Design Better Holes | Improve Tolerances | Reduce Sagging | Design for Mass Production 3D Printing

hello everyone and welcome to this episode of design for mass production printing in this episode we're going to go through how to actually design holes a simple feature and yet at the same time very easy to mess up if you don't know what you're doing so let's start with the very Basics let's look at a hole that is punched through the side of a part just like so this hole you can see it padded up it is just a generic hole there is no modification to it at all but if you look very closely at it you can actually see that there's a little bit of Rippling right there the reason for this is that these are perfect Corners which don't exist in real life the tool head is limited to the diameter of the tool and you're limited to the motion of the machine so you can actually cause a defective deformation of this hole by just punching it through minifully the correct way to do it is actually to go ahead and add some small fillets around the hole this rounds the outer edges and gives the tool path a smoother bit of motion so that it's able to create a much cleaner hole but now if you look at this hole that is now punched through the side of this part you'll notice that the top is actually kind sagging and while that's not the end of the world in most applications especially if you're making an electrical enclosure or some piece of Industrial Hardware it's not always ideal if you want something super Precision because it can cause resistance to the screw to where you have to basically manually screw the screw in all the way rather than just punching it through a through hole that's supposed to be a loose fit the way to get around to that is to actually add a point to the top of the hole this small Point make sure that there's no way for the layers to Sag in any sort of way but still maintains the primary outer profile of the holes so that it can reliably constrain the outer edge of the screw that you're putting inside of here or the dowel or whatever happens to be going in there so these little points are very easy to add in a very quick Edition that can help improve the sagging and kind of the ovality of the hole because when the hole is 3D printed the upper surface is like a flat line straight across which means it can cause a little bit of sag as the layers are deposited and if you look very very closely here on this you can kind of see that basically the layers are built up built up built up and then they have to cross what is essentially a bridge which causes a little bit of deformation in the top of the hole and those points get rid of it now side holes are fairly simple but what about top holes well traditionally people would just punch a hole straight on through but the problem is when you print a hole like that you end up with this kind of a mess and the reason for that is that the hole is an unsupported area as the first parts of the layers are going side to side they come out there and then they hit the hole and then they go back to the outer edge basically coming from here going in and then coming back out going in coming back out so they have nothing to actually clasp onto which can cause issues with how the part is printed and you end up with these sort of stranding pieces that stick out of the hole and either need to be removed or are kind of foreign objects within your assembly if you allow people to just punch through it and you would have to generally support this hole from underneath in order to make sure that that is not an issue now support can add a lot of extra post processing because it has to be plucked out at the bottom so one one way of getting around it is to use a sacrificial layer now this is only a Mild improvement from the previous because you still have post-processing you have to remove all of this stranding that is in here in order to punch through here or you can take the rod and shove it straight on through but now you have the additional problem of not only having the foreign objects that can break loose inside of there if this stranding goes loose into your part but you also have the delamination on the bottom layer itself because if you punch through on this then you can potentially just tear out that whole bottom layer and kind of compromise your part so sacrificial layering is generally fine for very small holes that are not super strength focused but for larger holes they generally have to be supported the best way to make this large hole would be to have it supported from underneath so that it can grow up grow up and then the outer profile is crisp and clear and the support can actually be removed more quickly than this stranding now if you're looking at a non-through hole there's a couple of ways to do this and the main thing to be concerned about is the actual tolerance of the hole itself 3D printing has shrinkage inside of its URL Extrusion that you sometimes have to compensate for so you don't want to just punch the hole straight in again you want to make sure to fill at the top and in order to make sure that it takes the part easily very often it's best to also chamfer the top of the hole just a little bit as well so that the part is able to get started but then is able to shove in and tighten as the hole gets narrower and narrower that way you have kind of a finding feature at the top of the hole which creates a very good fit without having to worry about the tolerance of the hole however sometimes you need a little bit more flexibility or a tighter tolerance you want the hole to be a very strong press fit but then you still don't want to plunge a hole straight into the material because you'll have side to side variation the best way to go about that is to design the hole basically at true diameter and then add relief features on the outer side which allow the part and the walls themselves to spread and split so that the piece press in there very firmly but still have some release features so that the hole doesn't resist it and doesn't get stripped or deformed in some kind of a way it's some sort of permanent deformation so these little relief features are very easy thing to add but you can actually increase these and basically rotate them all the way around to create what are called Crush ribs Crush ribs are parts that are meant to be deformed rather than having a solid wall where it has to basically stretch the material these features are kind of sacrificial so that when the part is pressed into them it kind of strips them away presses them away and you have a perfect press fit this is an easy way to get that perfect press fit because each one of these things can be made as thick or as thin as you want so that it is easier and harder to actually essentially strip them out but you can get a stronger grip on the part when it is pressed in there these are basically a one use type of a hole so you install it and then you're done these types of relief features also provide really good options for glue because if you're making a hole you need some place for the glue to go once you put it in there so these types of ribbons allow you to really strongly adhere a part together if there is some piece to be inserted into here but very lastly there is an advanced feature of hole that it depends on the application that you're doing if you want something to be removable and have a long life then you might use grip fins grip fins are basically a small flexible feature that goes around the outer edge of the hole and allows the hole to change in shape and to bend this is a really good way to have a hole that grips with constant grip Force rather than being forced in and being sucked in or glued in these are meant to just hold whatever Rod is inserted in there at a constant force so when we press this Rod into there it is fairly loose and easy but it will always grab it at the exact same forces before they essentially act as Springs compressing the rod that's inserted inside of there so this hole is often used for disassembleable parts or are sort of like tool Jigs and that kind of thing to where you want to be able to use this hole over and over again but you still want it to be able to grip with some force and you can change the thickness of the fins and how much tolerance they have against the hole like if this is a 12 millimeter Rod you might make the actual inner diameter of the grip fins like 11 millimeters so that they grip it more tightly but that is almost a whole video in and of itself so hopefully that was useful to you and now you know how to make holes down through the top of the part as well as how to make holes down through the side of the part there's more to it than many people realize you don't just simply want to make a hole inside of CAD you might actually want to get just a little bit creative have a great day everybody

Channel: Slant 3D

Views: 264,598

Keywords: 3d printing farm, 3d print farm, Improving product design with 3D printing, slant 3d, manufacturing products in 2023, 3d print manufacturing, design for 3d printing, mechanical design for 3d printing, useful 3d prints 2023, 3d printing design tutorial, 3d printed holes, fusion 360, tutorial, cad for newbies, 3d printed holes too small, how much to oversize 3d printed holes, 3d printing hole size, 3d print holes, 3d printed friction fit

Id: Bd7Yyn61XWQ

Length: 7min 48sec (468 seconds)

Published: Wed Sep 20 2023