Machining a Large Flat Belt Pulley with my Antique Lathe

Everyone, Alec here. Today I'm doing some machining on the old Victorian lathe built in the mid 1890s. I've got this large pulley in here which needs to be bored out three inches for a customer's line shaft. It's currently sat between centres so that I can test whether it's running through or not. It's a wrought iron rim pulley built around the cast iron hut. Very common at the end of the but I've been tweaking it here and there just to try and get it as close as I can and it's looking pretty good at the moment. So the next job is to get it mounted up on the lathe and see if we can open the bore up from two and a quarter inches out to the needed three inch. So this is a split pulley which as the name suggests it's made of two halves which makes it very easy to clamp onto existing shafting. It does mean that when we do the bore we need to make sure that there's clearance between the two halves. I'm going to achieve that by knocking in some washers just to make sure there's clamping clearance. There we go. Now we can tighten these up. It always needs a bit of fettling to get these to clamp up perfectly. You don't want to put the bore through wonky and then it won't clamp up nice. I've clamped the rim together with these bolts here and they're going to stay put and I'm just shifting the hub about. So I've got a central line here which is machined as a reference for when these holes are bored. So I'm making sure they line up properly and also this outside the hub is machined as well so I want that to try and be as consistent as I can. It's just a case of pushing down on one side and then tightening it up. It can be a bit awkward. So the general setup plan is I made this collar up and this is larger than three inches so this is going to go on the back side of the hub there and this side of the hub is machined for reference so we're going to use that side and then the face plate goes on that like so and then I'm going to line my slots up. We need to cut and drill some straps which will go across the spokes and then come through and then bolt in in several places in the face plate with some long old studs. The purpose of this collar is just to stand off the pulley from the face of the face plate and give me clearance for my boring bar tube. So we haven't got far to go really. I've been assuming it's two and a quarter but I can't actually remember. Yeah it's just over two and a half. All right yeah there's only a little bit to come out. So regular viewers might be wondering why I'm not using a crane that I just spent ages making and the truth is that it's not big enough. As in I don't have the daylight to lift a pulley this large in diameter so I have to do it the old way using wooden chocks from the bottom of the gap and then eyeballing it basically until I can get it hanging on the spindle. So I can't get the height right doing it this way but I can get the sideways alignment correct. So tightening these two hopefully I can then take the weight of the pulley on the lathe and then I can rotate it and it'll act like a cam lock and release the block. Then I can use more studs and gravity to bring it into alignment hopefully. The pulley's got on the machine a lot easier than I anticipated it would and it's not far off concentric but obviously from this angle you can see it's definitely not true this way. I'm just going to adjust the studs accordingly and see if we can get it to run a little bit nicer. Give it another spin. So we've probably got a 32nd of an inch out in that direction so that's that's good enough I think for one of these. As I said before the rim and the surface of them aren't even machined they're just rolled plate so that might just be the tolerance in the plate but we've just got to get it as good as we can. Check on the inside of the rim here. I'm just going around making sure everything's nice and tight. I'm happy with it. Concentricity wise I certainly have wobblier pulleys on my line shaft let's put it that way. So I'm using the back gears to get the speed down and it means we've got to do a bit of extra lubrication so the cone pulley spins around the spindle freely in back gears so there's three oil holes there those two are missing their grubs but this one still has it so we'll put it back and then there's a grub in the back gear itself one each end again this one has a grub in it drop oil in there drop oil in there and put some in the spindle oilers get them going engage the back gears and also the tumble reverse so we've got some power feed come on and then a few more oil points on those so these gears are driving our back shaft which is setting our feed rate so we might have to come back and revisit those I expect that probably be too slow down in back gears you need more of a one-to-one ratio the feed rate is proportional to the spindle speed so when the spindle speeds are down low like this you you need a heavier feed to keep up so I'm going to stop right there because that tool is clearly not having a good time this is not rigid enough I had an inkling that this wasn't going to be enough but I was really hoping that I would be able to get away with it I don't do this size work very often I was hoping to get away with not having to make a much bigger boring bar but the with the uninterrupted cut on the the split hub it just wasn't happy it's not going to happen so I made this beast I've also fiddled around with the change gears at the back to increase the speed slightly so with that change and new much more rigid boring bar which hopefully isn't going to bounce around I'm going to get this in the lathe now and we can finish the bore so we're getting very close now I think we're about 30,000 top so I'm going to dial in 15 and do a final pass so that was the last pass I'm going to come in and measure this now the shaft is three inches so we want to be slightly more than that I was shooting for a shade over three inch and five thou so see how we did 10 thou over that's all right not perfect but it's all right it'll clamp up nice and drive well with the key on the last thing we want with these split halves of them to be too small and they don't seat well on this shaft so the shade over is absolutely fine there we go that was boring out an old pulley on the old lathe the next job is to replace these shiny box with some nice old countersunk ones they will be made in-house and then this pulley is ready to go straight to work