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Busted Arm, 3A to Master "adapter"

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#1 Afton Grant

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Posted 18 December 2007 - 01:58 PM

As lunch was called yesterday I was securing my gear before leaving, and I quickly lost my appetite as something caught my eye. A large crack had formed in the collar that secures one of my arm springs to the lug that anchors it. A flurry of calls to everyone I know that's smarter than me (many thanks to Peter, Kyle, Brant and Alec) all resulted in a speedy consensus - I was very lucky nobody got hurt as she was about to blow. Needless to say, the arm was out of the game for the day.

Attached File  IMG_0096.jpg   61.01KB   234 downloads

The closest replacement (shooting in Providence, RI) was an old 3A arm from Boston Camera. The only issue that concerned me was the arm post of the 3A is considerably thinner than my Master series arm post. So the gimbal would fit on the arm, but there would be quite a bit of play, a great amount of torque would be applied to both gimbal handle and arm post, and I would certainly lose the ability to pivot the gimbal handle on the arm.

When the arm arrived, I tried a number of things to "thicken" up the 3A's post diameter. Gaff tape on the post, gaff tape inside the gimbal handle. Tape on the post eliminated any sloshing around of the pin inside the gimbal, but I still couldn't pivot the handle on the arm. I could've shot if I had to, but I wasn't satisfied.

I got out an offset bracket, applied a bit of gaff tape to the 3A post to thicken it up to where the set screws in the offset bracket could take hold. On the opposite side of the bracket went my trusty ol' Master post. Perfect fit. The setup as a whole was certainly not like flying with my regular arm, but it was a simple solution to a previously feared problem. I'll tell you, after letting the production down with the news of a failed piece of equipment as important as an arm, you'll take any victories you can get. This was a good one for me, and if it helps someone else out of a similar situation someday, that'd be great.

Attached File  IMG_0097.jpg   59.91KB   223 downloads

Sorry about the poor picture quality. Bad lighting offstage.
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#2 Brendan Riel

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Posted 09 June 2015 - 10:05 AM

I'm looking into an adaptor to fit a IIIA arm to an Actioncam sled. Is that .627 to .750 do you know? Like you said there is a lot of play and torque on the handle. Do such adaptors exist or should I get one specially machined at a shop? What would you recommend?

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#3 Erwin Landau

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Posted 10 June 2015 - 01:11 AM

Peter Abraham used to make a gadget called the POM or piece of mind adapter. A set of two arm posts that would convert the 5/8 (3A, PRO) size to the Master/Ultra size and vise versa... Just for such an occasion. Used to be in every operators bag of tricks.
Guess thats not that common anymore...
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#4 Brendan Riel

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Posted 10 June 2015 - 11:58 AM

Yeah he said he doesn't make those anymore since he started working for Tiffen.

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#5 nick franco

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Posted 10 June 2015 - 01:30 PM

Try Robert Luna , he might be able to make an adaptor post? 

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#6 David M. Aronson

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Posted 10 June 2015 - 02:44 PM

I didn't realize there was a name for that kind of adapter. I made one when I get a new sled and made an extra just in case. I could make a few extras if they're still in need.

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#7 Ants Martin Vahur

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Posted 28 June 2015 - 12:25 PM


Good to hear, that you found a solution.


I had very similar situation few weeks ago. My Master arm started making clunky noise and the only replacement arm nearby was lllA. I quickly ordered an adaptor post from Betz. It's a 3/4 (Master) to 5/8 (lllA) arm post adaptor. Managed to use the lllA arm  with great comfort with my Master sled. That adaptor should also work with PRO arm.


I wouldn't recommend using different size posts for larger gimbal hole with any other method. Gaffer tape, or similar, won't do the job. You need something really solid, because there is a lot of torque. A special arm post adaptor would be your perfect solution.


Ants Martin

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