In trouble I think
As much as I have read on here this makes me nervous to post,
Today while trying to print post cards I was drawing back th tympan to tighten it and noticed my platen rocked back to me some. Reading on here about such things I am sick
The rock is not side to side but if you’re standing in front looking at the platen it rocks up and down, not knowing but it’s about 1/8” I think, no it’s a 1/16, I just measured
it’s not loosely rocking,,, you have to grab the platten by its lower edge and pull up. It goes back down when you let go.
I have deduced its not the platen itself or impression screws but the whole of that assembly is sitting on a saddle over a main shaft, the saddle is what is moving…
Reading on BP I did close the platen in impression, no chase installed, and it did not rock at all, it just does it when it’s fully open or partially open and only when you grab the lower edge and try to pull up and to the rear towards you.
What I printed was even, so i sorta took cheer to that but I was having trouble inking,so it was light and spotty, yet all there, see other post. Any shimmering rays o light to encourage or is it doomsday clouds looming??
if its tight on impression i think i wouldn’t worry , my last c&p when it printed my flywheel would jump and make a loud noise, we put at least 2000 impressions on this press every day for 10 years. youink problem might be cause its cold, turn up your heat, i sometimes run an electric heater on the floor near my press in the winter.
I wouldn’t worry. i have read the same advice. One of my presses a 8x12 oldstyle C&P has exactly the amount of movement you describe. And like yours when it come up to impression it becomes solid because the platen lock slips into position. I’ve used this press since 1994 and never even worried until I read an account of how to check wear and then it got me worried! My press is 1904. So I just carried on and apart from worn rails, and roller saddles, etc, etc, still gives me a beautiful print. An impression slur would show as a slight double print because the sheet moves during printing. Mine doesn’t so if yours is the same don’t worry.
dennis Wild
http://lasting-impressions-letterpress.blogspot.com/
I dont know your machines but this is a theory and Dick G may see my point and clarify ,,
when the machine goes on impression the main shaft through the platen will turn slightly because of an eccentric shaft operated by the impression lever this has to occur because of the clamshell design (to over come the hinge effect) This means that the whole swinging platen must lift slightly at the point just before it closes and begins to lock with some block then raising to push the impression to full pressure. because of that effect when there is no pressure brought to bear and everything is free of load (as long as all moves easily) you probably would have a degree of play in an upward direction , dont take this as gospel but unless there is play when you stand to one side and pull the platen side to side i would never be concerned . a good test would be to lock up a form set up for some fine type , paste a clean sheet to the top tympan so that it cannot move and run the press in impression and just keep impression on for ten imps then knock the imp off and repeat on and off a few timesstill printing on the pasted down sheet . once done remove the sheet complete with packing and inspect the image looking for slurr. no slur no problem . its a test that cost you no more than a bit of time .!! good luck.
P s. if its that cold keep the ink disc indoors when not in use if the press has one that is removable !!
you don’t say what press this is, so assuming it is an old C&P a little rock is okay. on the gear side of the press there is a “race way” in the main/bull gear. there is a roller that runs in this race. the roller is on a stud that is bolted to an arm that is on the rocker. this is what makes the platen open and close. with the platen in the open position, rock it and look for movement in this stud/pin. there should be a nut on it. check for tightness.
Look, play when the platen is not on imrpession is just the difference between the diameter of the cam follower on the rocker arm, and the camway in the large gear. That is necessary and normal. The only time to worry is when there is play when the platen rocker lock (under the feedboard) is engaged.