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This topic comprises 2 pages: 1 2
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Topic: Bringing a motor up to speed
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Scott Norwood
Film God
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Posts: 8146
From: Boston, MA. USA (1774.21 miles northeast of Dallas)
Registered: Jun 99
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posted 02-11-2005 06:37 PM
If at all possible, try to get reels with 7" hubs. The 5" hubs are fine for 2000' reels, but I have a strong preference for 7" floating hubs when running 6000' reels. The 5" hubs are fine for feeding, but are less-than-ideal for use as takeups. If you can't get large-hub reels, put a few hundred feet of junk film around the hub of each reel and tape it there permanently (you may want to mark the edge of the reel so you can tell where the junk film begins in order to avoid missing changeovers).
You can set the tension without the spring scale, using old, brittle, junky trailers on acetate base stock. Basically, you want to use the largest reel you have and set the tension so that the film takes up evenly without breaking at startup or tearing perfs. With a 6000' reel, you won't get perfectly even tension throughout the reel (unless you have motor-driven takeups), but you want to make sure that the film winds fairly tightly out to the edge. If it winds loosely, the film will cinch when you rewind it. Be sure to test with 2000' reels (with both 4" and 5" hubs to make sure that you can take up easily onto those sizes, too. The whole process is a bit of trial and error and is far more critical when running the larger reels.
If you don't already have some junk film, you can order "picture sound fill" from an editing supply house (e.g. Christy's Editorial in Burbank, CA). This can usually be purchased quite cheaply.
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Monte L Fullmer
Film God
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Posts: 8367
From: Nampa, Idaho, USA
Registered: Nov 2004
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posted 02-12-2005 02:24 AM
True, this is where Simplex has it over with the slow ramp speed, esp when using the old SH-1000 soundheads when using 6k reels, with the absoluted needed floating hubs for takeup.
When doing this, just make sure that the tension is completely taught from lower holdback sprocket to reel when starting. Then when hitting the run switch, a practice that I did was to have my finger in the hole of the hub of the reel to make certain of the required taught, then when the motor took off, my finger would be assisting the rotation of the reel, thus preventing the inital slack that can happen when motor takes off and the takup belt and clutch having their delayed action before getting up to speed.
I had to do this many-a-times with MotioGraphs AA's with Mirrophonic 7400's soundheads - and we know how the Motiograph took off with their snap starts.
-Monte
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