Blender. How to cut and key a model for 3d printing

in this video i want to show you how to cut up and key this dog but instead of using the ball tool add-on as i did in the previous video i want to use just the boolean modifiers okay we'll start with this dog which is an imported stl one thing to note before starting this is you have to apply your rotation and scale to the object so you do that by selecting your model going into object apply rotation and scale it doesn't hurt to have your origin point in the middle of your model either you can do that by object set origin origin to geometry and we add a plane scale it up rotate it and i'll just move it into position okay that looks okay now we have to give the plane some thickness for this to work so i will add the solidify modifier now this is by default 0.01 whatever your units are thick and that could be a bit too thick for 3d printing it will take too much out of the model so i'm going to make this as small as i can get away with there we have a very thin plane now mine is flashing red because i have my face orientation set to on and this is so thin that you can see the inside through the outside but that's okay now we apply the solidify modifier select the model and we'll add our boolean which is here we set edit the difference and select the plane now we apply the boolean as well at this point you can turn the plane off it'll make it easier you can see here there's a very thin line in your model but there is still only one object so now we have to separate these two parts so go into edit mode and make sure that nothing is selected alton a will unselect everything now we need to do is hover your mouse over one of the parts let's say here and press l and that has now selected everything up into this cut we made now press p selection and then we go back into object mode we now have two objects and this one you can grab as you can see now i'm going to rename these objects just to make it easier for the rest of this tutorial i'll call this one front and the other one back not very exciting i know okay now we want to put in the keying object i'll use a cube as it's most simple first of all we'll turn off one half of the model the front half now i'll put the 3d cursor somewhere in the center of this with shift and right click and add a cube now i'll scale this up to something that looks sensible might actually be bit big but it'll do and then we select the model add boolean change this to union and with this select the cube apply it and if i actually turn off the cube now you'll see that this object now has a key let's turn back on the cube because we'll need it turn the back of the model off and turn the front on this is still the same cube but we don't want the hole it makes to be exactly the same size as the key we made in the other part of the model otherwise it won't fit so let's increase the size of this a little bit the easiest way to do this is simply by changing these now i will change it to 9.6 on the x y and z one thing to bear in mind is if we increase the x y and z dimension by point two as i did in this case that point two is an increase in scale from the center of the object which is where your origin is so you really get point one on this side and point one on that side same up here and down there which may not be enough it may be enough it's something that you have to experiment with yourself okay so we have the cube and we have it increased in size all we need to do now is select the front part of the model add a boolean and we keep it on difference select the cube again apply it turn the cube off and there you have it if we turn the back of the model back on there you go now in theory if we put the x-ray mode on we should be able to zoom in and if you look very carefully at the right angle you should see that there is a gap between one part of the model and the next so there you go that's how you do cutting and keying with booleans it's simple if you want to do a more organic cut it works in exactly the same way except you just need to make your organic cutting tool there are plenty of ways of creating a cutting tool it's quite common to create a circle and move it around until it's in the right place but i'm going to try something different on this one i'll move the 3d cursor to approximately where i want to cut the leg off and i'm going to add a single vertex here the way you make a single vertex is to basically add anything in this case i'll do a cube add mesh cube go into edit mode and with all the points selected press m merge at center okay one vertex now if we go back into object mode we can add a shrink wrap modifier to this single vertex and we'll use the dog as the shrink wrap target select the dog here and this will now snap to the dog make a little offset actually it just makes it a bit easier okay we should now go into edit mode that's the last single vertex selected turn on snapping to face and now with this single object we can extrude it around our dog pretty rough when we get to the end we join the two points together with f i'll just make sure that actually did happen by turning off the dog yeah you can see it happened so let's apply this shrink wrap modifier and turn off the dog for the moment that's our starting shape and just have a look at it in edit mode looks fine now turn the dog back on select all the points of your cutting tool extrude and scale i've noticed that doing it this way the normals on the last part are different from this part but that's okay just select them all go to face mode a recalculate outside they're all the same way around now that's okay now we need to turn the dog off for a moment select the inner loop here extrude scale extrude scale extrude scale extrude scale extrude don't scale but instead m merger center probably a good idea to turn snapping off here so we now have a cutting plane you can add a subdivision surface modifier here if you want it to look smoother but don't have to i'll apply that by going into object mode press apply then like in the previous example we also have to give this some thickness so a solidify modifier make this really small and we're basically in the same place as we were before apply the solidifier turn the dog bang on select the dog add a boolean use the pipette to select the cube apply the boolean turn our cutting tool off select the dog go into edit mode make sure you deselect everything alt a hover the mouse over the leg in this case press l p selection we now have two objects as you can see over here go to object mode grab that and then you can add a key in exactly the same way as we did with the other one i'll just quickly do that i'll just actually show you a little technique here of turning x-ray mode on so you can see that you have the cube where you want it to be might want it a bit bigger and rotated in this case i think that should be okay there you go and there you go in x-ray mode you can see that we have this is the cube stuck in the leg and this is the hole for the dog and there's a very small gap around so that's it simple [Applause]

Channel: Not Very Good Guy

Views: 56,479

Keywords:

Id: j5at2x0CcX8

Length: 14min 24sec (864 seconds)

Published: Sun Sep 12 2021