Film-Tech Forum ARCHIVE: How to do 3D Interlock. Selsyns the best way to go?

This is topic How to do 3D Interlock. Selsyns the best way to go? in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Frank Angel (Member # 248) on 04-18-2005, 11:28 AM:

Carried from here: Basement/Penthouse Readers Thread It is sounding like these things (electronic controllers) are run just for speed control, but what about interlock -- are selsyns still the way to interlock for for 3D? I know interlock is used extensively for passing a print to a number of projectors, but that doesn't need to have absolute; what would be the best/easiest setup for frame-accurate reliability to lock up two projectors for 3D? Can the electronic controllers with tach talk to each other to keep two machines locked? If I go selsys, that would mean that I would only need to get the bracket to hold the selsyn and wouldn't require changing the existing motors. Don't the controllers need the motors swapped out for synchronous motors? Sounds like a much bigger job than just adding the selsyns....I think I even have the brackets.

Posted by Mark Gulbrandsen (Member # 72) on 04-18-2005, 04:17 PM:

I would use 2 Baldor drives ad motors and slave them together.

Mark

Posted by Richard Hamilton (Member # 321) on 04-18-2005, 08:51 PM:

Frank,
The couple of 3d's that I've done use Baldor motors and controllers. They are sync'd via a Baldor Smartmove. Baldor actually helped us writing the original program. When you "home" them, they are dead on, and stay that way. It's pretty cool, if you turn the Master motor by hand, the slave will stay right with it.

Posted by Phil Hill (Member # 371) on 04-18-2005, 08:55 PM:

The absolute BEST 3D interlock system IS (as Mark and Richard mentioned) the Baldor drives.

Have used them on 35mm, 870mm, and 1570mm projectors at up to 5hp...perfect sync and shutter phase.

It's almost spooky to turn the master projector by hand and have the slave exactly follow frame to frame. YIKES!

Posted by Mark Gulbrandsen (Member # 72) on 04-18-2005, 10:02 PM:

Phil,

The Baldors are great but what really impressed me the most was the Allen Bradley automation system that monitors all the critical aspects in the 15/70 system. That is one really impressive system and one that no one else has. I think it even reminds the operator when his bladder is getting full........ [beer]

Mark

Posted by Phil Hill (Member # 371) on 04-18-2005, 10:14 PM:

The thing that I didn't like about the AB drives was when I was doing a 48fps 1570 rolling loop projector, and had it working perfectly, I discovered that the AB controller was wrong in it's display and the projector was only running at 42 fps! A POS! Never AGAIN AB!

(Yeah, I know! I was STUPIT to trust the display without a strobe verification!) So shoot me! [Roll Eyes]

Posted by Mark Gulbrandsen (Member # 72) on 04-18-2005, 10:27 PM:

No, I wasn't talking about drives, was talking about the automation system. The projection system automation that the show controller controled...... The drives in Lehi are all Baldor.

Mark

Posted by Phil Hill (Member # 371) on 04-18-2005, 10:50 PM:

Oh... Ummm... nevermind.... [Wink]

Posted by Frank Angel (Member # 248) on 04-19-2005, 04:02 AM:

So how much $$$ are we talking about here? And how complicated is the installation, i.e., replacing the motors, going to 1800 gears, etc.? I was under the impression the Jeff Joseph and his tech team that did the festival at the Egyptian did it their whole setup just with selsyns -- although I could be wrong on this -- and mind you, I didn't see every film -- I missed a couple of the morning screenings -- I can vouch for the fact that none that I saw ever went out of frame or a shutter go out of sync.

Hey, if I can get mine to be that reliable, I would be a real happy pup. If I could do it with just the installation of the selsyns that we already own and didn't have to spend a fortune, that would be even better.

Posted by Mark Gulbrandsen (Member # 72) on 04-19-2005, 07:51 AM:

Typically motor cost per machine for the motor and controller is about 600.00 for the Baldors. Since you "dial" in the speed you want it can run at what ever speed you want it to. 2 units have the capability to slave together. Its high tech stuff [thumbsup]

. Selsyns will also work fine. I just prefer to to keep things that I install up to date and currrent. You can also use the Baldors to project silent film at the correct speeds, you just need to add three blade shutters. Or you can project that "Cinestage" print of 80 days at 30 fps! Thats something that Jeff's selsyns won't do......

Mark

Posted by Paul Linfesty (Member # 214) on 04-20-2005, 12:29 AM:

quote: Mark Gulbrandsen
Or you can project that "Cinestage" print of 80 days at 30 fps! Thats something that Jeff's selsyns won't do......

I thought it was the "Todd-AO" prints of 80 DAYS that ran at 30fps. "Cinestage" prints ran at 24fps.

Posted by Mark Gulbrandsen (Member # 72) on 04-20-2005, 08:02 AM:

quote: Paul Linfesty
I thought it was the "Todd-AO" prints of 80 DAYS that ran at 30fps. "Cinestage" prints ran at 24fps.

Hummm, I thought they were 30 fps.... but at least the film would be over ALOT quicker......

Mark

Posted by Mark J. Marshall (Member # 1409) on 04-20-2005, 12:46 PM:

quote: Frank Angel
I didn't see every film -- I missed a couple of the morning screenings -- I can vouch for the fact that none that I saw ever went out of frame or a shutter go out of sync.

I saw every film, and never did the shutters go out of sync. The only film that went out of sync was Gorilla At Large, and that was because one of the negatives was missing one frame about 2/3 of the way through the second reel, so that wasn't the projector's fault. Thankfully, Bob F. was able to fix that print in time for Pete's show in New York.

Posted by Jeff Taylor (Member # 443) on 04-22-2005, 08:50 AM:

Unfortunately I did miss the 3D screenings at the Egyptian, but Jeff Joseph was kind enough to show me his personal 3D setup at his shop in Palmdale, and we screened some of the prints from the show. He used the same techs who set up the Egyptian, and his booth used selsyns with perfect results FWIW

Posted by Mark Gulbrandsen (Member # 72) on 04-25-2005, 07:23 PM:

I forgot to mention that selsyns should not be left in the locked mode and not turning for long periods of time. This may cause them to overheat and possible damage may result. Its best to lock them just before the start of a show and then unlock them right after.

The nice part about the electronic drive is that you have variable film run speed and variable run-up and run-down time. There is also an adjustable current overload sense that could possibly save your gear train in the event of a bad film pile up or bind up of the mechanism...

Just thought I'd mention this stuff too.

Mark

Posted by Jeff Joseph (Member # 511) on 04-29-2005, 03:54 PM:

We did not use selsyns at the Egyptian; there was no need. They already had the Master/slave system set up (just needed to be wired correctly).

Here is Palmdale, we have speed controllers AND the selsyn motors. I tried running without selsyns, but when the projectors start, they sometimes slip a frame. With the selsyns, no problem at all.

Posted by Mark Gulbrandsen (Member # 72) on 04-29-2005, 06:05 PM:

Jeff,
Not all speed controlers can lock together as a selsyn can. The older speed controlers generally cannot do this while the ones made in the last few years can... but the availability of this function again depends on manufacturer. Baldor does for sure as I have done it.

Mark

Posted by Kris Brunton (Member # 432) on 05-03-2005, 06:57 PM:

I did a lot of experimenting before a 3D project I was working on and after much experimenting with baldor controllers I went back to the selsyns motors. I was finding that after a shut down I was loosing sync on the roll down. The selsyns would not loose sync and start in frame everytime.

It is interesting to hear Mark and Phils comments.. I would definatly look into the Baldor system again after hearing about the systems they worked with..

Posted by Phil Hill (Member # 371) on 05-03-2005, 07:40 PM:

Jeff, what speed controllers are you using in Palmdale? I seem to remember a post of yours that you said in effect that their display did not coincide to the actual projector speed and were problematic in general.