Gear Cutting Basics and Cutting Pinion Gears on a Horizontal Mill

hello Keith Rucker here Vince Machinery org today we're going to be working on cutting some gears been working a while getting ready to the stage doing various things getting all my blanks turned I actually had a good bit of work to get the Machine ready to go for this but we're finally ready to cut some gears and we're going to start on this blacksmith blower repair project there are three opinion gears that are in there and these are all basically gears that are cut on the shaft they're going to be on so and I've already cut my lengths I've got those ready to go that was in earlier video if you want to go back and watch that if you missed it and but anyway these are all what we call pinion years and pinion gears are basically this given that to two years and one of them is a good bit smaller than the other gear the smaller gear would be what they call the pinion gear and all the different pinion gears in this particular project have 12 teeth on them now two of them are a 16 diametral pitch and one of them is a 14 diametral pitch I believe that's right I know it's 14 16 and so we're going to change some cutters out and whatever to do that but anyway we're going to start with these pinion gears so but before we get everything set up over here I want to talk a little bit about years for anybody that may be wanting to make some of their own and some of the stuff that you need to know and where you can find the information that you need to make those gears so again we have our pinion gears all laid out here and you can see the original ones that we're going to be copying and these are just worn very worn both the years as well as the bearing surfaces the bearing surfaces are probably the biggest problem on these but the gears are also worn so we've made the new blanks and they're ready to go but before I made the blanks I had to do some people were asking me so well how do you know what size to make the areas that you're going to cut into the years that's a really good question and there's a couple of ways I guess you can go about doing that you know obviously if you got the originals you can make you just measure what's on here but you know in this case we've got some significant wear on these gears so it may not be exactly the right outside diameter so to verify that information I basically did a little bit of math and calculated what that should be and as fairly easy to do that so if you're going to cut any gears you need to have a good reference and you know most machinists are going to have a copy of Machinery's handbook you don't have a copy of that you know this is a really good reference to have and there's a whole section in here I mean it's probably over 100 pages long it just talks about gears and gear making and I'll pretty much any information that you need to know you can find in here so what do you need to know well depending on your application you could start out with knowing several different things but in a case where you're copying gears the two pieces of information that you really need to know is number one the diametral pitch of your gears and the number of teeth that you're cutting now the diametral pitch is basically the size of the of the actual gear teeth and the pitch is you know it's going to be a number and it's going to come down I believe to the number of teeth per inch is the way this works it may not be exactly right but I'm pretty sure that's what the pitch is you know in my book here we got up showing like starting at a three pitch going up to a 20 pitch and how as you get to a higher number the teeth get smaller and you can use this this is the scale so you can use this up right here to determine what pitch your teeth are now what I've been using is I actually have this little gear gauge and this is made by Boston gear and you can find these there they're actually fairly expensive I found this one at a tool meet and got lucky I think I pay about ten bucks for it but these are basically just a little gauges that have the pitches on there and I'm let's zoom you in here will show you how this is used I determine the pitch so we'll start with its bigger gear here but you can basically just take this little gauge and come in here and find the one that matches you know we go to this one here that doesn't match and a you know through trial and error you can determine which one actually fits so this is kind of set up like a rack and the gear and you just see the one that fits and it's stamped on here that's the number 16 so this is a 16 pitch on this gear my other gear is this one here if you look at 16 pitch doesn't fit and I see we go to this one here this one there's a 14 pitch so you can determine real quickly it's a little bit easier to use this on bigger gear you know we go to the pinions and it's the same thing you know there's your your 14 and there's your 16 that just walks right down through there get that in the screen where you can see it that might help so anyway we've determined that we've determined the pitch and then of course the number of teeth you just you just count them in fact you can probably see on here where I put a little dots I took a little marker and went around that and just counted the number of teeth and double counting and make sure I had them right but with the pitch and the number of teeth then you can start doing calculations to come up with what the dimensions need to be so to help me work through this I basically went into Microsoft Excel and create a spreadsheet that will do my calculations for me but all of the formulas to determine this came right out of the Machinery's handbook and anybody can look up in there you go online and find these formulations as well I got all the formulas right out of the Machinery's handbook so up here at the top I put in my diametral pitch which will signify by P in the number of teeth which will be in that's the normal nomenclature for those also got pressure angle on here which all my gears are going to be 14 and 1/2 degree pressure angle and I'm not going to talk a lot about pressure angle generally speaking most gears are either 14 and 1/2 or 20 but it's kind of hard to measure that and again I'm not going to talk a lot about that if you want to find out more about pressure angle you know get out your Machinery's handbook or go online but I do know that mine are all fourteen and a half so you know one of the question was was what was the outside diameter of the piece that you're going to turn what does it need to be it was fairly easy you just use a formula number of teeth plus two divided by the pitch and you can calculate what the outside diameter should be in this case it comes out to point 875 for that gear and then I actually scanned to help me a diagram by the Machinery's handbook and actually put it on this so that I could help remember what's what most of these other measurements are not necessarily important to know when you're machining but some of marks on my marble some of these are used later on other calculations that I make but I went ahead and calculated everything out so the big thing is is was the outside diameter the gear need to be and then also what is the depth of cut that my cutter needs to make as I'm cutting these so that I kind of have a target to go for and if you look at the hole depth of the tooth it's just simply two point one five seven divided by the the diametral pitch and I'll tell you the how far down you need to go you also need to factor in some backlash you know these gears mesh together if you if you cut them just right to the book there's absolutely no play between them and the gears will bind up so you actually need a little bit of play a little bit of backlash and I can calculate a formula to calculate what the backlash should be based on the number of teeth in the and the pitch are actually from based on the pitch which is you know in this case you need about three thousandths of backlash and then again I had another formula here the depth of cut obtain backlash so is 0.137 so I need to cut 137,000 steep with my cutter to get where I need to be so anyway I've created all this there's the formulas that I used right here to come up with all this stuff and that's how you do it and and on these outside diameters you know I went back and measured the original gears to verify that I'm in the ballpark or you know and quite honestly I was right on the money the measurements were the same which tells me that I was doing it right so once you know what your diametral pitch is you know what you how many teeth you've got the next thing you do is get the right cutter to cut these and there are a series of what we call these uh involute cutters and if you look at the profile it kind of matches that that little shape that an involute spline of the years that you're cutting but because this number of teeth you're going to have different diameters of here you know one cutter for one pitch doesn't cut it you have to have multiple cutters because the geometry of that tooth is going to change depending on the number of teeth you have and there's actually eight different cutters generally speaking to be able to cut a range of teeth for each diametral pitch and again you go to your Machinery's handbook you know you can look this up and there's a little chart in here and we'll zoom in there where you can see that so there's there's two charts in here and actually I said there's eight in back a long time ago they used to have half series so there was a it was actually a gear you could get our cutter in between each one these numbers but generally speaking most time were just going to be in the in the in the eight cutters there may be some halves that are still out there you can find at least an old stock I don't think you can get it in new cutters anymore but what you look at here is a course for each diametral pitch there's the number cutter one through eight and each one of them cut a different range of teeth so I know that I'm going to be cutting 12 teeth at least in this first one so if you look at the number 8 cutter cuts 12 to 13 teeth so that's what I have is I have a a cutter for diametral pitch 16 and it is a number 8 and that's this particular cutter right here and you kind of see the profile on there of what that's going to cut so all of my 12 pitch teeth at least 4 and I got I got both 16 and 14 so I got two different number eights depending on the pitch my other bigger years what I've missed 40 years and when I'm our 40 teeth and when I'm is 50 teeth and it turns out that both of these will be number three so 35 to 50 14 you'll use the number 3 cutter but again I had to get two of them one for a fourteen and one for sixteen diametral pitch so I've got all my cutters I know by diametral pitch I know my number of teeth I've got my calculations all worked out for each one of my gears so I've got my homework done now I'm ready to start setting up the machine to start cutting years the next step is to get your dividing head set up for the number of teeth that you're going to be cutting and again I told you we're going to be doing we're going to start with cutting 12 teeth all the pinion gears have twelve teeth on them we have different diametral pitches which have to change cutters but as far as the dividing head goes along b12 so the first three are all going to be dividing it'll be set up the same so this is a brown and sharp light dividing head I don't think this is actually made by Brown and sharp I think this is one of the early clones now this dividing head was invented back in the late eighteen hundreds early nineteen hundred's I don't remember the exact year but when the patterns ran out on it it was such a good design that a lot of companies started basically just copying this thing and making their own versions of it and even today there's several of the import companies that are selling brown and sharp type dividing heads that is the design has been virtually unchanged for a hundred years which is a testament to this design it's a good design this one here is an older one I don't know who made it though it's not marked but that's not important but what is important to know about this dividing head is what the gear ratio is between this handle and what's turning up here so this part right here will be making revolutions around and what we want to do is we want to be able to index this thing exactly the right angle for the East number of teeth and but instead of doing it in angles we're actually using ratios to calculate how far we need to move this so this particular dividing head is at a forty to one ratio and most of the body has added us what they are forty to one I think the actual Kearney Curnutt recce or Kearney trekker dividing head that goes with this machine's actually it's five to one ratio I don't have that one though so it doesn't matter we're going to be using 41 to the forty to one so what that means is is that when you turn this handle here you have to turn it 40 times to cause the part back here to make one revolution it's forty to one so what we need to be doing is we need to figure out how many times we need to turn this crank to get it to turn where you will be stopping 12 times so again you can use math you know you take 40 divided by 12 you can get a number but quite honestly with dividing heads which really want instead of having a decimal you want to have fractions so you really want to do your math and fractions so anyway you do the math and what you come out with is this you need to turn this handle three and one-third times to get 1/12 of a circle if you do it on the calculator it'll be three point three three three three three or you can use fractions like I said you'll come out and then what you have to do is you notice I got this plate back here and this plate has a series of holes in it and each one of these series has a certain number of holes in a circle that are around the first one is a I see a 33 all right so the bottom hole is from 21 22 27 29 31 and 33 that's the number of holes that around this thing and I'm in the the series that has 33 holes in because I can actually come up with a third out of that number and I could probably get that out of some of these other holes as well but what I want to do is I'm going to go three and one-third times I'm not going to stop in every hole but I'm gonna be stopping and because this has 33 it's going to be eleven thirty seconds or 11:30 thirds excuse me so I go I've got this a March so I'm in this pin I got one two three four five six seven eight nine ten that's the 11th hole which is one third I've got this little little sceptre arms set so that I know that if I push this one up against this pin this will be the next pin I need to go to but I got to go three full revolutions in the part so I go one two three and a third drop it in that pin I move my scepter arm around one two three and third so on and so on and so on all the way around and you'll do that 12 times and you will come up with a full circle you can cheat I've got a table here that basically shows you for the number of divisions what plates you need to use and how many you need to make so for my 12 it helps me use a 33 plate and go three and 11:30 thirds we're going to be cutting a 40-tooth gear remember it's a forty one ratio so on that it's just one revolution go back to the same hole so you can use any plate you want to use as long as you go back the same hole every time for the 40's and then on the 50s I'll use a 20 plate and it is 20 and 16 xx is what I'll have to do on the ultimate to cut a 50 here so I'll have to change flights for the 50 here I don't think I've got a 20 on this one but I have another plate over there that has 20 holes in it so next thing we need to do is courses get our foot stock set up on the machine so that it is set up where it's exactly at the right height here and I have some adjustment in this that can go up and down it can tilt back and forth whatever and I apologize I did this off camera this is my parts going to go in here when I was setting this up actually actually what I used was a reamer a long reamer that had a nice ground shank on it had two Center holes one on each side and I set it up on here and basically took the dial indicator I went back and forth back and forth until I had that shaft running perfectly straight across there and like I said I can bump this around up and down and get it right where it needs to be it's set now so we're good to go that part was done off camera this is the part that we're going to cut and it's going to go between centers and of course we're going to turn this over here and that's going to turn that part but in order to keep that part to turn there's nothing that's going to make it turn exactly the right ratios or right index time so we've got a dog drive plate we're going to put a lathe dog on this to actually help turn it so you take it back out and this is the lathe dog I've got a little piece of brass shim in here because I don't want to Mar the surface up and I'm going to tighten this down good and tight let me get a wrench and we will put this back between sinners and this time notice that the slave dog is our the lathe the dog is going up into this a part behind us going drive it the dock the the part of drives the lathe dog I'm going to put it back between centers I want this to be tight but not too tight I don't want it to be putting too much pressure on the dividing hip so now there's a little set screw up here and we're going to tighten this screw up as well that's going to take any movement out of this at all this doesn't need to be super tight but it doesn't be tight so now as I'm turning this notice is turning that lathe dog around and it's making sure that that part is turning with the dividing head so now we're ready to put the actual milling Arbour in and all of our cutters that we're going to be using today are fit on a 1-inch Arbor so I've got my one inch harbor here this is 50 taper up in here and I always like to kind of clean this taper out anytime I come in here you know it's open to the elements and you can always get a little bit of dust and stuff up in there potentially even some trash same thing here I'm going to wipe down the mating part in this 50 taper Arbor goes right up in there and then we'll go around the back and I'm going to tighten that up using the drawbar and that will be holding it firmly in place next step is is to get the right cutter to go up on the shaft and again I've got four cutters for this job and to kind of make it a little bit easier on me I went and wrote on each one of my parts what the pitch is and I know this is a 12 pitch just because it's the pinion gear small one and I've got the cutter here and it's written right on the cutter scratched on here DP 16 for diametrical pitch and this is the number 8 and again the number eight is the one that cuts 12 to 13 teeth so I've got the correct cutter for this particular gear and now we're going to go ahead and put it on to the arbor some of them pull my nut off here pull off my spacers pull off my running bushing and pull off some more spacers this cutter has a keyway on it and there's a key on my shaft or on my Arbor here so now that cutter is on there and it's geared and are keyed into place and we put some spacers back on here put my running bushing back on I'm you know a lot of people will run this running bushing all the way out the very end the shorter that you can make this this section here really this the more stable your setup is and quite honestly I could probably even shorten it up with it more than this but it's going to be plenty good but notice you know my arbor oh my bushing is not at the very end it doesn't have to be at the end and this is a this is a rather long Arbor here I almost wish I had a shorter Arbor because I really don't need all of this for this particular job go ahead we'll tighten that up real good and tight all right so now that should be running good and tight right in there next thing I want to do is put the actual over arm support that will run on this bushing some are I'm going to come over here now and extend out the over arm supports these are a little rack and pinion I got a little hand wheel over here and I'm just going to extend these out pretty much all the way to the end and let me go grab my over arm support again before I put it on there I want to wipe these down make sure they're good and clean put that right on the end and I'm going to go ahead and tighten this nut up right here now one thing I have found is as far as getting this on to your running bushing if you try to slide it up on all three pieces on the over arm supports and on the running bushing all at the same time it's hard to get everything lined up just right but when you tighten this down this should be exactly at the right height to fit on the bushing so now I'm just going to pull this back over the running bushing and see it just went right on but I'm going to call that up real good first make sure I got plenty of oil in this running bushing to start with and there we go next thing we'll do is we're going to tighten up the over arms there's a two bolts up on the top here yet we'll tighten these up and make them rigid as we can get them my next step here is I need to get my cutter centered exactly over the center of this part and to do that what I'm going to do is I've come in here and I've got a machinist square just running right up to on the edge of this part I had to go put a 1-2-3 block under here because this is a five and a half inch machining square and I really needed about an eighth inch or at least a six and a half inch so anyway maybe I need to find me a bigger machinist square no big deal but I want to do is I'm going to come in here with the cross feet now and I'm going to pull this over until that square just touches right there and to help with this you can take and shine a light behind this and I'm gonna get in the way of the camera with the light because my arm anyway you can see that but you want to get it right up onto the against the side right there so I've set my dial indicator up on 0 where we were on the other side I've moved my scale around to the other side of the cutter now and what we're going to do is we're just going to move everything over and keep track of how far we've moved it to get everything to touch on the side so less 100 200 300 400 500 600 we are touching right there I'm 655 thousands all right now to find center I take that 655 thousands I divide that in half got my calculator here it comes out of three two seven five so I'm going to rezero this out right here and make sure I got a good zero there we go one two three hundred fifty sixty seventy no excuse me 320 so 320 five six seven and a half right there so now I'm going to lock this table down right there where it needs to be and the cutter should be running right on center so we're getting ready to start cutting here but before we do we need to we need to touch off so we can get our depth so I'm just going to raise the table up until that cutter is just touching and I will just ease into it and that's yeah vn all right we're just touching right there I see a little mark on there and that's going to be zero we're ready to dial in our depth of cut and according to my calculations that I had done before on my printout for this gear that we're cutting 16 teeth I'm double checking on my mark they're 12 a number of teeth 16 pitch I need to go a total of 137 thousands but I'm going to purposely go a little shy on the first cut because I want to get some measurements and verify everything so I think what I'm going to do is right now we're going to going to go a hundred thousandths on this first cut pass and then I can come in here after I've done my first round make some measurements and make sure where we need to be so we're right here on the verge of making our first cut what we do there's a couple quick things I want to mention about the dividing head so number one when you're cutting this or when you're turning this you always want to turn it in the same direction it doesn't matter if you're going left or right as long as you always go in the same direction there's a certain amount of backlash in the gears in this thing so if you have to go forward and back up and then go back you need to make sure you take that backlash out so you know go forward you have to back up back up where you can feel everything moving go past the point of backlash again and come back until you feel tension and then go into the pin that you want to go into as long as you take that backlash out you're fine the other thing is is you can't see it but on the backside of this a dividing head there is a lot that locks the everything in place so every time you get it set you want to lock it and that will take also take any backlash out from in this to keep it from turning ever so slightly while you're cutting so we're ready for our first cut a little bit about my feeds you know I can calculate what the feeds need to be using that calculator that I have but quite honestly feed is something that I just get a feel for so I'm going to start out in the low speed which is a half-inch per minute and will probably ease that up that will probably be too slow but I probably won't go more than about an inch inch and three-eighths 3/4 3/4 per minute somewhere along in there but we'll play with it and get it to where I feel like it's sounds right and then we'll get we'll leave it on that that feed right all right let's let er roll Tina's own a little bit all in there and is starting to cut I'll take my feet up to five eighths per inch take it up to three quarters per inch one inch per minute Inchon 3/8 per minute inch and 3/4 per minute probably leave it there well let that cutter go until it's past the center hi this through cutting and back it out back over to the dividing head well we lease are spending a lot and we're going to go one two three and a third we're ready for our second cut let's lock that back down all right so now it's time to do some inspection we're going to actually remove the part from the mill and take it over do some measuring so now we're it's time to start doing some measurements and figure out where we are and there's several ways to measure gears but probably one of the best ways to do is to actually use a system called measuring over pins so and this is a diagram kind of showing that we have an even number of teeth you take a pin and you put in between the the two teeth and you actually make a measurement over those two pins and that will give you a measurement to shoot for and again if you look at Machinery's handbook there are all kinds of formulas and stuff to determine what you need to be what what size pin you need to use and what these measurements need to be and I have done the calculations and for this particular diametral pitch of 16 you should use a pen that's 105 thousandths and there's a formulator 1.68 type / p and i will say there's actually several charts there's several different pin sizes you can use and in the later versions of Machinery's handbook they actually have tables for multiple pin sizes in my older version the Machinery's handbook this is the only one they give is the one using the 1.68 / p and that's the one i'm using here but again you can use your Machinery's handbook and use the formula for whatever ratio you're working with so I've got my two gage pins here and these are both 105 thousands and I'll take one on the top on the bottom and we're using micrometer to measure across those distances and figure out where we are so I determined while I was playing around with this that I didn't have enough hands to do this job right so I have resorted to lightly clamping my micrometer and a vise here and I've got the two pins in across from one another and I'm going to come over here with my micrometer and we're going to get a measurement across those pins and we are measuring let's see me up so it's awkward with the not being able to get there I'm trying to stay out of the way the camera so it looks like we're measuring nine hundred and our point nine six zero and about three tenths so we got a point nine six two zero and three tenths I'm just going to work with the thousands right now I'm going to subtract from that what I was going for my target which is a point eight seven five over the wires so I've got about eighty five thousands total to go but I need to divide that by two because we're going to take it off of both sides so we need to move the move the MIL up forty two and a half thousand so we should be right on the money so we'll go over here and do just that let me unlock my table and we'll come up forty two and a half thousand it should be somewhere right along and there and when I locked it it moved it a little bit so let me back off alright that's plenty close enough right there I didn't really mention this when I took it off but notice I left the dog on here and that's real important when you take this out if you leave that on so that if you have to take it out of the mill for whatever reason you can put it back on the mill and get everything index back up right where it was before and that's exactly what we're going to do here we'll tighten the tail stock back up and we'll tighten this back up and now we should be cutting back in those exact same grooves that we cut the first round with and we got our depth set to the proper depth now for finish cut so we'll knock these out took our pins back in here and come in and make a measurement right there and that's right on 875 which is right on the money that's perfect very happy with that hi guys one down a bunch more to go so I think you've seen the process I will probably cut at least the rest of these little pinion gears off-camera bring you back to the end and we'll show you a few things on cutting the bigger years when we get to those just finished up cutting last of these pinions and these are all done now I thought I'd give you guys a quick peek as to what they look like I've done some measuring everything seems to measure up alright on these very happy with how it's turned out so we're going to move on and we'll probably start next getting the the big ears cut and I got a little bit of stuff to get ready for that probably going to do that in a standalone another video just simply because I'm not quite ready to get started on that yet and we're going to probably and get this one pushed up so we will be back soon and show you those other gears being made

Channel: Keith Rucker - VintageMachinery.org

Views: 520,218

Rating: 4.8790321 out of 5

Keywords: Machine Shop, Machinist, Gear Cutting, Gear, Dividing Head, Horizontal Mill, Milling Machine, Kearney, Trecker, Milling (Product Category), Steel, restoration, Vintage Machinery, mrpete222, Mr. Pete, Tublican, Keith Fenner, Turn wright, Adam Booth, Abom79, Tom Lipton, Ox Tools, oxtoolco, myfordboy, Jody Collier, weldingtipsandtricks, Welding Tips and Tricks

Id: 9Dl5J9b8GBw

Length: 42min 33sec (2553 seconds)

Published: Fri Jul 10 2015