 Hey guys, Vladimir here with Desktop Makes. Welcome to our third and final installment here in this series of modeling a rack and pinion assembly. So in the last two videos I showed how we created all the parts you see here, the three different components, creating a spur gear and then using that to create a rack here. So in this final lesson I'm going to show you how you can add joints and motion links here to be able to allow the turning of the spur gear to go ahead and move the rack back and forth and put that relationship together. So right now as you can see I have a mask component so I can freely move these and when you do that make sure to always come back here and click on the revert position to bring everything back otherwise if you click on capture position it's going to go ahead and move that location. All right, before we jump in though there was one question I received that I wanted to address and that was from I'm going to say yeah, Usafa 1987. Good stuff, I'm enjoying this series. One critique, it wasn't obvious why you were making the pin as a separate body. I assume it is to be able to 3D print the base without supports but if you mentioned this reason I didn't hear it. Okay, that's actually a great point. I completely forgot to mention why I was doing that. What Usafa is referring to is if I untoggle the rack here and the spur gear you can see in my base component I have that as two separate bodies, the pin and the rest of the base here. He is exactly correct. It was in order to be able to 3D print this and I'll show you what I mean here. Let's jump into Prusa Slicer. But I send this to 3D print as one piece. I've got a few options on how I can lay it out. If I print it like this then I have to go ahead and enable supports to be able to support the pin here, which I want to avoid. Let's say if I turn it on its back like this then I don't need supports for the pin but I will need supports on the bottom here. Maybe I've got another option here where I can lay it on its sides like this but then I need supports for the pin here. I did try this out and as far as my options were I figured my best orientation would be like this and not do supports for the pin but have it for this sort of overhang here. It worked okay but the problem is that I would then have to clean up supports. Let me just show how that looks here. Supports everywhere and then if I slice that. So this right here, all the supports needed to be cleaned up and I was able to pull it out and clean it up. But the problem is you didn't get a rough finish over there then you do have to do some additional work to try to sand that and it's just extra work and if you don't get it perfectly right then the rack just doesn't move smooth back and forth as it travels across and you create extra friction there. So I wanted to avoid that as well. So what I decided to do was then to just go ahead and separate the two and print them in separate pieces. So if I click on the model here I'm going to go ahead and split to objects and here you can see we have the two different parts here. So now the pin can print perfectly fine like this without supports and what I can do with the rack is I can turn it and here let's see I can either you know flip it in this direction and that would print fine without supports or I can also flip it in this direction here and print that fine without supports. So that's the reason why I did decide to go ahead and split these out. If I can design my way out of supports I will normally do that. That's usually my first option is just to try to either separate the design into different parts or add sometimes it only takes like a filler or a chamfer to be able to get it to 3D print without supports. So yeah if you can design your way out of using supports I would definitely recommend that and that's what I did here. All right let's go back to Fusion now we'll continue with this design here. So what we're going to do is add some joints and since I modeled everything in place I can go ahead and take advantage of my Asbuild joint. So here you'll notice you've got a joint option and then you've got an Asbuild joint option. Now the nice thing about Asbuild joints is if you design your components in place you can just go with Asbuild joints and it makes the process a little bit more simple. So I'll simply click on Asbuild joint. Oh one thing you have to do before and I always kind of forget this and have to go back and do it you have to ground one of your components before you start adding joints because you have to tell Fusion which one is not moving and so we're going to ground the base here because that's the part that's going to be staying still. So I'm going to go here to my components I'm going to grab the base right click and go ground you'll see a little red pin there okay so now I can't move the base. Now I go back to assemble Asbuild joint I'm going to choose my two components I'm going to choose my spur gear and I want that joint around this pin here of the base so it doesn't matter where I click as long as I click on that component and I'm going to change my motion here to Revolut because that's the kind of joint that I want and the third thing I need to do is to tell it the axis of rotation so here I'm going to go and if you click you'll see I can select you know either the circle or the center point and it puts that little flag right in the center if you just like over your mouse it says select the snap point to define the joint origin I'll click there and now you can see that the spur gear starts spinning around that pin you can click here to preview motion and I'll click okay that looks good all right next we're going to go back and add a slider joint to the rack here so assemble Asbuild joint again same thing I'm going to select my two components I'm going to choose my rack and then choose the base and I'm going to go to motion and change it to slider now with the slider what you have to do then is tell it the where you want it to slide or give it the edge you want it to slide about so here if I kind of hover over an edge you'll see it'll show I'm going to snap to that middle point and if again I let go of the mouse it says select a snap point to define the joint origin so I'm going to click right on that edge right on that point where the arrow kind of shows the direction and now I've got that motion so there we have it we have the rotational and the translational here the slider perfect but one thing we can see here is we are defying some laws of physics so let's go ahead and fix it so that they interact with each other and to do that we're going to go back to assemble and we're going to select motion link now the motion link so if you just kind of read there it says defines rotational and translational relationship between joint degrees of freedom select the joints then specify the values okay the important thing to remember with motion link is you set it between joints and not between components if you try to click on the components nothing happens you have to go to your browser here and tell it which joints do you want to set the relationship with so here we want a relationship between the revolute the spur gear here and the slider the rack and you can see it happening there I'm gonna delete that for a second because it remembered my last value there but usually you see something like this it's just kind of spinning like crazy it's kind of hard to see what's happening because it's going so fast but if you look at this dialogue box you see you have your two different joints your revolute and your slider and it's asking you for every 360 degrees here of your revolute what is the distance that you want your slider to travel and you can change this angle if you want but it's you know I'll leave it at 360 and mix the math easier so for every 360 of this spur gear how far do I want it to travel well if you remember from our last lesson and the last video I did we kind of figured that out and that really just becomes the circumference of that pitch diameter circle you can go back and see the math in my last video but here we just have to type the formula for circumference it's going to be the diameter times pi now we determined that our diameter was 48 millimeters so we just typed that in times pi which we can just write as capital P capital I and then just click okay now we can see that these perfectly match up and you can tell if you kind of just zoom in here you know how if you go to the last gear that that's perfectly lined up you know and then you kind of go to the other side you can see that you're still perfectly lined up you know if there was any error there this would start to travel and your gears would start to interfere so perfect one thing I do want to show you let's go back to that motion link here in edit feature if you ever have it going the opposite way like let me just click that reverse button where you turn your spur gear one direction and the gear goes the opposite direction you see here it's not going in the correct direction you just click that reverse button let's go back here edit feature just you either check or uncheck the reverse and that'll fix that okay so that's how we get our joints and our motion links in place one last thing I'll do is we can see I can keep turning this and that rack will keep moving let's go ahead and set some motion limits and to do that let me revert position and go back to our slider joint here we're going to right click and go to edit joint let's zoom in here so what we're going to do is go ahead and check minimum and maximum here and we can just move these little flags so I'm going to start moving this out an important thing is you want your smaller number to be on the minimum your maximum number maximum sounds obvious but it can mess you up if you do it the opposite way and pay attention to the negative right the negative number is always going to be the smaller number so I'm going to take this out here I'm going to go just pick an extent and I can just drag this to where I want this to stop showing me negative 69.235 I'll just make that a nice even negative 69 and then I'm going to take this white flag here move it in the opposite direction and I'll just go the same distance in the opposite direction so let's make this 69 but positive 69 you can click preview limits to see that that works out and now if I click okay and I can start pushing the rack one way and it's just going to hit a stop at both ends so it doesn't keep traveling you know and I can either move the rack or I could move the gear here and both will stop when it reaches those limits okay that concludes this series and creating a rack and pinion assembly as I said before I've got a few designs in mind that I want to be able to apply this mechanism and this just understanding this part of creating it is going to go a long way in understanding how my designs are going to work all right and the final thing to do here is to print this out and see if this actually works in real life as it does in the cat environment here so this is really going to be where we get to find out if our hard work and efforts here translate to to real life so let's go ahead and 3d print this and see what happens all right I hope you enjoyed this series if you did let me know below if you want to see more content like this if you have any questions leave them in the comments below and make sure to check out my links to additional resources including my online courses infusion 360 including my weekly live class that I run every week I've got a free constraints cheat sheet that you can download or if you simply just want to support this channel and more content like this consider becoming a patreon supporter hi guys I will see you in the next one