Film-Tech Forum ARCHIVE: Simplex Pad Roller Arms Popping Open

This is topic Simplex Pad Roller Arms Popping Open in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Michael Elam (Member # 788) on 01-30-2005, 03:21 PM:

Other than bad splices and torn sprocket holes what else would
cause the pad roller arms to 'pop' open and lose the loop underneath the intermittment.

Posted by Richard Hamilton (Member # 321) on 01-30-2005, 03:55 PM:

Michael,
Which model projector?

Posted by Christian Volpi (Member # 2370) on 01-30-2005, 04:33 PM:

Is the roller that rests against the intermittent actually rolling? If it is you need to loosen up the tension in the roller so that there is just enough space to prevent it from spinning. If the roller is rolling it is putting too much tension on the film and when a splice goes through it will cause it to pop open. Of course this is just my opinion, listen to whatever Richard has to say, he worked on all 14 of my Apogee's.

Posted by Monte L Fullmer (Member # 2797) on 01-30-2005, 07:54 PM:

quote: Richard Hamilton
Which model projector?

Hopefully, he's talking about the middle constant speed sprocket pad roller assembly on from the XL's to Apogees-being that this sprocket unit is after the intermittent sprocket.

Sounds like the pin that the closure spring behind the arm is getting ready to bust. This is one of the design flaws of Simplex with that pad roller arm assembly for the middle constant speed sprocket. When that pin breaks, the closure spring will might stay there, but loses the spring tension greatly, and then the spring will come off all together, meaning that the pad roller arm will have to be replaced.

I've replaced a good dozen of these arms due to that pin behind breaking.

Why this pin breaks is that it's also the stop pin for the roller arm,which hits against the sprocket boss assembly and this pin eventally gets bent back and will snap without notice.

Another possibility is that the fibre gear on the other end of this middle constant speed sprocket is somewhat worn, stripped, or the vertical shaft (for XL's) is out of alignment, causing the teeth mesh between metal and fibre gears be somewhat loose, and during the run could cause the lower loop to collapse.

This could be from a bad brainwrap with "poly" film, or something to immediately seize the machine.

And lastly, this assembly could be just loose on the mainframe. Check those 9/64th allen screws that hold the assembly to the mainframe for tightness. For if these are loose, the assembly isn't square to the drive sprocket attached to the vertical shaft,causing the gear mesh slippage.

-Monte

[ 01-31-2005, 04:10 AM: Message edited by: Monte L Fullmer ]

Posted by Richard Hamilton (Member # 321) on 01-31-2005, 01:10 PM:

Monte, i was preoccupied when I first read post. I completely missed the below intermittent part. On the Apogees, the upper and lower pad arm assemblies are different from the simplexes. I recently serviced a 10 plex where every single pad roller arm was loose on the upper and lower. On these assemblies, the arm is attached from behind, so you have to remove the assembly to get to it. The spring is also located inside the casting that mounts to the mainframe. I realize this would not cause you to lose the intermittent loop.

I dont recall how the padroller closes against the intermittent sprocket, but on a recent call for a different problem, I had a tech complain that these were popping open during splices when the theater first opened. He had already fixed the problem, so I didnt investigate further and see how he fixed them.

Later,
Rick

Posted by Monte L Fullmer (Member # 2797) on 01-31-2005, 01:56 PM:

Thx Rick for your reply. Little goof on my part of the Apogee thing..

When the note of the pad roller on the intermittent thing, only projector that I know of using pad roller for the intermittent was the Cinemeccanica V series in which that holddown spring that lock down the pad roller arm might be getting weak allowing such a opening effect. Whereas other machines uses the shoes at the intermittent area.

-thx Monte

Posted by Robert E. Allen (Member # 1351) on 01-31-2005, 03:20 PM:

Your bottom loop is too small and the film is lifting the arm off the sprocket. This will happen on our Simplex Millenniums if we make the loop too small. On our machines there seems to be only a three or four sprocket hole difference between too small and too big.

Posted by Michael Elam (Member # 788) on 01-31-2005, 04:02 PM:

Turned out to be the intermittment tension shoe 'block' located in the middle between the inner shoes, the top portion was broke and missing, not enough tension when the splice passed by.

Posted by Richard Hamilton (Member # 321) on 01-31-2005, 05:58 PM:

Michael, thanks for the feedback and letting us know what the problem was!

Rick