[brianklein]

http://images1.wikia.nocookie.net/__...crewdriver.png
http://i884.photobucket.com/albums/a...h/PICT0230.jpg
http://i884.photobucket.com/albums/a...h/PICT0231.jpg


Can someone help explain to me the claw expansion/retraction mechanism of this toy??? How does it close in particular??? Thanks

[brianklein]

here's another picture of the claws extended:

[punish3r]

Nice sonic screwdriver

Currently searching for a picture or diagram on the intertubes, will attach it at the bottom if I find one. Systems like this are much better described in pictures or mathematics than in text.

Alright. For the sake of this explanation, let's imagine that there are only two 'fingers' instead of three. The two fingers are equally spaced around a central shaft; 180 degrees opposed to one another with the base of each finger in contact with the central shaft. Imagine a capital letter "Y" with the central vertical line extended slightly above the joining of the two diagonals.

Each finger (the 'arms' of our capital Y) has a pivot point on it, somewhere between the contact with the central shaft and the opposite end of the finger. For the sake of simplicity, let's assume it's halfway between the two ends of the finger. This point is the fulcrum for a first order lever.

The central shaft is not homogenous in cross section; towards the top (the piece of the Y that extends above the join) it begins to increase. This could be a simple taper or a spherical/circular segment or a hyperbola for all we know. Again, for simplicity let's assume a simple tapering of the shaft.

Now, the shaft is free to travel on its long axis. As it does so 'away' from the fingers, it causes the enlarged portion to come into contact with the inside ends of the fingers. This causes each finger to pivot around their respective pivot points, bringing the fingertips closer together.

Keep in mind that this is a very, very (VERY) simplistic view of this particular system, which probably has a mechanical stop to prevent overtravel of the shaft, a spring return to 'open' the fingers, etc, etc. It is also entirely possible that the opposite situation is true, with the fingers opened by the shaft moving 'towards' the fingers, with the initial positioning having the shaft retracted and the fingers closed.

The picture below is as close of a representation as I could find in my limited browsing. Note that this design diverges from the above description on three points. First, it utilizes cogging on a non-tapered shaft to transmit the motion of the shaft to the fingers. Second, the fingers are comprised of parallel shafts transmitting the motion and hence the fingertips stay parallel throughout the travel. Third, the central pivot point is negated. (This mechanism also operates 'backwards' from the one described above.) However, even with all of these discrepancies, the picture is still useful as the motion type of the original mechanism can be seen.

[brianklein]

Thanks for your response.

Do you know how the spring mechanism works or have picture of a spring mechanism for the central shaft to "spring" out??? Particularly the release button mechanism.