This is topic Century Intermittent problems in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.
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Posted by John Westlund (Member # 913) on 06-29-2002, 02:31 AM:
Our century SA is having problems with its intermittent. The first one had been in the machine for years when it started to tick. We got a spare and had it rebuilt and installed it while the original was rebuilt. I put the original back in and it soon after went out. So I then reinstalled the spare and now it is going out again. The first two were running with century oil. This last one we switched to lavezzi. What could possibly be going wrong with these intermittents? Thanks
John
Posted by Richard Fowler (Member # 893) on 06-29-2002, 08:30 AM:
Bad rebuilding job.....the end play on the flywheel not adjusted properly....the gear mesh too tight in installation.
Richard Fowler
TVP-Theatre and Video Products Inc. www.tvpmiami.com
Posted by Paul G. Thompson (Member # 655) on 06-29-2002, 07:58 PM:
I agree with Richard. Bad rebuilds. Hopefully, the company that rebuild them should honor the warrenty.
Posted by Gordon McLeod (Member # 33) on 06-29-2002, 08:30 PM:
The ticking maybe the clearnace between the star and cam
It is adjustable but you need to be very carefull doing it
Maybe it is that synthetic oil 
Posted by Mark Gulbrandsen (Member # 72) on 06-29-2002, 10:27 PM:
John,
Please clarify what you mean by "going out". That wording is too generalized. Since I rebuilt the movements please let me know exactly. I have the first one at the shop and can't find anything wrong with it(except that you took the sprocket off it for another movement). You claimed that it seized up but there is no indication of that at all. There is no galling at all of the shafts or bushings. Still looks like new inside and has been running just fine now for three days in our test head...... Are you meshing the gears too tight when you re-install it? That can cause overheating of the gears and possibly lead to other problems. A slight ticking noise, if thats what you are refering to as "going out", is not at all unusual in Century movements especially after break in time. Sometimes slight re-adjustmnent of star and cam clearance is necessary.
Mark @ GTS
Posted by Paul G. Thompson (Member # 655) on 06-30-2002, 01:47 AM:
John, I re-read your post. It is highly unlikely that the second one would go out like that, especially if it ran ok before. I would recommend you check your gear mesh. The movements have a little adjustable stop tab on them. It could be set for too loose or too tight of a mesh. If it was set for one machine, that does not mean "one fits all". What I have done, (although it may not be politically correct) is to loosen the little bolt that holds that stop key in place, install the movement, set it for a very small backlash in the gears, (notice I said small backlash) and tighten the movement down. Then I roll the machine through by hand, and check the backlash setting at different points to make sure it is not binding. After I am satisfied with that, I tighten the little locking screw on the stop tab after I physically position the stop tab aginst the stop. (sounds like double talk, but you will see what I mean when you eyeball it.)As far as the camshaft end play is concerned, that can be adjusted while the movement is installed in the projector, although it is best to have it out of the projector. That big shiney screw you see is basically a plug. Remove that, and inside you will see the screw that is used to adjust the cam shaft end play. I set that setting to just a "contact fit". The end play will then go away. Be careful....don't make that adjustment unless you need to. If you tighten it too much, you'll probably ruin the movement.
For the dwell or indexing adjustment is concerned, I don't do that unless the movement is removed from the machine. That adjustment requires a "pussy touch" (please pardon the pun) to be successful. There are two little set screws that are used to make that adjustment. However, all the parameter screws have to be just a slight tad loose so the faceplate of the movement can position itself to get the right dwell. Then you have to tighten down all the parameter screws, and check it again, along with the camshaft end play adjustment. It may take several attempts to get it right.
If you never did this before, I suggest you don't unless Mark steps you through on these adjustments. If you go at it yourself for the first time, you could really screw up the intermittant movement.
If anyone sees any fault in the way I set them up, please blast me. If I am doing it wrong, I want to learn how to do it right, and not half-assed!!!
Thanks
Posted by John Westlund (Member # 913) on 06-30-2002, 02:10 AM:
Let me clarify this a little bit. The noise is more then a ticking. On the movement that mark has now it was growling and violently shaking the projector. The film was jumping out of frame and was slowing down. We shut it down and then when I tried to switch the motor on and the projector would not turn over. I may also add that the intermittent itself was extremely hot, so hot that you couldnt touch it without burning your finger. It was the hottest on the cap that holds the sprocket on. When I took the sprocket off I had to really work at getting that end cap off the shaft. It was stuck on there pretty good.Paul, that is basically how I set the gear mesh. I did away with the stop and just moved the movement until it wasnt too loose but so that it was not binding up while turning it over by hand.
Hope this helps. Thanks for all the info.
John
Posted by John Westlund (Member # 913) on 06-30-2002, 02:14 AM:
BTW, the movement in the machine now has really quieted down. It was starting to growl but it hasnt since thursday night.
Posted by Paul G. Thompson (Member # 655) on 06-30-2002, 02:19 AM:
Hmmmm.....This is an edit. Was that your old movement that was growling? I can see that happening of the starwheel bushing was on its way South... If it was just a "ticking", it is probably a dwell adjustment.
Posted by John Westlund (Member # 913) on 06-30-2002, 02:28 AM:
Yes Paul, that was the "old" movement that was growling. It maybe had 150 hours on it. I think it probably was the starwheel bushing because thats where the heat seemed to have been generated from.
Posted by Paul G. Thompson (Member # 655) on 06-30-2002, 02:29 AM:
John, better check your gears. If you had that heavy of a load on them, the gears might have been slightly damaged. But if it is running smooth, chances are, you'll be ok on the gears....but it is still worth checking.
Posted by John Westlund (Member # 913) on 06-30-2002, 02:35 AM:
Thanks Paul, thats sounds like a great idea. Do you know what could have caused the starwheel bushing to fail that quickly? This is the same movement that Mark has been running for 3 days with no problem. It could have freed up when I took the sprocket off but I would think it would have seized up by now. Maybe it was just a faulty bushing.
Posted by Paul G. Thompson (Member # 655) on 06-30-2002, 03:01 AM:
It could have been a bad bushing. Sometimes they will run for days without problems, and then sometimes not.
Posted by Pete Naples (Member # 761) on 06-30-2002, 06:41 AM:
Two things spring to mind.Are you getting the flywheel on tight enough? Some of the latest ones will not tighten correctly once they've been removed, I end up drilling and tapping the flywheel to take a bigger screw (One which has a diameter closer to the hole in the intermittent inupt shaft). I've found countless of new'ish ones where no matter how tight you the screw, the flywheel still moves slightly on the shaft which makes a horrible noise!
How much gate tension are you running with? I've seen new and rebuilt intermittents wrecked in a very short space of time due to excessive load placd on them by grossly excessive gate tension. I've always thought that you should be able to get teh picture to jump at the minimum setting, then increase until it just goes steady. Too many people turn it up and leave it up, also too many machines I've come across have the trap set up so that minimum tension is not really minimum!
The points made about gear mesh and shaft end float are very very vaild indeed. Century intermittents are pretty robust mechanisms if set up properly.
Posted by Steve Guttag (Member # 268) on 06-30-2002, 09:46 AM:
I did have one theatre that had some powdering problems that manifested itself in the intermittent endbearing...perhaps you are having some polyester sheding? Also, what type of cleaner are you using? Is rubbing alcohol in the booth? When you set your intermttent gear lash, do you run the "shutter" knob up and down to verify that the vertical shaft is vertical? If the projector starts to "whir" on any point of it's travel you have a worn intermittent drive gear/key or the vertical shaft isn't. Note this will also tend to make the shutter shaft move fore and aft. Steve
------------------
"Old projectionists never die, they just changeover!"
Posted by Paul G. Thompson (Member # 655) on 06-30-2002, 01:17 PM:
John, I think Steve is right on target with his assessment.Steve, I am glad you mentioned the "shutter" knob. I never did that when I set the lash, but your suggestion is a damned good idea. I will start doing that now...thanks.
Posted by Mark Gulbrandsen (Member # 72) on 06-30-2002, 03:17 PM:
A note on re-installing verticle shafts in Cehturys....
When you place the intermittent drive gear bracket into the intermitent carrage be very careful and check for excess paint which may have seeped through onto the upper and lower tangs of the carrage. It can require undo amounts of pressure to force the bearing block into the carrage and you can end up actually bending the verticle shaft. Its best to check the bearing block for fit in the carrage before tightning the upper and lower bearing blocks down. It should be just a loose fit with no binding at all. If you suspect that the verticle shaft has been bent it is best to replace it with the LaVezzi stainless steel version as it is very resistant to bending and also to being chewed up by a failing bearing at either thr top or bottom. Its also best to ahve a set of laps to clean out any burrs fomr inside the sprocket sdrive gears before attempting to use one of these shafts. The stainless is quite hard and if a gear has a small internal burr it will not come back off the shaft without being pressed off. Perhaps I should ship you out a loaner SA head this week and you send yours to me for a testing and checkout with both of the movements.
Mark @ GTS