Film-Tech Forum ARCHIVE: Simplex 1050 trouble

This is topic Simplex 1050 trouble in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

To visit this topic, use this URL:
https://ft-forum.com/ft/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=1;t=001411

Posted by Andy Davis (Member # 262) on 09-11-2000, 11:39 AM:

I have a projector making a loud clattering sound. The sound is coming from the film getting stuck to the intermittent sprocket teeth. Instead of rolling off the bottom of the intermittent sprocket, the film sticks to the teeth. The film becomes detached from the teeth when the lower constant feed sprocket pulls the loop down. I've cleaned the sprocket, run different prints on the projector, and tried adjusting the loop size, but it still does it. The projector can still run prints but it makes a horrible clattering sound. Any ideas?

Posted by John Pytlak (Member # 331) on 09-11-2000, 11:55 AM:

Sounds like you may have badly worn or "hooked" sprocket teeth on the intermittent sprocket. There's a good discussion and illustration of this in Kodak's "Film Notes for Reel People, Issue #H-50-4 Troubleshooting and prevention of damage" that is in the "Manuals" section of Film-Tech.

Look at the sprocket teeth with a magnifier or pocket microscope (Radio Shack sells a nice illuminated 30X pocket microscope). Replace the worn/damaged sprocket. In a pinch, sometimes "reversing" the sprocket on the shaft will work as a temporary fix, since the other (undamaged) side of the teeth will now be driving the film. Fix it soon, as worn or damaged sprocket teeth do damage the film perfs.

The same "clinging" behavior can sometimes be seen on other worn sprockets. The snapping/clattering sound was sometimes referred to as the film "singing on the sprockets".

Check your gate and sprocket shoe tension/alignment/adjustment, and be sure the film tension is as low as possible while still maintaining a steady image. Excessive tension wears out both film and sprockets prematurely.

------------------
John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services, Entertainment Imaging
Eastman Kodak Company
Research Labs, Building 69, Room 7419
Rochester, New York, 14650-1922 USA
Tel: 716-477-5325 Fax: 716-722-7243
E-Mail: john.pytlak@kodak.com

Posted by Pat Moore (Member # 380) on 09-11-2000, 12:36 PM:

I think John has this one nailed.

I would even venture that reversing the sprocket to run on the other side of the teeth is more than a temporary solution, as long as the sprocket is in otherwise good condition (noo nicks, burrs, etc.). You should get as long a run on the other side as you did on the first. Be sure it hasn't already been reversed, of course...

Have you changed an intermittent sprocket before? The challenge is in its alignment. On a Flat (Straight or "Studio) Film Trap, use a proper alignment gage such as a LaVezzi AG-1.

It's a little tricker with the curved Trap, though the procedure is outlined in the Operator's manual as I remember. Use a small straight-edge off of the outer edge of the lower holdback sprocket to locate the intermittent sprocket to the trap. The outer edges of both sprockets should be in line.

Steel film is an alternative with either of the above.

Good luck!

By the way -- how old is the projector and (approximately) how many hours do you have on it?

Posted by Andy Davis (Member # 262) on 09-11-2000, 02:27 PM:

Thanks for the info John and Pat! I think the hooked sprocket teeth are on the inboard side of the intermittent sprocket because that's the only side that the film seems to stick to. I have never replaced an intermittent sprocket before so I may need to get our rarely seen or heard field engineer for this one. The projector is 21 to 22 years old. We have 6 Simplex 1050's and they are running well except most of them leak oil pretty badly.

Posted by John Pytlak (Member # 331) on 09-11-2000, 02:46 PM:

Andy:

Let's see: 21 years of 5 two-hour shows per day is:

21 years x 365 (days per year) x 5 shows x 2 hours x 60 (minutes per hour) x 90 (feet per minute) = 413,910,000 feet of film, or enough film to circle the earth's equator three times!

Yep --- time to get a new sprocket

Posted by Randy Stankey (Member # 64) on 09-11-2000, 03:03 PM:

Also check your inboard-side intermittent pad shoe.

I have seen projectors where the pad shoe gets bent or somebody didn't put the thing together right and the shoe grinds up against the sprocket, wearing the teeth down.

I wouldn't say it's a "commom" nistake but it's also not UNcommon. Sometimes people just make mistakes...

PS: Your projector is ONLY 20 years old? Heck! It's still just a young 'un! I had a projector that was at least 40 and it made a better pic than a brand new one! (That was back when they knew how to build 'em! )