As Parts Officer of the S Scale Model Railway Society, I've run into a problem with obtaining reliable supplies of wheels from our suppliers. The problem will most likely be exacerbated fairly soon since we have commissioned masters for several wagon bodies for resin casting. I've got plenty of split spoke wheels but the wagon prototypes will be Groupling era, so solid spoke wheels and three hole disk wheels will be required, and I am pretty well out of them. So I could have the embarrassment of having new wagon bodies available with all the bits to go with them - except for the wheels. With my recent messing around with the 3D resin printer and printing parts for the 1:32 scale loco directly on the base plate, I found that parts were coming out quite accurate and square. I had also seen other people using resin printer for wheels centres. So I decided to have a go at some wheel centres to see how I got on. I had a small stock of turned tyres which had been produced some years ago when the Parts Officer of the day also started investigating DIY methods. I also found out that the 2mm Society made up their wheel sets and I had an excellent exchange of information with their Parts Officer about how they did it. But their turnover in parts is way more than the SSMRS and their use of moulded plastic centres ordered in thousands could not be justified for us who think in tens and occasionally hundreds. Another test run of the three hole disc centres just after the printing has finished and they are still on the base plate. This is version "L" to give some idea of the fiddling about that has been going on. Printing straight onto the plate avoids using the normal thick base raft and supports for parts so a lot of resin is saved and the time to print is much lesss than if rafts and supports are used. The Stanley blade is the best tool for getting them off the plate. This is the image from Fusion 360 for the disc wheel. I wanted to glue the centres into the tyres with cyanoacrylate glue so there has been a fair bit of experimentation with allowing clearance for the glue yet still allow accurate location. I found that if the centre fitted too well in the tyre, there was insufficient gap for the glue. If I reduced the diameter to provide sufficient clearance around the rim then there would have been play which could have meant loss of concentricity. So the above design is used where there are four spacers around the centre to fit well in the tyre and the reduced diameter of the main body provides clearance for the glue. There has been a fair amount of experimentation until I got the diameters which seemed to work. Here are the centres with a couple of the steel tyres. The cocktail stick is the best tool to hold them. The small blobs of glue have been placed on the edge of the centre. I'm still trying to acquire the light touch to get small blobs - the one on the top is a bit large. Six wheels with the centres inserted. The cyanoacrylate takes about fifteen seconds to set so there is a bit of time to make sure that the centre is seated properly. The wheel is then held in the lathe and the axle hole is opened out with the taper end of a 2mm diameter hand reamer. The brass collar sets the depth so that the taper hole provide a good press fit. The next process is to fit the axles and they are pressed into the wheel using the lathe at the moment to make sure that they are fitted square. The second wheel is fitted to the axle and the axle is pressed in until the back-to-back fits a gauge. Two axles finished on the back-to-back gauge. Finished disk and solid spoke wheel sets with more trial wheels. The next test I have to do is set up a small rig to check the concentricity of the wheels. I'm hoping that the wheels can be put together using a bench drill for reaming the axle holes and press fitting the axles. I've use my lathe for this purpose primarily to get the axles pressed in square. But the 2mm reamer can not guarantee that the axle hole will be concentric since it is flexible enough to follow an off centre hole. So I'm hoping that the 3D printed centres will be accurate enough to be assembled concentric in a drill press with no need for special attention to the axle hole. If this is not possible then I will print the centres with no axle hole and use a setup in the lathe to drill and ream the axle holes. Jim.