NOGA knock offs

[whateg0]

I have a few of these articulating arm things now. One is used for my webcam at work. Two are currently in the shop on magnetic bases. I just ordered two more - one to be used for dialing in round stuff on the mill, and the other for an as yet undetermined role. So far, all have been ok, but not great. I'm not griping, mind you. I paid less for all of them than a single Noga would have cost new. But, one of the two I just received is amazing. I don't have a Noga to compare it to, but compared to the other 4, it is incredible.

The good one looks like this.

It locks up solid with very little force. I haven't put a set of pliers on it, but with my bare hands, I cannot move the ball ends with even moderate torque on the locking knob.

All of the rest require a ton of torque to get them to be almost solidly locked. But they all can be moved with my bare hand. And if there's any leverage, such as the indicator clamp, it is almost easy to get at least a small amount of movement.

I don't know what makes one better than the others, but I do know that the one that locks solid has a ball-bearing thrust bearing under the knob. Could it be that just a little less friction there is all it takes to make the locking mechanism that much more efficent? Maybe. I don't intend to take them all apart to see if I can improve them, but if I buy any more, it will definitely be of this style.

Do Nogas have ball bearing thrust bearings under the knob?

Dave

[armscor 1]

I have 3 Noga knock offs, perform faultlessly.

[pete]

Why the Noga knock offs can vary in how well they work compared to the real one's ? https://www.youtube.com/watch?v=qnHfHl7LI7Y My guess is with a bit more attention to getting things flat and smooth as well as adding a proper thrust bearing mentioned in the video like the real Noga's have would make even more of a difference.

[John Hasler]

It's also possible that the good ones have acme threads.

Those aluminum surfaces he ground the anodizing off of are going to wear rapidly.

Interesting design.

[whateg0]

I agree that removing the anodizing was a bad idea, but with the plastic washer in the middle, it might not be too bad. Of course, with that washer there, I don't really think that it would matter if it was anodized. The camera mount versions all have a hirth coupling between the arms, so that joint locks up well. At least all of the ones I have do.

A friend of mine asked me, what does it matter if it's not rock solid? The DTI doesn't exert enough force on the arm for it to move. From what I've seen, even that small amount of force can cause a tiny movement. Since I intend to use mine on the mill in place of a coaxial indicator, I could see the arm getting bumped while being spun, or even being spun by nudging the arm. So, it needs to be pretty stout for that to work.

Dave

[Harold_V]

A friend of mine asked me, what does it matter if it's not rock solid? The DTI doesn't exert enough force on the arm for it to move. From what I've seen, even that small amount of force can cause a tiny movement.

True, that. If the setup on which a DTI mounts is not fully rigid, the reading will be suspect, which is especially true when using a DTI like a Starrett Last Word. It will spell the difference between success and failure when tenths matter. Been there, done that. That's one of the reasons I no longer use a Last Word.

H

[armscor 1]

There is no such thing as fully rigid in this world, a tongue in cheek engineer described when a fat Horsefly lands on a railway track it sags 1 millionth of an inch!!
My mentor who taught me machining scolded me for leaning on the tailstock when machining between centres, everything moves when a force is applied, no matter how small.

[Harold_V]

That's also true. I spent several years in precision grinding. Touching the machine while it's in operation (any of the slide surfaces) is absolutely not a good idea.

H