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Old February 8th, 2010, 04:02 PM   #1
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Building a tripod head

Hi,

I am just looking for a few thoughts to see if I am on the right thought pattern. I am thinking most all tripods use some type of fluid in the head to create a smooth movement. I have a couple of rare earth magnets and I wondered what if I took two of these and pointed the north and south poles towards each other so they repel each other. Then if I secured each of them to an aluminum metal piece in a half ball shape they would rotate do to the repel action of the magnets. All this would have to be tested out to get to the specifics of the design.
My question is this....
Will the magnetism destroy/ hurt the HDV tapes and or the camera? I am thinking Yes, so I would have to find some way to shield / contain the magnetism from escaping into the air.

John Gerard
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Old February 8th, 2010, 04:25 PM   #2
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I'm not sure how this would work. A fluid head offers constant resistance, I get the feeling that the magnetic set up you've suggested would have variable resistance depending on the physical relationship of the two magnetics. The fluid also only applies resistance when the head is moved, this magnetic approagh seems to apply a force even when the head is static.

BTW An alternative is to use gyros, although they do have a down side in that they tend to want to keep moving, which I suspect is the reason that fluid became the favoured method.
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Old February 8th, 2010, 07:21 PM   #3
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About a decade ago, I tried taking apart an old Bogen head. I was surprised to find that there was no fluid inside. Instead, the moving parts were covered with some kind of very heavy grease, something much thicker than peanut butter. I tried experimenting with all kinds of puttys, gels, and lubricants to see if I could get the right consistency. Out of everything I tried, the smoothest pans were obtained by using the thick glue from a hoy hoy trap a roach, mixed with a tiny dab of vaseline. I pulled out the gummy stuff from the roach trap and spread it inside the head. It seemed to work fine, except that it was on the stiffer side and there was some backlash on quick pans...lol
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Old February 8th, 2010, 08:01 PM   #4
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interesting
magnets could be used as a "counterbalance" vrses spring, possibly , and i remember a trick with magnets sliding down aluminum, wherin there was a "resistance".

as far as TAPE goes, you would never use even speaker magnets around tape, even if it doesnt repolarise them immediataly your magnatising various metal things in the camera to very teeny degrees, and decreasing the polarisation differentials on the tape.

so although you could probably get away with a tripod head that had massive gausse of magnatism, nobody professional would risk using it around tape or even the tape mechanisms.

now chip, that would be different, how much i dont know, because there are still other magnets in use throughout the cameras, like the motors, actuators, even accelrometer micro machines could be effected.

i think you should certannly continue your experimentation, to learn and reveal interesting information, as far as how usefull it would be, would depend on the design. intricated enough design would use minimal magnet, and have sheilding to prevent departures of polarised magnetic feilds from the unit, or to limit the distance of the feilds.
everything is "possible" if you go beyond our present knowleges.
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Old February 8th, 2010, 08:30 PM   #5
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I'm led to believe that the term "FLUID" only refers to the "fluid" type movement of the Head and that there is no actual fluid contained in the head itself.
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Old February 9th, 2010, 01:15 AM   #6
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Well, I always thought that a real fluid head had a fluid inside and worked on the principle that moving the head pumped fluid though a small opening. In this kind of arrangement there would be no backlash because the fluid would not have the elasticity of the grease in a lower priced fluid head, nor would the fluid compress and rebound.

I thought the grease filled version was basically intended to achieve most of the same effect at lower cost by relying on the viscosity of the grease.

But what do I know?!?
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Old February 9th, 2010, 04:07 AM   #7
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Vinten heads had greased pads (I'm not saying all their models), true fluid heads have do have a fluid - I've had the stuff leak.
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Old February 9th, 2010, 06:12 AM   #8
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Over the years I have made three fluid heads for different applications. I use a high viscosity silicone fluid to provide the necessary drag. Fluid is different from a grease in that it flows and you have to provide seals to keep in place. The drag effect is produced by “shearing” the fluid between two surfaces eg a piston in a cylinder. The greater the shear gradient the greater the drag. To produce a high gradient and a high drag you use a very thin layer of fluid, or a large piston or both. The beauty of a fluid head is that drag increases with the speed of rotation – however there are limits.

Viscosity is measured in centipoises and the fluid I use is 600,000 centipoise – it was the highest viscosity I could get as a free sample many years ago. It is now available up to several million centipoise.

There is also drag provided by mechanical friction. For a fluid head mechanical friction is both a necessity and a nuisance. It is a nuisance because it takes more force to start something moving than to keep it moving – this makes the movement jerky although high quality bearings can greatly reduce this problem. A bit of friction is desirable so that the camera will stay in place when the operator takes his/her hand off the pan handle.
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Old February 9th, 2010, 09:02 AM   #9
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Am I missing something here?
There are already many high quality smooth heads available.
Whats the point?
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Old February 9th, 2010, 02:32 PM   #10
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Quote: -Whats the point?


The main point as far as I was concerned was to make a head that I could use under seawater so by starting from scratch I could select more sea water resistant materials. I was also interested in getting the camera as low as possible so I use a side mounting system. Not only does this get camera low but if the tilt axis is set at the center of balance there is no need for compensating springs. This reduces the size and weight of the head as well as its complexity.
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Old February 9th, 2010, 04:49 PM   #11
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Sorry Alastair, with John's original post.
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Old February 9th, 2010, 05:43 PM   #12
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Hi David,

I too am a little vague as to how the proposed mechanism using magnets will work. However I am all in favour of experimentation as this is how we get these products in the first place.

I joined in the discussion because there seems to be some confusion as to whether fluid heads use fluid. Some certainly do.

If any one is interested the fluid I mentioned in the post above came from General Electric. Another source is Clearco and they have some interesting offerings.
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Old March 23rd, 2010, 04:09 PM   #13
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Building a tripod head

hi,
great information. I was just playing around with two magnets I have and I thought I would through out the idea. I like to build things from time to time. And the repelling action of the magnets is really strong. So I thought it might work. The only way to really know is to build something. I wouldn't use my camera on it unless I could really isolate the magnetic fields.
Maybe I could use gears In stead but I don't know how fulid that would be.
Ps. On the simpler side I did make my own mic blimp and that works great.

John Gerard

Quote:
Originally Posted by John Gerard View Post
Hi,

I am just looking for a few thoughts to see if I am on the right thought pattern. I am thinking most all tripods use some type of fluid in the head to create a smooth movement. I have a couple of rare earth magnets and I wondered what if I took two of these and pointed the north and south poles towards each other so they repel each other. Then if I secured each of them to an aluminum metal piece in a half ball shape they would rotate do to the repel action of the magnets. All this would have to be tested out to get to the specifics of the design.
My question is this....
Will the magnetism destroy/ hurt the HDV tapes and or the camera? I am thinking Yes, so I would have to find some way to shield / contain the magnetism from escaping into the air.

John Gerard
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