bonus tip: if you want a perfectly smooth, round hole with more resistance to delamination, make the hole oversized and print an inner liner vertically that you then glue or friction fit into the oversized hole. this also helps with clearance issues because you can just adjust and reprint the liner to get the exact fit you want with minimal waste.
This can also make the part stronger at this potentially high stress area by orienting the pieces at 90 degrees like plywood. The insert could also act like a ring to keep screws from splitting the main part with layers parallel to the screw
I usually add about 0.5mm to the radius to allow for material expansion with any hole. Even then some are too small and use a razor, drill or deburring tool. A lot depends on the nozzle size, print orientation and detail settings of the slicing software as well.
Simpler fix: 1. Design a bit larger hole so that when you print, you get more tolerance. 2. Drill a bit smaller hole then rim it with a rimming tool to your proffered size.
It's also worthwhile to remind people about *PLA creep*; even if the fit is very snug and tight, and even if you use screws to clamp it, PLA will deform over time under constant loads. So a hole which was initially very snug and tight, will after a few months be loose because the PLA has permanently deformed. So any design that requires snug fits and constant stresses, should be printed in other types of plastic that don't suffer from this (really annoying) property.
My experience, it's hard to keep deburring tool centered. I resorted to vertical stand drill. But looks aside I now would employ Angus' teardrop holes for simplicity.
Good design tips even for the more seasoned designer. On the teardrop holes, with everything ideal your slicer and printer should work together to where the "Flat spot" at the top of the hole is at the correct height. It's possible that you get a small amount of droop when printing that bridge that makes those holes too small. For the sake of proper parametric sketches, it'd be far better to define the angle of that point, then you could make it 40 to 50 degrees to the horizontal to ensure that the overhang can be printed and that also allows you to change the diameter of that hole without having to also change the dimension you had to the point. For example you had an 8.2mm hole for your rod and 5mm from the center of the circle to the point of the teardrop. If you decided later to go to 6mm rods your teardrop would have a much sharper point and a much larger amount of material removed relative to the size of the rod. If you decided to go up to 12mm rods your "Point" of the teardrop would be inside your circle. This in conjunction with your tangent mates would probably throw up an error on that sketch until you changed the dimension for that point. I'm sure you were building based off of a preset pile of parts and you knew what size was going in there and weren't going to change your mind but practicing Parametric modeling even where it's not necessary really helps keep up skills (In my opinion anyways).
All this can be eliminated if you simply constrain the angle of the spike, not the height. It will not completely be aesthetically pleasing as it will look too high for bigger holes. You can avoid that if you specify the height, but not from the center rather from the perimenter and you have to drop the tangential constraint. The phenomenon is that with smaller holes the layer hight thus the quantization effect has much bigger impact on the accuracy that with bigger holes. You can print a larger hole with proportionally smaller teardrop.
Some really cool tips Angus! In addition to the last example, at 6:32, if you needed to, you could always drive 3D printed wedges (or even just wood screws) into the "smiley face" cutouts to make the fit even tighter.
@3:01: "it's gonna give us the clearance we need to shove the rod in - and to keep it nice and tight" to that I say "these are not the clearances you're looking for"
Hey Angus, I know this is an old video, but I was searching around on some Fusion tips and teardrop holes are a real game changer when folks start designing. I am always happy when I see videos that are so helpful to others. I always appreciate what you do.
I like to leave the holes under size, then use a reamer in a drill press or milldrill to get the hole to size. I also use Slic3r's modifers feature to make the walls around counterbored holes thicker (or solid infill)
I also found this method to be the best if your looking for precision. Often a number drill size or fractional bit will work for most fitments. For perfect bearing fits then go with a reamer if you can afford it.
Drilling - depends on how tight tolerances you need / want to hold. The harsh truth about drills is that they skate and skew everywhere. Reamers are used for finishing a hole, drills to rough cut. Reamers can also be very expensive, though.
I wish you would've mentioned if, in the compliant holes, you change your clearances at all to alter the pressure. As in, do you continue using the slight gap you need based on your clearance test or do you use exact values and count on the plastic to take up the flex and increase the pressure on the part?
Thanks for the excellent Newbie tip, really useful. As an aside I’m assuming you use a paid for Fusion subscription. If that is the case please could you tell me how many documents your custom printer required in Fusion? Many Thanks
I was on the free plan for some time but eventually it was wound back and I started paying. It's all built in the same document as separate components / bodies.
Maker's Muse I like the idea about the 'tear drop' mod however the corner you have created introduces a stress concentration point which may lead to cracking. Perhaps this is something to be mindful of.
I saw the notification come and I pressed play and I just got the first comment I love your videos 11 year old boy from Sydney Australia here My name is Sean and I'm not old enough to get my own email so I'm using my mum's and also does my phone and like it automatically puts my mum's email in so yeah
Angus, I am very new to CAD design and 3D printing. However, the information contained herein is EXCELLENT. Very good tips; much appreciated. This will save time and trouble down the road as I try to master this new knowledge base. Thank you for sharing.
A great article about vertical holes based on Prusa's development into this is by Gregoire Saunier who runs the Prusa Bear project. He's been using teardrop holes which came from Prusa's own openScad project on bridged holes. You can find more information here github.com/gregsaun/vertical_hole and the refinement here github.com/gregsaun/maker_cheatsheet/blob/master/3d_printing/techniques.md
Step one, draw a simple box and then using the draft, slice, through hole hyper forming chamfering stage one tool, with the 6.765 recurring offset over the original layer you get the geometric rhombicosidodecahedron (actual, wiki it lol) shape... 🤣
Before i watched this i used to think that holes are accurate!! But now i know that they are inaccurate and also how to solvr it! Thanks Angus for helping me!!!
This is awesome. Thanks Angus. I've had this problem over and over (with the tops flattened). I try and print the holes vertically to get perfect circles.. but you cant always do that.
@06:55 If you're only getting one thing out of this video _then_ this is it - Been using this tip to form proper holes in my 3D Prints whenever I'm working with Inserts like when I did my recent hanging Dining Lamp: imgur.com/gallery/2wJoAGu ( one of my biggest 3D Prints )
Nice work Angus, looks like you have enjoyed your break from things! As a retired design engineer myself I’m impressed-you will go a long way bud. As for me, I need to somehow convert from PTC Creo (used when at work) to Fusion if I’m going to keep up with the world I think lol
You probably know these things by now, but just in case someone finds them useful ... Oficially, there's a table for the hole sizes you need for machine screws like M3, M4, M5, etc... Unofficially, I tend to make those diameters 0.2mm larger, so the M6 will go in a 6.2mm diameter hole without having to fight its way in. On the other hand, sometimes you want to cheat and make the bolt self-cutting; since it's a metal bolt and the plastic is a lot softer, you can easily get away with this. For M4 I use a 3mm diameter hole in wood; so when printing, I'd say start by making some small test-pieces. I'd suggest the first test to be a 3.5mm hole for M4. Officially: Make space for a nut on the other side; make it 'snap-in' A.K.A. 'click-in', so it will never fall out, by making the nut's entrance slightly smaller than the remaining space. For anyone living on an island (like me), use A4 for nuts, bolts, screws and other things; everything on islands (and near the coast line) rust; even A2 (unless we're speaking about paper, but that was not what I meant). =) For the rods, you can make 'blind ends' or one 'blind end' and the other one can be a 'snap-in' A.K.A. 'click-in'. Snap-in / click-in: -0.2 delta diameter should be enough for this, especially because the 3D printer often 'adds' an extra 0.25mm.
I do a lot of stuff that most people would consider a waste of time...like magnetic motors, better turbine designs...………..just be creative....design the holes slightly smaller and ream them out by hand or with a drill. Ya gonna have to do it a few times for sure, but that's what makes it so damn frustrating and fun at the same time. A little early, but Merry CHRISTmass to all from North Carolina U.S.A. Love ya all :)
For anyone who needs to use screws, I used to make holes for nuts, exactly how this has been done here. But threaded inserts are SOOOOOOOOOOOOOOOOOO much better! Check out CNC kitchen's episode on threaded inserts to see what I'm talking about. Due to the geometry of nuts, they often want to split the part along the layer lines, or will actually torque out and be unusable with fairly low amounts of force. Threaded inserts are incredibly strong, and will actually increase the strength of the part because they fuse the layer lines within the hole itself.
Angus - I am printing a part with two holes on the sides in PETG using PLA as my support and it leaves stings of separated layers right after the hole on one side of the print. Do you guys know how I can fix that problem? Much appreciate the help in advance.
Thank You, I just designed 18mm x 50mm cable chain links for my CNC and the tear drop trick will really help. I was having to file the tops back into round. You most definitely help to empower.
Might prove to fiddly but I wonder if you could replace of the tangent lines that make the tear shape with a spline to make an ovoid (egg-shape). My guess is that it would compensate for the top flat enough that the ovoid would appear almost circular.
Yep that'd be another solution and one I've also tried in the past. Honestly I haven't noticed any significant difference in functionality between each approach, but the straight lines are easier to draw in.
With touch screen devices, it is quite easy to click/touch a button by mistake while scrolling or just moving your device while it’s on. With such a low dislike/views ratio, I wonder if there’s even one intended dislike for this video!
teardrop holes will not allow the rods to be at the exact spatial location BUT this is only an issue if you have the teardrops pointing in different direction, just FYI and yeah, we are talking (less than) a fractional micron off
Why dont to use horizontal expansion option in CURA to make print with proper holes? I found it minute ago when look over custom options instead of recommended.
Angus, do you remember if you designed the hole with the compliant press fit exactly to the outer diameter of the bearing or did you add a tolerance? In my way of thinking, a no tolerance design with these compliant fingers makes sense but wouldn‘t we then need at least half of the circumference being compliant? This on the other hand may lead to a weaker fit. Cheers
Im not a CAD pro but whenever I need tight holes I just print the exact size as the rod without any clearance, then use a blow dryer to make the plastic more malleable. As the plastic cools, it expands again such that the rod is stuck in the hole. Ive seen that this is an installation technique for metals as well.
I dont understand why someone doesnt make it so you can change the layer height/detail for certain sections of the print. That way you could do much more gradual steps at an overhang like this :)
Someone get this man a job teaching people how to 3D print things in college!!! I showed one of my friends that have to learn to 3D print in college, and he told me he prefers him over his teacher.
Cool design. Another thing I do is anneal the parts. While they are hot, rods and what not fit in fine, and upon cooling parts are both annealed and grip like a mo-fo. No need for tricks that way
I find a more appropriate term for over-sizing or reducing certain dimensions in order to meet a proper fit due to the missed accuracy of printing would be 'compensation', since although we may say we have designated a "clearance" within the CAD software to do so, the actual measured value of the part will be quite different, making it not so much a clearance but a compensation amount. I hope we can adopt this.
I'll be watching this again. As of this posting, four people don't recognize talent and ingenuity when they see it. When you do the math, 0.6% of people don't recognize talent and ingenuity. So 99.3% of us are very appreciative and obviously more intelligent.
Sorry for beeing a little out of topic (and also sorry for my bad english), but i want to know if you will ever review the new tiertime line, up300 and x5. Love your content and thanks for your work on youtube!
