IMPOSSIBLE Miniature Internal Keyways and Worm Gears

hey guys joel pi here at advanced innovations welcome back to the shop we are getting down to the nitty-gritty on this model and the part that i will be attacking today is this one right here center screen part number 41 the clutch worm it is not a big deal to do a part like this there is a 125 hole through the center i will drill and ream for the drive shaft but the feature on the outside the gear mesh on the outside is a 40 degree tooth like a 40 degree thread instead of a 60 degree thread to a very specific depth so it engages all this happiness here and makes the carriage move along the bed when it spins the only big deal about this is the fact that it is a captured thread the od of the thread is the same as the od of the bosses on either end so this has to be threaded between undercuts starting is no problem stopping you better be on your game now to do something like this depending on the aggressive or lock aggressive nature of the thread increase or decrease the rpm of the machine to control how fast the thread dial is going around i'm going to do this at around 270 rpms i'm going to start on a digital zero and move over a certain amount and just lop it off by eye every time hopefully it'll go well and i'm going to leave it attached to a slave bar so i can broach a keyway down through the center of it i may or may not have time to do that today but i will for sure show you what that part looks like when it's done let's cross over to the lathe some chips on this particular part it is very important that the od is concentric to the id never assume the material is straight never assume there's no chip in the collet or whatever double check it if it can't get it to run straight smack it until it does [Music] so so by knowing how wide the tool is and allowing the tool to make contact with the face of your part in a very superficial manner it is easier to set the tool for distance for specific undercuts i am just barely going to scratch the face of this tool zero my digital and i'll know exactly where that tool is for the undercuts that i need to put on either side of the thread this is a 1.5 millimeter wide or o 60 tool and i'll be looking straight down on top of it with this guy right here old faithful next step in the operation is to use the actual threading tool i will put the lead on both sides of this to give myself a little bit more stopping room this will also be done by eye i will set the position of the tool directly in the center of this back undercut that will be my rear zero and i will look at what it takes to get it to here on my digital readout you can also do this with a drop indicator and i will watch the dro or the digital readout to disengage i may look at the part but it's nice to have two options i'll look straight down on this for now center up the tool 307 is the shift okay running in reverse i'm going to put the tool to the finished depth move left and right and chamfer the center boss time to run the thread back off the rpm 235 i'll run this out considerably slower than turning so my compound is currently set parallel to the part i will be making a couple of thousands shift to reduce the thickness of the crest of this thread so it seats completely within the gear and i will also go back in there right now and redo the champions i'm going to advance the tool two thousands towards the column two final depth as well so that is in fact the gear the clutch worm this will translate uh rotational motion to a 90 degree axis so let's run this a little bit slower put a gear on there and show you what i mean you definitely want to see a good mesh between these gears it is better to have this too deep than not deep enough because if it's not deep enough it'll bind and the center to center on the apron face will be wrong so nice mesh let me just confirm it any way you have to all right all goes well when i hold this gear against this worm this gear should turn relatively slow let's check it out maybe already lead the bird let's go over to the mill and need to broach a 132nd keyway inside of this all the way down i recommend doing it with a hacksaw blade believe it or not so jerry rig it any which way you have to unless you of course have a 130 seconds approach with a 1 8 diameter guide which i doubt anybody does i know i don't let's pop it on the mill figure out how to do that moving on to the final feature i have to say that this is probably probably the toughest feature on this entire lathe the whole kit is is wonderful but this little guy right here this 130 second by 130 second deep keyway in a 1 8 4 is just going to be a head scratcher i have a pretty good idea how i'm going to do it i am going to try to do it sequentially i am going to make a broach and it's going to be a broach style that i've never actually done and if deflection doesn't come into play and ruin everything it has an actual chance of working i think you're going to like what you see i know i like it if it works so let's check it out the technique that i plan to utilize to do this keyway is i'm going to make a little spade out of the front of this 1 8 diameter bar this is 17 4 stainless and can be hardened should i choose to but i think the stainless is going to be harder than the brass long enough to get through the feature i am going to neck this down to about 0.35 just under 1 millimeter and per pass on the part when the part is in the machine i'm going to tap the back of this and i'm going to bend it so that it kicks off center a little bit and that'll do the digging per pass so let's see if we can make a 035 wide spade out of this and set it up for the broaching it'll make a whole lot more sense then okay the width is complete i am going to take some off of the back side of this to make it more of an off center finger so that i can kick it and it's going to bend i don't think it's going to want to bend the way it is it's got to be relief in the back i think very possibly just a small undercut a notch to control where it bends will be sufficient i will adjust the tip accordingly so it's going to cut on this corner right there and clean all the burrs off and chamfer that back edge right there because that's going to want to deflect and hit the bore i'm looking forward to seeing this hang on okay quickly look at the brooch itself it is size to width it is relieved i will be banging on the back edge right here to kick this knife section forward it is sharp on the bottom and it will not protrude any more than it needs to because if you smack it too hard i have to imagine that the shaft of this tool may bend and actually not deflect up here i necked it down so that that's the weak point and it will move forward at least that's the plan i think it's got a good shot of success let's try it the part is indicated true to the spindle of the machine the broach is indexed true to the x-axis and as of right now everything has not been influenced at all it will still fit all the way down inside this part and hopefully when i hit the back of this the shank doesn't bend only the tip i will make very small adjustments on this and the keyway has not been made yet so knowing the cross section of the front wall i can measure how thick it is and that will give me the depth of my feature at least that's that's the theory so let's see what happens i do have a piece of white paper positioned directly beneath this collet block and i will be looking for shavings so and i wish i could get a camera down inside that because that actually appears to be working i do have shavings present on the catch cloth which is good a little more aggressive on that now bear in mind it is really important not to move the table do not move the table you so the next piece in line on this particular sub-assembly is the worm key this is the little guy that fits down inside of the worm gear and for anybody at pm research that may be watching this video these dimensions are no good the pocket in the casting is 6 30 the pulley itself or the worm gear is 625 and this thing is offset so it would never go together as shown 570 max on the od is what i'm going to do and there's 1 16 well that's up for grabs as well i'm going to do this piece blind because it's very small this is only a millimeter and a half thick and in order to machine this keep it straight keep it from bending this could be quite challenging i have a little nest right here it's just a piece of aluminum with a shelf on it between these two bosses is 570 so long as the part registers between that i should be able to machine the aluminum to this profile and when i'm done simply lift out the piece of steel that matches those numbers that's the plan let's put it in the machine make it happen i have to admit that this is going to be extremely hard to film you can see the piece down in here stuck right in there sandwiched between two sacrificial pieces of aluminum so you will not be able to see this being formed but after the machining i will make sure that i pull the camera out and show the release sorry about that it's just some things you just can't even see it's not even worth looking at stay tuned as anticipated that was extremely boring you can't see anything that's going on it's just a pile of chips there's a sacrificial piece of aluminum on the back of the part the part is sandwiched down in the middle and there's a sacrificial piece on the front so it's easy to register the part once you know how thick the part is vertically i'm going to open up the vise and we're going to pull the piece out and with any kind of luck it's an extremely skinny little l shape and if there was a band standing by i would say drum roll please because this is one of those parts it's not a difficult looking part but you can't hold it let's see what we got it's in there somewhere hey that's tiny let's see if we can get a shot at it all right see it in there now for all you guys are gonna say i need to hire a camera man forget about it that's the piece right there so it is an extremely skinny l take it out here is the fixture that i used to do that little keyway and you can see the final remnant of the part right there that little l-shape that is this guy that was completely blind i trusted the numbers on the dials and had to make only one adjustment that was the thickness of this end right here because that's the oh 62 wide tab going through an o62 diameter hole and that's just never going to happen so i put on a sander and bump the end that does have to fit into the clutch worm because that little feature right there that hole is what holds this in this goes inside the clutch worm and indexes this way and this pin lines up with that hole and keeps this key from walking out along that shaft let's see if we can put this together ultimately this worm will be trapped in this pocket right here on the back side of the apron as the apron traverses the length of the bed this worm will be sitting still within the carriage but it will be spinning until you engage the clutch which will then engage the gear that engages the worm then the power feed will start because this will turn the gears that engage the gear on the bed the rack and then the whole assembly moves whatever direction you have it set to so you can see you don't want to go too deep with your undercuts too deep with your gear teeth or too deep with that broached hole or brooch canal in the center for that slot you can see some pressure remnants showing up in the bottom of the undercuts that will not interfere with the mesh i've checked it so that's a good thing you can see how the hole works i think that's a great idea for keeping the keyway in place that's not going anywhere in order for that key to come out it has to go down and it's not going to go down because it's engaged anyway there you go and make sure that when you do this it floats freely along the entire length of the shaft which it does don't let the key hang out of the top of the worm gear too far or encounter the inside of this casting and that autofocus how cool is that make sure everything clears i am going to put champers on the ends of this particular gear because this pocket needs to be opened up and i'm sure i'm going to end up with a cutter radius in these corners so it has to clear first step in the apron cross drilling process is working off my little fixture plate i set a pair of stops these are my little toe clamps that i use [Music] and right now all i am doing is establishing that they are true to the y-axis which they are when i use this particular setup i'll be using it in this rotation and now i have a vertical surface to reference the apron casting from with the part securely clamped and the fixture plate positioned vertically install a pin to pick up the center line of the hole that the dimensions are referenced from sweep the pin accordingly find the high spot find the low spot looking at six before around do it again find the high spot find the low spot six before you can effectively call this your x zero use an edge finder from the reference face on the print move over drill and ream the hole the setup on this particular hole is everything the part is now correctly positioned in the fixture i added a one inch this is a 25 millimeter can't twist clamp on the outside for added security and now is the time to drill and ream the hole in position so before i start or show the final assembly on this there are a couple of notes i have to point out on the print so any of you guys of pm research if you're watching this video you really need to take this into consideration because anyone looking to build this model is definitely going to fail at a certain point and that's on this guy right here and let me detail why that's going to happen this particular pocket on here and the boundary of this pocket is really only called out in three places the 630 and that's about it it doesn't really call out to clean up anything else in there it just shows a bunch of dotted lines well these hidden surfaces behind it this surface under here which is that red line right there and the bottom of it let me find it for you there we go this surface in here all need to clear this worm gear so when you put this hole in depending on where that hole ends up right there this 250 diameter absolutely must spin freely in this pocket now mine's been modified i'm about 20 thousandths of an inch beyond let's see if we can refocus that there we go i'm about 20 thousandths of an inch beyond every possible dimension on this thing back and forth and there's a reason for that and i'm beyond the hole that way and i am low as well so when the gauge pin goes in or when the shaft goes in and this is a gauge pin same size as the shaft everything clears okay that is problem number one that is not called out on the print and you really need to pay attention to that you do not want to get in trouble at this stage of the game additionally uh the pocket is called that is five thousandths of an inch longer than this component right here normally you would be satisfied with that but i'm not satisfied with that so i cut the pocket 50 thousandths of an inch longer that's about 1.25 millimeters longer i see the gap on either end of the worm gear here and there and of course i had to make teflon bushings for either end of the worm gear so there is no friction between the worm gear and the apron now let's move on to the fun stuff this keyway right here another detail full of wrong numbers if this were truly 625 long and this gear is 625 long when you engage that protrusion into the drive hole in the end that keyway is going to hang out the end of this worm gear and it's going to be too long to fit in that pocket so that's 625 that 5 8 is absolutely wrong don't do it it doesn't even say fit at assembly like it should mine i'm going with 570 that's about 25.55 it's about a millimeter and a third shorter than it should be the tang also 1 16 rectangle got to fit in a 1 16 hole oh 56 diameter is what you need to make this if you want this to fit where it's supposed to and as far as the projection is concerned 1 8 well that's another big fail and this is not criticizing the kit this is just saying there's a few dimensions that they missed i love the engineering i love the challenge of it but you want it to go together and you want it to work if this were 1 8 when this tab goes in here it's going to come shooting out of that hole right there you can see it and it's going to be proud of the diameter considerably proud of the diameter and when it does back to this guy right here it's going to go 30 of the way around and it's going to hit this wall or it's going to hit that wall and it's going to bind up and everything is going to scream and you're not going to know why there it is oh 94 max 056 max 570 max on the left and you should be okay as far as this pocket is concerned just don't mill it so deep that you go into the hole where the clutch gear fits and the front you have plenty of material on so just clear it out i use the 100 diameter end mill so i have a nice small radius in the corner and i allowed for that radius with the mating chamfer on the part that's going in all right let's put this thing together and see if it was all worthwhile well i hope so that's a fussy little assembly that's being polite all right i think that's a winner dipper sure is all right i'm going to leave it facing down for the next couple of hops i'm just going to put it off camera here for a second bring in the apron this is the gear cluster made from the previous video if you didn't watch it check that out that was a very interesting build position the key way on the slot down i want that gravity working with you you're down feed it through the bushing uh really not a bushing it's more of a friction washer engage the key and you can see how my little friction washers are going to play out key is in position keyway is lined up with the key which is everything's looking good at this point i'm going to pull back on this for a second see if i can drop this guy in there and get lucky bingo that is a 5 000 end play on there and it is keyed it is going to move i guess we can prove it this way just watch for the keyway to come around anybody with a sharp eye knows that this is the front of the apron and this gear cluster should be on this side but for sake of test fit and assembly it shouldn't matter let's put the clutch gear on there see what happens clutch gear should mesh with the worm gear ankle bone connected to the thigh bone or whatever it is right stick that in there okay i'm going to leave this loose right now so i can turn the drive shaft this is the gear that's going to encounter the rack on the bed that should not go i'm going to put my finger on it so it doesn't just from gravity okay you can see the worm gear is turning this worm gear is hitting the inside boy this is really hard to light and film this guy right in here watch this gear here that's going to turn all the time no matter what okay now when we tighten the clutch feed clutch on the front and you guys run an old south bend you know how to do this right torque that down and now when the drive shaft turns this gear should turn as well which it does that is a thing of beauty i just love it let's un-loosen everything there we go and this assembly should drive freely along the length of the drive shaft which it does that's a beautiful thing right there guys that has got to be one of the fussiest areas on this entire machine make sure you pocket it out as required you do not have to add those little plastic washers i did that just to alleviate friction and or debris downstream and i considered putting them on either side of that gear right there to take that slop out because i'm not thrilled about that but i don't know if it's in there for a reason or not so i'm not going to mess with it that's it that's all you get loose tight love it as usual thank you very much for tuning in thank you very much for putting up with all my intricacies on this build i am just i want to make sure you have all the information that you can stand and then some wherever you are in the world i hope you're well hope you're happy this is joe pi advanced innovations in austin texas i am out uh yeah let's take a close-up look at the fixture used to do that little keyway i think it is really important that you understand what's going on it may be very helpful in the future this step right here is thinner than the thickness of the material that's going to rest on that shelf that is number one that allows for these movable side jaw to come in and squeeze it to a thinner gauge than the part held okay so that's really important make sure that little gap right there that little elevation is thinner the two slots that i put on top initially which have been chewed away represent the overall length of the part this is a visual so that when you lay the material in here and i'm going to go for a pointer on this when you lay the material on that little shelf right there you want to make sure that it overlaps into each one of these that way you know where you're at because when you squeeze this you're not going to be able to see it the very first thing that i did was decked off the top of the blank to a rough height that way i knew exactly where my z height was let's put the part in here this is a little guy come on there you go now with the rough z height established i knew exactly how far down i had to move to get the overall height of the part that's good because once you have this plane then you know how far down you move to get this one that's an easy z adjustment okay so this is a two step operation first step is to rough the height on one side of the blank flip the blank over and re-clamp it of course measure the blank before you reclamp it that way you know how far to move down on the next setup establish the overall length because you know center to center and then the step falls right in for you that is a very handy way to do such a small part that is basically impossible to hold by any other means and when you're done like i said before you have a footprint of the part right there completely blind you got to trust your numbers if you have a digital it makes it a lot easier if you have a dial well you just have to pay attention but that was done with a 1 8 cutter and it was minimal tweaking at the end i did have to thin the end out here on the belt sander so it fit in the cross hole on the worm gear but i didn't see any other way to do that so that was my approach

Channel: Joe Pieczynski

Views: 52,733

Rating: 4.9744411 out of 5

Keywords: Joe Pie, JoePieczynski, Advanced Innovations, advanced innovations llc, how to, machine shop, shop tricks, shop hacks, shop techniques, shop tutorials, pm research, miniature lathe, worm gears, power feeds, scale models

Id: lY9ECgwr3kY

Length: 48min 5sec (2885 seconds)

Published: Sat Jul 31 2021