Anatomy of a Claw

Here is the claw machine using the pop can mechanism:

This is also showing the app capabilities of the claw machine.

To clean up the look of the claw machine, the three fingers that reach down were milled at an angle. Here is how they looked prior to machining:

With them machined and belt sanded:

New fingertip extensions were made to allow the claw machine to pick up smaller apple juice and orange juice cans. They are roughly 2.05 inches in diameter (5.5 FL OZ can) as opposed to the 2.25 that the (7.5 FL OZ) narrow pop cans were. Along with this the finger tip bar was also pushed down to the bottom of the angle. Here is a comparison of the two different angle extension side by side:

The holes were extended out a hundred thou (.1 inch) from the edge of the angle.

The Pop Can Claw is now finished and picking up pop cans. It is not capable of picking up the large cans (they are too heavy for the current design). Instead it can pick up the short 8 FL OZ or narrow 7.5 FL OZ cans.

The design uses the extended fingers that reach out far enough down to grab the can low. The finger tips are generic electronic box feet that have been attached to short rods. These are fixed to the fingers with small pieces of aluminum angle. Here is a view of the claw in the open state:

The weight of the center plunger would allow for it to fall to the lower limit. This was too far down for the solenoid to pull it back up. Adding angle limits to the links movement stopped the plunger from going down too far. This was added to all three links.

With the plunger retracted into the solenoid, it will allow for the rubber feet to center and grab the pop can:

Now that the claw can pickup cans, the claw machine had to have the program modified a bit to allow for the can to be gently set down. Check out the claw machine build for details.

After a few trials of the claw to pickup cans with short extensions (removing the longer brake line fingers and using the intermediate linkage with short extensions as the fingers), there was a need to extend the reach out further. Deciding to extend the reach out 3 inches would allow for the popcan to be picked up lower. Here is the part being machined:

I have been searching for a cheap CAM/CAD program and ended up using CamBam. This has a free 40 time trial use and after the use, will limit the output to 500 lines. Or it can be purchased below $200. This seems like a fair price for what it can do. It is able to act as a CAD program, the post processor can be modified (to an extent), and it outputs usable G code for FANUC controllers. All of which I was looking for. Granted it is no GibbsCAM, but it does get the hobby jobs ran.

The part was radius'd on one end and 5 holes were center drilled. I used a drill press to finish the part for trial. Once assembled and tested, I found that the extension was enough that the solenoid lost its leverage and did not allow for the claw to fully close (where the most pull is seen on the plunger of the solenoid). I plan on modifying the extensions to allow for full closure on the popcan (or at least close to it).

As fun as it would be to build a new claw, somebody suggested that I should just try the old claw to pick up pop cans.  After a trial test with an empty can, this appears to be promising.  To do further testing, I am going to modify the claw machine code to be more "open" in testing environments, but still able to revert it back to claw machine mode.  Check out the claw machine logs for further details.

After seeing if the refrigerator compressor would work, I quickly realized this was going to be a specialized tool that will be used very little due to space and oil being blown out of the compressor.  I will forfeit this option and pursue mechanical options. 

The plan for the next edition of the claw tool is to allow for it to pick up a pop can.  Two frames of thought on this:

1. Use a vacuum source to suck the pop can up into a cylinder.  The vacuum could possibly be a refrigerator pump.  Not sure if there is enough cfm, but it gives me an excuse to make it an accessible tool.

2. Use 3 tracks located 120 degrees around the pop can radially.  Have a spring loaded tension to drag it up into its grasp.

The problems that I see with this is having to have a grid of the pop cans to allow for a user to move over the can standing up right and away from other cans.  There will be a material with holes drilled/profiled a little larger than the od of the cans.  These holes would be on a grid.  

That will keep the cans upright and ready for picking.  Now how to locate the claw exactly over the pop cans. . . This will be just a matter of keeping track of steps to the locations of the pop cans.  Make a sort of "snap to" grid that the claw would hover over.  The problem is not having enough "game" to it.  The kids would just pick what pop they want and always get one (as long as a can was under it).  

At this point, I will start to work on the vacuum pump getting it ready to be easily applied to projects.  Make vacuum connections easy.  We will go from there.