This is topic Are all brain wraps preventable? 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=005734

---

Posted by Blake Zaugg (Member # 1455) on 01-09-2004, 01:15 PM:
 
Are most brain wraps are due to film-handler error, incorrect threading etc... or are there some wraps that just happen?
And the next question is how often should the prints/platters/projectors be checked while the show is running? (10min, 15 min, etc...) Thanks.
 

---

Posted by Paul Konen (Member # 41) on 01-09-2004, 02:01 PM:
 
Some can happen during threading errors on Christies if the clear leader gets caught around a white post on the brain. Otherwise, they run fairly clean.

Speco's on the other hand can happen out of the blue. Static is a particular problem because it (static) will cause two layers of film to get into the brain causing the payout fingers to max out causing the wrap.

I expect my staff to check every thirty minutes but it is essentially more because they have to pass projectors multiple times during a normal start schedule.
 

---

Posted by Brad Allen (Member # 470) on 01-09-2004, 02:10 PM:
 
I've had Pott's platters have brain wraps out of the blue as well. Sometimes caused by static, and sometimes caused by a stuck micro switch. Even when checking every 15 minutes, it seems it knows to happen between checks.
 

---

Posted by Brad Miller (Member # 2) on 01-09-2004, 02:19 PM:
 
The only brain wrap I've ever had in my booths is from someone misthreading, usually something stupid like the example Paul gave. Even changing tons of trailers every week and relying on start timers 95% of the time, it just doesn't happen. Sure it sounds like a sales pitch, but the truth of the matter is that if you use FilmGuard it eliminates the static and sticky spots on the film (from cheap splicing tape and such) and the brain wraps DO stop because there is nothing left to trigger them except a physical malfunction of the platter, such as a stuck microswitch on a Strong platter. Otherwise yes they ARE preventable. Anyone who has used the product knows this to be true.
 

---

Posted by R. Andrew Diercks (Member # 1725) on 01-09-2004, 02:34 PM:
 
I have used Potts/Strong platters for most of my career and it's a good idea to replace the micro every 18 mos. or so, even if it's working. I don't remember one that has made 2 years. We date the bottom of the brain as to how old they are to keep track. Otherwise all brain wraps have been human error. Static hasn't ever caused a brain wrap, we will babysit if there is static. I do wish I had film guard though. Our theatres are slowly getting them.
 

---

Posted by Manny Knowles (Member # 1171) on 01-09-2004, 02:34 PM:
 
I witnessed a dramatic OVERNIGHT decrease in the incidence of brain wraps when I got rid of ORC platters and switched to Christie. They are wonderful machines, so long as you keep them maintained.

The few brain wraps that have happened with the Christies have been due to either human error or sudden equipment malfunction (dead card, motor, etc) so while most are avoidable, it would be wrong to say that you can eliminate them completely.

dCinema will end this problem once and for all.
 

---

Posted by Dustin Mitchell (Member # 372) on 01-09-2004, 02:46 PM:
 
Andrew, what model of Strong platters are you using? I have six AP3's with a total of 12 brains that were all installed in Ocotober of 1997. To date I've had two micros go bad.
 

---

Posted by Paul G. Thompson (Member # 655) on 01-09-2004, 03:50 PM:
 
If you have the Potts or CFS platters that have that 3-amp microswitch you can expect them to fail especially if the ballast resistor in the motor that shunt the switch burns up. Most of those resistor failures are due to someone having the switch on the motor in the wrong position during make-up.

If the platter pay-out heads are equipped with the huge micro switches, generally the switch should last a long time. However, if the ballast resistor is still burned out, the platter is subject to whipping which could toss the print on the deck.

Some of the pay-out head wraps I have seen with any platter is poorly made splices or poor quality splicing tape that sticks to the convolution before the splice or after the splice.

Other than that, most I have seen were due to mis-threading.
 

---

Posted by Jason Black (Member # 684) on 01-09-2004, 03:55 PM:
 
Dustin,

Consider yourself lucky. I have 32 of them (AP3's) and my micro's have to be chnaged out every 2 years or so. I find that when you have one go bad, it's best to start the round of changeouts. At $12.50/switch, it's cheaper to ensure that a bad switch doesn't cause a show to go down where you'd lose more moeny and piss plenty of people off.

I've had three go bad in the last week. I can't prove that they were bad, but there simply is no other reason that the decks show have hung wide open (continual feed mode) to the point of a "fast-wrap". I just ordered another dozen for changeout and will order another dozen once those are used.
 

---

Posted by David Favel (Member # 1125) on 01-09-2004, 05:05 PM:
 
Agreed, There is no reason for wraps on Speco's. In reality, an improperly threaded AW/CNR should be apparant before the movie starts. I have gotten into the habit of checking all splices going thru the first play on the Speco.
 

---

Posted by Mark Gulbrandsen (Member # 72) on 01-09-2004, 07:09 PM:
 
It is absolutely true that Strong/Potts micros should be changed out at least every 18 months to two years even if they are still working......da...don't wait for them to fail! Waiting for them to fail is about as stupid as giving your car an oil change when it runs out of oil . Also those micros are available in .5 oz internal spring tension instead of the standard 1 oz internal spring tension.

Hey Brad, using the above mentioned .5 oz tension micros is our secret to making a Strong/Potts run very, very smooth. The .5 oz switch performs far better and is almost mandatory with estar film. There is no hint of the platter wrapping the film back around unlike when the standard 1 oz. switch, which seems to need 1/2 to 1 turn wrap to pull the arm over and activate the switch! The switches the factory sends out are the standard 1 oz internal tension!

I will post the actual Honeywell Microswitch part number for the .5oz switch next time I'm in the office and can check to see what it is.
Mark @ CLACO
 

---

Posted by Dominic Espinosa (Member # 2122) on 01-09-2004, 08:58 PM:
 
Mark is correct.
Lower tension makes all the difference in the world.
One operator error that wasn't pointed out, probably because it's stupid obvious, but I'll metion because I've seen it...
Someone forgetting to set the payout platter to ... PAYOUT!
If you're new to the booth, or new to a Potts/Strong platter, double check your work.
Also, beware when adjusting your payout speeds. A tech once set one of my Christies and the thing speed wrapped because it was way too high, off wasn't truly off.
 

---

Posted by John McConnel (Member # 2000) on 01-09-2004, 11:24 PM:
 
We use old Kinotone platters, and don't have many brain wraps. But to prevent damage when there is a brain wrap, we installed Kinotone's tension safety switch as a retrofit. They work well. Since installing them, we've had no film damage.
 

---

Posted by Manny Knowles (Member # 1171) on 01-10-2004, 09:26 AM:
 
One really terrific aspect of the Christie platter system is that there is no need to switch each deck to payout or rewind. It just "knows."
 

---

Posted by Peter Mork (Member # 1336) on 01-10-2004, 02:16 PM:
 
I built my own tension sensors, out of junk that was lying around (the springs used to stretch screens worked very nicely as counter-tension providers) to use in our two Speco houses. They have really helped stop film damage in brainwrap situations. Unfortunately if a brain jams (due to static or whatever) it happens so quickly that tension sensors don't help - they will shut down the film but you still get damage in the form of ripped perfs at the projector.
 

---

Posted by John McConnel (Member # 2000) on 01-11-2004, 07:50 PM:
 
Our Kinotone tension sensors stop the projector before there's sprocket damage. Perhaps if would help if you used a spring with less tension.
 

---

Posted by Brad Miller (Member # 2) on 01-11-2004, 07:53 PM:
 
Guys, tension sensing failsafes are wonderful and all...but the real point here is to prevent brainwraps in the first place. Any time the tension failsafe trips, a brainwrap still happened and as a result your show went down. That's just not acceptable in my book, and most paying customers don't appreciate the show interruption either.
 

---

Posted by Peter Mork (Member # 1336) on 01-12-2004, 02:58 AM:
 
John, the thing is when the film jams (as opposed to wraps) the tension sensor may trip, but can't stop the projector quickly enough to prevent some damage.
 

---

Posted by Bill Carter (Member # 156) on 01-12-2004, 10:43 AM:
 
I would have to agree with most everybody else here. Aside from a once in a blue moon card failure, the only platter wraps I've encountered have been due to static or sticky goo on the film...
both preventable.
 

---

Posted by Tom Wienholt (Member # 1510) on 01-12-2004, 12:09 PM:
 
I don't understand how static and sticky spots can cause a wrap. That causes the film to get jammed into the center-feed, not wrap around it. Wraps in my opinion can only be caused by poor threading or a mechanical malfunction.
 

---

Posted by David Favel (Member # 1125) on 01-12-2004, 02:01 PM:
 
On a Speco if you have a sticky piece that pulls it plus some more film thru the dancer. What then happens is the projector jams but the platter keeps paying out - wrap.
 

---

Posted by Tom Wienholt (Member # 1510) on 01-12-2004, 04:24 PM:
 
That makes sense but the wrap wasn't the cause of the problem.
 

---

Posted by Timothy Eiler (Member # 383) on 01-12-2004, 04:53 PM:
 

quote:

---

I don't understand how static and sticky spots can cause a wrap. That causes the film to get jammed into the center-feed, not wrap around it. Wraps in my opinion can only be caused by poor threading or a mechanical malfunction.

---