys

Setting ink keys, a big subject! Its not so difficult if a few basics are followed. First thing is cleanliness. Its no good trying to get and maintain a good zero set if the keys are full of crap, covered in dried ink across the front etc. Keep them clean and wash them up at least once a week, spraying the keys under the blade with a light oil or anti oxidant (a light oil). DO NOT spray with WD40 as this has no lubricating properties whatsoever (look on a tin of it, lubricant isn't written anywhere). Make sure there is grease under the bottom front edge of the keys to stop ingress of solvents and ink fly.
Zero setting should be done using fresh ink into clean ducts. Used ink contains emulsified blobs that gives a false setting. The first thing to check is the overall position of the duct independent of the moveable keys. To do this manually wind all the keys out and look at the fixed key scrape on the duct roller. It should be even with about 5 microns of ink showing. If it is too tight or slack adjust the stops to get it even then slightly loosen and retighten the duct up to the stops. You should be able to feel the duct hitting the stops, not the fixed keys. This is fiddly and can take time to get right but is absolutely fundamental as unevenness caused the duct base to twist.
Once this is ok gradually wind in the keys evenly across the duct. Don't wind one all the way down then move to the next, do it by degrees across all keys until the zero is the same as the fixed key. Finish with a closing action. If you wind one in too far, unwind it back past zero and wind back in, This takes backlash out of the mechanism. Once zero'ed lock off every other key and do a few alternating full set zero sets as described above then open all the keys to about 20%, zero and recheck zero set, adjust as necessary. Flashing red lights mean a difference in the PQC setting relative to key motor position, usually a sticking key(s) or a duff motor.
If the duct won't zero set then it is key out time. Unscrew all the eccentric pins in the keys half a turn. Choose a key near the middle and carefully lever it out with a screwdriver under the metal bracket on the back of the key. I usually lay them out in order on the duct cover plate placed on top of the unit. Keep them in order! To clean them I have a tray that fits 2 units of L40 keys in or 4 units of L26/28. I leave the keys in a strong solvent for a time dependant on the shittyness, sometimes overnight, sometimes even taking the springs out. Clean with a stiff brush, don't scraper with anything metal.
Remove all the pins from the duct bed and put them in the solvent. Clean the duct bed until it is as new. If there is corrosion and it needs stoning do it in the direction of key travel not across. Use a small screwdriver and poke a rag down the pin holes to remove excess solvent or it will be removed onto your clean bed when you screw the pins in. Take the clean pins and screw in fully then back off one full turn and set them with the eccentric back. SPARINGLY spray the bed with a light oil spray.
Get the clean keys and take number 1. If the keys need stoning use a good quality oil stone that is flat. I prefer one about 120mm x 40mm and I run the stone along the key rather than the key on the stone. I do the bottom first then the sides and finish with a light stroke along the angled edges to remove burrs. Stoning is a subtle process, many times I've seen a duct be worse after some gorilla has stoned the bejesus out of the keys leaving the burred up. Put some grease in the reservoirs on the side of the keys front and back, carefully removing the excess with a plastic scraper.
Introduce the key to the duct tip down holding the spring back, move into position, repeat with no2 key. Be carefull not to disturb the grease and every 3 key tap them towards the fixed key with a plastic drift, but not on the contact faces. Do tis to the middle then start with the last key on the right and repeat until there is one key left to go in. This key should be tight to get in. I have a plastic T tool that you can put between the keys and twist forcing them apart, the front edge of the last key should then drop in with light pressure. If you have to force it you have done it wrong. If you have to move the fixed key you have done it wrong. If it just plops in someone has done it wrong before and moved the fixed key invariably causing skewed keys when zeroing. When all the keys are in spray lightly with oil, plate on and zero as detailed above. That's it really, sounds easy doesn't it.
Taking all the blocks, motors etc out is another ball game for another time.

Print4colours - If you set zero ok then open to 30% and it is uneven, try evening the 30% up by eye then zero. If the discrepancy follows at zero then your blocks have too much play in the screws and they need replacing, not cheap.

YG

 

We use crisco to lube the front of the lys it works good. The hard part is getting all four shifts to clean up properly and not get in a hurry. And never turn the keys up by hand if you max out your setting please turn the others down and your sweep up don't open the keys more by hand.