Videos - The Coin Bot

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00:00:00	can you power a robot with a rubber band that's what we're trying to find out in this video today hello everyone and welcome back to the channel if you've been following along so far you know that I'm trying to
00:00:11	build a robot that's capable of sorting coins by date if I can do that I should be able to easily identify coins to add to my own collection but in this video we're going to continue working on the coin Grabber mechanism the part that
00:00:26	grabs a coin rotates it into position between two cameras so that both sides of the coin can be photographed at once and identified so I had this crazy idea back in the day that I would be able to power at least a small portion of my
00:00:39	robot using just a rubber band if you watch the last few videos you'll know that my goal really is to have positive control of the penny at all times so I want the default to be holding on to the penny and you actually need to trigger
00:00:56	the machine in order to let go of the penny now because these components are so small I got thinking about what size rubber bands I could use to uh actually power this and I was thinking like back in the day when I had braces we used to
00:01:12	have all sorts of uh rubber bands and little Contraptions that would attached to the braces and that made me think like maybe those particular very tiny rubber bands were available but I did a quick search on Amazon and of course
00:01:27	they have them for sale so I'll leave a link in the description below if you actually want to purchase some for yourself but you can actually buy orthodontic style um small rubber bands just on Amazon so that I thought that
00:01:40	was really cool now when you're trying to create things at this small scale you actually run into issues of the printer resolution and in this case these rubber bands are so small that I wanted to create hooks in the coin Grabber that
00:01:56	would actually hold the rubber bands and Lots so that they wouldn't interfere with the rotation of the coin slider um that became a particular challenge in freecat as well because as I was building out these layers I had to think
00:02:11	about exactly how the layers lined up and also freead does not allow you to draw a sketch that when padded out will result in multiple bodies so that really became a challenge some holes went partly through the layers and then once
00:02:29	I got those cut out I actually had to build a small hook on top of the lowest layer but all in all I got it eventually figured out and I was pretty happy with the results these little hooks worked out pretty well to hold on to the rubber
00:02:44	band and I ended up with a finished design that looked like something that was created by the Kardashians on Deep Space 9 coincidences happen every day and really the only thing left to do was print it out on the 3D printer and see
00:02:56	how everything worked together I took a lesson from the last video and printed everything out in two different colors so that we could see a little bit better contrast and see how everything was working a little bit better on camera so
00:03:07	once I got everything printed out here you can see that it worked pretty well the hooks are like almost the perfect size for these rubber bands that I purchased on the Amazon but the issue with them is that the rubber bands are
00:03:21	actually a little too firm and when you push down on the the lever here which is meant to trigger the releas Rel of the coins you can see that it actually the lever itself bends without actually opening the Gap to
00:03:36	release the penny so that I felt was going to be an issue when I got thinking about this I was thinking that to correct that problem I can actually just take this layer and make it a circle and make sure that the lever extends all the
00:03:52	way around that pivot point so that we have uh we can apply pressure on both sides of the pivot point and then that allows you even with the strength of the rubber bands holding it closed that allows you to actually open up that Gap
00:04:07	and drop the penny so again I had to go back to the drawing board and redo the design a little bit here you can see me here working to get this uh situated a little bit better and then once I do that we of course have to print it out
00:04:21	again now at this point I was pretty confident that we would have a working prototype at the end so I just decided to print a complete part the entire coin slider in its full circular shape and as you can see it works pretty well the one
00:04:37	issue that I have with this design is that these rubber bands would all have to be very specifically sized and they stick up a little bit beyond flush so that is an issue you can see here that it works pretty well it holds on to the
00:04:56	coin positively which is exactly meets the design requirements and when you press the lever it releases the coin so again that meets another one of the design requirements but I'm still not happy with this and I I really don't
00:05:09	want to call this a finished design what I don't like about this right now is that there really are too many parts one of my design requirements is to reduce the number of parts and then uh especially the number of moving parts so
00:05:22	I really want to try to get the part count down even further if I can and in addition because there's so many parts and adding rubber bands to it just adds additional parts that are actually finicky to install I really want to see
00:05:37	if I can eliminate these rubber bands entirely and now that I have a a rough idea of how this mechanism is going to work I think I have some ideas that we can use to create an even better design the other thing that I don't like about
00:05:50	this is that I would really like to be able to print as many parts as I can right in place so that they work as soon as I pull them off the build plate and we're not quite there yet so we're going to be working towards a compliant design
00:06:05	that I can print in place and uses the pla plastic as sort of a spring that will help to actuate this coin Grabber in and out my ultimate goal for this piece of the robot is to reduce the part count from seven down to just two but
00:06:22	we'll save that adventure for the next couple of videos for now that's my two cents thanks for watching everyone stay awesome hey everyone it's future me I just wanted to take a moment to say that I've
00:06:33	been doing some work on our website at the coinb.in collecting the latest developments and machine learning and get early access to my YouTube videos