3D Printed Gears: Strength, Efficiency & Materials Guide

[00:00:00][Music] hello Dan here from how mechatronics dcom in this tutorial we will learn everything we need to know about 3D printing gears tips and tricks that I acquired by 3D printing quite some gears and doing dozens of tests with them we will cover which type of gear is best sted for 3D printing Spar helical or Herring bone gears in terms of strength efficiency and backlash how the module of the gear affects its performance how the infill of the print affects the strength of the gear and what material is best for 3D printed gears I put six different materials to the test pla pla carbon fiber ABS ptg ASA and nylon we will see which one is the strongest by doing strength test to failure okay so first let's compare the different types of Gears Spar helical and Herring bone Spar gears are the simplest type of Gears featuring straight tit mounted parallel to the gears axis the tit of a helical gears on the other hand are set on an angle relative to the gears axis hearing bone gears are a combination of two opposite helical gears with right and left helixs in the real world or in the industry Spar gears are usually the first choice when exploring gears options because they are the easiest and cheapest to manufacture then come the helical gears as more difficult and expensive to manufacture and lastly the hering bone gears are the most complex and expensive if to manufacturer however in the world of 3D printing manufacturing or making or 3D printing any of these three types of Gears is exactly the same and as simple as it gets a 3D printer can easily print any to profile and layer by layer form the gear so in this comparison the manufacturing cost won't be taken into consideration but let's take a look at the other advantages and disadvantages each gear type has Spar gears are the most effici gear type because they have the least amount of contact surface when the gears are engaged the contact surface is a straight line and occurs suddenly with each TI engagement this sudden contact though is the negative side of The Spar gears as it causes impact loading to the tit that affects the gear loading capabilities and durability as well as results in increased noise and vibration on the other hand helical gears provide smoother and quieter operation have better load carrying capacity longer life and can be used at higher speeds that's so because the contact between the mhing ti occurs gradually it starts as a point and gradually becomes a line and then leaves as a point on top of that at any given point they have more contact surface compared to spar gears we can notice from this demo here that three or two teth are always engaged in the power transmission whereas in case of a spar gears two or at some point only one to carries the whole load however like most things in life all these features of the helical gears come at a price and that's the introduction of XL force due to the inclin tiit depending on the Helix angle which ranges from 15 to 25° a significant axal force can occur which must be taken into consideration when designing the gearing system we can clearly notice that from this test as I apply radial Force to the Gear an exal Force occurs which tends to move the gear out of its place in order to avoid this axial Force there is the hering bone gear which is basically two opposite helical gears with left and right helixs in this way the AAL forces that occur cancel out and so we have all the great features from the helical gears without any EXL force acting on the gear but then again we get another disadvantage and then get difficulty in assembling the gearing system with Spar and helical gears we can simply slide in the gears in place and they will start meshing even if one of them is rotating with hering bone gears we cannot do that we should first MH the gears and then put them in place on the shafts at the same time or insert the shafts afterwards nevertheless now let's put the 3D printed gears to the test and see what results we will get for each type for Designing the gears I used onshape which is also the sponsor of this video onshape is a professional great cat and PDM system and they are now offering up to 6 months free of their professional version to engineers and their companies the thing that sets on shape apart from traditional cat systems is that it was built entirely in the cloud and works in a web browser there are some really great advantages because of this like being able to share and collaborate in real time with others similar to Google Docs with on shape every single action you make is recorded and you can always revert back to changes you made before onshape also has a GitHub inspired method of branching and merging so if someone has an idea to alter part of a design they can create a branch and work on their idea without disturbing the main design and they can also merge in that Branch later if they want with own shape everyone on your team always has access to a single source of truth of the upto-date design so no more searching around for the latest version of a file you can also run on shape on nearly any device or operating system even on the iOS or Android mobile app I highly recommend engineers and product designers to check out onshape you can get started with onshape for free at onshape dopro how to mechatronics back to topic we can easily create the gears with the custom feat feature script called spar gear we can choose the module of the gear number of it gear width at chamfer and Center board we can also choose the gear to be helical and choose the Helix angle and what orientation will be the gear left or right for heringbone Gears we just need to select the double helix option there is also option to add offset to the whole gear profile which is very helpful when it comes to 3D printing I used my new creality k1c 3D printer for printing all the gears for this video when 3D printing gears or anything else that we want to be dimensionally accurate we need to use the horizontal expansion feature in our slicing software this feature compensates for the expansion of the filament and in my case I used a value of minus 0.15 mm but you should do some test prints to see what value will suit your 3D printer also when 3D printing gears it's particularly important to avoid the elephant tooth effect that happens when the bed leveling is not right the nozzle is too close to the bed when printing the first layer and so the material gets compressed and the part first couple of layers are not dimensionally accurate this directly affects the performance of the gears in order to avoid this we should adjust the bed leveling or in the slicer adjust the gcode offset value of course we need to do some test prints in order to find out what value will suit our printer in my case that was a value of 0.1 mm and so the gears came out perfectly there's also another way to avoid the elephant too effect and that's to print the gears with a raft underneath the part but again you need to do some test prints to find out the right settings in case you cannot get rid of the elephant tooth effect you can also transfer the edges of the gear by hand anyway I would like to give a shout out to C for providing me this 3D printer the creality k1c is a really great 3D printer a complete package with a lot of features and great printing quality at high speeds it's fully enclosed which makes printing materials like abs and ASA a breeze the printer bed can reach 100° and a hot end 300° C in combination with the hard and steel nozzle tip it can also print wear resistant filaments with carbon fiber overall the creality k1c ticks all the boxes you would ever need from a 3D printer it's a great choice for both beginners and enthusiasts you can check it out on the creality store the links are in the description and the comments of the video okay so now let's see how the gears performed this is the first test setup I have a 12 volt DC motor on which I attached a gear with 20 TI and module of 2.5 this gear will drive another Gear with the same number of it and from here we can observe two things the noise levels the gear will produce and its efficiency the voltage supply to the DC motor will be the same for each gear type and so we can track the power consumption required to run the gears and so tell their efficiency first the spark gears produce noise levels of around 77 DB and the power consumption was from 5.36 to 5.61 wats next the helical gears noise levels were around 7 25 DB and the power consumption from 5.61 to 5.85 WS lastly the hearing bone gears levels were around 47 DB and the power consumption from 5.61 to 6.1 wats so the results that we got match with what we talked earlier about each gear type The Spar gears use the least amount of power which means they are the most efficient type but also the loudest the and the heing bone gears on the other hand were less efficient but quieter next for testing the backlash and the strength of the gears we will use the following setup one gear will be fixed with four bolts and the other will be able to rotate with two bearings attached to it the gears have a module of 2.5 and they are all printed with the same settings first I am testing the backlash or how much play or Gap there is between the two maching Spar gears there was a total play in both direction of about 2.5 mm at a distance of 10 cm next the helical gears showed better results there was a total play in both direction of about 1.5 mm at a distance of 10 cm and at the hering Bon gears there was a total play in both directions of about 1.8 mm at a distance of 10 cm again the results were as expected the spar gear had great backlash compared to the helical and the hering born gears however I felt like this test was too simple to make a proper comparison so I decided to make another test setup I made a four stage gear reducer with 16 to1 reduction ratio which is a more common scenario for Gears usage so the idea here was to use a Nema 17 steer motor and in four stages with 2:1 reduction ratio make a total of 16 to1 reduction ratio the dri gears have 17 tit and the driven gears have 34 tit the module of the gear is 1.5 the spar gear reducer had a free play of around 2.5 mm on the output at a distance of 10 cm or to be a bit more precise I use the force meter to apply a particular amount of force on each side and capture the displacement at that point I will use the force of 5 Newtons as a reference and I will use it for the other gears typ ppes as well in this way I got a total play of the bar of 4.4 mm at a distance of 10 cm to express these measurements in backlash unit arc minutes first we need to calculate the angle of displacement Alpha we do that with the help of some simple trigonometry and the angle comes out to be around 2.

[00:12:21]52° one arc minute is 160 of De so the backlash of this part gearbox is around 150 one arc minutes the helical gearbox had a total displacement of around 5.1 mm or translated into arc minutes that's 175 arc minutes the hering Bon gears had a total displacement of around 4.9 mm and that's around 168 arc minutes of backlash now these results came out opposite to the first test here the spark gears showed better backlash results than the other two types I mean I can tell a few reasons why that is so we can notice how the shafts of the gearbox have a little displacement when the force is applied because they are supported only on one side and that affects the results another thing is that there is some Play Between the bearing and the gears it's actually hard to 3D print parts that will fit perfectly with some mechanical Parts I tried adding some tape to the bearings to tighten that Gap and reduce the play it helped the gears go tighter but there is no guarantee that they will be the same for each gear of course we can make the holes for the bearings smaller and then insert the bear Rings into the gear with some Force but that might have a negative effect in terms of the efficiency there is no way that the two bearings will be placed precisely on the same axis by using force and that will cause more resistance when the gears will rotate just like we can see here the gears with the looser bearing spin longer than the one with the tighter bearing anyway for measuring the efficiencies of the gearboxes I measured how much force or Torque the gearbox will produce at the same voltage level of the steer motor with the spar gear I got a maximum reading of around 32 Newtons of force the helical gearbox maximum force reading was 28 Newtons and for the hering bong gears 30.4 Newtons of force these results say that the spark gears are the most efficient type but they are all too close next for testing the strength of the gears I'm using my Force meter to pull down a bar attached to the gear at a distance of 20 cm and see when the gear will break the spar gear broke at 180 Newtons of force or that's 38 new M of torque that's quite a lot but if we take a closer look at the gear we can notice that it didn't fail because of its too rather the inside or the infill of the gear failed as I TR printed every Gear with the same filament and slicing settings I got similar results for each gear type the helical gear broke at 230 Newtons of force or 42.6 n m of torque and the hearing bone gears at 152 Newtons of force or 30.4 new M of torque in order to get more meaningful results and find out how really the gear type affects the strength of the gear I had to make the Gear S weaker the strength of the gear is directly proportional to the width and the module of the gear so I 3D printed new gears with lower module of two and 12 mm of width I also increase the distance from the axis of rotation to 30 cm so it will be easier for me to pull down now the spark gear filed at the ti instead of breaking the whole gear at a force of 160 Newtons or 34.8 n m of torque we can notice here though that the four bolts holding the fixed gear bent a little bit under the force and so the central distance between the gears increased a little bit this caused the load contact to be at the very top of the tit which actually decreases the strength of the tit but that's okay as the same scenario will be for the other gear types and so the results will be comparable the helical gear failed at a force of 112 Newtons or 34 Newton M of torque which is quite similar to the spar gear the hering Bon gears as expected showed the best result in this test it failed at a force of 120 Newtons or 36 new M of torque so the difference in strength between the three gear types is not that huge but still it can be noticed we can say that the hering bone gear is the strongest one anyway all three gear types are actually quite close with the results the only difference that I could really notice between them was in the 16 to1 speed reducer and that was the vibration levels though very subjectively I could only tell this by touching the Output bar when rotating at a maximum speed the spark gears had significantly higher vibration level the helical and the heing bone gears were much smoother so my final verdict on what's the best gear type when it comes to 3D printing is as follows try to avoid Spar gears use hering bone gears whenever possible and use B bearings that can accept axial forces when using helical gears that's it now let's see how the module affects the Gear Performance the module of the gear defines the size of the tit and the gear itself here I TR printed gears with five different modules from 1 to 2.5 first to the test are the gears with module of 1 and 50 tit these gears failed at 98.3 Newtons of force or 29.5 new M of torque there were broken TI on both gears next are the gears with module of 1.25 and 40 TI you see I changed the number of TI so that the size of the gear change appropriately to match the test rig which has fixed Central axis distance between the Gear these gears failed at 126 Newt of force or 37.8 new M of torque the gears with module of 1.5 and 33 TT failed at 108 Newtons of force or 32.4 new M of torque though there was quite some displacement here on the fixed gear and the contact point was moved to the very top of the tit that's so because the bolts were already bent from the previous test I was doing on this R the material strength test that we will later see this R is only for the gears with module of 1.5 as with this module I could get a central distance of 49.8 mm and with all other modules 1 1.25 2 and 2.5 I could get a fixed 15 mm Central Distance by changing the ti number of the gears anyway the gears with module of 2 and 25 TT broke at 149 Newtons of force or 44.7 Newt M of torque the gear spe module of 2.5 and 20 TI failed at 121 Newtons of force or 36.3 new M of torque actually here the whole gear broke instead of the tit because I guess the infill was only 30% of this gear I 3D printed another Gear with 45% infill and that one failed in similar manner at a force of 124 Newtons then I try printed another one but this time with 100% infill now it didn't break the whole gear it broke at the ti but at the exact same force of 124 newtons that didn't make sense as it should have been stronger but the problem here I think was that I used an older spool of the same blue filament for this gear that of course can make a difference depending on how old or how dry the filament was when 3D printing also every pla filament brand has different strength and even the same brand but different color makes a difference in the strength of the material therefore I 3D printed another Gear with 100% infill this time with the creality hyper pla filament now the gear broke at the TI and at a force of 156.43 4 Newtons or 47 new M of torque so to sum up this test the bigger the module or the ti of the gears the stronger they are I mean that's obvious and logical the same is with the width of the gear if we want stronger gear we can also increase the width of the gear the infill of the gear also contributes to the strength of the gear I recommend a minimum of 35% infill when 3D printing gears and up to 100% infill if needed though probably the more important setting is the wall line count which I recommend to be five or more lastly let's find out what material is the strongest for 3D printing gears for this test I will use Spar gears with module of 1.5 first the test goes the pla filament the pla gears broke at a force of 11 16.9 Newtons or 35 new M of torque the next gear set is printed in pla carbon fiber fil El from creality these gears failed at 111 Newtons next is the ABS filament this one failed at around 90 Newtons of force however it happened more gradually compared to the pla the ABS can withstand some bending or deformation before it breaks which is good feature in some cases then the ASA filament gears broke at a force of 12.9 new mut the ASA behaved like a combination of PLA and abs they were as strong as the pla even for Newton stronger but still had a little bit of bending or deformation before breaking like the ABS next the ptg filament gears failed at 87.2 Newtons of force this one also had a little bit of deformation before breaking lastly I tried printing the gears with nylon this material is the most diff difficult to print but the creality k1c managed to print it however the results were not that good the gears failed at a force of 66 Newtons but I don't think that's the real strength of a proper nylon filament I had this filament bought like a year ago from an unknown source so I guess it's a bad one overall the results that I got from this test were quite accurate and match with this filament properties table from simplified 3D the pla gear had the greatest strength but also the greatest stiffness on the other hand the ASC gears showed the same strength as the pla while having lower stiffness just like the ABS now as for the durability of the materials I wanted to make a durability test with the 16 to1 reducer set up and see which material is the most durable for 3D printed gears but I didn't manage to do that I started doing the tests but the gears were surprisingly good good and couldn't fail the test even after like 1 hour of spinning even with a significant load on the Output bar the test was too loud and my current Studio or Workshop didn't allow me to conduct this test properly or long enough so therefore in future I will try to make this durability test and I will share the results in the description of this video and on the website article for now you can use this table by simplified 3D as a reference because it matched with my tests as well I will put a link to it in the description as well I hope you enjoyed this video and learned something new don't forget to subscribe and for more tutorials and projects visit 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