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Does anybody know how and when dynamic balance was first discovered?


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#1 Shawn Sutherland

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Posted 27 March 2013 - 02:44 PM

What were the circumstances?

 

I heard, for example, that Cinema Products got help from NASA with the R&D.

 

This may be just a rumour, but I'd like to believe it's true.

 

What did they do?


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#2 RonBaldwin

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Posted 27 March 2013 - 02:58 PM

I remember seeing Chris Haarhoff's 3a in 1988 (ish?) -- he had just run the cables up the post so spin balancing would be possible. There are articles in the old steadicam newsletter about some early fooling around. I am sure Garrett was playing with it by the late 80's. I think Eric's equation proving it was possible was published around the same time as Jerry's program (came with a slide rule and abacus)
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#3 Janice Arthur

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Posted 27 March 2013 - 03:08 PM

Shawn;

 

After a few years of use, when operators started figuring out that you could swish pan with a rig, (which no one thought was possible even before that); some rigs would tilt up or down at fast speeds.  (The Shining was a big testing ground for lots of this stuff.)  This was known as precessing.

 

At about 10 years in, maybe mid 80s, dynamic balance started getting attention and everyone started trying to figure out what caused some rigs to precess less or more than others.  Some rigs were just nicer feeling too and we all scratched our heads at why.  The idea that rigs could be vastly improved started to take hold but it was also the era when we started putting on lots of crappy extra accessories and they really just got stuck on anywhere you could fit them.

 

This was the era of model 1, 2's and early Model 3s.

 

Ed Diguilio, brother, attached some math to the problem, that's where the math came from, not NASA.

 

This is a thumbnail sketch of the criteria of how it came about.

 

Janice


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#4 Tom Wills

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Posted 27 March 2013 - 03:25 PM

And here is that article in the Steadicam Letter, discussing the math of the Steadicam and how it balances for a whip pan. Very interesting to read, as someone who spent a lot of time mucking around with very similar formulas in high school physics.

 

http://www.steadicam...es/v1n2su88.pdf


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#5 Jerry Holway

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Posted 27 March 2013 - 03:55 PM

January 1988 - GB and I independently came to the conclusion that the raised monitor required a different way of balancing, i.e., WHEN the monitor is raised, the camera c.g. is NOT centered over the centerpost, but slightly behind it.

 

Garrett was way ahead of me in all this, and he got Arnold DiGuillio, Ed's brother, to come up with the math, because we wanted balancing to be based on science, rather than on voodoo or misguided intuition, as some previous practices and "logic" - including ours - had been.

 

We then published the concept and Arnold's math in the Steadicam Letter.

 

Jerry


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#6 Shawn Sutherland

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Posted 28 March 2013 - 09:17 AM

Rats!

(Yes, I'm one of the few people who still use that expression)

I sort of pictured a "Manhattan Project" team of experts at the Kennedy Space Center: Garrett Brown, Jerry Holway, Ted Churchill, and the Late Dr. Isaac Newton busily taking notes while the latest sled spun merrily in a wind tunnel. (Hey, I don't get out much)

OK let's see if I got this straight:

By the mid 80s, dynamic balance started getting attention and everyone was trying to figure out what caused some rigs to precess less or more than others. Then in January 1998 Jerry Holway and Garrett Brown came to the conclusion that with a raised monitor, the camera c.g. was NOT centered over the center post but slightly behind it. That's when Garrett Brown asked Arnold DiGuillio to come up with the math because he wanted balancing to be based on science, rather than on voodoo or misguided intuition, and furthermore rant, rave, etc....

So far, so good?

Then in 1990, the Steadicam EFP Training Video was produced:

http://www.steadicam...am_efp_dvd.html

From what I see in the video, the Steadicam EFP was not like previous models with wires running directly from the stage to the bottom of the sled. This time, all cabling was wired through the center post and out of harms way. So for all intents and purposes, this rig could spin freely about the pan axis until the cows came home, or until it eventually stopped from then inevitable pan-bearing friction. Whichever came first.

OK here's the question I've been dying to ask:

Why wasn't there any mention of Dynamic Balance in the EFP Training Video?


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#7 Jerry Holway

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Posted 28 March 2013 - 11:00 AM

Although we knew about dynamic balance (and I certainly wanted to explain it in the video!), the original EFP's could not be put into dynamic balance, for reasons unknown. The previously released Steadicam JR did account for dynamic balance, BTW.

 

George Paddock took his first workshop shortly after the EFP was introduced, and bought one, and then modified it - nicely - to get his EFP into dynamic balance. We published that mod - touted it - as soon as we could get out the next edition of The Letter.

 

Later EFP's were made to get into dynamic balance... too late for the video, and we were editing on 1" tape back then, so no quick fix available.

 

Jerry


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#8 Shawn Sutherland

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Posted 28 March 2013 - 12:46 PM

Just had another look at the EFP Video, and I noticed that the fore and aft adjustment of the lower electronics box had very little range. Knowing what I know now, I would've designed it with a longer slot, along with a worm-gear adjustment for fine tuning.

 

But hindsight is always 20-20.

 

Was that George Paddock's modification?


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#9 Jerry Holway

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Posted 28 March 2013 - 01:23 PM

exactly what you describe.... and it was the one feature of the EFP that we "operators" did not get but really wanted.

 

I saw a lot of EFP dynamic balance mods - based on George's model, and on the math in the Letter - that got those EFP's into dynamic balance. One I remember had a big brass threaded weight  (1kg?) to the rear of the battery, easy to adjust and the rest of the rig was so light and agile it made a lot of sense.

 

Lots of ways to skin that cat!


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#10 Shawn Sutherland

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Posted 28 March 2013 - 01:47 PM

The last time I skinned a cat, I ended up with a bald ...(censored)

 

I want to show you something  I shot a long time ago:

 

 

See if you can guess how I did it.

 

(it'll be fun)


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#11 Shawn Sutherland

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Posted 29 March 2013 - 08:59 AM

Uh,...  Jerry?

 

Where did you go all of a sudden?


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#12 Alec Jarnagin SOC

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Posted 29 March 2013 - 09:34 AM

Shawn, its been less than 24 hours mate!  Not everyone here can mange to stop by so often.  Patience will serve you well.

 

I'd add Chris Haarhoff's name to the mix.  In addition to developing the original Donkey Box (and being an amazing operator), didn't he have some of the early theories on dynamic balance?

 

Take good care.


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#13 Shawn Sutherland

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Posted 29 March 2013 - 09:56 AM

Yeah, I know.

 

It's just that I was really getting into that discussion.

 

By the way, did you check out my youtube link?


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#14 Eric Fletcher S.O.C.

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Posted 29 March 2013 - 12:38 PM

I want to show you something  I shot a long time ago:

 

 

See if you can guess how I did it.

 

(it'll be fun)

 

What does that shot have to do with Dynamic balance?

 

Pretty funny thread with some VERY funny replies....


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#15 Victor Lazaro

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Posted 29 March 2013 - 01:15 PM

I want to show you something  I shot a long time ago:

 

 

See if you can guess how I did it.

 

(it'll be fun)

 

What does that shot have to do with Dynamic balance?

 

Pretty funny thread with some VERY funny replies....

I was wondering too. The beginning of the thread was instructive, then...

anyway, we can see you in the mirrors, looks like you used something like this: 

make_your_own_steadicam.jpg

To stay on the subject, this above rig cannot be dynamic balanced either...


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