Repairing a Broken Gear Tooth Part 1 - Milling a Dovetail Slot on a Horizontal Milling Machine

[Music] hello my name is Keith Drucker they were back out of Georgia Museum agriculture and working on the next project on restoring the J a Vance planer master that I've been working on now for about a year and still have quite a ways to get it to today's project is to be working on this gear I say two days it's probably when I actually take me several days in short bursts that I have time to work on this but this is one of the drive gears that drives and powers the feed rollers on the milling machine are on the planer master and unfortunately right here one of the teeth has been broken out this happened properly when the machine crashed at one timing to pass there's several telltale signs to the crash took place on this machine I think that a board got stuck going through the feed rollers that wouldn't turn anymore but the years or so turning and eventually this year here throat along with some other damage that was done to the machine that we could have it to repair I've run this restoration so the game plan for this is we're going to come in here we're going to actually mill off this old tooth coming here from the swap with a knit meal and then using a duck tail to come in and make a duck tail in the back of this we can make a new tooth we're gonna be doing this on the horizontal milling machine mainly because small here and large gear side-by-side we can't get into the work on this on the vertical mill plug then the machine like this which is not going to be very rigid horizontal a lot some work on it letting down flat like this coming in from this side here and it's going to require making a special Arbor to hold my cutting tool using the overhead one of the outboard of arms to give it support and rigidity while we're doing that this is going to be a great job for using my horizontal moving machine home so first step is we're going to take this piece here and make a little jig or fixture that we can put on the milling machine to mount this I'm going to turn this down the same diameter of this board here and then I'll bolt this to the table and then slide this down on there and I can clamp it down and get a good rigid in fixture of the hole in place so the first step is we're going to be working on this once we get this tooth done we'll also have to come in here and press out the old bushings put some new bronze bushings in here this goes on here and this is very pitted from years of use and this is an inch and a quarter in diameter and when I measured mic'd out this the bushing the inside bushing is actually one point four four inches so it's actually worn almost two hundred thousand suspicion hands so we'll be pressing this out and actually making a new shaft because it's pitted here so we've got quite a bit of work to do on this piece and get this brought back to life and that's where we're going to start off today first thing we're going to work on here is making this jig to hold it in place so we're just going to take start out by taking a center drill punch it in there drill a half inch hole about five inches deep in here then we're going to turn this outside down to that one point four four zero diameter that the gear can slide over and then that'll give us something we can clamp down on the table we'll cut this off and base that off flat but I'll give us some we can clamp down the table amount that you see so we'll get started you we're within about 60 thousandths of our final dimension here whose piece has gotten pretty therefore the you 80,000 total forecast let this cool down a little bit because the heat was in the pot right now can cause it to expand to ambient temperature bottle dimension can this one like this cool oK we've let this cool down and I was a measure to get out of curiosity and we were she wanted to that trunk for thousandths of an inch just by cooling down so we've still got about fifty four thousands to take off of it so we'll just sneak up on that number you here make sure right it's spitting on both sides there's actually two bushings in there [Music] the purpose of this giving us [Music] and make it fit this is just kind of give us [Music] I'm gonna take a little bit more you you we have our holding fixture made now and we'll try on the milling machine so I've got a just a t9 slot here our T nut with a long piece of rod in there slide that over it like such and then on top of that we'll come in and put the gear which fits in on there very nicely I'm gonna make a special clamp to go on the top but for right now I'm just going to take a hold down out of my clamp set we'll put that on there just to try out that started I sit down now I have a very rigid way to mount this gear to the milling machine that's going to work very good for us to come in here and mill this out so step one making the holding fixture success we're ready to move on to the next step we've got everything mocked up here now just to kind of show you what the game plan is for next so we've got this built now that we can hold the gear in place I've just got a sitting here now it's not bolted down yet but we've got to get a cutter into this section right here and because of the way this gear is the way of sticking out it's gonna be really difficult because there's just not a lot of clearance in here to get a arbor right up there next to it normally we get this right up next to chuck or put it on the vertical mill do the same thing but because the size of the quill on the vertical mill we just we just can't get in here so my idea is I'm going to build an arbor that we go from here and it will extend out to here I've gotten this over arm support right here that will give this some support out here over those so that shaft go over the long gear but we'll be working close not to the chuck but to this over arm support here to give us the rigidity we need with our cutters so that we're not flexing so the over arm support is mounted on here everything looks like it's going clear just fine but we've got to make an arbor to go through this so I've have a bushing inside this right now that will take this three-quarter inch I know that my cutters that I'm using have three-eighths inch shanks on them so my idea is I'm gonna take I got a piece of inch and a half a bar here we're gonna turn this down to three-quarters of an inch except up here on this this end which will drill and a ream a three inch hole right in the middle and this will actually become the Chuck that will hold my cutters and it will just stick out right here and give us enough room here that we can work and get done what we need to do and then we'll have a this will be turned out of three quarters of an inch to go up into the arbor on the mill so that's the game plan so next step here is we're going to make the the arbor that will be used here we've got the piece of steel set up here in the lathe now we're going to come in and just do a center hole drill it out to one size under 3/8 and then use a 3/8 reamer to ream that hole out for our tool holder and then we'll just put a face on this end which will be the working end and then we'll flip it around start cutting the other side you I'm limited on camera angles because of the way the flavor hoping he can see this I've got the compound Center cut the leading edge off this awful face listening you we put the part over now we're gonna face off this Center India this would be the backside that'll be turned out three four [Music] commentators sitting in the chunk because his truck has run out leave it we're always going to have a certain how to run out of so always this penny compression make sure that I've got a perfect [Music] happy Arbor now mounted under lay between centers parting between centers is founded value I guess apart laughs to me although this is very common still has a very used for that patient exactly with the hole that I've drilled into the end of my putter reporte to lose a little bit of run out of it now before someone although coming between centers is also very useful if you need to flip a part over and keep there what kind of Chuck you have a little bit of run out [Music] probably not going to home is absolutely perfectly turning between sooner [Music] exactly on sinner with [Music] you you we've got this turned down now to about 25,000 over I did stop at that point and actually I went Pam grab some lunch and came back but the main reason was was it gotten pretty warm I was taking about a forty thousands cut off of this once I got going and kind of figured out what I could safely take with this cutter and so that was taking 80 thousands total off the dam to reach pass so we're take us a pretty good meat off of it and as you can imagine it got it got fairly warm to the touch and again just like when we're making the the fixture to hold our piece on when it gets hot like that it will actually expand just a few thousandths of a mansion because we need this to be very close to exactly 3/4 of an inch I wanted to let it cool down so that's what we did there so what I'm going to do now is it is cool to the touch we're gonna come in here and just finish this out I have the bronze bushing that is out of the arbor support on the milling machine and I'll be testing the fit with this it really doesn't matter what the diameter that is the main thing is is that it fits in this bushing just right so we'll be checking that fit as we get down close to the end [Music] we've got this harbour set up on the milling machine now and we're going to come in here and mill a flat right here on the end and this is where this Harbor will go into the tool holder on the milling machine and they'll be a set screw that engages here and that'll keep it from marring up the shaft where we can get it in and out we're also going to come in here drill a hole in here and tap that for a set screw that will then be used to clamp down on the tool that we put into the Arbor this around in device and now we're going to find the center of this and pop a hole in there and drill it and tap it out to 3/8 16 so first thing we got here is our Center finder in here we'll turn this on piss I have my visual readout along zero out my down back down why to find the center of the shaft I know that this is a half inch in diameter so first thing I'm going to do instead of having the edge running just right up to that next edge of this I'm going to move it over to the center is right on the edge of the part so that means I need to bring the table to me a quarter of an inch half of a half-inch b250 thousands so again using my digital readout I'll pull it over there and there I am it flips 250000 right on the money zero out my digital readout and now I want to get this to the center to the center of the edge into the very center I know that this is an inch and a half so again half of that would be three quarters of an inch which is 750 thousands so I'm going to move it over again 750 thousands and playing where they get it just right there it is 750,000 ivory zero out the the readout again and I locked my table in place now I know this is right in the center I could have just moved it all an inch they've been a quarter of an inch plus three quarters of an inch but I typically like to zero out the edge finder it just it just brings less air into everything is stead of trying to add it together and make sure the sum of the two is right I'll just zero it out it's easy enough so we're set up there now let me put a center drill in here and we will get a drill sound right there we will want it as you can tell I'm at the Museum today and it's Saturday and the trains running our steam locomotive as you can hear running around the tracks alright and I'm going to move that over just a little bit about right there I think I grabbed the dull one again we flip it over put my drill bit in here okay I'm now set up with my tap I'm using a little spring-loaded Center up here that keeps everything right in line unfortunately this tap does not have a center hole on the inside to put this tap handle that does on there which caused me to have to drop my table way down but it's just the way it is we'll put some tap magic around there and this just helps make sure that as you're starting this at that tap this thing perfectly straight up and down which is so easy to start on start it to a hole out and and get it crooked once you get it going it's really not necessary that you have it the whole way down but it does help you get started right [Music] taps all the way through almost over this piece the last thing I'm going to do is we're just going to turn this nose piece down here a little bit we've made it out an inch and a half stock I measured one of the tool holders on my 40 taper our 50 taper tool holders off the middle machine this was an inch and a quarter so we're going to turn that down the same diameter probably don't have to but we're just going to do it anyway you we have everything set up over here on the milling machine now I just play the first test nut just to see how things are gonna go but on staff forgot to get the camera set up but we're gonna bring you in here now I've got a half-inch in there and first thing we got to do is just kind of cut this whole tooth out we're actually going to middle slot down into that we can come back and cut our dovetail we cut that slot for food the same we'll raise the table up to actually make the cut Horace feeds and speeds go let's see right now we're running the bid at about two hundred and fifty rpms and I have my feed set right now on the slowest possible sitting and I may play around with this as we go through here and see how Thank You Patti right now we're feeding it at a half inch per minute so it's a fairly slow process right now Alexa I'm gonna play around with these feeds and see if we can speed things up just a little bit that I like the way that was cutting right there we haven't interrupted cut right man - so I probably start out slow slowly feet in there so but looks like things are going pretty good I've got this centered with that tooth is I'm going to be cutting out and again I'm just going to be feeding straight in and making a slot down through there that I will then cut into our we'll get going [Applause] even though we went to a lot of great pains and effort I do have a little bit of run out on this harbour after everything said but there's pretty slight and I think it's going to be fine for what we're doing to go with the darkness [Applause] you what I'm doing right here is actually getting my first full death because of the over armed support right here on the gear the first couple of tests I had to stop shot go all the way to the bottom but now we have it out where it's going to give us that clear so we need this is as far down as I go now the next thing I need to do to Riga an indicator or something along those lines that I can watch to be able to tell where I get to zero each time in his pet so I can stop in the same place so I'm gonna take a break right now get my indicator out and see if I can rig something up to be able to watch the depth of this cut each time all right here's what I reaped up as you can see I got an indicator set on zero there and that's basically where I just stopped that last cut so that's my reference what I did was I matted the the base of the indicator to the machine itself and I rigged up a little stand that goes down to the saddle which is going up and down with that feed so that this bottom piece basically will come up it will engage the indicator and I've got about 90 thousandths of travel to be watching for is it comes in there to stop it to be able to keep it from hitting the bottom each time and I'll probably just get it close and then raise it up a little bit by hand to finish that out so this should work pretty good for me I looked at a couple of different options I started to say well I'll just indicate off the top here then I got to thinking that the tables going to be moving in and out and that might change my my bearing surface for 0 each time not by a lot but this way working off the saddle there's nothing moving on that saddle except up and down there's no in and out moving on it at all so I feel pretty comfortable with that I'm not crazy about these arms sticking out but there's plenty clearance around shouldn't be anything hit them so I should be good to go and actually it's all choked up pretty tight in here so I won't be having a lot of play in that indicator and then that be going down to the base there just with another of magnetic holder that I had that I just rigged up give us something to indicate off we'll give this a try see how it works you you you we have our group so now while we're still in this setup I want to put the dovetail hit the end and put the dovetail bit so it's basically touching the bottom of that cut and we'll make one pass down onto the same depth you can cut a dovetail in there my total depth of this cut is about half the thickness of the hub which is kind of about where I want to be it's not an exact measurement I measured after we get it all out and figure out how deep it is and then make to make the gear the new tooth to fit that this should be should be ready to go for the duggar in there now the same dentist last Oh of the half hitch lock in Hardin County you you hey that's looking good I'm gonna put the regular ml back in there now and just kind of clean up the rough edges around here and clean the bottom up I didn't want to do that to like get out everything done so this dovetail be running exact center of that slot but now we're going to clean that clean up around it to get that tooth down in there rip you alright here's a view down the duck tail and you can see what I'm talking about I've got just a little bit of a right here and over here it's just a rough surface I will just clean that up and also down here at the bottom so that in bill was going in an arc will then coming here just trim that down flush for this back piece was cleaning it up okay now we've got this turn around here we can just really see what we've got so you got that dovetail slot he goes down through there it actually doesn't go all the way to the bottom we weren't able to get it down there because of the way that it was but we've got enough of a dovetail there that we will have more than enough to keep that teeth from pulling out as it's twerking around so I'm going to call this part of the job done and the next challenge it's going to be to make a new tooth that we can just slide down in there and either solder or braze in place I haven't decided yet how I'm gonna permanently a fix it but at least we've got something to work with now [Music]

Channel: Keith Rucker - VintageMachinery.org

Views: 1,004,549

Rating: 4.6959882 out of 5

Keywords: Machine Shop, Georgia Museum of Agriculture, Kearney & Trecker, Lodge & Shipley, Dovetail, Horizontal Mill, Gear, Milling (Invention), gear repair, horizontal milling machine, keith rucker, repair gear, milling, gear tooth repair, milling machine, milling machine operation

Id: PI96CzxFUPI

Length: 35min 35sec (2135 seconds)

Published: Mon Nov 04 2013

Reddit Comments

[u/sev_o]

Part 2 if you got through all of that.

[u/vivalarevoluciones]

Engineer here: This is only acceptable for this type of gear. For instance if you have a tooth that broke of from a helical gear how would you repair that. ? Gears that take tremendous amounts of torque should never be repaired. Its an accident waiting to happen. Stress concentrations actually increase , and are not distributed well like with one whole piece .

You can see the stress concentrations on a normal gear here

http://www.greenstorm.com.au/fea_myths.html

[u/freshmas]

Fun to watch, but the audio is awful.