Machining and Fitting a Brass Bushing to a Cast Iron Wheel

hello my name is bob and once again i'd like to welcome you to another episode on the white dog garage youtube channel this video is going to be another in my metal working videos it's going to be a machining video but a relatively simple one but you might find it interesting in america you might call this i think a heyman video here in australia it ends up more like mate can you do a little job for me anyhow what it's about is i have to machine some bushes for two little cast iron wheels now they've already got a bit of a bush in them and a bit of an axle but uh the client wants them to run a bit truer there are a number of ways of doing this and i'm going to show you what i did you could find a piece of pipe that fits it came with a piece of pipe that fits or you could machine the bush to go inside the hub and that's what we're going to do here now there are a number of ways of fixing that bush or you could let it run but this is cast iron and you don't necessarily want it to run because eventually it's going to wear so what i'm going to do is i'm going to put a brass bush in the center and i'm going to fix it in place with an interference fit that is the diameter of the bush is a little larger than the diameter of the hole it's going into there are other ways you could do this of course you can use a give key but cutting a keyway is more time than i want to take the other alternative is and fit what's called a scotch key the issue here is the scotch key is i just drilling a hole essentially and fixing a key in place around key but again that's a bit more work and i want to keep this pretty simple so i'm going for a straight bushing a press fit slight press fit because this is cast iron cast iron is good in compression that means take a lot of weight across the wheel but what it doesn't like is tension which would be a lot of pressure outwards it's going to be a good press fit 0.0508 millimeters two to three four over size to the shaft pressed into the center and then the axle hole or the hole for the axle drilled in the center of that again i hope you find it interesting and i hope you follow along i start by machining the wheel centre but first i wanted to check the run out i find it's not too bad considering that these are well used cheap cast iron wheels i used a small boring bar to machine the center i fitted this bar with a high speed steel bit which with the right speed will work fine for cast iron cast iron machines well but the swarf is difficult to clean out and can damage the lathe ways so i'm laying a cloth on the bed to catch the bulk of the turnings moving the boring bar up to the wheel center i wanted to remove the minimum amount of material to give a concentric hole to the wheel [Music] rim [Music] [Music] i'm trying to keep the amount of cast iron turnings lying around to a minimum so i'm regularly cleaning the tool off it takes more than one pass to machine the wheel centre to be perfectly round [Music] [Music] [Music] once i'm happy with the center of the wheel i move the boring bar back out of the way and then use the telescopic gauge and micrometer to determine its exact diameter i'm only showing one measurement here but i actually repeat the measurement a number of times and take the average although i'm not showing it here i'm doing two wheels so knowing the final position of the cross slide for the first one i then machine the second wheel center to the same dimension with the wheel centers done i then moved on to machining the two brass plugs that will be used to form the actual bushes i'm using a length of brass round for this and i start by using a center drill to form the mounting point for the live center that will support that end with the end supported by the live center i then machined the diameter of the bush to enable a press fit into the wheel center that is 0.05 to 0.08 millimeters or about 2 to 3 over size i use a rule to make sure the bush is long enough to stretch from one side of the wheel to the other and i stop a couple of times to make sure i'm on track to finish at the desired [Music] diameter before i remove it from the lathe i put a slight bevel on the machined end of the plug to act as a start point pressing at home although i could have parted off the plug on the lathe it is quicker and easier to do it on the bandsaw viewers will notice that i've left the lip on the bushing blank this both acts as a stop for the press and provides more surface adhesion when the plug is drilled out to take the new axle it will be machined off when the wheel is finished i am using a two ton arbor press to press the plug into the wheel center as mentioned previously cast iron does not deal well with tensile forces and the plug is essentially expanding the wheel center a beta to very small amount if i needed a heavier press to do this the interference fit would probably be too great and the wheel center would likely crack or shatter with the plug pressed home it is back to the lathe first i face off the plug-in flush with the front of the wheel hub so so then i swapped the wheel side and proceeded to drill out the center as i mentioned previously i've left the lip on the plug intact this was intentional to provide an additional contact surface for the plug to the wheel center preventing any rotational slippage as the hole is drilled to suit the new axle i start with the pilot hole and follow up with the drill to the final diameter the axle feeder is not that precise for this job so simply drilling out the center does the trick without having to resort to a reamer with the hub center drilled out i locked the saddle and manually fed the tool using the cross slide to face off this side of the wheel jesus the second wheel is an exact copy of the first and the two wheels were ready for their new life you

Channel: whitedoggarage

Views: 374

Rating: 5 out of 5

Keywords: techniques, videos, whitedoggarage, whitedogarage, homeshop, makeit, lathe, press, brass, machining, machinist, interference fit, press fit, cast iron, make it, making stuff, how to, maching cast iron, machining brass, machining and fitting a brass bushing to a cast iron wheel

Id: X21BFyRENEg

Length: 14min 21sec (861 seconds)

Published: Fri Oct 23 2020