About this 3D model

This is a new iris box design which is perfectly spherical when closed (81mm in diameter). The design requires 24 M2x6 countersunk screws to assemble (or M3x8 screws at 150% scale etc.). No support material is required for this design, although on some parts a brim is recommended. The multi-colour designs are achieved by simply doing material swaps on a standard single nozzle FDM printer. The box is opened by turning the twist collar to unthread it and open the mechanism. It is further rotated, while holding the base stationary, which turns the gears and actuates the iris door. There is an optional stand makes holding onto the base and using the box easier (and stops it rolling away when you put it down). There are a few decorative styles for the components: 2 stands, 2 bases, 2 collars, 2 gears and 4 top door patterns. Beware that the second top door style 'Top door 2' will only work with 'Bottom door 2' and vice versa. In addition there are blank versions for a smooth sphere surface which are not numbered (although the smooth base makes opening the box quite difficult). Edit: I have updated the base files, extending the pattern to the edges more and making the central pattern better for filament swap multicolour printing. Edit 2: I have increased the size of the alignment notches on the 'Internal collar' to make assembly easier (not included in the zip file). For the box you will need to print: 1x 'Body', 1x 'Base', 1x 'Internal collar', 1x 'Twist collar', 7x 'Gear', 7x 'Bottom door', 7x 'Top door'. There are optional 'Screw covers' for the doors and the 'Stand' to sit the box on. Printing and assembly instructions (also see pictures) When printing the bottom and top doors, I highly recommend using a brim to help them stick to the build plate. You also need 24 M2x6 countersunk screws to assemble (same as my other designs). To test the fit of the screws, print one 'Top door' and one Gear. The screws should be tight (but hopefully not splitting the print) in the blind holes, and loose in the through holes. You can use contour/hole compensation in your slicer to account for this if there are problems. 1) Trim away the brim on the door parts using a craft knife and remove the print-in-place supports from the 'Bottom door'. 2) Screw the rounded end of the 'Bottom door', to the top point of the 'Top door'. Then screw the other end of the 'Bottom door', to the middle hole of a second 'Top door'. Repeat this process until you have a chain of four bottom/top doors. 3) Take the two 'Top doors' on the ends of the chain, and match up their edges to form a loop. Then take the loose 'Bottom door' on the end of the chain, and fit the cam into the slot of the matched up 'Top' door. 4) Fill in the gaps in the loop with bottom and top doors to complete the iris mechanism. The screws should be tight enough to keep the mechanism moving accurately, but not too tight to make opening it wth your hands difficult (it will loosen a little over time). 5) Next move on to assembling the body mechanism. Take the 'Internal Collar' and thread it, gear end first, into the narrow end of the 'Twist Collar' until it stops. This may be tight at first depending on your printer tolerances. Place this collar assembly, gear end first, onto the narrow side of the 'Body' component. Then place the 'Base' component onto the same end of the 'Body', making sure to line up the internal screw holes. Now you can screw the 'Base' and 'Body' together using three screws. This should also retain the collar assembly, but it should be free to rotate. 6) Tighten the three body screws all the way, and then back them off 2-3 turns. The gap between the ring gear on the body, and the ring gear on the collar should be just large enough for one of the small gears to snap in place, to help prevent it falling out later. Adjust the screws until they just allow the small gears to fit. 7) Now for the fiddly bit. The internal collar has 7 notches around the perimeter, these are to line up the small gears around the body; the gears need to be both evenly spaced and at matching angles for the mechanism to work properly. I find it easiest to take each gear, and line the raised hole up with the notch on the collar. Then lightly press the gear into place on the body, making sure it is straight. I then repeat this process around the body pressing in all the gears. To prevent other gears falling out during this process, it can help to use a rubber band to hold them all lightly together (see pictures). It also helps to lightly hold the body and base together to hold the gears in place. Do a quick check to make sure the gears are evenly spaced and match around the body, adjust any that are out of alignment. Now you can tighten the body screws to firmly hold the small gears in place (but not too tight to lock up the mechanism). 8) The small gears should turn in a synchronised fashion as you turn the collar. Turn it until the raised gear holes line up at the open side of the body. Yo