Home shop made EDM + Fusion 360 : Making planetary gears

hi there and welcome to the back idiom YouTube channel if you're interested in making your own metal planetary gears or something similar and this is a right video for you in this video I'm going to cover how I designed these gears in Autodesk fusion 360 how I made the two paths in the Autodesk cam functionality and how actually machine these parts myself on my shop mate wire EDM machine so there is a tutorial on my youtube channel that covers all videos that you need to know in order to make such a machine yourself so if you do so you can make these cool gears yourself as well so hope you enjoyed video so in order to design the planetary gear we first need to figure out what the number of teeth are for each individual gear inside to set but let's first discuss the planetary gear and its components so the annulus is the outside ring the Sun gear is the small gear in the middle and planet gears blue ones here revolve around the Sun care and the carrier is fitted to the rotating world of the planet gears now if we define row as the ratio between the number of Angeles teeth and the number of some teeth then we can define a formula that relates all the rotational frequencies of the different bodies the carrier the annulus and the Sun so the rotational frequency of the carrier times 1 plus Rho is equal to the rotational frequency of the annulus times Rho plus the rotational frequency of the Sun so normally in a design you would fix one of these three the carrier the annulus or the Sun and then if you fix it you can set the rotational frequency to zero and then you can derive the relation or the gear ratio between the two remaining degrees of freedom so for a fixed carrier turns out that the ratio is minus Rho for fixed annulus the ratio is Rho plus one and for fixed song the ratio is 1 divided by 1 plus 1 divided by Rho this relation is always true so the number of planet teeth should be equal to the annulus teeth - the song teeth divided by 2 and what is also is important and that makes it a bit of a puzzle the number of teeth on both the Sun gear and the annulus should be a multiple of the number of planets so let's calculate it for our example here so I set a fixed annulus so Omega a is 0 and that gives the ratio between the Sun and the carrier as being Rho plus 1 now I would like to have a gear ratio of 9 and then I can derive that Rho is 8 so the ratio between the angular's teeth and some teeth should be 8 so I picked my son to be 12 teeth and then the annulus needs to be 12 times 8 which is 96 teeth then I choose to have three planets I need to check if that's possible because the number of some teeth and the number of annulus teeth need to be dividable by 3 and leave all numbers so which is true 12 divided by 3 and 96 divided by 3 are whole numbers so that's going to work then finally you calculate the number of teloth teeth which is the annulus teeth - Asante is divided by 2 and that in this case gives 42 so for our design of which we will get a gear ratio of nine when we fix the annulus we need a son of 12 teeth we need planet teeth of or we need planet gears with 42 teeth and we need an annulus with 96 teeth okay so let's design a demonstration model of a planetary gear for that I'm going to start a new project which I will name demo model planetary gear new projects open the project first thing I'm going to do is save this empty file as devil and now to demo I will add a part in the component and let's name database because I need a base to fit all the gears on - let's start sketching inside the base face is selected yep sketch inside the base and I always like to sketch on the front to start okay press the D for diameter let's pick 75 mm safety 70 is a nice size okay extrude it 30 millimeters so here's the base now I'm on the top surface of the base I want to put the annulus the outside ring for the planetary gear but it would look nice if it sinks a bit into the surface so let's make a small cuts from the surface sketch a circle on the top here and let's pick the diameter of the annulus at 65 so let's make this cut slightly bigger sixty five point two and let's make a cut only slightly shallow cut okay now I need some holes here to align the gears too and let's draw those so let's make a sketch I'll sketch a line on this surface first a few construction lines to help me out sketching the line I'm just drawing them arbitrarily now as I will put dimensions to them so first the length of these sections how to calculate those well that's we have a Sun gear of 12 teeth and a planet gear of 42 teeth so the radius of the Sun gear is 12 teeth times the module divided by 2 and if we add to that the radius of the planet gear which is 42 teeth times 0.5 module divided by 2 that's 10 and 1/2 plus the Sun 13 and 1/2 so the distance should be distance that's that's sketch the distance from here so here should be 13 point 5 and the same holds for the others from here to here 13 point 5 and from here to here two point five okay now I want the angles to be the same so 360 divided by 3 is 120 and from here to here 120 as well so now I have my construction lines and now let's sketch the holes circles on here one here one here on here and let's set the diameters of these holes to three millimeters three three and three okay let's cut these holes this one this one this one and this one make the cuts four millimeters deep okay now I have the holes on which the gears can be aligned now I need pins in these holes so let's drop in sketch a circle the top diameter three extruded ten millimeters okay save it as a pin and now I can drag the pin into the demo model like so move it around a bit so I can see it and now let's meet it with one of the whole so that's a joint and it's a rigid joint of this surface and this G at the bottom and now it's reversed so I have to flip it press ok that's the first one it looks nice let's do it again okay make the joint between this surface and the bottom of this hole okay and again between okay between this one and this one and the last one so in this one and nothing well here it is actually added the pins to my base I don't like that I wanted to be in the roots so moving it over that's better now I'm going to make the base out of aluminum and I'll make the pins and the gears out of Steel so let's say give the aluminum a different look the base that's at the physical material as being aluminum there is looks a bit different okay now I can start adding gears so let's add the annulus first normally in your list if you look around there is a script for generating external gears but there is not scripts for generating internal gears and drawing an internal gear manually can be quite cumbersome so in order to help you guys out I made a script the script can be downloaded on Beck's EDM comm so be a ex EDM calm and if you go to the download section you can download the script no script it's a zip file save it to your drive and pack it and then there's a folder inside and yeah just store the folder somewhere and then you can add the script by pressing the green button here applause and navigate to the script which is called internal gear select it and then you have it here then when you double-click it opens and you have a nice window where you can generate your external gear so let's generate my 0.5 module that's already okay 96 teeth I gave a thickness of 4 millimeters and outside diameter of 65 and a pressure angle of 20 degrees that's okay now it gives you a small warning here because this script has not been optimized for speed it works great but it takes a while so I press ok and yeah wait about half about half a minute and then I'll all generate the the gear so get yourself a cup of coffee ok the gear has been generated can't select it that's inside so I can't see it so let's move it around press the M for a move select the gear move this is SEC this one of it and let's move it into the view ok now I want to add a joint I want to add a joint between the annulus and the base a revolute joint so I press capture position otherwise it disappears again I want to make a revolute joint between this ring and this ring here and there are this ok now I can add the smaller gears and for that I can use the standard generator spur gear so I want a module of 0.5 for the planet gears I want 42 teeth small bit of backlash 0.1 no root Phillips agir thickness of four millimeters and all diameter three okay there it is so let's move it this one move the gear now I can see it I could see that their sketch has been turned on I know like that so let's turn it off and just want to see it here now let's make a joint capture position it's a revolute joint it's between this circle and for instance this one here oh okay that looks great let's do it again now all the parameters stay the same so you can just press okay then there is the next one so let's select it move drag it okay turn this sketch off and add another joint between this one and okay now for number three okay and joint between this edge - okay that's great now I can see the teeth are misaligned by alpha teeth so I need to rotate these and by which degree I need to rotate them by 360 divided by 42 teeth / - that's the rotation let's copy this and let's rotate rotate these wheels this one move it rotation this axis paste my number not something that wrong let's see here move select the gear and select the rotation axis let's say I want this one and then select my angle now it's good yeah let's do it again move this gear selective rotation axis paste the angle okay do it again this gear select the rotation angle okay now we need the middle gear which is a 12 teeth gear so we add in another spur gear Steinman's 12 teeth and I dropped backlash okay no it's over there so let's move it and let's make a joint between this whole and the Sutter axis let's see here there it is press ok and now this one also needs to rotate by half a tooth which is 360 divided by 12 teeth / - 15 so let's rotate it around this axis by 15 degrees okay so now this looks really nice but when I rotate something now I lose all my alignments so I want to add ocean links in between in order to make a simulation and for that I need to ground the annulus first rounding means you fix it so let's ground the annulus or is it internal gear crowd and now let's add some motion links so the first Ocean link that I want to do is between the annulus and Latakia now there should be a relation so if one makes a full turn the other makes a known full turn and what is this relation that's 42 teeth for the planet gear and divided by 69 times 360 so 150 175 and a half and paste it here that's that looks really nice okay let's do that for the other planet wheels as well emotion link between this one and that one paste the angle okay and another one emotion link between this one and this one go okay and now the final motion link between planet gear between the Sun gear and one of the planets and which angle should that be that is 12 of the teeth of the Sun gear divided by 42 teeth of the planet gear times 360 that's the angle a relation angle copy it and then I had a motion link in between the Sun and one of the planets let's see reverse it okay let's see if I rotate it now see this looks really nice I can fully animate it let's turn the joints off it looks better that way so if I rotate it now oh I see that there's still sketch turned on it's not nice let's turn it off and there's the finished model that looks really cool okay so next step is to start machining this now that the models finished that's switched to manufacturing because I would like to start machining so we're in manufacturing mode now and we need to need to create the two paths so I've pre-configured a tool for EDM which is a set as a laser cutting machine so I can select my tool and the local library selected it and it automatically such the feeds and speeds to 15 millimeters per minute well actually the machine itself will determine its own feed rate so this is only as a starting number in in the machine while you're machining it will determine the most optimal cutting speed itself so tools been selected now we can select a tool path so I'm not going to make the two parts for whole parts here I'm only going to show it for a single part because for other parts it will be exactly the same and otherwise this video will get a bit boring so I'm going to show it for the inside of the annulus so the inside teeth here so let's start I select one and then after selecting I click again and then you get the selection tool and this really helps because then you can move around the curve until you see it fully completed then you click again and then you click the plus now it is fully selected so that's it for the geometry for the Heights no need to change anything and the height in the EDM machine is fixed anyway so next pauses tolerance is one hundredth of a millimeter which is accurate enough and for compensation type I'd shields in computer because I would like already selected the correct size for the curve width of my EDM machine and I'll need to compensate for it on the machine itself next and do not need reading entries or radar entries and as an entry position let's start at the top here somewhere here ok press ok generating the code now so the path has been generated let's see if the cut is on the correct side yeah it's on the correct side of the teeth this is not the case then during a selection of the contour there's a red arrow and then if you press it it will switch sides so you can do that if it's on the wrong side all the contours correct but I see that I have forgotten to move my coordinate system because I want my decode coordinates to be in the center of the wheel so let's change that and it stopped no hear setup and then I select the origin as a selected point it already jumps to the center by itself so that's good now it's in the center and now I can generate my code when G goes by right-clicking post-processing I have selected the black CD on post processor and this is a post processor that you can download from Beck CDM comm which has been tailored for the donor motion control solution in combination with wire EDM machining I press post it offers me where to store the files or let's store it on the desktop and then it generates the code so quite a long list almost 9,000 lines for the inner gear and I can save this file now to my to the computer of my EDM machine and then start machining so the process for the other gears is exactly the same and the the holes and the gears I'm going to machine those on my lathe because that's quicker then I do know that so we thread the wire so this is the material that I will be using it's 4 millimeters thick stainless steel 304 and this is cold-rolled which is actually wrong because the cold rolled steel contain a lot of internal stress and it might be so that once you start cutting that the stress is relieved and then that the part deforms because of stress relief so if you use cold rolled steel there's a chance that you will lose some accuracy on your part however cold rolled steel is readily available and nice and flat fat stock that this stress free is a lot harder to get so I actually got the cold rolled steel which is why in the design of my gears I added a little bit of play to allow for some small deviations in part accuracy just because I'm cutting the cold rolled steel instead of something that is a stress relieved okay that that's the note about the stock so this is the shop made wire EDM machine that I'm going to use to cut the planetary gear I've made a youtube video tutorial on how to build such a machine so check out my channels playlist and there you can see the whole tutorial which goes into all the details of this machine now here's the stock all mounted in the water tank so now it's time to float the tank with water and start machining by I'm running a g-code here and that will start off the arc generator and move the motors in order to cut the workpiece so let's fill up the tech you you so this is some footage of cutting the Sun gear and sped up 20 times the actual speed is 5 millimeters per minute I'm not going to show the cutting process for all gears just so on this one and maybe a little bit of footage on the cutting of the annulus [Applause] okay let's see how it turned out move the upper water kite up see if I can fish it out there it is and there's the Sun gear here I'm making the outside cut of the annulus ring it is same cutting parameters as the other gears so it's now cutting at five millimeters per minute and this footage has not been sped up so you can clearly see that it's quite violent floor wise in the in the water around the workpiece and flashing it quite a high pressure and yeah you can actually see when you look closely you can see cavitation around the wire because the water pressure drop there is quite big so it's not interesting to see so here's my stock with the gears already cut out now this is a nice example of what the cold rolled steel does if you look at this cut here you see that the gap of the cuts so these parts have been cut you can see but the gap it should fit the wire but it doesn't work not fit through anymore which means that there was internal stress in the part and due to stress relief the gap has closed but this this is an effect that will cost you accuracy so what I have actually should have done and I did it wrong was not to cut from the outside into the inside and then start my part I should have made a starting hole then thread the wire and then cut the outside of the part because then a lot less stress will be relieved and you will get less deformation so that's a note to myself don't do this again it's easier but it will cost you accuracy here are the finalized gears so after I cut them from the stock material I sanded them with a oil stone on both sides gave them a bit of a polish and clean them and here's the final result so let's put them on the carrier start out with the Sun then the planets it rose really nice another planets another the planets are not in place then the annulus the outside ring there it is that's the final result hope you enjoyed this video if so then you can subscribe to my channel so you won't miss out on future content thanks for watching

Channel: BAXEDM

Views: 84,907

Keywords: BAXEDM DIY EDM Home shop planetary gears fusion 360

Id: OuI3vj0prnw

Length: 37min 39sec (2259 seconds)

Published: Tue May 14 2019