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Crack in post. Is it serious?


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#1 Afton Grant

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Posted 02 November 2005 - 03:51 PM

Hello,

I've just returned from my first couple days of shooting with my new (second hand) rig. We were shooting on the new JVC HD camera which is quite light (7lbs) so I needed to add the weight plate which brought the gimbal way down. About 3.5 inches down the post, I noticed a small crack. It doesn't necessarily look like a stress crack which I would expect to be vertical. It looks almost like it was pinched a bit too hard in one small spot. It's about 3/4 of an inch wide with a few vertical little branches coming off of it. I've attached the picture.

Does this look like something serious? I know I'll replace the post someday, along with the rest of the sled as a step in routine upgrading. I'm wondering if that upgrade might have to come sooner than I expected.

It's a Master Elite Sled & post.

Thanks as always,
Afton Grant

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#2 joe mcnally

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Posted 02 November 2005 - 06:29 PM

Afton
I am afraid the simple answer is yes it is serious.
It may of course last for the next 10 years but the likelyhood is that it will fail catastrophically at some point probably on your most important shoot. take it to a carbon fibre expert or Tiffen maybe they can patch it up but I think they will say new post, sorry.
PS I am no expert and may be wrong, I hope I am. Good Luck
Joe
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#3 Matt Burton

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Posted 02 November 2005 - 06:33 PM

Is the post carbon ?
If yes then this could be verry serious !
am i right ?


-matt :ph34r:
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#4 Afton Grant

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Posted 02 November 2005 - 06:52 PM

Yes, the post is carbon. From what I understand about carbon fiber is basically what has been said already. It is incredibly strong and shows almost no signs of failure up until its breaking point at which time it fails extremely quickly, loudly and grandly.

Goddamn. Just bought the thing too.
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#5 charlesneufeld

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Posted 02 November 2005 - 07:07 PM

Hey Afton, Sorry to hear about your post... Yes it is bad as you know.
As a TEMPORARY fix you could inject an epoxy and try to bond the fibers of crack together - use a release agent and saran wrap to keep the proper external dimension...but I would start looking for a new post, as it will fail.

OH and don?t sand/cut is yourself unless you are very careful. Graphite slivers are NOT good.

~C :unsure:
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#6 Matt Burton

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Posted 02 November 2005 - 08:00 PM

. Graphite slivers are NOT good.


I have to second this quote with all mighty force !
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#7 Alec Jarnagin SOC

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Posted 02 November 2005 - 09:01 PM

Afton,

Contact Peter Abraham (email me off-list if you need his info). He owned an Elite for a long time and I seem to recall him dealing with this problem. Granted, he probably changed the post, but he has already gone down this road and he happens to have a great relationship with Tiffen (and he is a Flyer dealer too).
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#8 BRIANBUSBY

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Posted 03 November 2005 - 02:31 AM

HI ALL

PLEASE NOTE PLAYING WITH CARBON FIBRE IS NOT
A GOOD THING.
YOU NEED SPECIAL BONDONG AGENTS
TO CLEAN USE ACITONE
DO NOT USE ANY POWER TOOLS AS CARBON IS A GOOD CONDUCTOR
AND ANY DUST CAN FLASH BACK.
ALSO IT CAN SHATTER. !!!!!!

LEAVE IT TO THE EXPERTS

BRIAN
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#9 RobinThwaites

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Posted 03 November 2005 - 05:17 AM

Hi Afton

I have seen more than one post like this and most have lasted some time with no catastrophy but that is no promise. The gimbal body probably covers and braces the area a lot of the time with any normal weight camera. Dings like this are usually caused by docking stand accidents e.g. knocking over the whole thing or removing the sled battery with a heavy camera in place or in a totally unbalanced condition.

I would not recommend trying to epoxy the area as many resins are not compatible with each other, there are other things you can use (e-mail me if you feel up to having a go) but ultimately replacement is the real answer.


Robin Thwaites
OpTex
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#10 Robert Eder

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Posted 24 November 2005 - 03:18 PM

in this kind of carbon tubing a vertical crack is nearly impossible. so a horizontal is the only thing that can happen here. i do not know the structure of carbon used on the post under the top wwich is viewable. if the fibres are vertical at the inside the crack would not be that bad. if not the lower sled could break away within a second cousing a terrible accident.

try it, just hold the sled and put the lower rig under a lot of weight, if the crack gets bigger throw the post away.

my 2c

greetings, Robert
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#11 Jason Torbitt

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Posted 18 May 2006 - 03:24 PM

Hi Afton
How did you get on with your post replacement? I'm looking at having the post on my Master Series replaced within a year due to a small wear mark in the carbon fibre, where it looks as if gimbal or docking ring pinching has occurred in the past.

Has anyone had their Master post replaced, and if so, who with? Obviously Tiffen and MK-V spring to mind straight away.

Thanks
Jason
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#12 Afton Grant

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Posted 18 May 2006 - 03:49 PM

Hi Jason,

Yes, the post has been replaced. I sent it to Tiffen in February. It took about 3 weeks due to a busy workload there. They only replaced the top post, since that was the only one with the crack. I believe before it went, the estimate for the post replacement was around $1600 US. I also requested to have the top stage dovetail mount upgraded from the old thumbnail screw, to the newer drop-in lever release. I think that was about $1200.

While it was being repaired, the technician found a few other problems within the top stage and monitor. That jacked the price up a bit, but it was worth it to get a sled back with a completely clean bill of health.

I'm not a materials expert, but you might want to check on the severity of your situation. A wear mark or pinch might not be as severe as a clean-through crack. Replacement might not be immediately necessary.

Best of luck,
Afton
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#13 Jason Torbitt

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Posted 18 May 2006 - 04:05 PM

Thanks Afton

Good to hear your sled is sorted now. I agree, spending the money may be a nightmare but ultimately worth it, as you say having a sled in spot-on condition is priceless. It's good that you only had the one post replaced too - useful info.

My mark is a wear mark, about 1 inch across, where the top couple of layers of carbon fibre have worn away. I've bonded it for the shorter term, thanks to Robin at Tiffen for the good advice, and I'm happy with it. But replacement of the post in the long term is the solution.

Thanks
Jason
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#14 Iain Baird

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Posted 18 May 2006 - 05:08 PM

Hey Afton,

I had a crack exactly like the one in your photo on my old Master Series. I watched it for years and it never changed. It was right below my Jerry hill post ring for the docking stand. Since the crack was a vertical crack I figure that the post ring held the post together and prevented the crack from growing. After six years it still hasn't changed. I sold the sled two years ago and took the price of replacing the post off the sale price but told the new owner not to worry about it untill he sees any growth, to this day it is still the same size. However your photo seems to be more in the middle of the post which might concern me more as there is nothing to brace the post from further splitting.

Iain "just my two cents" Baird
Toronto
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#15 Bruce Alan Greene

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Posted 19 May 2006 - 02:23 AM

Looking at your photo, it does look bad.

If yours is a telescoping post and there is a post inside, behind the crack, you might get away with using it. If you extend the post so that it has no internal support all bets are off. I would expect it to snap when someone lifts the rig with a heavy camera on it by hand.

Carbon fiber posts are very strong in only one direction. You can place it between two chairs and stand on it (maybe:)) but if you tighten the gimbal too tight you can crush it pretty easily.

So, when you have the tube replaced, make sure your gimbal clamp is properly adjusted. Otherwise, you may just crack the new post. If you think about it, unless your gimbal is a perfect fit to your post (round wise), and it won't be, I promise, than it always puts pressure on just 2 points on the post rather than distributing the pressure around the pole. If it tightens with a cam latch, maximum pressure occurs before backing off at the locking position and that might be the problem.

I built my own rig so I have some true life experience with failure of the carbon fiber (and dropping a panaflex). I now carry a spare pole at all times :)

Good luck.

-bruce greene
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