Broken Gear Repair: Brazing Up and Machining New Teeth

hello Keith rocky revenge machine org so in the first part of the series on making this or repairing this gear we made the mandrel this is going to mount on when we put it on the lathe and on the horizontal mill and that's already so the next the next step is going to be coming in here and actually brazing up these broken teeth so that we can machine that out and basically recut those teeth so let's get over here and I will get ready to prep this part for brazing get them braised and get this done so this is one the broken teeth here and you can see it just basically snapped off right down the bottoms cast iron and don't know what caused this this is just the way it was when I got it so again the game plan here is we're going to grind this out some good material in here we're going to basically braze this up fill it in with bronze and then we'll come back and machine it all out and put that tooth back in so you know this is raising up a piece like this this is a method that's often done for repairing gears I'll be the first one to tell you it's probably not the most ideal solution to the problem but it is a fairly easy fix compared to some other things you know if this was a steel gear we can weld it up but because this is cast iron it's difficult to get a good weld on cast iron and there's a lot of opinions out there is the best way to do that the braze it there are some like nickel rods and there's some cast iron rods supposedly that you can use an arc welder you can even TIG it in with some like a again a silicon bronze or nickel to bond to the cast iron my preference is raising the reason it is because that's just what I'm familiar with that's what I've used for many many years and quite honestly I've had really good luck with brazing done very well for me and I just don't see a need to change the way I'm doing things and have to learn another method so anyway that's what we're going to do we're going to braise this up so to grind this out I'm just going to use a bench grinder here or not a bench grinder but an angle grinder with a good abrasive wheel in there and we're just going to get down in here and I don't want to go too deep with it but I do want to get you know kind of down behind this you know to kind of get down in here just a little bit so there's enough material for the the braze to actually bond to on the backside of the skier so we'll get a good good penetration and get a something for that metal to just grip into so we're just going to basically grind a little slot in there with brazing it's always real important that you have good clean material that you're working with so you always want to get basically grinded out and get any impurities and junk just out of there so that's what we're going to do I want to leave most of the original material on these gears on the side we're going to recut those we've got a little bit of braised material in there but I want to leave the cast iron on this as much as possible so I'm just barely barely skimming those and I I think that looks good so we're going to go ahead and flip it around and I will do the other one as well that we got to repair again I think that looks good well my best laid plans are being put to rest today I go here to fire torches and looks like we're out of a settling and it's the weekend of course so we have to wait and get those tanks filled up next week and darn I was really wanting to get this done today oh well nothing I can do about it now we'll be back on this project soon we got our gas tanks refilled now and I'm not going to go ahead and start braising this up so we've got everything set up here again and we're just going to preheat this fill that in do a little dentistry work here we've already extracted a tooth now we're going to put the filling in and then when we get the filling put in we'll we'll polish her up make her look real nice and pretty start by the slowly putting some heat in here roughly staff flow what we get a good preheat tip on there then I'll start concentrating my heat in the area that we want break see a little bit of red on those two and we're getting pretty close the goal here is I want to have I think I've accomplished that so we'll turn the torch off you know I can always tape material off I want to make sure that you know it's above the grade on on the top here and it's actually sticking out on the front and back because we're going to put that on the lathe and cut it off so I'm gonna let this cool for a minute or two and then we'll rotate it around and we'll do the other tooth all right it's still pretty warm so I carefully rotate this around you know our other tooth where we want it and we will repeat the process I think I'm pretty happy with that and again we're just going to let this cool down nice and slow so one thing I don't have that here at the Museum that probably need to get at some point in time it's a good blanket to put on stuff to help cool it down and we did just recently get a couple of fire bricks so I've got this gear sitting on my fire brick and I just kind of sandwiched it in there give it a little bit of insulation and hopefully that will let it cool down a little bit slower and we're going to just sit there for probably an hour so I've got a couple other things I need to be working on out here we'll let that cool down and come back this project in a bit I've let my gear cool down about an hour now and you know it's still warm but you can handle it no problem at all we're going to put this back on the mandrel which is back coated on the lathe the gear on there got my little washer here bolt on there and tighten it all up so I'm I Center up on that and we will go ahead and face off this back side I get the top here turn back down pull that around there you can see the braze on there we got to knock down so we'll flush that up on the side again cut the top down and then I'll change cutters and come in here and reach behind it and face this back side back off in as well I think we're ready to go here we got everything mounted up I got my cutter in here again we're gonna face this off ha I'm coming here to this farce touching and what is kind of ease into this who hit close cut off on that only much more we're skimming the cast iron in a couple places here I think that's good so now we're work across the top that's my feed there one little too fast getting real close come on dude this coming here just touch that tooth again and that should be left cutting it pretty flush we just skimmed a couple of the teeth around there but we didn't really take this puzzle in fact some of them aren't even touching so I think we're good there let's change cutters and we'll get the backside so I've got this cutter set up in here and basically what I did is I came in and touched off on the backside of this and I got an indicator down here to know when I'm at zero change that right there coming here and we'll start by with Astana work that down and I can watch my indicator right here zero to be facing the side there I like that I am going to take a little bit of Emery cloth and just kind of blend that in on the back I think I like that I will pull this off and see what it looks like all right so pull this off and you can really kind of see where the Braves went in there and I'm overall I'm pretty happy with it so I got just a little small I'm not even called that an inclusion really what that is is I just didn't quite get it out to the surface but it's not very deep it's not going down into it I could heat it up put another little dab on it but I'm probably leave it alone and kind of got the same thing on the backside here but actually most of this is going to get milled out where that tooth gets cut there'll be just a little bit down the bottom but again it doesn't go very deep like I said I think I'm just going to leave it like it is so I'm happy with this we're going to take it out this all over now and I get the dividing head set up I already had the dividing head bolted down the table here so we just came in and basically put our mandrel in here with the gear mounted on it and we're going to be adjusting that in a bit but right now I need to get this set up for doing the the cutter on the horizontal side so first thing as always is I like to get in here and wipe out my spindle make sure I don't have any trash or anything up in there same thing on the back here just wipe it off a little bit and this is a one-inch arbor go ahead and put that in and tighten up the drawbar on the back okay I wish I had a little bit shorter one-inch Arbor but this is the one I have so this is what we're going to use pull some of these bushings off see ya with the arbor in place now I want to go ahead and build this out and get my cutter mounted so we're going to run the cutter about right here you know the idea here is you want to get your working area up as tight as you can in here to the main machine just so that you don't have a lot of arbor sticking out more are but you have the more room you have for deflection what have you no I've got to really aren't long Arbor here I really wish I had a shorter one to go this longer one anyway that's what we're going to be so we're going to start there I put my key in here this is what will of course drive the cutter I want the cutter turning counterclockwise cutting toward the dividing head that's keyed on the shaft of course come in behind that with another fishing and then put another short one in here and then we're going to put our running bearing on this is where the over arm support will be right here and again that would just keep this distance as close as possible and I'll have to build out to the end with some bushings just to be able to tighten the nut up I need to go find me another bushing to finish that out I put these on the end and I'll start my nut on here I'm not going to tighten it up until I get everything on the arbor support on here just because there's a lot of leverage out here and I could bend this if I tighten it up right now next thing is we're going to run our over arm supports out I got a little rack-and-pinion type system in here that moves these out with a crank on the side that's to be far enough and we find my overarm sport I've wiped this overarm sport out real good gotten all the any dirt shavings or anything like that out from them and we're just going to put them on the over arm supports right here tighten up this on here which will lock it in place and put some oil on this bushing I just like to make sure there's plenty of oil in here it feeds all in but I like to make sure it starts out with plenty in there and we again come back over here and I'll pull this on to that last the running bearing I find it easier to get it mounted on the over arm supports and then pull it on this one rather than trying to line up all three once they get down here it should be in perfect position and it just pulls right up onto that running bearing like such and once that's there will lock the over arms down so that they can't move as well the next thing I need to do is I need to get this cutter actually centered up where it's running perfectly down the center of the dividing head here so that my gear will be cut exactly in the center and to do that I'm just going to use a method I've used this before so I take I've got a square I'm rubbing up against the actual mandrel that I made this the center diameters that is going to be the same no matter what diameter I work off of and I've just basically bumped bumped this cutter over just just touching that and I've got a dial indicator on here zeroed it out what I'm going to do now is move my square around to the other side and we're going to basically do the same thing and measure the distance that we have to move to get it to touch this side of the cutter so let's come in here it's one hundred thousand two hundred three hundred four hundred five hundred get my flashlight out here where I can see a little bit better that's just touching I'm not getting any light behind it so that's it so fifty thousands right on the nut number there so we moved it a total of five hundred fifty thousand from one side to the other so to Center this up now what I basically want to do is just move it back in the other direction half of this distance of half of 550 thousands will be two hundred seventy five thousand so let me use ear oh this and we will go back oops wrong way that's zero there one hundred two hundred and seventy five right there I'm going to lock my table in place the next thing we need to do is get the cutter here lined up in one of the existing teeth since we got we got to mesh this together we're not cutting a gear from scratch we just can't put these anywhere so I've got the Chuck loose over here on the dividing head where I can rotate this gear back and forth the table was down a little bit more it would make a you can see it just goes around and around around we're going to come back up here and I'm going to put that cutter roughly down into the bottom and we're going to raise the table up to depth that's a little bit high I need to put this a touch basically going to right here it's just it's just touching in the bottom I'm going backwards with my cutter here I think that's right where we want it to be so I'm going to do now is tighten up the Chuck over here on the dividing head where it won't spin anymore and I'm going to lock the table on the height I locked it raise it up just touch right there feels good i lock it down now and I can still spin it but you can hear it rubbing so that's right where I want it to be so now we're just about ready to go here but I want to just verify that I got my dividing head cutting where I want and everything is indexing right so a little bit about this gear this gear is a the diametral pitch on here which is basically the size of the tooth is a 16 diametral pitch the 16 pitch gear and there are 78 teeth around the whole perimeter of the year and I've used I've got a table I can look up from my dividing here this dividing head is a 40 to 1 ratio so you turn this handle 40 times it turns the dividing head around one time and using my chart I looked up 78 and what I needed was 20 30 nights of a revolution so I've got a plate in here I'm in the 39 the second row on here is the has 39 holes around it and I've counted it out so that I've got when I index this I got my sector sitting here so that it moves it 20 holes out of that 39 pattern so it's 20 30 nights going around and when I do that it should move the cutter the right amount to go from one tooth to the other so just to verify that I've got my sector set here and we're going to come up let's see oops there it goes right there and that should be lined up on the next tooth let me get over here and verify and it is I'm going to do that again I will move my sector around so that it's this little sector in here basically it's set so that I just move it over to the hole right here where it's at a word and we should be on the next tooth and we are okay so I'm actually going to probably just run down this tooth here just to make sure everything's looks good on it that's a clean to that any thing but I just want to be skimming it and then we're going to index over and do this next tooth here it's got a little bit of flux downer needs to be cleaned out we'll cut the actual tooth and probably just recut the tooth on the other side of it again to clean out any flux so let's fire the machine up we should be about ready to go bird and we should be on the next tooth I'm all set up now to make my first pass and so just to kind of let everybody know where we're at everybody always wants no speeds and deeds so we're running the Arbor at 73 RPM I've got my feed right now on the half inch per inch or half inch per minute which is the slowest speed I got I just want to take my time I'm not gonna get a hurry on this everything should be lined up with this tooth we're going to basically come down this for outside tooth here there's a little bit of flux and stuff down in there so we're going to run it through there and just clean it up then I'll index over and we'll cut the the two notches here to make the center tooth and I probably clean up these outside ones as well I'm going full depth on this one we're just cleaning it up I think what I'm going to do on the these cuts where we're cutting the bronze out is I'm going to take it in two passes so I've actually got I'm going to see it my dial indicator set up here and I'm going to drop the table down a hundred thousand so make a pass and I'll raise the table back up a hundred thousand make another pass clean it up and hopefully we should be good to go so anyway that's the plan we got miss cooling on here dividing heads locked down we should be ready to go so let's let it run through there just engage the table we pull it up going so slow I'll let it go from there alright amour back back out of here now get past that cutter I'm gonna unlock the dividing head and we'll index it over a two like that back down and again I'm going to drop the table down 100,000 and make this into passes so we'll go right there and then come back and make another path we're two of that cut let me come back out so I did just make a little slight change in plans here on the fly I went looked at my total depth of cut of this piece is 135,000 so I'm only making about a 35,000 pass I think next time I want to drop the table down seventy five thousand seven hundred thousand I think they'll be closer to about a half cut so I think on this one I'm not gonna go to four hundred thousand so I think I'm just going to go fifty thousands and we'll make another pass on it and like I said we're gonna things that plan up on the next two alright let's cut this one all right we'll go up back to zero again right there it could be the final depth here the guys I'm pretty happy with how that work so I think I'm just going to follow the same pattern and do three passes so I'm going to drop my table back down another hundred thousands just like we did before I'm not gonna get in a hurry on this only got a couple of teeth to cut so we're back down for a first pass I need the index punch dividing head loosen that up there we go all right we'll let it go through this process again just gonna do free passes again so this last pass and this can go a full depth and it's just going to clean up that gear next to it that tooth next to it really shouldn't be doing much cutting this is going to clean any flux and stuff out there so here's the first set of teeth I noticed it did raise a little burr on the top of this that'll clean right up though but I'm real happy with how those teeth are formed I think this is a total success so I'm gonna go ahead and do the other one I'll probably do those off-camera yeah processes exactly the same but anyway we got a couple more teeth to cut on here and I'll bring you back at the end so we're all done now we got all the new teeth cut in this gear I will admit I gotta say confessions good for the soul we got into the second tooth here which one we were doing off camera I got looking down in there after we made that first cut into the bronze and I noticed there was a little bit of an inclusion in there where it looks like the the the Bray's just didn't fully melt over itself and I said you know what that's not good enough so off-camera I pulled it off we ground out all that that braze that was in that one and I basically raised it up we turned it back on the lathe and then we went back and cut them in up this time got a nice finish on them I'm real happy with them so anyway I think this is going to work for Hector we're going to send this back to them if it doesn't work Hector let me know and we'll make you a brand new and not a cast iron and go at it from that direction so that would be another wrap not a little gear cutting exercise for you guys I know you guys always like to see me cutting gears and seem to be getting more practice at it here lately but anyway we're going to put this in the mail send it back to Hector along with the other parts that we did for them a couple of weeks ago and again Hector I hope you have success with this and if you don't let me know we'll attack it from a different direction and just make a whole new gear anyway that'll be a wrap on this uh this gear repair series and thank you guys for watching thank you my many subscribers hit the like button down there if you haven't already subscribed to my channel and we'll see you guys later thanks you

Channel: Keith Rucker - VintageMachinery.org

Views: 1,183,419

Rating: 4.8360953 out of 5

Keywords: Machine Shop, Machinist, Gear, Cutting, Horizontal Mill, Dividing Head, Kearney & Trecker, Shop, Brazing, Grinding, gear repair, keith rucker, dividing head index plates, dividing head gear cutting, dividing head calculation, kearney \& trecker milling machine, Kearney \& Trecker, repair gear teeth

Id: YWaF_QhcxA0

Length: 40min 8sec (2408 seconds)

Published: Fri Feb 26 2016

Reddit Comments

[u/yoodenvranx]

Keith Rucker is amazing! If you like this video then you have to watch the rest of his channel as well.

[u/Meltingteeth]

Well that was pretty sick. He's got some pretty specialized and complex equipment, it seems.