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FLYER Dovetail slipping


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#1 Andrew Pascoe

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Posted 25 September 2007 - 11:58 PM

l was just wanting to know if anyone else has come across the problem of the dovetail slipping due to the locking knob failing when you have a heavy setup on the sled of around 7kgs and you are tilting the rig eg. 45 degrees angle forward. I did a shoot last night that had a Z1 with a P&S adapter using some 35mm primes and no matter how hard l try to tigthen the locking knob with my fingers it never keep the dovetail in place when tilting the rig as above. My only thoughts to fix the problem is to replace the locking knob with a wingnut so at least l can get some torque with my fingers when trying to tighten locking knob. Does the dovetail ever slip on the bigger rigs like the Archer & Ultra? as the design of the dovetail plate looks exactly the same except for the locking mechanism.

Andrew Pascoe
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#2 Rob Vuona SOC

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Posted 26 September 2007 - 12:14 AM

l was just wanting to know if anyone else has come across the problem of the dovetail slipping due to the locking knob failing when you have a heavy setup on the sled of around 7kgs and you are tilting the rig eg. 45 degrees angle forward. I did a shoot last night that had a Z1 with a P&S adapter using some 35mm primes and no matter how hard l try to tigthen the locking knob with my fingers it never keep the dovetail in place when tilting the rig as above. My only thoughts to fix the problem is to replace the locking knob with a wingnut so at least l can get some torque with my fingers when trying to tighten locking knob. Does the dovetail ever slip on the bigger rigs like the Archer & Ultra? as the design of the dovetail plate looks exactly the same except for the locking mechanism.

Andrew Pascoe

---------------------
Yo Andrew,
This used to happen to me with my EFP . . . .Get a new Kip Handle to replace the knob or even go to the local hardware store and get a new plastic knob with 3 points for leverage.

Good Luck
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#3 Andrew Pascoe

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Posted 26 September 2007 - 02:16 AM

Thanks Rob, l'm getting an engineer to add a wingnut to a bolt that l supplied him with which is the same thread of course as the orignal so hopefully this will solve the problem. Rob once you made the modification to your EFP did it completely solve the problem or not?

Andrew Pascoe
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#4 Jerry Holway

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Posted 26 September 2007 - 09:22 AM

Thanks Rob, l'm getting an engineer to add a wingnut to a bolt that l supplied him with which is the same thread of course as the orignal so hopefully this will solve the problem. Rob once you made the modification to your EFP did it completely solve the problem or not?

Andrew Pascoe


Andrew-

The Flyer mechanism is the same as the old Model I, II, and III (and the same as some othe big rigs manufactured today), so if tightened enough, it should hold.

If it doesn't (it's possible), it may mean that the dimensions of wedge and the dovetail are just enough out that the wedge "bottoms out" and does not completely tighten against the dovetail.

IF that's the case, sand off a few thousandths of the bottom of the wedge.

FYI, the Ultra, Clipper, Archer and PRO (and some other rigs) no longer use that type of mechanism for locking the dovetail.

Jerry
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#5 Andrew Pascoe

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Posted 26 September 2007 - 04:13 PM

Thanks Jerry.

Andrew P. :D
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#6 Rob Vuona SOC

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Posted 27 September 2007 - 02:06 PM

Thanks Rob, l'm getting an engineer to add a wingnut to a bolt that l supplied him with which is the same thread of course as the orignal so hopefully this will solve the problem. Rob once you made the modification to your EFP did it completely solve the problem or not?

Andrew Pascoe

Hey Andrew,
Ya . . .it solved the problem . . . . I bought a couple of Kip Handled wedges from Tiffen and all is good in the world

If for some reason that doesn't solve it .. . .default to Jerry's fix . . . he's the guru!
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#7 Peter Hoare

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Posted 09 February 2008 - 09:19 PM

Im using an FX1 with a 35mm adapter, total weight about 6kg, and ive had no slipping... The sled is brand new though, so I dont know if this makes a difference but il keep an eye out... Does it slip much or just a few mm?
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#8 eric ramahatra

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Posted 11 February 2008 - 08:20 AM

i didn't got this problem before yesterday: it was the first time i flew in Low Mode and the camera setup was a bit heavy.
When the camera is at the bottom side, the dovetail is reversed and seems not to "grip" on its rails !
No matter how un tightened the knob, it was slipping.

But this problem occured only when the rig is reversed because of the low mode setup !
So it was nearly impossible to balance.

Would like to solve this problem too, i was very frightened the first time it appeared !
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#9 Jerry Holway

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Posted 11 February 2008 - 09:22 AM

Eric,

In low mode, lift the camera before you clamp down; i.e., support the camera's weight so the clamp isn't trying to do that job as well as clamp.

Jerry
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#10 eric ramahatra

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Posted 12 February 2008 - 04:27 PM

i would like but in 'normal' mode i think it could happen to when it is time to adjust the drop time and you have to let the camera 'fall' from 90 deg horizontal. It is the worst case because the clamp would fully support the camera weight.
in this case do you also have to support the camera weight "by hand" ?
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#11 Jerry Holway

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Posted 12 February 2008 - 04:44 PM

i would like but in 'normal' mode i think it could happen to when it is time to adjust the drop time and you have to let the camera 'fall' from 90 deg horizontal. It is the worst case because the clamp would fully support the camera weight.
in this case do you also have to support the camera weight "by hand" ?


Eric,

No, in high mode and the post vertical, the sled supports the camera weight.

If the dovetail slips when you tilt down in high mode, then most likely the clamping wedge is bottoming out because either it or the dovetail (or the combo) is just enough out of spec, OR possibly the camera weight is just too much for the little wedge to hold.

Can you get ahold of another dovetail plate to test?

Otherwise, see remedies above. Also check if somehow your stage is bent open. Lay a straight edge across the top. That used to happen to 3A stages if stressed, I think. I have this recurring nightmare of hitting an old floppy stage with a large rubber hammer or chicken...

You only need to support the camera weight when clamping with the camera hanging below (low mode) Good advice for all makes and models, not just yours.

Jerry
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#12 Mikko Wilson

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Posted 12 February 2008 - 05:17 PM

Jerry,
does lifting the camera slightly while locking the plate force it harder in sideways against the opposite (fixed) rail (Into the "V"), making sure that the locking clamp isn't just compressing the place down against the face of the stage?

- Mikko
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#13 Jerry Holway

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Posted 12 February 2008 - 08:22 PM

Jerry,
does lifting the camera slightly while locking the plate force it harder in sideways against the opposite (fixed) rail (Into the "V"), making sure that the locking clamp isn't just compressing the place down against the face of the stage?

- Mikko

Mikko-

Yes. It's sort of like this - a proper dovetail clamp wedges things in two directions - against a flat and sideways into the angled surface of the opposite side of the dovetail, and this is key - compressing against the flat as you say, but also on the side opposite the clamp.

When in low mode, if the force applied to the clamp has to lift the camera as well as shift it, there's a chance the plate won't shift sideways and fully engage the beveled surface - it will be out of square slightly and not pressing hard against the flat on the far side. Then when you tilt or move the rig, things can shift, get loose, and slide.

Every dovetail in a machine shop works this way (and some of the mechanics are absurdly clever); look carefully at them next time you visit your local machinist.

Jerry
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#14 Mikko Wilson

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Posted 12 February 2008 - 09:17 PM

Yeah, that's what I was getting at Jerry, thanks for the clarification! :)

- Mikko
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