FreeCAD 0.19 - Basic Course - Part 3 - Advanced Sketching (EN)

i'm back here with my freecad basic course part three so we are starting in the freecad version 0.19 so we are currently in the 0.19.3 that's the recent version of freecad 19. so let's start sketching right the first thing i want to show you is the concept of the sketch mode there are two modes of sketching the first mode is the standard mode all objects you are drawing here in the sketcher will be visible here in the 3d view and can be used for 3d tools like the pad command or the rotation command or whatever but there is another mode and that's the construction mode construction means you only have some kind of help geometry that will not be used in the 3d view like for example we can use this button here toggle construction mode you will see that all tools here in the upper toolbar become blue that means we are currently in the construction mode we select a circle and when we draw this circle you easily see that there is a different color from this circle compared to this rectangle this is a construction mode element means that we can still give it some constraints we can give it a diameter here we can use other constraints but when we close the sketch and we go into the 3d view this circle will not be processed so it's ignored in the 3d environment so when we want to toggle the circle here from construction mode into the regular mode we can select it and also click the same button here toggle and then we toggle this selected element and now when we open the 3d view you will now see that all lines will be processed and when we pet this object here we will get this body here with the circle hole that's a construction mode why do we need it i should first um constrain this sketch symmetrically here to the origin point give some dimension 40 for instance here and now we have some ideas like creating three circles in the plate the first circle to be right here in the complete center of the plate and a circle here and a circle here on a line that's diagonal here from upper left to bottom right and we can do this as close as we can but actually we are never 100 sure how accurate it is so we need some kind of helper geometry and now the first option is to simply draw a line from here to there constrain this center point on this line here and the same here of course we need at least one coordinate for this one and we need the diameters of the three circles here let's give it 10 millimeter whatever so still two degrees of freedom that's one degree of freedom for this one and the second degree of freedom here if we now close the sketch you will see that we get kind of a strange uh sketch with some intersecting lines and frequent is absolutely not like intersecting lines so we now pet this one here you will see error fail to validate broken phase many of you might have seen this error before so we cannot work with it properly so we need to get back to the sketch select this line here and set come on you're just a helper geometry you are just in construction mode you are not to be processed in the 3d view and now it turns blue we close the sketch and easily we can use the sketch that's pretty much it the second option to do it is just before we even draw the line we toggle the complete toolbar toggle and now we can select the line tool and from the beginning we draw a construction line so always keep in mind that you have to make sure construction mode or in the regular mode so that's a very important concept in cad so let's continue with a very common mistake especially by beginners who are new to cad they start with a sketch and they have their complete toolbar set into construction mode they make a nice drawing here a rectangle a slot hole here and some kind of circular hole here everything is nice define everything nice constraints and everything is pretty cool they leave it and then where is my sketch and that's just because all the elements here are in construction mode and will not be processed in the 3d view so we can select all of them with the rectangle selection and toggle the complete geometry here then we have this sketch here easily padded and have fun the next tool i want to show you in freecad is the polygon tool you can draw a polygon from triangle to octagon or even more sides of polygon here with the regular polygon command it's very straightforward just select for example here the hexagon you draw it and as you can see the hexagon is created by drawing a circle that's in construction mode you see it because of the color and the rest of the geometry is regular geometry so if we constrain it you will see in the 3d view you only see this hexagon shape the circle is just construction geometry so question for you what's going to happen if i select everything here with the rectangle and then toggle the construction mode let's try it you see that now the hexagon is construction mode and the circle is regular sketch geometry and when we leave it here we have a circle let's pad it okay go back into the sketch select everything toggle close and now we have this shape here so very easy to understand and very easy to do always keep in mind what's construction mode and what's regular sketch geometry so i hope when you watch this video here you have already completed my freecad basic course exercise one the carburetor flange and if not you should do this exercise first try your best and create this little flange here if you completed it i will now show you in this video two other possibilities how you can create a sketch like that so we start with this sketch that i already prepared for you it contains this center hole here with a 60 millimeter diameter and the two small holes with the 24 millimeter diameter here i used in my solution the polyline tool just because it's probably my favorite tool in the freecad sketcher but there are other options that we can use um let's start with a diamond shape that we are creating first either with simple lines here or with the polyline tool i will do it with lines and avoid the polyline tool completely for this kind of solution so i create four lines first line from here to there the second line from here to there from here to there the third line and from here to there the last line so we have these four lines here something like a parallelogram here so and now we need to have rounded corners we don't want to have these sharp corners here so we need something to fill it corners and to fill it corners we have two options in freecad 19 that's the sketch fillet and the constraint preserving sketch fillet the difference between the sketch fillet and the constraint preserving sketch fillet simply is that this vertex here the point where the two lines collapse will not be deleted if we select a constraint preserving sketch fillet i can show it to you we select constraint preserving sketch fillet and fill it between these two lines here we receive this little fillet here we can select the center point of the arc and center point of the hole to be coincident and we still have this little vertex here that has been the point where these two lines collapsed we can use the different command the regular sketch fill it between this and this line here and as you will see you still receive an arc you still have the center point of the arc you can set it to coincident but you are no longer able to manipulate here this point where these two lines met before i created the fillet so let's fill it these two lines also and these two lines also and now what do we have to do we have to set an equality constraint between these two arcs here and set the radius of the arc to be 24 millimeter as well and then we have to set coincident constraints between this arc center point this arc center point and the center of the shape yep and the last thing we need to do we only have one degree of freedom left here is to set a radius for this outer shape of 50 millimeters and then completely avoiding the polyline tool we also created this shape and if we wanted to we could pad it up and create exercise one the next topic we should talk about is trimming trimming means that you create more geometry than you actually need let me show you an example we will create this larger and a smaller circle here and connect these two with tangent lines have a close look if they are really created tangent at the moment they are not at the moment they are just created with constraint that means that the endpoint of the line is somewhere on the sketch on the circle but not tangent so we have to do this manually tangent constraint circle and the line and the same here now we have tangent constraints here you see that we should give the proper dimensions maybe 24 millimeters here and 50 millimeters here now let's drag it a little bit to the left and define a horizontal distance of 100 so now i can show it a little bit better so what does trimming mean here trimming means that we will remove unnecessary geometry i will draw another line and do the exact same give the tangent constraints here and if we now go to the 3d view you will find out that this geometry is not useful to be padded so we do the pad and as you already know fail to create face from wire and sketch that means that there is not one single outline and we need a single proper outline that means that this part here of the mid circle and this part of the left circle are just too much here many other cat systems will work with sketches like this without a problem but here in fricative it's not possible so far so we need to trim we select the trim command here from the toolbar and click this part of the circle and click this part of the circle now you will see that the constraints have changed we now only have this change in constrain here and it looks clean on the first side it looks clean we can close it let's try to pad it and we have a proper geometry here if you want to add holes we can change the sketch and create maybe a circle here and a circle here give proper diameters here 86 and maybe 30. and we have a fine nice tool here so you see you need one single outline and therefore you can use the trim command i don't work with the trim command too often but because sometimes it will mess up with your proper constrained geometry it might delete constraints and set some new constraints that are not valid you always have to be a little bit careful when using the trim command here so that's trimming complete opposite of the trimming is the extend an edge so you could for example draw this line here and then just click extend this line until here and then you extended it but actually i don't really need this tool very often so you can play around with it and maybe you need it more than i do um extension is by far not as useful as the trimming the next tool we want to talk about is to create linked edge to an external geometry let's stay in this example here we have a 3d body and we want to create another sketch that references on the previous sketch we select the pad click spacebar make it invisible click the sketch press spacebar and make this one here visible we create a new sketch that's placed on the x y plane and then we can reference to the first sketches geometry simply by selecting create an edge linked and then link these two edges and these two circles into the new sketch let's close it and have a look at it we hide the first sketch and you will see sketch 0 0 1 is not visible because this link geometry that's in this pink color is not a real geometry that will be displayed in the 3d view but we can reference on this geometry and that's what we are going to do now we just select um the line tool create one line here create one line here then we create an arc with end points here here and here wow that was an auto constraint that i did not want to set so i go to undo and an arc from here to here so like that and now we can set this center point of the arc and the circle center coincident same here coincident we make this line and this line parallel same here parallel so we have four degrees of freedom left let's give the proper radius here 52 and maybe 26. let's see what's still undefined okay that's pretty simple to solve point and edge and distance 15 point and edge distance also 15. so now we created another sketch that references on the other geometry let's close it and you can see this is second sketch this is the first sketch so let's enable the pad here select sketch 0 0 1 and create a pocket from it reverse through all and we created this little pocket in the 3d geometry why did we have to use another sketch you could ask it's completely unnecessary just draw this pocket also in this sketch here yes of course that's possible but imagine the following idea you don't want to pocket this pocket here all the way through but maybe only let me change it maybe only um six millimeters then you see you have the pocket here on the bottom but not through the whole geometry so if you put it in this sketch it will be completely always through the whole geometry so don't create too complicated sketches keep the sketches at an appropriate complexity and always try to go for different sketches so always be careful with the create an edge linked command and prefer to link 2d geometry like other sketches but avoid linking to 3d edges and 3d geometry in freecad so that was basic chorus part 3 i have one other recommendation for you if you go to the freecad forums i'm showing you a document by a freecad veteran here chris b who created a document that's called the sketcher lecture that has in-depth information about how to create proper sketches in frequent i will give you a link in the video description and i'm showing you what i mean i will open the document here so this is the sketcher lecture by christoph blauer and who created this for the freecad forums it's a super in-depth guide how to use the freecad sketcher it has so much information at hand for you and completely for free if you go to the freecad forums i will post you a link to this in the video description you should absolutely check this out and become better in creating great and proper free cat sketches so if you have any questions or comments you want to leave me under the video feel free to do so and have a great time the next video will contain another exercise for you because exercising is key to learning freecad have a great time flowy is out goodbye

Channel: Free CAD Academy

Views: 107,343

Keywords: cad, free cad, Freecad part design, free cad part design, cad design basic, cad design basics, Freecad documentation, Freecad help, free cad help, free cad documentation, free cad wiki, Freecad basic tutorial, learn Freecad, flowwie, flowwies, cad education, Freecad beginner, Freecad newbie, freecad 0.20, free cad 0.20

Id: sXPapS0WLgk

Length: 19min 58sec (1198 seconds)

Published: Fri Feb 04 2022