Making a Mandrel and Turning Between Centers

we're ready to start making the uh Mandel now that will turn this uh on the reason I wanted to put on a Mandel and turn it between centers is is that way we'll be turning the outside diameter of the pulley on exactly the same um axis that the pulley will be turning on on a shaft so basically we're going to make a little small shaft to mount it on we'll put it between centers on the lathe and uh you can take it from one machine to another and it will always run exactly true uh and because we are going to have to take this to another machine to actually do the profile um that's going to be very important that we be able to do that so I've just got a piece of uh inch and a half stock uh in the lathe right now just a piece of scrap we have laying around the Sha uh shop here and um we're just going to face off each end I'm going to actually turn one diameter down just a little bit below because that would be the side that the dog goes on uh for turning between Center and uh that'll just give a little bit the grip on without actually messing up Maring the surface of the shaft we riding on and uh then we'll put a keyway slot in here uh so it will turn and and uh pretty much the man will be done so let's get to work we're ready now to set the machine up to perm between centers and uh to do this you basically need what's called a dead center on the drive side on the ch stuck side here and then of course a live Center on the other and we will put the piece of stock between those now uh most laes actually have a uh Center kind of like this that will actually fit up into the it's on a taper it will actually jam up into the headstock you take the Chuck off and it'll go right up in there or it can even fit up inside the Chuck and there's nothing wrong with using one of these uh the problem that I always run into is driving the dog uh when you do that it's a lot easier to drive the dog with the Chuck actually on the LA so instead of using a just a standard uh uh dead center what I will often do or what I I do on this La is I actually just got a little short piece of metal and I just turn one and I'll just Chuck it in the Tre JW Chuck now the secret here though is is that U because every time you Chuck something on a three go Chuck it doesn't always turn true instead of sitting here trying to line it up with the dial indicator or something like that I just put a fresh cut on it right before I start turning so I have my compound set to 60° and uh we're just going to put a real light cut on here clean this up in any uh slight variances that was in the from the last cut we'll just take it right out and I just throw it up here above the lathe in my box and it's there uh for the next time I get ready to use it so we'll freshen this uh this 60° angle up make it true to the being chucked in the Lathe for right now we'll be ready to go we've got the uh blank nandel here that we uh set up before I have a uh center drill in one side a center drill in the other side I did turn one side down just a little bit below the final diameter and that's just a place for me to mount my dog and if you look I also took it over to Mill to the mill and just m a little flat there for that to clamp down on uh that's not necessary but uh I just like that it's a nice little touch to make uh make turning these things just a little bit easier so this is now ready to mount between centers so we just going to put it in lath put that on the dead center we'll tighten up the live Center on the other end and voila it is set up between centers now you may ask why do I want to do it this way rather than just putting the Mandel in the Chuck and and having the live Center on the other end and the reason is is repeatability and being able to take it from one machine to another um as you know again with the three jaw Chuck or uh you can never really get it in there exactly the same every time you remove it from the Chuck it's just always off a little bit and even the best chuck with hardly any run out at all is going to have probably just a tiny amount of run out in it still and this Chuck on this lathe uh has has got a more run out than I really like but you know if you're if you're turning a piece one time it's only going to get Chuck one time a Chuck is a great thing but uh in this case you know we want to have a man that we can take it off of this La we got to put it on another La later on and uh we won't be turning exactly true so turning between centers is really the way to do this back uh many many years ago back in the old days uh before they had things like real good Chucks uh turning between centers was a very common way of of doing most work on La and also was used a lot in U uh production work uh up until really uh we we've gotten better Chucks and and CNC machinery now has really replaced a lot of that if you think about it uh back a long time ago if you were making a complex part uh often time it was easier to set up different parts of that production run on different machines rather than doing it all on one machine so you may have one machine that all that does is is turn the uh um the the shaft diameter another machine set up to to do another operation and so on and so on and so on even on a turret La you're you're limited by the number of operations that you can do at one time so uh it was very common uh on shafts and so forth like that to to have to take it from one machine to the other and it was very important that when you took it from one machine to another repeatability so again because we're going to send this out to another shop and have them do it we'll send the mandrel along with it and uh uh it'll come back and it'll be turning perfectly true on that Mandel so now uh basically all we have to do is just turn the final diameter down here uh to the diameter we need 1.4375 and uh then we'll pretty much be ready to go just have to cut a keyway and uh we'll be ready to mount these uh uh pulley on the mandrel so here we go all right we have our mantle now uh turned uh it's ready to go uh test f looks pretty good so we'll just cut a keyway in here and be ready to send off we've got this U Mandel Now set up in the uh Vertical Mill to cut the keyway or for the key stock that will then uh engage the pulley as we're turning it between centers so basically what we're going to do here is we're just going to find the center uh of the of the shaft uh I just do that by going down and millon and just kind of eyeballing it and'll get it pretty much right on every time alternatively I could use a u edge finder and use my digital readout do that but I find that uh this method is just a little bit quicker and works just as well um from there um we'll go half the the depth of the key stock so it's 38 in we'll go 316 C deep actually I'm going to go just a little deeper than that um it's probably about 200,000 deep and that'll give me just a little bit of clearance on the top uh so that it doesn't get too tight and uh we'll have a set screw in the pulley to tighten it down on there so here we [Music] go get have the key in here now I just took a piece of key stock and grounded it down and and uh made it fit down in there and we just uh put the arbor press and pushed it in there good and tight and we get a good tight fit and uh test fit on the uh on the pulley uh they are a little tight going in but they do go in without any problem so I think we're good to go uh we have the Mandel pretty much complete now uh Next Step will be for us to uh drill a drill and tap a hole in the pulley uh that would be a set screw to tighten up on this uh to make sure that that pulley does not go up and down on the shaft we're ready to go ahead and tap the hole that we drilled in the pulley I've got it set up on the on the midle machine again uh using that same setup we use the drill with so that the uh the hole will be lined up and what I've got in here is a little spring loaded um punch looking device but what it does is it just it it engages in the top of your of your uh tap wrench here and it keeps that tap running perfectly straight up and down with the hole that was boarded or drilled out so uh it just helps get get that hole started and help get it started straight so it's a nice little uh um nice little tool to to help with tapping Hol so any we're going to start tapping this we're tapping at 3816 uh which is the same uh uh the diameter of the hole will be the same as the thickness of your key stock so it should engage it uh very well when we get down the hole so put a little bit of tapping fluid on here I'm just going to use this to get started I'm going to probably switch over to a tap wrench that has a little bit bigger handle on it to give me a little bit more leverage but we'll use this to get started [Music] with all right I'm feeling a little tension there so the tap is actually just starting to touch the tap so I'm just going to slide this out um where that tap can still go all the way through that hole put on the shaft there there we go I I'll get it down and that way we can get that hole tap all the way through good clean all right I have the pulley mounted between centers now uh this is basically how we do the first thing I'm going to do or the really the only thing left to do this pulley before I send it off to get the actual uh face machine is I want to go ahead and clean up this one side right here and I'll just be one less thing that'll have to be done by some other shop so I've got this mounted on here um this flange is actually at a little bit of an angle going in and that's just because the way the pattern had to be made to be able to extract the pattern from the mold so uh there is a uh probably 1 to 2° angle on here so it's basically thicker at the bottom is the top we want to clean that up and make it flat uh all the way down so we're going to go ahead and do this I may get into the shaft just a little bit right down here I don't think that's going to be an issue because that's really not the part of the shaft that is going to be bearing so and and this is more or less a sacrificial um uh Arbor that I'm I'm turning on so even if I do get down into that a little bit it's not going to affect us being able to use it down the road this is AR will be just used to this one job and that'll be it so here we [Music] go w we're through this job now is ready to send off to have the actual face of the pulley machine um as you can see we bored and and um roached out the the keyways on both of the pulley uh finish the inside uh of the the flange on the on each of the pulley and then also finish the outside of the out side flange on the pulley so now really the only thing that's left is to actually turn the face and as you can see we've also have the mandrel the custom mandrel made uh that will go with these parts wherever we send them to to get a machine to be able to turn these on Center and uh have good pulley when we get them back so uh I'm going to be investigating now where I can actually send these off to get them uh machined talking to some different shops to see what we can work out and like I said hopefully we'll be able to get some video of showing that process as well

Channel: Keith Rucker - VintageMachinery.org

Views: 134,906

Keywords: Turning, Mandrel, Betwen Centers, J. A. Vance, Georgia Museum of Agriculture, Machining, Lathe, Machine Shop

Id: 3WLai2inSpM

Length: 18min 44sec (1124 seconds)

Published: Sat Jul 27 2013