single knob indicator arms

D

DMO

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Hello, this is my first post. I was wondering if anyone knows how those single-knob indicator arms and joints work. Some advertise "hydraulic", but I'm not buying that. Yet.
Dave
 
Aha! I found a video that shows the simple mechanism for the Noga holder arm joints mechanism. I was beginning to think it was a closely guarded secret.

[video=youtube;PAqzmFdov1Y]http://www.youtube.com/watch?feature=player_detailpage&v=PAqzmFdov1Y[/video]

And someone has also taken one apart here:

http://www.garage-machinist.com/usenet/rcm/noga1.jpg

I was thinking along those lines. I can believe that someone may have at some time made one to operate "hydraulically", but I can't believe the design would be practical, reliable, or otherwise affordable.

Dave
 
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I've got a Noga. I always wondered how it worked, but never took the time to find out. I used to have the multi-segment type arm. It used a cable inside the pulled the links together to lock them. The Noga is far better.
 
Apparently, there are some models that will support up to a 15 lb. monitor. Can you imagine the tension in that thing? I'm impressed, and I'm looking forward to seeing how easy it would be to make one for general-purpose applications, like lights or coolant hose, or dust pickup.
Dave
 
Thanks, DMO. I like those. Simple and elegant.
 
Does anyone know if these Noga type indicator holders have any built-in spring tension to keep things from flailing about while loosened?
Dave
 
When I loosen my Noga, it goes as limp as a wet noodle. Amazing device.
 
It looks like there is a cavity around the tightening rod below the ball. If so, a spring could be placed there to keep some tension on the ball. If not, a cavity could be machined there to hold the spring. The locking force is derived from the curved surface above the ball.
 
I can imagine that some conical springs (Belleville washers) could be placed in series with the push rod(s) to provide pre-tension, and then would also collapse into solid contact for the locking force. Otherwise, they could be placed over the rods to always provide a minimum tension, but I can see where totally loose could be useful.
Dave
 
There is hydrolic indicator bases I have several. The first one I got was given to me becouse it wouldn't tightin up, so I took it apart replaced all of the O rings and it works like new. I also got a noga the same way, the rods where wore out so I made new ones for it and it works like new also.

Marty
 
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