Videos - The Coin Bot

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00:00:00	so basically what we're trying to do is perform a heart transplant on a robot hello everyone and welcome back to the channel in the last video you saw that we tried to redesign the Beating Heart of My Robot but even after that design
00:00:15	change it still has a few flaws and we're going to try to rectify those today specifically we're going to try to provide a way for the robot to grab onto a coin and rotate that into position between two cameras so that we can take
00:00:29	nice pictures something but the problem is I really have no idea how to do that yet I started doodling on some pages and you can see some of my work here you know I got thinking about how we could actually grab this so but I really think
00:00:45	that the idea is that a follower could be running along the outside edge of this coin slider and actually push down push down into this space so that you're positively holding on to to the coin I
00:01:01	was thinking about how that might work you can see that you can create areas that slide up and down and I was thinking on this one that maybe there'll be a little Cog along the outside edge here that that moves this piece back and
00:01:16	forth around a pivot what I ended up with was having a line drawn here with a small pivot and then of a circular portion or an arc out here and this whole piece will rotate into position and actually positively hold on to the
00:01:33	coin I can draw that in more detail here but my theory is that you can split the coin slider along this point here you can create a pivot around here and if you know what the center of that pivot is here you can use that Center Point to
00:01:55	create an arc then this whole piece here that we we've shaded here can rotate in and out of this space where the penny is and actually hold on to it positively so I started playing around in freead to see what the finished product would look
00:02:11	like and I ended up with something like this you can see that this half moon shape here is really just one of those holes that's in the coin slider and this part here this piece here is that part I was talking about you have a small Pivot
00:02:26	Point here with a with its Center here and this outer Arc here also centered on that pivot point there that allows this whole piece to rotate into the space held by the penny and this piece will now hold on to the penny we need to
00:02:44	think about that a little bit more but that is my major plan for how to grab onto these coins and hold them positively as we rotate them through each of the three positions on the robot and again once I have that in 3D modeled
00:02:58	space I can 3D print that and then we can test out how it works and see if there are any problems with that and this is what I ended up with so you can see here that we have these two pieces um that we showed on the screen before
00:03:12	in freecad and I was really surprised at how good the tolerances are on my 3D printer that you can actually snap these pieces together and that piece rotates along that Arc
00:03:31	and it will rotate into the space occupied by the penny and you can use that difference in Geometry now to hold on to the penny more positively and when you're done when you're ready to release it you can move that piece back into
00:03:45	position and the penny will release we can kind of see how that works here that now positively holds on to the penny and won't let it drop but when I'm ready we can just rotate that back out of place and the penny will fall through so
00:03:59	that's great um that's really the rough idea of what I wanted to do I wanted to have a grabber that positively holds on to the penny as it rotates through each of those positions but as I got thinking about it a little bit more in one of my
00:04:12	previous designs I had this idea of using a rubber band to move a piece of the coin slider into position so you can positively grab onto the coin and I thought maybe that I could use that idea in this rotational idea as well but that
00:04:28	also requires a little bit of design tweaking so we're going to just continue to iterate on this coin Grabber idea that I have but we're going to change the geometry just a little bit so that we can finish the design and make sure
00:04:41	that it's actually going to be robust enough to work in the finished machine so let's just start with a blank sheet of paper and we'll start over again um using this you know General starting point and we will use that to kind of
00:04:54	finalize the design or kind of iterate on it at least a little bit hey everyone it's future me I just wanted to take a moment to say that I've been doing some work on our website at the coinb.in collecting the latest
00:05:09	developments and machine learning and get early access to my YouTube videos I hope you'll get a chance to check it out and let me know what you think down in the comments we're going to use a new piece
00:05:19	of paper here and I will use my rotary coin slider here and we'll talk about what else I have in mind for this so this is sort of that half moon shape that we had shown in freecad I'm going to take that again and we will split it
00:05:33	here and we know in the center of this machine that we have a gear about here so we're going to try to avoid that in this new design that I'm thinking about I'm thinking that we need to have a pivot point somewhere on this side of
00:05:51	the coin but we're also thinking about this Cog that needs to be along the outside edge of this on some sort of follower so we should incorporate that follower into the finished design and I'm
00:06:05	thinking if we have a larger lever out here we can actually open and close this much more efficiently so let's create we're going to create a little lever here that actuates around this pivot point so we split that here and then
00:06:23	again we have we know that the center point of this pivot is there and and we want to create a much larger Arc now so I'm going to use this as the center point and create a larger Arc out here and continue this split down to the
00:06:46	other side so now we've significantly changed the geometry of this shaded portion we can see that this lever is longer this will allow us to open and close this and there will be positive stops
00:07:00	for this on both sides of the coin we need to leave a little wiggle room here so an open space up there for that to rotate around but this Gap will open and close down here so I think that's going to be a much better design and we
00:07:18	can actually attach a rubber band somewhere around this point down here and as we follow around as this is rotating we'll be able to push down on this lever in order to open and close this
00:07:31	mechanism I know that's a little confusing so I'm going to try to draw that up in freecad and we'll see how that goes once I got laying out all the parts in 3D space in freecat it became clear
00:07:43	that most of the pieces rotate around some Center Point usually the this Center pivot here but sometimes it would be the center of the coin slider itself but that all became clear and you could actually lay out all of the parts and
00:07:58	how they rot rate based on the center of one of these [Music] circles when I tried to 3D print this you can see I was trying to be clever by using two different colors to
00:08:10	differentiate between the two pieces so that they'd show up better on camera but that ended up being a mistake you can see that the 3D printer is screwing up here a little bit and every time it needs to change color it needs to go
00:08:21	back over and remove the excess filament from the hot end so that ended up being a mistake and I think that this caused problem with the accuracy of the print and this is what the finished print looked like as you can see this
00:08:38	Pivot Point here wasn't quite large enough and the print resolution wasn't good enough to make that a clean round shape so therefore these pieces don't really fit together all that well you can kind of you can see air between all
00:08:54	of them so that means that I may need to make this a little bit bigger but the idea is there like I I'm happy with this on some level because at least I can see that this will work the idea is to get this to Pivot around there and
00:09:11	open and close to grab the penny and release it so we will go back into freead and redesign this part in at least two Dimensions with with this pivot being just a little bit larger I think that's the major change I think we
00:09:29	can also make this bar up here this push bar a little wider I looked back at my original design for this and I was looking at this particular pivot here um this pivot is about 6 and 1 12 mm across so I think I just need to make
00:09:50	the pivot in all future designs at least that big because that seems to work well these fit together well and that that works well as a pivot so in freecad this time what I'm really trying to accomplish is to make that bar
00:10:03	just a little bit thicker so that it's easier to push down and release the penny and I want to make that pivot Dimension just a little bit bigger so that the pieces snap together and they rotate
00:10:13	better I ended up printing everything in a single color again just because that makes it easier and the print resolution seems to work out a little bit better if the the print nozzle stays warm the entire time it's not switching between
00:10:27	colors for each layer but this is what I ended up with um I think there's some tweaks that I can still do here uh but it seems to work pretty well this lever is much thicker now and it rotates in and out of position so that
00:10:44	we can actually grab onto the coin so you can see that when there's a follower that comes along this path here it will push down on this and release the coin and I can kind of show you that in action too if we're pushing down on
00:11:00	this side of the bar and that'll be controlled by a rubber band that that spans this Gap here um when we use that follower along the outside edge here that'll push down on that and release the penny so that actually works very
00:11:15	well the thing that I can do is I can tighten up this Gap a little bit it doesn't need to be quite that wide and the other thing I'm interested in is using some of the thickness to control how this
00:11:30	moves you know in the z-axis this way because I think we're we might have run into problems with that so that in the next iteration we're going to use the same design but we're going to control that z-axis play a little bit more so so
00:11:44	that's great so stay tuned I'm going to play around in freat a little bit and we'll see how that goes but so far I'm pretty happy with the two-dimensional aspects of this we're going to take this and uh use half the thickness to control
00:11:58	that that's way here though so stay tuned in the next video we're going to use all three dimensions of this coin slider to really help us fine-tune the design of this coin Grabber but until then that's my two cents thanks for
00:12:03	watching everyone stay tuned and stay awesome