Peters 7-seg all mechanical display prototype 2

thingiverse

This is a prototype ! I am currently working on prototype 3, so I won't put more time into this one. However, by request, I uploaded the current prototype to Thingiverse. Remember that it's not a polished finished project yet. First, watch my video about it: https://youtu.be/oHPHFjFOA3I Current status: It works and can count from 0-9 when turning the gears. But it is still a prototype and not elegant yet; I want to reduce complexity more and reduce friction. I have many ideas in my head, but hard to find time to do make them. I am working on 10 position indexing gears so that one turn of the input changes display one number. See the included file for my current idea regarding that: test_10_pos_index.stl The reason I did this was the following: Big led displays draw a lot of power and can be poorly visible in daylight. Mechanical displays that exist today have one electromagnet for each segment, which requires a lot of wires and electronics. This display can be used without any electronics at all, for goal keeping, clocks, etc. And of course I wanted it to be as much 3D printed as possible. My goal is that when it is finished, multiple display segments will be serially connectable so that if you connect three units they will be able to count to 999. That's when one segment switches from 9 to 0 it also switch the display connected to it +1 and so on all mechanically. The main use of a display like this is that it can be run all mechanical, for goals/points keeping, mechanical clocks, counters, etc where no electronics at all is needed. To make it electronic just a $2 stepper and driver is needed to drive multiple segments. Like this one: 28BYJ-48 stepper motor and ULN2003 driver, which makes it very easy to control from an Arduino and other controllers. Great for temperature display and YouTube subscription counters and so on, only draws power when switching numbers. Printing: Print the parts; I have added multiple parts in each STL file so it should be easy to print. Use a different color for the digits than the rest. I printed my parts with 0.15 mm layer height. Extra parts required: Superglue and one rubber band Assemble: First make sure the digits can slide freely in their slots on the bottom part; some filing might be required, but do not file too much so they can twist in the slots. When you can move them with minimal friction, then put the corresponding knobs on top; make sure they still can slide but have no play in other directions. Apply some superglue to hold the knobs and digits together. The center digit is different; it should be placed in the bottom's center slot with its number 7 towards the center digit knob. Now put both the index wheels with their number 7 towards the center digit knob. And keep them in this position when assembling the other index gears. First, it might be a good thing to temporarily mount the two spur gears and turn to see if the center digit moves freely; if not some filing might be required. Now it's time to mount the other index wheels; every wheel is numbered. The numbers represent the current digit being displayed, but also one of the numbers on each index wheel has an arrow on top of one of its number, which represents what segment it belongs to. The segments are numbered from top, left to right; the top segment is 1, the top-left segment is 2, the top-right segment is 3, the center segment is 4, the bottom-left segment is 5, the bottom-right segment is 6, and the bottom segment is 7. So now it's time to add the indexing wheels and match them up with the segments. And if you have the bottom indexing wheels pointing with 7 to the center, then when you mount let's say number 2 indexing wheel, its number 7 should also point at its segment. When all the indexing wheels are mounted, then mount the spur gears on top and put a rubber band around all the digit knobs. Now make sure you can turn it and that the display works; here some more filing or sanding might be required, and also some universal oil or lubricant might be helpful. Now put the assembly in the front part and make sure it still works. If everything works, now put some glue to mount the front part, be careful not to glue any segments. Final step is to mount the two bottom knobs to the bottom with some glue to secure the index wheels and gears from coming loose. Good luck, have fun!