Videos - The Coin Bot

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00:00:00	hello everyone and welcome back to the channel in the last video we were talking about how uh we could add a a large gear to the outside of that coin slider that could be rotated with a pulley um so we we talked about that and
00:00:16	the advantages of that basically that you can apply a lot more torque to this coin slider as it's rotating the other thing that I wanted to point out is um we were going to rotate that with this Center gear here but once we discovered
00:00:29	that that was to too small to actually be effective um we no longer have a need for this gear so in the in the latest designs um we just eliminated that gear uh completely and we're just leaving uh small I'm calling it a donut we're
00:00:45	leaving a dut there so that we can actually use that to Center the coin slider and rotate that around the donut but there's really no need for there to be a gear there anymore now the next challenge for us is to figure out how to
00:01:02	get a stepper motor attached to this in such a way that it will actually be able to to rotate this outer gear um on on this part here there'll be a sprocket that attaches to this through a belt I'm I'm thinking about running a belt around
00:01:19	here the only problem is I didn't know exactly what size belts are available and I just started playing around with CAD before I really got um any information about that what I wanted to test was whether I
00:01:32	could get uh the tolerances of this to line up pretty well so that I could actually insert the stepper motor here and get these screw holes to line up which they do pretty well that took a lot of work in CAD just playing around
00:01:46	but try to get all that lined up now you can see that these screw holes here they interfere with where the coin slider is going to rotate and if you counter sync the the nuts enough here the the screws enough here it it won't be a problem so
00:02:02	this was just really a test piece to see if that could get that working and I actually was able to screw that down pretty pretty tightly um they they were counter sunk so they didn't really interfere with anything my goal was
00:02:14	really to have the Cog in this position so that the belt was actually pulling this together and and closing that Gap that we saw in the compliant mechanism before but you can see as this rotates around
00:02:30	um you're going to get closure here as this picks up a [Music] coin and this all really does work well but as you can tell there's still a lot of friction there we'll have to figure
00:02:44	out a way to deal with that later but the next challenge for me was really to figure out what belts are available and um to figure out exactly where the center of the stepper motor needed to be in order to drive this whole mechanism I
00:02:59	decided to look on Amazon and it looked like there was a few popular sizes of GT2 belt the problem was I didn't really have any of those and I didn't know which to order so I ended up buying a bunch uh but then um a lot of those
00:03:13	parts are coming from China and I didn't want to wait around trying to figure out what exact belt size I needed but then I came up with an epiphany that I could use the C = pi D the circumference equal Pi * diameter to
00:03:28	figure out how to 3D print a temporary belt just so that I could get the distances right the three sizes that are available on Amazon pretty easily are 410 mm 430 mm and 450 mm like I have
00:03:46	here so what I did was just print out three belts uh 6 mm wide which is the exact width of the the final GT2 belt and that allowed me to kind of look at this and see how far away the actual stepper motor had to be now in for this
00:04:07	450mm version you can see that that's pretty far away it's it's an okay look but I actually want that to be closer the the goal for me is to really make this as compact as possible you can see that this gives you a good enough
00:04:21	distance that you can figure out where all the parts need to be and I think that 430 mm for the belt circumference is actually going to be a pretty good size at that distance you can move the
00:04:37	stepper motor out a little bit further and in this position you can see that I've actually moved the stepper motor out quite a bit and now that these bolt holes don't interfere at all with the cam followers so even though they're
00:04:53	counter sunk and it wouldn't really been a problem but at 430 mm belt size that's going to be just about right to keep that outside of this outer gear but also close enough so that the Belt doesn't have to be too long the other thing that
00:05:07	I'm really proud of with these designs is like chamfering the uh the coin sorer slot and also chamfering the coin Studio slot on the back side that narrows down the am the field of view to so that you don't get all the intricate gear work um
00:05:25	when you're trying to take a picture of this if you put that in and you wrot rotate that into position you can see that it actually shows only the penny now and I think that's going to work out really well for the coin Studio as I
00:05:38	talked about in the last uh video These cogs are time so they're not trying to push down on two compliant mechanisms at max pressure at the same time to try to reduce the amount of friction that we have in this mechanism but you can see
00:05:53	that even though I'm using the outer gear now it's still very sticky and hard to to turn so the thing that I came up with to fix that was to see if I could actually reduce the amount of friction by
00:06:09	removing the cogs entirely and replacing them with bearings so now these bearings are going to be what's responsible for pressing down on those cogs and when we get this into position now this rotates much more
00:06:27	freely so I put a little Sharpie marker mark there you can see that I created a little bit of a gap here and this post on the inside is really tight so that actually allows the outside of the bearing to rotate and the
00:06:44	inside of the bearing stays in position locked on that post so that has been really helpful it has created a lot less friction and now I think this whole mechanism will turn a lot easier now
00:06:59	with the those Nema 17 stepper Motors that I purchased so I'm pretty excited about that the finished mechanism when it's all put together looks like this and I'm pretty happy with that you can see that we have a a gear on the
00:07:14	stepper motor now those are screwed into place with these uh an three bolts and this rotates through all of its positions and it rotates on these bearings so that's going to work great you can see that
00:07:32	when we rotate through that by this first bearing here that's going to grab the penny it will then be taken by past the camera studio on the bottom side and then when it is rotated past
00:07:51	the coin sorter it will hit another bearing here and then be released and at this point I'm just waiting for that form 430 mm uh belt to show up so that I can actually get this powered on and working the way it's supposed to so all
00:08:06	of that works really great I'm excited to see how this works when I actually get the belt in and we'll see how that works once it's powered up so hopefully in the next video we'll have those parts come in and we'll be able to continue
00:08:18	working on this um there's still a part that needs to stick out of the top here that will hold on to a stack of coins and the top camera and the bottom of this mechanism have a lower studio and also the coin sorter so we still have to
00:08:33	work out all those mechanisms but I think the most complicated pieces we've got worked out already here so I'm pretty excited about that so thanks for watching everyone that's my two cents have a great day and stay tuned for the
00:08:35	next video thanks a lot everyone