Assembly of 0.32, testing

I spent last evening assembling the latest revision of 0.32, the current production prototype. Below are some images from throughout the assembly process:

Cutting new interface plates from a sheet of steel

Cutting the first version of the new interface plate.

One of the major changes was the move of the interface plate from the inventory chute, to the axle/bracket assembly. Along with the front plate, which has been modified to a curved profile, these components help make the axle assembly far sturdier.

Completed "Magic Box," note the 2nd revision of the interface plate, using countersunk screws

 

 

Countersinks.

This technique requires using a thick (~2mm) steel (preferably) or aluminum sheet for the interface plate -- something rigid enough to hold up under the weight of the inventory, as well as smooth and flat enough to vend smoothly. Below, you can see the thickness difference between the thin casing sheet, and the interface plate's sheet steel.

Note the radius of PN008, the front plate. The interface plate, PN003, is resting edge-on in the vending tray lip.

I've also chamfered the corners of PN008, hoping to reduce the occurrences of condoms catching on the plate during vend. This hasn't been too helpful, as testing has shown. I'm optimistic that improvements could be found by tucking the plate under the interface plate -- a kind of tabbed arrangement, that would eliminate any and all edges from the process. I'd hoped at one point to convert PN003&PN008 to a single part, reducing the number of cuts to two cutouts for cam clearance, but requiring a sharp and accurate bend at the leading edge (where the two parts currently meet). Using the thick steel for the interface plate, however, prevents this -- so I've got to find a way to eliminate the corners between the parts which are causing the problem.

This revision also includes the new cam design, which I'm quite pleased with. I'm going to attempt to produce more of the cams over the next few days, and make sure this design will work for production in Ghana.

Upon assembly, I've collected about 100 data points of vending, 50 per chute. Below are the results:


I've also eliminated the gap designed into the inventory chute: by moving the interface plate to the "magic box" and doing this, the inventory chute is now symmetric -- with the exception of the interface bar, the bottom of the "W" shaped section on the face:

Inventory chute, old design. New CAD model to come soon. Note the W, however.

 I've experimented with flipping the inventory chute over, to determine if the interface bar is necessary for reliability. Below you can see the results.

Compare this with the results after reorienting the inventory chute to utilize the interface bar:

There's an appreciable number of double vends and a few non-vends. Those were all caused by a condom becoming trapped under PN008 during vend, which then necessitated a manual clearing of the jam after another failed vend -- thus a single jam shows as two error points. I'm optimistic that improving the PN008 design can eliminate this issue.