Well our spray mechanism worked good but we wanted it to work flawless, so we decided to add plastic bearings to the mechanism, so it would slide smoothly and to reduce friction. But then a problem occured, the problem was that we used threaded rods, the rods kept hanging on the bearings, so it didnt move smoothly. We changed the threaded rods to smooth rods as you can see in the picture below, but then we faced another problem and that was that the rods were slightly big so they didnt slide smoothly, so our solution was to turn the 10mm rods to 9.5mm.
The next modification we wanted to do was to keep the spray cap in its place so it couldn’t rotate, so we came to a solution to drill a hole on top of the mechanism and to put a pin through the hole and through the cap.
We started designing the spray mechanism by dividing the problem into smaller problems. These problems were holding the can, fixing the spray direction, pressing the cap and fixing the mechanism on the robotic arm. We decided to fix the nozzle and push the can to get the paint out, this way the distance to the nozzle is always a fixed distance. The first concept also involves a bench vice mechanism to hold the can and a pin to hold the cap. Furthermore an air piston is used to actuate the can.
First sketch of spray mchanism
After reviewing the first design we’ve made a few simplifications to make the mechanism easier to manufacture and more convenient to use. First of all we decided that using air pressure solely for the spray mechanism would be unnecessary. So we’ve decided to change this to an electronic system. We’ve also decided to fix the can by fitting it into a slit and leave the pin. Instead of a (complicated) bench vice system we have decided to create a cup. By making the top part of the mechanism removable the can will be able to slit in, thus fixing it in all directions.
After reviewing and redesigning we started on manufacturing the spray mechanism from aluminium.
Representation of the first spray mechanism design. Note that the empty space below the can is reserved for the piston.