4th Axis Build

just when you thought things couldn't get axis here the components I'm using are really much to write home about this is the equivalent of like an eBay or Craigslist special used China stepper motor it's nine Newton meters which I'm sure is overkill for what I'm trying to do here so not much of interest there in gearbox it's a moto Vario I mean reasonably good quality this is a sixty to one now the big problem with this type of fourth axis is the backlash you're not going to be able to see it on camera but I can feel it see if I start right about 12 o'clock if I turn this and you know I can feel the resistance when the worm is changing directions and I can go about I don't know 40 degrees or so so 60 to 1 that comes out to I think about Oh point seven point eight degrees of backlash now that's a one point eight degree per step so that's a half a step more or less of backlash now the first step in getting these two to get to intimately know each other is to make an adapter Motors got I think a fourteen millimeter that's a fourteen millimeter shaft and an 11 millimeter bore we'll get rid of this I think this is a D style flange obviously that's not a much help so we'll get rid of that make a new adapter flange and then some type of a base to get this to the correct Center height and give me something to bolt this on to the machine bed width again not rocket surgery but maybe you'll like following along terrible put her in the vise it's always got to be one troublemaker in the mix it's got a poorly formed torques I didn't make it any better with that drill a couple of these yeah that's more like it sorry I didn't realize that went out of frame it was just a impact driver anything in your garage or gives you a lip one of these oh no it's got a built-in seal right motor adapter goes between the stepper in the box is now going to have to accommodate two seals there's a seal in the shaft that are in just a little over in groove not at the end of the world I just assumed this was going to be closed off and it was just a mechanical mount before we get that far I need to know how big the adapter is going to be and so I'm going to turn up a small ball like a stub extension you all right so I got to thinking maybe I shouldn't assume that everybody knows how a worm gear gearbox works not that it's all that relevant I guess to using this for a fourth axis so there's our worm wheel this has got two gears but we really only need one I hope no one out there is allergic to analogies there's the four jaw Chuck or maybe the face plate whatever ends up on the outside of this gearbox and this will be our worm I'll touch that - a stepper motor all right here goes nothing keep your eye on those two hash marks put some tape on there maybe that'll be easier to see the moral of the story here is the worm or the screw here it's got to do a hell of a lot more turns compared to the worm wheel so in order for this screw to advance this wheel one tooth it's got to make one full turn right one one thread land needs to quote unquote advance to push one tooth around because it's got so many darn teeth your inputs got to do a lot more turns in order to get some amount of motion on your output in this case I don't know this might have 100 teeth so one turn to this screw is a hundredth of a turn of the gear set another way to get this gear to turn one time the screws got to turn a hundred times 99 100 so there you go that's basically what's hidden inside this little blue box and since what I do for my YouTube viewers knows no bounds I'll download an inset a cross-section of this gear box so there are two fundamental problems really with using a gear box as a fourth axis and I suppose it's up to you to decide how important they are the first one and I suppose in any fourth axis design is the backlash it's going to be hard to show that to you here but conceptually when the screw is turning in one direction it's the the screw lands are pushing up against the back of one of the gear teeth when you switch directions reverse that rotation the land that's pushing up and set up against that sort of forward leading tooth is got to back up and the angular space let's say it needs to travel before that land hits the tooth that's behind it in order to push it the other direction is called the backlash now since I plan to users primarily for indexing meaning it won't be continuous motion while the machine is cutting I'm hoping it's not going to be that big of an issue it could be and I may have to add some kind of a break so once it gets into position the gear is locked so the other potential issue is concentricity as you saw this one is obviously pretty darn good and that depends pretty much on the bearings in your fourth axis or your gearbox if you were to really build one of these from scratch you'd want to use some type of angular contact or thrust bearing but I'm hoping that because this load rating on this even this small of gearbox is so much more than what it's going to see on my little CNC router that I'm hoping it's close enough and that's actually the biggest problem with picking one of these up used which was my first route you'll get the gear reduction but these bearings will likely be so shot that that central axis will be all over the place so my apologies if that was a state in the obvious let's keep going now we'll connect this motor to the gearbox if you're wondering what this is I mean heck it's just an old shirt I'm using for a rag it's a bernhard a pratt bernhard collet Chuck this thing's a little long in the tooth but it uses these crazy contraption of a collet the nice thing is it will go from 1/16 of an inch up to 1 and 3/8 in the span of twelve collets each one of them's got a heck of a range on them despite their age these things are still pretty expensive I happen to have gotten this with the lathe otherwise I don't know if I would have sprung for something like this but anyway you saw me turn and bore the back of the stub Arbor and to keep it concentric your options are either put it in a four jaw Chuck or some kind of a collet Chuck you so a masochist might have tried to cut a key way in that blind hole but I've just opted to go for some set screws I've got two set screws they're m5 five millimeter the same diameter as the keyway on the stepper motor I don't know if that counts for anything but might help us out a little bit more and you know I just wanted to share what I think was a real Christmas miracle happened right here my garage this m5 tap it's the same one that did all the tapping in the CNC router I mean it's been through I don't know three billion holes and it's still gone strong now you'll notice I waited to tap both these holes before I told you that story there's the key that goes in the gearbox got a set screw in there I just ground the tips off for good measure the points rather and the dimension I'm looking for is this one here just approximately so it's about two and a quarter inches I'll make it just a hair longer so I'm not binding anything up when I clamp this together so this chunk of aluminum is what will become the motor mount flange you saw me sort of square it up I've get it pressed up against the four jaw via that Center punch just that never-ending battle of making square stuff around and brown stuff square originally I was actually going to do this on the CNC router I thought it might have been a you know a fun project there but by the time I would have gotten it in CAD with all the dimensions and gone through the cam I mean it's a pretty easy part it's just faster to do it the old-fashioned way actually plan to start on the hollow on the inside that way I can flip it around switch over to the three jaw Chuck and knock all the square corners off and I have the seal area you know away from the Chalker closer to me had I done this side first when I flipped it I'd be you know two and a quarter inches down inside of a bore trying to get the seal dimension correct and although I'd be the first to admit that there's quite nothing like getting all up inside your spinning chuck with the flashlight in your teeth and the wind going through your hair trying to see what the heck you're doing I think I'd rather just have easier access to probably the only important dimension on this part you know orders of operations how you're going to attack apart doesn't usually get much airtime but obviously it's very important it's always worth I mean it's not that big a deal on this part but it's not all that hard to get yourself into a situation where you have no way to hold on to the thing anymore so it's always worth thinking through what you getting yourself into you might notice that the chips coming off of this drill are different between the two flutes so it looks like I got one flute sharpened pretty well and the other one must either have added a small Nick or an off angle I'm also not drilling all the way through I want to leave myself just maybe a quarter inch a half inch of material to Center drill and support this thing when I flip it around so maybe they state the obvious you don't want chip cells like this you want chips that get the heck out of the way ASAP this long stringy stuff is extremely dangerous to have flying around at you on your lathe you'd be like playing jump rope with barbed wire walloping web snappers messed up my external seal this should have been one a single diameter with a groove for an o-ring I caught that mistake just in time to save a bit of a diameter so I still have a like a locating feature locating shoulder but I'm not going to be able to use that o-ring focus Daniel son I guess I'll have to use some goop anyway let's get that internal seal in there all right so that ID looks like it's the right size that would have really screwed this part up turn the boring bar on the turret I'm going to try to reach inside and just chamfer that inside edge alright no blood good chamfer hey so that whole thing from before about having screwed up this OD seal you scratch that I took the part off and I realized I was measuring from the wrong reference face this anyway still too close for comfort but for entirely different reasons so we're over in the middle I just wanted to pick up the center I'm going to be doing the six hole pattern for the gearbox and the four hole for the stepper motor I've got a dro in this machine so once I pick up Center I can just step through all ten of those holes easy peasy you really should spot drill first Center drill I tend to be a little on the lazy side these are just clearance through holes for the screws and the registration is being done by that Center boss so I think I should be alright you I'm using the parallel to sight across the six hole bolt pattern these slots are just for you know visual access inside in case a set screw comes loose or I need to take this apart or not to break the whole thing down it's that seal fit in nice I done buggered it up a bit trying to get it out to the other flange if it leaks it's cheap to replace it's my reputation that I'll put this over in lot and I don't know if you heard me over in the mill but the slots were just eyeballed in again just to keep an eye on whatever's going on inside so it looks like everything fits okay I can't screw it together just yet because I don't have any screws after that router build guy couldn't find an m5 and m6 screw and 100-mile radius of this place I put those terrible old screws back in I just needed something to keep this on for now so it's not pouring oil all over the place anyway the next step is to build essentially like a faceplate Chuck backplate some kind of a platen that the work can be attached to this is some maybe five eighths just hot-rolled it'll be round of course I just clipped all the corners off of a square plate to save myself some time in the lathe and this will just get a center shaft keyed and fit on the gearbox so just a quick look through the cut-off spin and I've got a 35 millimeter round that's one in 3/8 here more than one three-eighths I think this should work perfect so this will get a shoulder put a hole in the plate get to press through with a key way to screw so I'm not going to bore you with how this is made I'll just kind of walk you through about there should do it got my safety glasses on huh get a bigger hammer alright there's our cue a threaded hole for retention and hold on them there they are a couple of keys let's put it on the gearbox all right let's get the plate on there I've got some Loctite in there this is going to be almost a tooth out press fit I don't think this would be much of that Loctite left but cheap insurance so what do you say to a and all's well that ends well well looks like it turned out alright I think I got a little overzealous with trying to round this thing out I can't believe that spun in the collet I mean it's bad enough when that happens in one of my trucks but in a collet darn it just breaks you guys heart somebody should write a country song about that I haven't put any holes in here yet because I'm not quite sure what this plate will accept I wasn't even going to put a center hole in there and then I thought I might regret it once I took it off the lathe otherwise I want to put that in sooner but for now I might just drill and tap it for some clamps or some screws maybe some through holes for I don't know whatever the first project turns out to be all right last part is some kind of a base so you know the drill grab your stock a big hammer I'm just kidding everybody knows it doesn't work with aluminum so the base was a no-brainer just a piece of stock milled to the right height and it's got eight holes in there for for the gearbox and for to mount it to the table all right so let's have a look at the backlash all right you can probably see that that should give you an idea of how bad it is all right so that's a 1,000 Decatur and I'm pretty much as far out I'm at the rate like the maximum radius of the of the table which is of almost three and a half inches so that's 30 whopping thousandths so I mean if we don't consider the fact that this thing will break a lot of end mills probably result in poor surface finish on all the parts and is not very accurate I think it turned out pretty all right all kidding aside unless I'm just screwing around with some wood or plastic maybe this thing definitely needs a break I know I know I heard you guys mumbling under your breath there are so many things wrong with this test I don't even know where to start but guys could have some fun right so first of all other than the brake this thing definitely needed some kind of like a tail stock or a steady on top of that I'm not writing my stepper at full power I think it's two amps maybe an amp so I don't really have all the holding torque available I'm also using the longest end mill in the world and I totally messed up that can program like zero it on the center in this pockets not in center so when it flipped over it was in a different spot but you got to admit that was pretty darn cool so I don't know when I'll get into this or if I'll make a video about it but I thought I'd just share what I had in mind for a break I think I'm just going to use a little air cylinder and hook this up to you know the air line and a relay in the control box and just to make essentially like a big brake caliper that closed off on the shaft of the fourth axis I think you guys are sharp enough to pick up what I'm getting at here so I'll bolt this to the gearbox air cylinder goes in here somewhere and when I actuate that I can close in on the shaft sorry I don't know if I got that in the picture frame so there's the gearbox excuse my terrible sketch here and again just essentially a big brake caliper with the air cylinder and I think I can show you where how many people squeeze that in so I know if you can see that space in there right between the platen and the gearbox I've got about a centimeter I think I can clamp on that the small cylinder can maybe go up in space or down underneath it'd be nice if that space

Channel: This Old Tony

Views: 1,483,909

Rating: 4.8992634 out of 5

Keywords: cnc router 4 axis, cnc routher 4th axis, a axis, cnc router, diy 4th axis, diy a axis, mach 3, mach3, machining, metalwork, mill, lathe, rotary axis, cnc rotary axis

Id: jkgmjIlOVKc

Length: 28min 46sec (1726 seconds)

Published: Mon Feb 01 2016