This is topic Moving Simplex XL heads 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=010842

---

Posted by David E. Nedrow (Member # 4981) on 03-13-2011, 09:18 PM:
 
As some of you may know, I've been trying to correct a problem with one of our projectors. It's a jitter issue.

This projector was "inherited" with the theatre when we took over. To give you an idea in what shape it was, twist ties were used to hold the gate on, there was about 1/4" of water in the oil, the light exposed parts of the projector were carbon scored ("looks like you boys have seen a lot of action"), and there was rust on the shutter and douser mechanisms, along with other evidence of a past water leak on the projector. I've done the best I can "in place", and think it's probably time to take it out of services and completely tear it apart to work on it.

Our #2 projector was purchased last year from a reliable source who had completely rebuilt it, and it runs nicely.

The problem is, #2 has no red reader or lamp house/rectifier (we rent them when necessary, until we save money for a matching pair of new ones). It also does not have a permanent cable run yet for the sound head, etc., nor is it hooked into the automation.

My thought is that it may be easiest to simply remove the #1 projector head, and replace it with the head from #2.

Having not done this before, is it a workable/reasonable idea, and, if so, is there anything I have to watch for? I think the only thing I'm unsure of, looking at the Simplex manual, is precisely what they mean when they call for a "scarcely perceptible backlash between the mating gears" when adjusting the horizontal and vertical shafts. Backlash means? And scarcely perceptible?

-David
 

---

Posted by Randy Stankey (Member # 64) on 03-13-2011, 10:24 PM:
 
http://en.wikipedia.org/wiki/Backlash_%28engineering%29

Backlash refers to how much play there is between the gears as they mesh together.

Generally speaking, the tighter you press two gears together, the less backlash they will have but at an increased risk of jamming/binding or failure due to premature wear.

The manual is instructing you to mate the gears together so that they are tightly meshed but still loose enough to move freely. You will feel a "barely perceptible" amount of movement between the gears as you begin to turn them.
 

---

Posted by Randy Bowden (Member # 587) on 03-14-2011, 12:13 AM:
 
Hi David,

I've been running a full time 35mm projector repair shop for the past 14 years, so I think I can help you out a little here. Moving the picture head over is really not that difficult. If you are running a simplex soundhead then you have 2 bolts securing the projector to the soundhead via a bracket attached to the bottom of the projector, the bracket extends out the front and back side of the projector. Do you have an SH series gearbox soundhead (this would be the style you add oil to) or do you have a newer belt driven soundhead? Assuming you have the older gearbox style, you will notice 3 gears that make up the gear train between the soundhead and projector. take a close look at your machine, get your hand in there and wiggle the gears back and forth, the slop you feel in the gear train is what we call gear lash.

Basically, you just need to remove 2 bolts, disconnect your douser wiring and you can then swap the picture head over. You will notice that the projector will move fore and aft once it's 2 bolts are loosened and that is how you adjust for gear lash. You just need a little slop in the gear train to keep things from binding up.

Good luck. Feel free to post any more questions.
 

---

Posted by Monte L Fullmer (Member # 2797) on 03-14-2011, 08:30 PM:
 
I've done the old "paper thickness" trick between the gear teeth to get the right amount of gear lash.

Another trick was to leave the bolts loose and literally "hug" (moving the machine laterally across the sound head) the machine with it running to get that 'sweet spot' so the gears quit whining.

When it hits that 'sweet spot' is when I tighten down the two 9/16" bolts.

XL's are fun to work on..

-Monte
 

---

Posted by David E. Nedrow (Member # 4981) on 03-14-2011, 08:40 PM:
 
Cool, great info from all.

I should have time tomorrow to work on this. I'll post an update. Or a call for help. Whichever is appropriate.

-David
 

---

Posted by Joshua Waaland (Member # 287) on 03-15-2011, 06:57 PM:
 
What part of Columbus are you in?
 

---

Posted by Sean McKinnon (Member # 612) on 03-15-2011, 07:44 PM:
 

quote: Monte L Fullmer

---

Another trick was to leave the bolts loose and literally "hug" (moving the machine laterally across the sound head) the machine with it running to get that 'sweet spot' so the gears quit whining.

---