Videos - The Coin Bot

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00:00:00	hello everyone welcome back so in the last video I was talking about how it is extremely difficult to turn that coin slider from the center post as I had originally planned with this um Center gear here I don't think that the stepper
00:00:15	Motors that I'm using really have enough torque to do that they're Nema 17 and I think they're pretty small I don't think they're going to have enough torque in order to turn this whole coin slider with the cogs and all um from that
00:00:28	Center position so what I've decided to do is try to figure out a way to turn this coin slider from the outside edge so that we get a little bit more torque what I came up with was adding a GT2 gear if I can create that we can have a
00:00:47	belt that runs around the outside of this and we should get a lot of torque that way so I just kind of printed this out as an example of what that gear ratio would look like you can see that the the teeth are pretty small on this
00:01:00	there's I I believe there's there's 200 teeth on this and that is the perfect amount of that particular gear tooth ratio to fit directly over one of these coin sliders one thing I noticed though was
00:01:19	that these coin Grabbers that I have here these white pieces they don't quite make it all the way out to the edge here so you can still see a pretty large piece of that coin Grabber this white piece here you can
00:01:35	still see that that's inside the circle here I was thinking that one of the ways to secure this just a little bit better to the coin slider would be to push these out so that they're closer to the rim so if
00:01:49	you make these just a little bit longer you can see that they will push out towards the the edge of the of the coin slider a little bit and you can actually use these posts if
00:02:05	we make these posts just a little bit longer like I've done here they'll not only come up through the coin slider but they can actually recess into the bottom of this gear so that actually will help it hold together a little bit
00:02:22	better so I began by recreating the coin slider with slightly longer with slightly longer coin Grabbers we're calling these coin Grabbers at this point just making up names as we go along but as you can see
00:02:39	I pushed these out to the edge a little bit more so that they were closer to this lip here and when I put these in position I'll put two of these in position these are very tight tolerances so they really just snap
00:02:55	together and once you do that they're flush like I said they're very it's a tight fit there once you do that these are flush here and they stick up pretty significantly from the top here and when I created this I created
00:03:15	it in a way that there are little recesses I'm very proud of the way that this came out cuz I created a little recess here for this coin slider to slide up and down in I made sure that there was no interference between this
00:03:28	gear and the the compliant mechanism that we talked about in the last episode and also these posts will fit into these holes here on the ring so this actually helps hold the whole thing together and if we flip that over we can now snap
00:03:43	that into position [Music] there and we have a pretty solid piece now that all locks into position that all fits together like that and you you still have compliance
00:04:01	here but at the same time you also have this really rather large gear around the outside that you can get a a lot more torque when you're trying to rotate this with a small stepper motor like I am I'm pretty proud of the way this part came
00:04:14	out I like the way the design worked out but I think I can still make some improvements the main idea here is to improve the the pulley design so that it holds on to a belt a little bit better and in the next iteration you can see
00:04:31	that I actually I did that I put a little follower here so that the the belt pulley can actually stay securely in that Groove this is uh pretty much exactly like the other one except I've added those two little features there
00:04:46	the only thing I and I did differently in this one this one was printed with 100% infill which means that um this is a completely solid part and this part is just a lot l lighter because I only used 15% info but the rest of it is basically
00:05:04	the same the problem with this particular piece though is that when we add that to the coin slider there's not much room between the actual edge of the coin and the edge of that ring there so I would like to take that edge down a
00:05:18	little bit I was nervous that in the camera studio position that this actually might cast a shadow onto the penny which would not be ideal so we're going to champer that edge a little bit and then in this version you can see
00:05:31	that this this lip has been chamfered down so that we make a a much closer connection here we save a lot of plastic around the edge here and I don't think this any longer will cast any Shadows on the coin as it goes through the camera
00:05:45	studio position so that's actually a much better design I'm happy where this is going and you can see now that we can now drive this this part with the belt uh that runs around the outside of this in the next video we're going to add a
00:05:58	stepper motor to the whole design and we're going to be able to drive that from the outside with a belt so stay tuned for that and I look forward to sharing that with you thanks everyone