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old school motor question
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miles&Jules
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old school motor question

Any ideas on why this 1940-50s camera motor doesn't spin? Im not sure of the polarity but i have tried everything ...but still nothing. It won't spin. Its got a 5mm shaft so I'm thinking if i can get it to work i might lath up a new housing and put a 775 in it instead. Im not sure why there is 3 wires and what is that thing at the back with the two wires going to it..its not magnetic…an electro magnet... a temp sensor?

[URL=http://s1091.photobucket.com/user/milesandjules/media/IMG_2061.jpg.html] [/URL]

[URL=http://s1091.photobucket.com/user/milesandjules/media/IMG_2063.jpg.html] [/URL]

[URL=http://s1091.photobucket.com/user/milesandjules/media/IMG_2064.jpg.html] [/URL]

[URL=http://s1091.photobucket.com/user/milesandjules/media/IMG_2065.jpg.html] [/URL]

[URL=http://s1091.photobucket.com/user/milesandjules/media/IMG_2066.jpg.html] [/URL]

[URL=http://s1091.photobucket.com/user/milesandjules/media/IMG_2067.jpg.html] [/URL]

[URL=http://s1091.photobucket.com/user/milesandjules/media/IMG_2068.jpg.html] [/URL]

[URL=http://s1091.photobucket.com/user/milesandjules/media/IMG_2069.jpg.html] [/URL]
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Post Fri Nov 28, 2014 12:02 pm 
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Knightrous
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That's a series wound motor, very much the same as a car starter motor.
It has coils instead of magnets. Try joining two of the wires together and putting it on ground and the remaining wire onto power.
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Post Fri Nov 28, 2014 12:31 pm 
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miles&Jules
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Genius...thanks dude ….so the thing at the back(coils) is doing all the work? That makes sense cause the motor is so skinny there is no room for magnets on the sides. Very Happy Very Happy Very Happy
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Post Fri Nov 28, 2014 12:38 pm 
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miles&Jules
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Just tried that. When i do that i can hear the coils clicking. but no spin spin. it's a 24v motor I'm attempting to run it on a 6s 22v... maybe not enough grunt?
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Post Fri Nov 28, 2014 1:49 pm 
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Knightrous
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Where your thumb is, that is the field winding coil, you can even see the screw that holds it into place.
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Post Fri Nov 28, 2014 2:04 pm 
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DumHed
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the coil on the end of the motor is probably a brake.

You may need to energise it to allow the motor to spin.


Connecting power across "brush -" and "field winding coil -" in Aaron's picture should make it run - but you may have to check the internal connections to work out exactly how it works.


It might actually be shunt wound rather than series - in which case you will need to run the field coil in parallel with the brushes.
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Post Fri Nov 28, 2014 2:55 pm 
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miles&Jules
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i posted this on the cinematography forum but thought i should post it here to seeing its for the same camera as this motor question.



im so happy with how this worked out that i thought i would post some pics of my camera hack.

Our new cameflex arrived last week and while I'm still working out how to get its ancient motor running i thought i would turn my attention to getting it nikonified.

The Camefex lenses seem rather scarce on ebay so had no choice but to see if i could get our nikon lens to fit it. By taking out the 3 grub screws holding the brass bayonet mounts in place its possible to unscrew them from the aluminium turret…..then i sat a nikon lens directly on the empty socket on the camera…and it looked pretty sharp at infinity….so then i pulled the nikon bayonet off a f-c mount adaptor….and thought this will fit nicely on the cameflex mount…..but it needs to go down 1mm and it should have infinity focus.

So the turret on the Cameflex is kind of a weird and scifi submarine looking but i worked out its around a 10 degree angle that the lens sits at.

So made a chipboard support thats bolted to the mill …this will hold the turret still and then a bolt through the turret shaft into the mill table will hold that in position solidly.

IMG_2071.jpg

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IMG_2081.jpg
[URL=http://s1091.photobucket.com/user/milesandjules/media/IMG_2081.jpg.html] [/URL]



So using a dial indictor i got the angle by making sure the mill and the existing lens mount were the same…within .04 of a millimetre.

IMG_2085.jpg

[URL=http://s1091.photobucket.com/user/milesandjules/media/IMG_2085.jpg.html] [/URL]

looks like its going mental in the picture but i milled it really really slow

test fit the nikon bayonet plate
IMG_2086.jpg

[URL=http://s1091.photobucket.com/user/milesandjules/media/IMG_2086.jpg.html] [/URL]

omg it fits perfect but after test fittng some of my lens it needs a bit more edge taken off ..
IMG_2088.jpg

[URL=http://s1091.photobucket.com/user/milesandjules/media/IMG_2088.jpg.html] [/URL]

and now need to mill a space for its release clip….

[URL=http://s1091.photobucket.com/user/milesandjules/media/IMG_2090.jpg.html] [/URL]

IMG_2090.jpg

[URL=http://s1091.photobucket.com/user/milesandjules/media/IMG_2091.jpg.html] [/URL]

IMG_2091.jpg

i knew there was a reason i bought that pack of 1.6mm tappers….for the 4 screws to hold the nikon plate on….

IMG_2089.jpg

[URL=http://s1091.photobucket.com/user/milesandjules/media/IMG_2089.jpg.html] [/URL]

infinity looks shape and close focus looks correct. I'm surprised

there it is all done….so next pics will be the film test.

Also i have to rebuild the motor next…..i'm thinking a 775 brushed motor inside a new aluminium shell connected to the old motor gear ..the 5mm shaft size is the same so should be a win to fit the old pinion on it…will also need an esc and a servo tester for speed control. Will work something out.
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Post Sun Nov 30, 2014 11:25 pm 
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Nick
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That looks brilliant! Is the Nikon mount the same as the old still camera one, or something special for cine cameras? You might want to seal the motor up so that carbon from the brushes doesn't get into the rest of the camera.
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Post Mon Dec 01, 2014 9:18 am 
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miles&Jules
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Thanks Nick….yep regular nikon f-mount lenses…that we use on our digital and film slurs. You just need the old style ones that have the aperture ring on the outside of the lens rather than the new dx series that have it all internal (annoying)…

with the motor…yep the good thing with it is that it bolts onto the side of the camera and forms the handle that you hold to shoot with. So no danger of carbon getting into the camera…only danger would be it getting so hot that you can't hold it…i doubt we will be shooting that much film in one go though…he he. Very Happy

thats the motor out the side that jules isn't holding he he.
[URL=http://s1091.photobucket.com/user/milesandjules/media/IMG_2058.jpg.html] [/URL]
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Post Mon Dec 01, 2014 10:11 am 
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miles&Jules
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...back on the motor idea, do you reckon there would be any reason that a 775motor running off a bot bits 40amp esc controlled by a servo tester ..would be any less constant than this old school motor? Also could i get a tachometer from hobby king …point it at the camera shutter to work out the speed..then fps?
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Post Mon Dec 01, 2014 10:20 am 
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Nick
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I don't know anything about the performance of series wound motors so its hard to say if a 775 will have better speed regulation - I guess it will be fine if the load from the camera mechanism is constant.

I have some Nikon F mount lenses if you are interested.
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Post Mon Dec 01, 2014 12:25 pm 
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Valen
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How accurately do you need the motor speed controlled?
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Post Mon Dec 01, 2014 12:25 pm 
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miles&Jules
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Big yes to your nikon lens Nick…. Very Happy Very Happy Very Happy Very Happy

Well motor speed would be good to be as constant as possible…real movie cameras have a thing called crystal sync and it was always an expensive component. i wondered if there is a cheap way of doing that these days with stepper motors or some hobby king devise or something?….it would be good to have it variable to, thats why I'm thinking it would be good to base it off a botbitz esc. What I was planning to do was to look through either the eye piece (cause the image flickers) and film a tv and adjust the motor until the rolling bar stops on the tv…that would be 25fps….then see how long it takes for the bar to start to roll again that would tell me how content the motor was Very Happy
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Post Mon Dec 01, 2014 1:16 pm 
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Valen
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open loop control is going to be very variable just with temperature.
I'd estimate 10-20% variation between 10 and 30C

take a look at perhaps a brushless with "governor" mode probably bring it down to 5% or so and it won't vary with load (much) then either.
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Post Mon Dec 01, 2014 2:11 pm 
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miles&Jules
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like it Jake …how does a governor get connected and are a hk item ?
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Post Mon Dec 01, 2014 2:16 pm 
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