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Dimensions for curved track?


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#1 Daniel Wallens

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Posted 14 September 2008 - 09:52 AM

Hey all,

I am desperately trying to find the exact dimensions (well, the diameters) for 180 degrees of various Precision (aluminum) curved track. On Fisher's site, it really only lists the 45-degree curved (which is 20'). And that's steel track (although they should be the same). The rest of the diameters listed are for their square tube track.

Does anyone have the diameters for all various degrees of Precision (aluminum) curved round-tube track? (looking at standard 24.5" track for Fisher dollies).

Thanks :)
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#2 Daniel Wallens

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Posted 14 September 2008 - 10:07 AM

sorry, forgot to mention that I'm looking for outside diameters -- think, whats the smallest room it will fit in.
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#3 Daniel Wallens

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Posted 14 September 2008 - 10:33 AM

Now i'm confused.

according to this, 90-degree track makes a 10' semicircle:
http://comtel.ua/lig.../...s&Track.pdf
(last page, Matthews 90-degree steel track)

but according to this, 90-degree track makes a 14' semicircle:
http://www.chapman-l...ar-Aluminum.htm
(Chapman aluminum precision). Same thing for their steel version of the same track.


I don't get it. both are 24.5" and 90 degrees. Why does one come out 4 feet wider than the other?
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#4 Jamie Metzger

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Posted 14 September 2008 - 12:06 PM

Could it be that there is different manufactureres of track (hence fisher and chapman) and that's where the difference comes in?
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#5 Ira Ratner

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Posted 14 September 2008 - 12:07 PM

Now i'm confused.

I don't get it. both are 24.5" and 90 degrees. Why does one come out 4 feet wider than the other?


The length of it:

The distance between the rails will always be the same for your dolly, 24.5" here. That's what THAT figure refers to.

For example, a full circle with an 8-foot diameter, cut into 4 pieces, gives you each piece at 90 degrees. 90 degrees times 4 pieces equals 360 degrees--a circle.

The same is true for a 16-foot circle. BUT...

Each piece of the 16-foot would be longer, and would also have a totally different circumference radius--the actual curve of the track. (Ignore the word radius here as meaning half the diameter of a circle; this is a different usage.)

Its that 90 degrees that they're throwing at you which is confusing you. They're just saying you would need 2 pieces for a semi-circle, and 4 for a complete circle.
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#6 Warwick Hempleman

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Posted 14 September 2008 - 03:36 PM

It may also be good to know where the diameter is being measured. Fisher's 10' is measured from the center of the track (i.e., 12 1/4" in from the center of outside rail).
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#7 Ira Ratner

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Posted 14 September 2008 - 04:14 PM

It may also be good to know where the diameter is being measured. Fisher's 10' is measured from the center of the track (i.e., 12 1/4" in from the center of outside rail).


I didn't think of that and that makes total sense:

Assuming the camera sits dead center between the rails, you would be getting a true EFFECTIVE working diameter of the measurement they specify. But I 'm a little skeptical whether they actually measure like that:

My guess is that what they specify is the inside rail diameter, but who knows.

I can't afford that expensive stuff anyway.



.

Edited by Ira Ratner, 14 September 2008 - 04:15 PM.

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#8 Onno Perdijk

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Posted 14 September 2008 - 04:34 PM

Thanks Daniel for asking,

I wanted to give you a correct answer so I looked at my website and saw that I did not notice where the diameter is being measured..! I changed it immediately to Outside diameters!!!

Curved tracks can be made in any diameter you want (or the diameter the manufacturer decides to make them.) I can cut my 10m70 into 16 pieces of 22,5 degree (which they are) or in 12 pieces of 30 degree. The difference however is that the 16 pieces curve will have pieces of 2m10 long approx, and that a circle cut in 30degree will have pieces of 2meter80...

We are manufacturing aluminum precision track at a 90 degree, 3m32, 4 pieces, as our smallest curve. Our largest circle manufactured as listed item is a 22,5 degrees, 10m70, 16 pieces as our largest curve. We di have manufactured a 21m30 circle at 11,25 degrees, consisting 32 pieces. (It was a hell of a job!!)

Good Luck with your quest,

Onno Perdijk
Keygrip and manufacturer
www.solidgripsystems.eu
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#9 Daniel Wallens

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Posted 14 September 2008 - 05:05 PM

Hey all,
Thanks for the great responses. I never was good at math. :) I now feel I have a better understanding of how things work.

However, I'm still really wondering about my original question. I need to fit 180 degrees into a room that's about 10' wide. Really, custom track isn't an option -- I have to go with something from Fisher, chapman, matthews, etc. or anything that's readily available in NYC. It seems like my only real choice is the 90-degree square tube track. Or would even this not work either (since we don't know where they are measuring from?). But i HATE using square, and I'd MUCH rather have aluminum tubular precision track. Can I? Does anyone have all the measurements for these various, readily available tracks?

Thanks again!
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#10 David Erlichman

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Posted 14 September 2008 - 06:27 PM

Would it not be easier to lay dance floor?
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#11 Daniel Wallens

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Posted 14 September 2008 - 07:12 PM

we're trying to stay away from that.
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#12 Ira Ratner

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Posted 15 September 2008 - 07:43 PM

Daniel, I have the same exact needs coming up. Nothing IMPORTANT mind you (hobby stuff), but damn--pretty much the same exact thing:

I need track circles (semi-circles actually, but it's the same math) at 10, 12, and possibly 14 foot diameters. So for your particular working purposes, to fit in a specific room, this is what you have to do:

Unless the room is perfectly square, you have to measure the SHORTEST wall to wall distance. This will be your outside track, EXCEPT you gotta subtract at least 3 feet from this, to give you some room to MOVE without hitting your ass on the walls if you want to shoot while viewing in the finder. Subtracting 3 feet--and this is all relative d on the diameter of the circle but for small diameters like 10, 12, etc.--that 3 feet less only gives like 1 1/2 feet of free space clearance off the wall.

So for a 10-foot long room (you said that, right?), forget it. Not enough space.

I just finished building my dolly, and I plan to build my own tracks out of cheap heat-bended 1" PVC.

Spielberg may be able to afford the stainless steel stuff that costs a fortune, but not me.

He also has mathematicians to figure out those circumference radiuses. And THAT'S what matters:

Whether it's 4 pieces or 30 pieces for a 14-foot circle, that circumference radius is the same.

Just envision 2 hoola -hoops of different sizes. (Are you old enough to remember those?) Cut each into 6 pieces, or into 24, and they will each both make that same final circle when put together.

But the larger one will always have a lower circumference radius than the smaller--less of an angle/curve/slope--whatever you want to call it.
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#13 Onno Perdijk

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Posted 16 September 2008 - 03:01 PM

Hello Daniel,

You can always think of a customized track: Go to a workshop which has bending facilities, get them some tube of around 38mm diameter and let them bend you two curves withe your requested radius and thus diameter. You can lay them flat on the floor, without crossties (or sleepers?) Sure they will "walk" around on the floor but some sandbags will keep them more or less in position. With some tapemarks you can reposition to the original intended position. You just need to be able to get these huge 'single-tube-curves" into the room, it will be fun to maneuver them in!

I have done this a couple of times and it worked.

Good Luck,


Onno Perdijk
Keygrip and manufacturer
www.solidgripsystems.eu
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#14 Warwick Hempleman

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Posted 16 September 2008 - 04:11 PM

10' O. D. is a very tight circle, you'll probably have to go custom for it.

If you do try Onno's idea and still need or want sleepers, notch 2x4s on 24 1/2" centers for the tubes to lie in. This sort of system is often used with speedrail. And Onno's 38mm = 1 1/2" pipe diameter.

With a circle that tight you'll probably need skateboard wheels.

Good luck!
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#15 Sanjay Sami

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Posted 19 September 2008 - 09:31 AM

Hey all,

I am desperately trying to find the exact dimensions (well, the diameters) for 180 degrees of various Precision (aluminum) curved track. On Fisher's site, it really only lists the 45-degree curved (which is 20'). And that's steel track (although they should be the same). The rest of the diameters listed are for their square tube track.

Does anyone have the diameters for all various degrees of Precision (aluminum) curved round-tube track? (looking at standard 24.5" track for Fisher dollies).

Thanks :)


Hi Dan
Standard curved track (45 degrees a piece) will give you a circle with an Outer Diameter of 20 feet.
A tight circle (90 degrees a peice) will give you a circle with an Outer Diameter of 14 feet.
Some companies (Filmair in North America & South Africa / Panther & GFM in Europe - and maybe Solid Grip Systems as well Onno?) make a very tight circle which will give you a 9ft 6inch circle. You will certainly need articulated skate channels for such a tight circle , such as those made by Portaglide or fishers new wheels.
Hope that helps .

Sanjay Sami
Key Grip
www.thegripworks.com
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#16 Onno Perdijk

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Posted 20 September 2008 - 01:36 PM

Hello Sanjay,

Thanks for your reference. Yes we do make the tight circle; it is a 3meter32 (10ft) outside diameter. Making it more narrow will definitely mean a customized array of wheels.

Good Luck Daniel,

Onno Perdijk
KeyGrip
www.solidgripsystems.eu/prodcurved.htm
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