Double image

Hi. I m running a 1985 sm 102 5color press with double perfector...i m getting a problem of double image in 1st printing unit which is normaly black...specialy with smal texts...anyone knows whats the reason. its happening on all stocks paper/board. we normaly run box board 260gsm and some magazines on 52gsm newsprint.

 

I would check for a stuck or sticky gripper, or dirty gripper pads. That is a common problem we tend to have.

 

Maybe check your infeed settings also.

 

my press is a bunch of problems...

 

i want to set my transfer cylinder grippers...what is the right method?

 

Why do you think the transfer cylinder grippers are creating the double?

 

yes i m quite sure...but if there r some other causes then plz tell me what can be those....i ve checked the cam followers...look ok...also its the perfecting unit..

 

Ok, here is a couple things to try. First off there is really no way of readjusting grippers on any cylinder on your press without the proper tools. You will need a degree wheel, post to hold the degree wheel, zero gauge to position the degree wheel in the proper position, and you will need to know the opening and closing times of the cylinders. Trust me, its the only way to adjust grippers on your press. That being said, one easy check of the transfer cylinder grippers is just inch a sheet into the press, once the impression cylinder has the sheet, grab the tail of that sheet and give it a firm pull as you continue to inch the sheet into the transfer cylinder, if the impression cylinder lets go of the sheet before the transfer grippers are closed the sheet will be easily pulled out and you have a problem that will cause a double, if the sheet continues into the transfer cylinder that means your gripper timing is not too bad. Try the same procedure with the sheet going from the storage drum to the reversing drum in straight printing also. Other than that you are taking a huge gamble by trying to adjust grippers without the proper tools. Ive been fixing Heidelbergs for over 18 years and just my experience tells me that its the perfector. Check the spring loaded and fixed gripper for any movement. The fixed gripper should have very little movement, the spring loaded should be the same other than the movement from the spring tention.

 

thanx exheid for ur advice...tell me one thing...as the transfer grippers and pads have a sort of engraved lining on them but on the pincer grippers there is no lining...is it ok? bcoz when i touch those grippers with finger they look smooth...and plz tell if we have those tool then what is the way to set the gripper timing...thanx in advance.

 

Yes, the grippers on the pincer bar will be smooth this is normal. However the spring loaded side should have a urethane or rubber type surface to them. If you use your fingernail you should feel this. If you have the correct tools to adjust grippers you will need 2 people, one above the machine and one under the machine. Loosen all the grippers on the bar execpt 1. Ajust that one to the proper opening and closing times by the adjusting screw or by bumping the cam. Once the gripper is set correctly then adjust all other grippers to match this gripper. Follow this procedure on all cylinders.

 

will you explain BUMPING THE CAM....is it possible to adjust the timing with the two springs in the gripper bar with a 17mm lock nut? this was done by a mechanic recently on our press...but i could'nt understand his logic...that was transfer cylinder.

 

I would not bump the cam unless you absolutly have to, i probably shouldnt have even said that. I dont know of a 17mm lock nut on the gripper bar. The only thing I can think of is maybe the 17mm lock nuts on the pad bar. If you loosen the nuts there are adjusting screws on either side of the bar that allow you to raise and lower the pad bar. This will change your gripper timing as well. There is a dial on the pad bar with numbers around it. The number should be on 1 and all pad bars throuout the press should be in the same position. Moving the pad bar to adjust gripper timing is never a good idea because it will screw you up in other areas.

 

thanks exheid...there is another thing that i noticed when our press was being installed...it was installed by a british engineer...when we were doing the proofing on press there was a difference in print length between 2nd and 3rd unit on one side of the sheet...he adjusted this dif ference from pincer grippers using a 3mm allen key...do u have any idea about this?

 

Probably he was trying to adjust the grippers on the pincer bar. 3mm allen is needed to adjust these grippers. This may add to your doubling between units 2+3.

 

thanx exheidmech for sharing ur knowledge....one more question which is not related to the topic...how can we check the correct tension of the delivery chain?

 

Open the door on the oerator side of the delivery. Behind the door you will see 2 lock bolts I think they are either 17 or 19mm I forget. unlock the bolts. Attached to the mechanism you are loosening is a round bolt with holes in it. Use a pin wrench to turn this round bolt. Turning the bolt one way will loosen the tension and turning it the other way will tighten it. If you look closely at the bolt, on the opposite side of the threads you will see a dome at the end of the bolt. This dome is spring loaded. As you loosen the tention should see the dome come out of the bolt head a little bit revealing a shoulder. Once you see the shoulder retighten the chain till the shoulder is flush with the head of the round bolt. Once its flush your tension is set. Repeat this on the drive side. Just be aware that your machine is 25 years old, things may not move the way they once did. Also, that age of machine has a very noisy delivery, which is normal. Very difficult to get that quiet. If you are running anywhere close to 8kph you are doing great.

 

yeah we normally run at 7 but chain is really noisy...to get rid of this we tried to tighten the chain...noise was gone but no paper coming out of delivery...lolz...

 

Try to readjust the delivery grippers, I think I told you how to do that already in a previous post. If you still are dropping sheets then you can slightly lower the closing cam for the delivery grippers, this will make them close earlier.

 

ok i'll try this...regards...