C&P 8x12 NS Clunking Noise with Impression
Long time reader, first time question asker! My C&P 8x12 NS, treadle powered, just starting making a new clunking noise. I have a feeling it has to do with too much impression since I was pushing it further than I have in the past. I get a metal clunk noise with impression *just* as the platen starts to open again. It seems there is enough pressure to cause something to slip, then reengage, causing the noise. I can see the large gear cam wheel drop a small amount just as the sound happens. Looking inside the gear as I’m slowly treadling, I can see the cam roller in there stop turning briefly, then start again when the noise happens. I got a videos of all this then backed off the impression. With less impression the sound is quieter but still present. I swear it wasn’t happening before but maybe I’m paranoid. And with impression off, there is no (new) sound as far as I can tell. Wondering if there is a diagnosis… and if I’m using a light impression in the future if all will be fine or if the problem will get worse?
Here’s it running with impression, sound just as it opens: https://drive.google.com/file/d/1f6V9gw5LDGtnrfL6qSlW-cBPnlzZTySN/view
Here’s it running without impression, no unusual sound for my press: https://drive.google.com/file/d/14cEl134aCcMzwVTMKy8kXXxlJwSggDio/view
Here’s the cam roller in the large gear from the top down, you can see it rolling smoothly, then stopping, then rolling again as the sound occurs: https://drive.google.com/file/d/1P3ezqr5T9IlYWdzohVqb8o4wmD5lgTi0/view
Thanks!
Wished I could help, I ran those for years, and they sound normal to me.
Mine’s the same model but motorized, though it does sound similar in this case. Has it affected printing at all? When you say “pushing it further than you have before” do you mean just with packing or did you adjust the platen? I would try watching it from below to see if its anything to do with the throw-off mechanisms. Probably unrelated but it could be good to go through and clean out and re-oil all the oil holes if you haven’t in a while.
Mine’s the same model but motorized, though it does sound similar in this case. Has it affected printing at all? When you say “pushing it further than you have before” do you mean just with packing or did you adjust the platen? I would try watching it from below to see if its anything to do with the throw-off mechanisms. Probably unrelated but it could be good to go through and clean out and re-oil all the oil holes if you haven’t in a while.
Just glad you’ve both said it sounds relatively similar/normal to you. It’s definitely a new noise for my press but perhaps just a louder version of the same noise it’s always made, but made worse by extra impression depth?
Tyler - pushing it further with more packing, I didn’t make any platen adjustments. Also a good cleaning is probably in order - I always find it a balance between keeping clean and accidentally removing that little bit of gunk that was somehow making everything work haha. Throw off also seemed to be functioning as it should but I will double check.
Make sure the “Gate Lock” is not kicking out. i can post a google drive video link Wed.
I think the gate lock is behaving normally but I’m mostly self taught on the C&P so I’m making some assumptions. The gate lock slides smoothly into place beneath the rocker, maybe about 2/3 of the way? A portion of it does stick out beyond the rocker still. It doesn’t pop out during impression though, is that what you mean?
yes! You are doing fine if you know what the gate lock is. it should not move at all during impression. the rocker should not move at all either. hitting hard “high up” or above the center of pivot will cause this. it is a very harmful condition for the press.
Can you rock the platen a lot in the open position?
I too have the same style/size press with the same noise. This noise (knock) is only on impression, but does not affect the print at all…..just like everybody else has stated. I’ve been over and over it trying to figure it out and gave up a couple years ago and enjoy printing on it…..just part of the rhythm of printing on that press. Each press I have has a different rhythmic pattern when printing….really cool listening to them!!!
http://libertypressia.com/PressRoom/CP810.html
Steve - Liberty Press
Another good spot is to check for any, free play, in the pinion gear key. It will “load up” coming onto impression, then as the crankshaft and gear pass through “full on impression”, the pressure from the image will Throw the gear forward, causing a banging noise. The more pressure, the louder it will be.
Check for a tight key. Replace if there is play. Original is probably just square “key stock”. If so, an option, if the head will fit, is a tapered Gib Head key. need to check for clearance and, if so, it will solve the problem. those need a speacial puller, and some care to fit. Fitting them is another topic. I can send pics of the puller, and process if needed. Otherwise, just replace with new square key, when banging, they wear out, and will wear both the shaft and the gear.
https://www.mcmaster.com/gib-keys
https://www.mcmaster.com/square-keys
Steve - good to know I’m not alone! It doesn’t seem to be affecting the print quality over here either… but just want to make sure I’m not causing harm over time.
Eric - The platen rocks a *very* small amount when open - how much is an issue? And thanks for the tip on the pinion gear. I’mm check when I’m in the print shop next and will post any further questions about the key/replacement/etc
a few degrees of movement is fine. it is very hard to see in to where the roller is, but have an assistant move the platen while you look down in from above, or in from the back,in to see the roller in the race. See if you can see that the roller pin is not moving. This is seen by the roller itself, “Cocking to an angle” in the raceway…. Sounds like you are in good shape tho.