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Stepper on Mitchell?


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#1 Paul Bruening

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Posted 09 December 2008 - 03:07 PM

John, Hal, or any takers,

What NEMA size and length do you think is strong enough to run a Mitchell NC and 2000' of film in single frame and constant speed, .000 resolutions?

Here's a link to a NEMA 34 spec sheet. Anaheim has others. But I'm looking for motors at $150.00 or so, ball park.

http://www.anaheimau.....pec Sheet.pdf

There's also this controller which looks cheap and monkey simple. What do you think?

http://cgi.ebay.com/...1742.m153.l1262
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#2 John Sprung

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Posted 09 December 2008 - 05:54 PM

The required torque will depend on how fast you need to go. Try hand turning the camera through a torque driver -- the kind that gives you a reading, or the kind where you set a limit, and it releases at that setting. For instance, one of the motors is 1700 in-oz. Set the torque driver to release at maybe 50% more than that, and see how fast you can crank before it lets go. You want to leave yourself a safety margin.




-- J.S.
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#3 Patrick Neary

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Posted 09 December 2008 - 06:47 PM

Hi Paul-

If it helps any, I've got a Slo-Syn SS50 stepper on my Mitchell at the moment (driven by an older JK controller). You can look up the specs for that motor, but it's a .3A, 50 Oz. In., 72rpm.

I'm only driving it with a 400' load, but I'm sure it can pull a 1000' as well, and possibly a 2000'.

One thing the guy at JK told me (apologies for forgetting his name at the moment) was to pull the big brass flywheel from the camera ( a GC) for single frame work so that the motor isn't fighting the weight and inertia of the flywheel.
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#4 Paul Bruening

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Posted 09 December 2008 - 08:21 PM

John,

I've got a click, torque wrench. It never occurred to me to use it that way. Brilliant. Thanks.

Patrick,

Thanks for the tips. Do you have links to the parts you used? It seems the Slo-Syn SS50 stepper line has been sold to Danaher. But, I couldn't find a reference to it on their site. Is the other reference to JKMicro or someone else?
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#5 Patrick Neary

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Posted 09 December 2008 - 09:14 PM

oops- JK is JK Camera http://www.jkcamera.com (Jaakko Kurhi). I have one of his animation motors that has the Slo-Syn and a controller of his own design, I got it from an animator-special effects guy recently, but it's an older unit (it worked on Evil Dead II!) It's limited to a single shutter speed of 1/3 sec.

For a brief bit I looked into making my own animation motor, and there's quite a bit of good info about that if you search the forum for "mitchell motor" or similar over at stopmotionanimation.com. Somebody over there posted rather complete plans and diagrams.
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#6 Herb Montes

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Posted 10 December 2008 - 06:23 AM

oops- JK is JK Camera http://www.jkcamera.com (Jaakko Kurhi). I have one of his animation motors that has the Slo-Syn and a controller of his own design, I got it from an animator-special effects guy recently, but it's an older unit (it worked on Evil Dead II!) It's limited to a single shutter speed of 1/3 sec.

For a brief bit I looked into making my own animation motor, and there's quite a bit of good info about that if you search the forum for "mitchell motor" or similar over at stopmotionanimation.com. Somebody over there posted rather complete plans and diagrams.


I have a JPG copy of the schematics for wiring a Slo-Syn motor for animation. And you can still buy these motors on the surplus market from this place:

http://www.herbach.com/
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#7 Paul Bruening

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Posted 10 December 2008 - 03:28 PM

I have a JPG copy of the schematics for wiring a Slo-Syn motor for animation.


Yes, please. Thank you. I'll PM you my email addy.
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