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Beefing up your Arm with rubber bands

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#1 Erwin Landau

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Posted 08 March 2007 - 05:12 PM

I was going through the Archives and thought that that topic would be of interest...

Date: Thursday, September 18, 2003 01:23 PM
From: Larry McConkey

Topic: XCS Ultimate. Message: 3 of 11 Read 390 times

An update on my Ultra... I had the new stiffer tilt arc installed on my sled this year and at the same time Tiffen adjusted the bearings in the X/Y stage. Along with my own mods to the tilt stage I now have a sled that I can run with without worries about vibration. This is the first time in years and it is a wonderful feeling. I now only have to use the mast stay rigging for very long post lengths and vehicle mount shots with gyros. It is possible to have all the adjustments the Ultra offers along with structural rigidity, but everything has to be perfect.

On another somewhat unrelated note, after a quick call to GB, I tried beefing up my Tiffen arm for an IMAX shoot with rubber bands. Incredibly it worked very easily and very well. I got another 5-6 lbs of lift by stretching a couple of heavy duty rubber bands diagonally across both sides of each section of my arm. To do this, I simply screwed short (1/4") 4-40 bolts into the remaining internal threads of the appropriate trunnions. The arm's spring rate did change with position much more than normal, but this was not a problem with the extra inertia that the IMAX cameras offered. The film was a documentary about the brain and followed Tyler Hamilton in the Tour De France. An incredible experience and an incredible performance by Tyler who fell early on and suffered a double fracture of his collarbone, but continuued and finished 4th overall!!


Date: Friday, October 03, 2003 03:08 PM
From: Phil Rhodes

Topic: XCS Ultimate. Message: 8 of 11 Read 325 times


When you say "rubber bands," you really do mean... rubber... bands.

Exactly how much extra did this get you?


Date: Saturday, October 04, 2003 08:18 AM
From: Larry McConkey

Topic: XCS Ultimate. Message: 9 of 11 Read 344 times

Theoretically, at least, as much as you want - it just depends upon the strength and number of bands you add. I did not have any time to really work this out carefully... the day before going over, my equipment had already been shipped to France... I borrowed my brother's Master arm to see if I could come up with someway to do this and took over a kit of 8 4-40 bolts and a bag of various size rubber bands. As expected, when we added all the stuff on our wish list to the camera/steadicam (mattebox, video transmitter, Iris motor, on board video recorder, low mode bracketry) the arm shot straight down to the bottom. I would guess I was about 5-6 lbs too heavy. I quickly added 4 heavy bands to each side of each arm and this time the arm shot up to the top! I compromised on 2 bands in each of the four locations and "Voila". The arm had a little more lift than necessary with the arm adjustments all the way up. I cranked them down a couple of turns and stayed with this system for the rest of the job. My only other alternative would have been to strip all those wish list items but the documentary nature of this shoot begged for all the little tricks and conveniences.

As I mentioned, the linearity of the arm's action was significantly deteriorated, i.e., it took more effort than I like to lift it up or push it down (no longer "iso-elastic" and it definitely sought the trimmed ride height more aggressively, but because the IMAX cameras are so massive, the extra inertia easily countered the tendency of the arm to interfere with the inertial stability and the results were magnificent! I will always carry this little kit with me from now on when I need a little boost. Total cost about $2.00 US. The idea came right from the man himself (GB) who threw it out to me as the obvious thing to do in this kind of situation - but he left it up to me to figure out how to attach the bands! I am thinking about a small mod to the trunnions that would allow better mechanical rigidity to this accessory as my own arm only offered a few threads to screw the bolts into. (A few times I knocked a couple of them out of their threads when carelessly handling the arm between shots). My brother's arm actually had plenty of threads (about 4) available, so there is some variation in trunnion mounting bolt lengths and all arms may not have the threads necessary to add these external bolts.

Date: Saturday, October 04, 2003 12:14 PM
From: Dave Bittner

Topic: Re: XCS Ultimate. Message: 10 of 11 Read 325 times

I seem to remember something from the old Steadicam Letter about
someone using medical tubing in the same way.


Attached File  Tour_IMAX_Rubber_bands_on_arm_MS_640_x_480.jpg   50.2KB   420 downloads
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#2 Todd Ferguson

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Posted 08 March 2007 - 09:06 PM

Has anyone else tried this? Anyone try this with another type of arm?

Todd Ferguson.
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#3 Alan Dague-Greene

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Posted 08 March 2007 - 11:32 PM

Found this. If I'm not mistaken, you can just make out the rubber bands on the outside of the arm.
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#4 Edmund Olszewski

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Posted 02 April 2007 - 01:29 AM

Hey this is very interesting, I was wondering what should I do incase my arm is not supportive enough for the weight of the camera etc..., and you gave me some ideas!

Thank you

Edmund O.
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