FreeCAD Scissor Lift with Kinematic Skeleton in Assembly 4 Animation Mechanical Movement Beginners

hi viewers and welcome to the channel and this is a assembler for tutorial for creating a scissor lift now i'm using freecad 0.19 but this will work in 0.109 and above and what we're doing is creating this model and this animation and we're going to show you a few problems around topological naming issues and how to resolve those and actually how to create the arms the skeleton and the animation all in one sitting okay so let's give it a go if you like this video please hit like and also subscribe to the channel i also have a kofi site where you can actually donate to my contributions to the community and that's at ko hyphen fi dot com slash min g0 okay so the first thing we're going to do is create the arm for the scissor lift so i'm going to start a new document or a new scene and i'm going to go into the part design and in here i'm going to create a new part because we're going to be using an assembly so that would have made a new part so it's a part there and we're going to create a body and create a sketch i'm going to place it along the x y plane okay that and this is going to be a simple arm in a kind of meccano type style so we're going to use the slot in the sketch and i'm going to create that in here and we're going to put some constraints on here so i'm going to place a symmetrical constraint between this point this point and use the center point so to place that symmetrical to the center correct create symmetrical constraint in there places that there we also need length constraint now i'm just going to constrain this to about 100 millimeters but the length is up to you also that's got to reflect in the skeleton that we're going to build and i'm going to put some height in here as well so about 15 millimeters and i'm just going to zoom in and i'm going to create a circle now i've got the auto constraints on so when i hover over the center line and that center point you can see this can constrain a point on point constraint in there i'm just going to create the circle in here hit escape i'm going to put a diameter on there so go up to here and constrain the diameter and 10 will do us so 10 on there and what i'm going to do is just zoom out i'm going to copy that circle in there hit ctrl c and now constrain this to somewhere else and this will make a copy of that circle and i'm just going to hover over that point place it there i'm going to do the same on the other side as well so now just move over to the other side and take that hit control c and do the same and use the auto constraint and strengthen there next i'm going to close i'm going to add some padding to that that's 10 millimeter pellet padding so i'm going to put something like 5 mil in there and that will basically do us for that arm so i'm going to okay that so i'm going to save that now hit ctrl s or cut file save and i'm going to create a new folder in here put scissor lift this is lift assembly jump in there i'm going to call this arm that's it that was painless that's our arm done and that's what we're going to use for this is left arm you can be more complex if you like but this is just a simple tutorial to put you in a place where you can refine the model but for the time we're just going to use this that's more than enough so we'll move on to the assembly next with the assembly we're going to close down the arm and we'll create a new scene again or a new document and this time i'm going to go over to the assembler 4. if you haven't got this then if you come up to tools handle manager and you'll find the assembler 4 down here and it's well worth updating this if you haven't done for a while because there's new updates coming out every now and again and we can install updates if we so desire it's already out today just close that so the first thing we do with assembly is create a model now we can use the little icon on the toolbar create a new assembly model or cut assembly and new model and if you click on the model tab that would have created it there so we've got the parts and the model now the first thing i'm going to do is create the skeleton for this now our parts 100 millimeters long so each of the arms of the skeleton require to be 100 millimeters there's a few gotchas around here we're going to be looking out for topological naming issues and we'll do something to get around those so what i'm going to do is come over to the parts and i'm going to create a new part in here and this is going to be the skeleton that drives this assembly create a new part i'm going to call this skeleton part so in parts i've got skeleton part now and in here i'm going to create a new sketch and this is going to be the skeleton so i'm just going to call skeleton sketch at the moment we don't have to worry about attachments that's fine so let's okay that and now we can go into the skeleton find the sketch and double click on it and that will open the sketcher where we can actually start sketching first thing i'm going to sketch is a single arm now this will be controlling the scissors so we're going to have to connect arms together in the center if you think about a scissor and it's connecting in the center and that's what this sketch is going to be but we're going to do this a different way to stop this topological issues happening what i need to do is create a line like so and attach a point to this line so i'm going to hit escape i'm going to use the point there is a reason for this i'm going to do is place the point on the line and i'll make that point the center point so i'm going to click both these points and i want that point to be dead in the center of those two so we click that last point last and then we use the symmetrical constraint that places that in the center so we can place a length along here of a hundred you remember back to our arm it was a hundred between the two holes at each end 100 millimeters and that's created our first arm and we'll duplicate this and connect it to this point in the middle now why didn't we just click on the polygon and use this and then created a equality constraint against those and a parallel constraint against those and then put the length of just say one of these to 50 millimeters well again this will cause a bit of an issue when we get to the topological naming problems if you haven't come across that that's when freecad basically optimizes your model and renames parts of your model when you exit the sketch or exit a pad and what happens is if you've got something connected to it it will get dissociated with it freecad has a tendency to do that when you've edited something further down the chain and this also happens in sketches now the reason why i've used a center point here rather than this type of approach is because these are actually two individual lines and there's a chance that these lines will become renamed so the arm if attached to here may swap to here or it may swap back depending on what kind of name it happens in freecad so this is the reason why i've used a single line because there's no way to rename this this is one single line it hasn't got anything attached to it so there's no optimization that i'm renaming it's a single line with a name and when you attach something to it you're attaching it via a point on object constraint which means it doesn't become part of the linked lines that are connected to this though it's linked it's connected by a different kind of connection if you're doing point-on-point constraints then they'll be linked they'll be part of the linked list so for instance if i place a line here and connected it to that point there like so those two lines in freecad when it lists them are not really linked then i know they they are connected via this constraint and it moves with them they're not really linked if it's connected to the end so if i take that line and connect it to that end that is linked so the topological naming problem will happen there because the name will be passed from here to here or swapped back depending on what type of renaming happens it's one thing to look out for and that's why i've taken this approach and there'll be other approaches we'll be doing in this to stop this issue so this is one arm now we want to make a scissor so i'm going to copy this on hit ctrl c and i'll just place it down and i'm going to move it so it crosses and i'm going to place a point on point constraint on those two like so so they are connected now that's a point on point constraint on the actual points so it's not part of the line because if we sever that symmetrical constraint in there then these lines will become basically they'll slide up and down so they're not actually connected but the symmetry constraint allows that to be connected like so so it scissors but there's still two individual lines that we shouldn't have any problems with now that's done constrain this middle point to this line here and that is going to be a fixed point on the object line so that allows that to move up and down that line i'm also going to do that with this point because that's moving up and down the line we've got freedom of movement down here i don't want that so i'm going to use that point and this line and do the same so point our object constraint and do the same here that line and just put it onto the object constraint now we've got a single scissor like so and what we now do is actually duplicate this up and connect them together but we're going to be wary of our connections and what i think i'm going to do is get the arms onto this and hook up the lcs system so we know what's happening so let's close that's enough for a skeleton for the time being you can see oscars and is sitting there and what i'm going to do is place a local coordinate system on these lines now if you don't know what a local coolant system is it's also abbreviated to lcs well for instance this is an lcs there that comes when you create a part it automatically comes with an lcs there so what that lcs will do is because it's a default one there that will attach to the assembly the main assembly and then we'll place an lcs on each of these lines and that will orientate any parts we add to this ie our arm in the direction of these lines all this is is an x y z coordinate system that's aligned with any of these lines and it's very easy to attach these and once they're attached you can understand how they work and what we'll do attach the lcs's to this line and this line and then we'll start attaching the parts before i do that i'm going to save my assembly and the reason why i'm doing this is because when we start importing parts or adding lcss then we must save the assembly first otherwise you can get something called a a link rather than a actual part that's imported and we can get some problems around there so it's best to save that first before proceeding now we've saved let's add the lcs to those arms so we take the skeleton sketch here we need to click on the part this is where we add the lcs to we mustn't add it to anything below this sketch so if we had say a body in here then we mustn't add it inside the body it must sit just below the part to add lcs system we've got an icon here great data module we can drop that down this is a new coordinate system there or we can go to the assembly and come down to new corn system this is create a new lcs and i'm going to call this arm1 because i'm going to attach arm 1 to this lcs r1 unscore lcs we get an attachment window come up that we need to select something in our sketch now our selecting is showing that we need to select something if this isn't selected selecting like this just click it and what i'm going to do is place in arm1 now i know the bottom my sketch is in line with this lcs system here so i know this is the bottom so this gives me a bit of reference to where we are so i'm just gonna click on that line there and now i've got to use the attachment mode to actually align it on there now z tangent to the edge you can see it will place it right on the edge and the blue is the z axis red is the x and the green is the y so the z is in line with that and but i want inertial cs which places it in the middle which is exactly where i want it so you can see if i move it you can see the z-axis is flashing there so there's the z-axis if i scroll in zoom in then that will actually shrink but you can get an idea of whereabouts of this by just zooming out and just moving this up and down to see where it is and that's exactly where i want it let's okay that so what will happen when i add my arm that will attach to it now i'm going to place arm two along this one as well so we've got it attached to one but obviously when we pull in another arm we need to attach it to this one so that's our first lcs in there and we can click on the lcs and we can see the attachment how it's mapped etc etc and if we want to change the mapping we can come in here click on the icon on the end and change that mapping blank happy with where it is now we're going to add arm 2 in i'm going to do exactly the same click the skeleton part to make sure it actually goes into the part nowhere else and using the drop down for the new coordinate system or the menu item i'm going to call this arm 2 and score lcs and again we've got the selection mode so remember which one we select first we select left now we need to select the right and inertial cs for the center and you can see where the z-axis has been aligned to and okay that and that's everything we need for just that one scissor of that sketch i'm going to save that and what i'm going to do is jump over to my arm now because i'm going to need that open so i can actually import it into the model because we import it by clicking on the model and clicking the insert a link to a part and then the only thing that's there at the moment is the skeleton part so i'm going to cancel out that and i'm going to go to file and it was a recent file so i can come down to here and recent file is the arm and that will open it down here you can see the arms imported in so now that will be available to actually import in the assembly and if i click the insert apart you can see the arm part is there but we're not going to insert it just yet we need to do something on the arm to allow it to be inserted and that's also add a local coordinate system to the arm so we've got our arm in front of us we need to add a local coordinate system to it so we can align it onto our lines in our sketch now if you think about it what's actually happening is we attach an lcs to an lcs so an lcs of the skeleton will have an arm attached to it via the same lcs and they connect together so i'll be connecting this arm in the center of this arm and aligning it with one of these lines so to do that i need to be in the assembler for okay i need to click on the part of the arm and it's the same process so come in here new corner system or up to assembly new coordinate system and we'll give it a name so i'm going to call it um lcs okay and now it's asking me where to place it now i've got a number of options i could come out to the model and select the body like so come back so the body isn't saying solid solid there's body is selected and use the inertial cs there and that's placed that in the center like so i could also instead of selecting the body i could come in here and select this face inside here now place it in the center using the inertial cs as well i could even select this circle edge like so use the concentric now place it up against there and if i wanted it in the center i could come down and change the if i look at the coord system so that blue there is the z-axis as you can see on here go down to the z-axis direction and change that and move that into the center so it's five millimeters so that'll be minus 2.5 there we go so that's in there in the center now thinking of how this is going to be placed along that skeleton i think in the placing in the center is a good idea i could have the skeleton laying across here if i so desired i think that's fine and i'm actually going to go for that so that's fine let's okay that so go on the pad edge 21 which was that circle and i'm going to okay that so that's connected that up so there's multiple ways you can connect that i'm just going to save that and jump back to the assembly now we've got our arm open and if i double down with the tabs down here we can import this into our assembly but first we're going to import the skeleton so i'm going to come up to the skeleton part and i need to import this into our model now the model was an lcs as well and that will be in the same position there so if i actually come in here and transform this out of the way like so and okay you see the lcs of the skeleton and the lcs of the model so i've got the skeleton there those two are two individual lcs's now the very first part you import into an assembly will be connected to this lcs origin origin here you can have multiples of these if you have multiple parts that you want to connect to the base of the model but we've only got one skeleton in here so we only need to connect those two so click on the skeleton i'm using the insert link to a part or you go out to assembly link apart and then we've got our name model there that should be our skeleton so you can see that our skeleton doesn't seem to be there but it's actually the unnamed model so we need to reopen our assembly to have that name come through and take effect so let's do that now now we reopened it let's try to import that so let's click on the model and now you can see it's saying assembly skeleton part that's much better so we can see what we're doing now let's click on this the skeleton part insert and now you can see it's copied that model down so that was our original and that's our new and what we need to do is take the skeleton part and this lcs system here click on it so lcs and we need to connect that to the parent assembly and there's an lcs system there so connect those two together and those are connected together there and we can use rotation if we so desire to change the rotation of it and i'm actually going to go for that so that's fine and okay so that's our skeleton in there but you could see that our other skeleton part in the part is still visible it's best idea to click on that and press the spacebar and that makes that invisible so don't get these modeled up and this is the problem that you have with creating parts in the assembly you can create them as sustainable files as we did the arm in that they can clutter up the assembly if we create them within here so that's our scissors sketch in there so that's our skeleton sketch part in there and we can come down to our skeleton here open this up and double click on the sketch and you can see our sketch is set here and we can modify where the legs should go along that edge maybe easier to actually pull the top in there we go got more control over there close that you see a skeleton has moved but our lcs system has kept in line with these edges so let's add the arm to this so same again click on the model and we need to attach the arm to one of these lines now i'm going to use this as a reference so this is the bottom of of the skeleton let's bring this around and i'm going to use the insert link part i guess click on the arm insert so an arm has been placed in there we use the arm lcs which is this point here this lcs here drop this down and now we want the skeleton the sketching has just also been highlighted show that we're connecting it to the skeleton and now we pick an lcs system so at the moment it's sitting on lcs01 click on the arm one you can see it's connected there but around the wrong way and lcs2 you can see how they connect there so i want arm one and i want to rotate this so let's have a look of where this placed it so i want to rotate it around this red line which is our x-axis so we'll come down here go rotate x now that's placed it in line with that skeleton that's exactly what we want okay that that's in there now now what this means if i change the skeleton let's pull one of these arms out slightly close that then this will follow and that's how the skirt controls our model so let's place another arm in there now and to do that we go through the same process so use the insert link part first clicking on the model insert link part or go to the assembly link apart click on the arm insert so we're reusing the arm again click on the arm lcs drop this down to the skeleton and now we want arm 2 and it's probably going to rotate in the same direction which was x i believe was it y can't remember that yeah x the red so that's rotated around there and place that along there now we may want to offset that because it's going to intercept the other arm so we'll look at that and we look at where it's placed so we can see the blue there and the green and i want to move that along looks like the blue or could be the green so let's go for the green it doesn't matter because we can always bring that back let's bring that into the center so we can see what we're doing so i'm going to translate that along the y and see where that goes so just translate that and now let's offset that to that point there so it's not intersecting so i'll set it by 5 remember we padded by five so that's a five millimeter offset along there okay that's and now we got our first part of our scissor so i'm just going to click on one right fit section that fixes the rotation of our scene and we can see there's one part of our skeleton there's the upper part of our skeleton sitting there so that's the two arms in there's the bottom if i double click on that skeleton and we'll move it like so close you can see our arms move now we need to duplicate this up and do the same for a second set of arms at the top and this is where we may get into a problem with the topological naming issues but i can show you how to resolve that let's demonstrate this topographical problem so we've got our assembly in front of us now watch what happens when i edit the skeleton i'm going to add another line in the skeleton now this line is going to be for another arm i'm just going to add a line in here normally all what i'll do is duplicate this line but for demonstration i'm just going to add a line so i'm going to create a line that runs from that point let's constrain from that point to that point hit close look what's happened this has jumped from here so what's actually happened here well what's happened inside is that when we went into the sketch we added that line you can see this one's called edge one this one's edge free this one is h2 now look at where our arms are connected to so i'm inside the pattern inside the skeleton the original skeleton arm lcs is actually connected to h1 and arm lcs2 is connected to h2 so why is it connected up here well it's because the new line has been renamed so we come down to our arm parts and i'm just going to hide those so you can see that the lcs system has is actually connected to here and it hasn't reconnected and what what's actually happened is a new line has been created up here and has been renamed with edge2 which this is connected to and now this is edge free the process of actually connecting another line here has reconstructed our sketch and placed an h1 an h2 an h3 and h4 it's kind of optimized the layout because these are connected by a point-on-point constraint now to resolve that it's quite easy done coming to the skeleton sketch let's just get rid of that line and that's close now we're back to normal you can see the lcs systems are sitting there and our arms are sitting on top of those systems now if i come into the sketch and this time place a line but instead of connecting it by point on point constraint on these two i'm gonna use a different constraint i'm going to use that point on this line and constrain it via fix a point onto an object i'm going to take these two points and add distance of something really small like 0.25 millimeters if i close that now you see that line's been added and the else's lcs system and the arm haven't moved because there's been no renaming going on that's because freecad has not looked at this line and this line at one that connected and has tried to optimize the sketch let's jump back in and remove that line because i don't need it so the same process i has to be done to the scissor now i've got one scissor here and this scissor i just need to duplicate so i've highlighted that scissor hit ctrl c and you can see there's a line that goes to that center and that's the center of that scissor that point what i'm going to do is come over and just hover over that center line and you can see we've got a constraint that's come up a point on object constraint i'm going to just click that's all to constrain it to there now they're not constrained here because if we do constrain them with our point and point constraint we're going to have the same problem with the topological naming issues i can demonstrate that close that there we go there's the problem so let's go back into our skeleton so i'm using skeleton it doesn't matter actually matter which skeleton you use but i use the discussion in the original part they have a link between each other so any moments you do on one will appear on the other but it's best to go to the other origin let's double click that and just hit ctrl z and undo that so what we're saying before come in i'm going to move that point and just place it near that line i'm going to use the point on the line and constrain it on a point on line constraint and i'm going to take this point and this point and use a length constraint of something like 0.25 millimeters and i'm going to do the same on the other side bring the point down you can see it's the point of the new scissor that i've added click the point click the line and use the point on object constraint and we don't need to constrain that length there because it's already been dealt with on the other side and all the other constraints made mean that if we tried to do that it'd be over constrained so if i take this top and move it up and down you can see that's working and we just duplicate this up each time that we need a new set of arms now the thing that i need to do is add the lcs system to these arms so let's close out this see we're all good we haven't got any jumping of parts around and now we've got the skeleton sketch that has an extra set of arms and i'm going to add an extra set in so we want to do the same so come in here drop this down new coordinate system this is arm3 lcs and at the moment it's disappeared and that's because we've got this invisible so select the skeleton hit spacebar to bring that back and now we can see our skeleton there we go so it's this arm here that we're looking at let's go back to tasks click on any because it's now selected because we've come out there get rid of that and select this line here and do the inertial cs on that one so you can see that's got the blue line in line okay that and now we need to make a second arm don't worry about what it looks like at the moment it looks broken but we'll fix that in a moment and that's because we have got both the skeletons open and remember what i was saying about it becoming quite confusing when we have models with parts inside the model well this is what's actually happening here we've got a bit confusing here so i'm going to come down to the model and hide that and that makes life a lot easier so we've placed an lcs system on here let's place another lcs system so remember selecting the part coming into new corn system this is arm4 let's go lcs and select our edge inertial cs and that's in there okay that so those are all in there ready to have arms connected to them so i'm just going to show the model now and hide the skeleton part there so you can see now we've got the lcs system sitting there and now we can actually bring in the arms so click on model and we can start attaching the arms to this model and again using the insert a link to a part arm part insert select the arm lcs drop this down to skeleton this time on free rotate it along the axis which i believe was not y do that again just bring that back long x that's in there okay that and one more part in there as well so let's go for assembly link apart just to be different click on the arm part insert um lcs drop this down to the skeleton this time arm4 rotate along the x and okay so that is our scissor lift basically done there so any amendments to either skirt and here or the skeleton here will change that so click on that let's bring this down hit close i can see our scissor lift is animated nicely to control this by a variable we need to place something else into our sketch so in our sketch i'm going to place a length between this point and this point here and that's just going to be a single constraint but first of all we need a variable and the reason being is that that constraint will be linked to the variable it's quite easy to do that so in model we've got variables you can see it's great out there if we come up to here we've got variables which we can add or to assembly add variable and now this has got to be a float because we're working in floats in this so 0.5 0.6 0.7 etc and i'm going to call this lift this that'll do initial value is 10 so i'm going to make that about 50. okay so that's our variable sitting there now we jump into our skeleton and we're going to make that constraint so between these two points so this point and this point of the scissor i'm going to place a length or distance constraint in there and now we're going to not put the length in there what we're going to use is this little icon here which is the formula icon so get the formulator up and if we type v and we'll start seeing variables let's place the dot in there so if we start typing capital d you can see that these appeared in there because there's d in there hit capital l then you got a lift dist there and the result is 50 which is remember back we set to 50. okay that okay and that's set that to 50. it's got orange so it's sure it's referenced outside or externally constrained hit close and now our scissor lift has changed and we can animate that variable or include it into some python now we've added a variable we can actually come down to the variable in the variables in the model and we can change this variable to 20 60 70 80 etc and that will move the scissor lift up and down and we can animate this as well just be careful if you go to a hundred and then come back from that you may find that this will break and you just have to undo it so just be careful if you go seed in the middle and the max of this so i said this is something like zero and then try to come back from that you can see we've got some problems and things have started to break so we've got a conflicting constraint in there and we need to remove the last one and re-add it so let's bring this back out and you can see we've got some real problems going on here i'm just gonna hit ctrl z a couple times and bring this back there we go just watch out for that so it's worth saving this before you do anything with that one so that's all back to normal so watch out we're exceeding the minimums and maximums in there so we can animate this now let's click on the animation and i've already selected lift dist in there so we can select the variable select lift dist beginning range and remembering we have to be careful with the min and the max so 50 to 80 i'm gonna use steps two for through round every step and run that and this is a lift we'll start running stop that now close it and that's how to build a simple silver lift with the problems with topological name issues resolving those and building that in the assembly full hope that's helped i hope you enjoyed the video and i'll see you again soon if you like what you're seeing please subscribe to my site and also i have a kofi site where you can actually donate a few pence or a few pounds dollars or whatever your currency is and that's at ko hyphen fi.com ming0 and there you'll be able to help me fund my site and all the money that i actually get from any funds will actually get pushed back into the channel thanks a lot for watching and subscribing i'll see you next time

Channel: MangoJelly Solutions

Views: 2,093

Keywords: CAD, three, 3D, CNC, Printing, solidworks, autoCAD, animation, assembly, assembler, assembling, mechanic, mechanical, Free, 3CAD, beginner, guide, easy, 0.1.19

Id: Eka_0k5l0oM

Length: 47min 5sec (2825 seconds)

Published: Tue May 25 2021