Friday, August 3, 2018

Axle Hole

Having separated all four wheels for Ivor from the sprue they were attached to during printing the first step is to drill out the central hole to take the axle. Normally if I was trying to make a hole to fit an axle I'd drill it slightly undersize and then open it out slowly with a reamer to get a tight push fit. In this case though I'm going to turn the axle as well, so I can make the axle fit the hole. This means I can use a cheap drill to make the hole and not have to worry about buying an expensive reamer. That isn't to say this step doesn't include expensive tools as not only did I do the drilling using my lathe but I bought a set of step chucks specifically for the task.

Specifically I bought the 20.00mm to 24.50mm step chucks from fohrmann-WERKZEUGE. As you can see these allow me to hold the wheel (or any other appropriately sized cylindrical object) in the lathe for accurate centre drilling. In this case I've used them to widen out the axle hole to 2mm in each of the four wheels.

Visually the wheels all look good and the hole appears to be nice and central so hopefully that's the first step successfully achieved, and now they all have an identical sized axle hole I should be able to mount each in turn in the same position in the lathe which should make turning the flanges on each in turn a little easier.


  1. I can't help think that casting the axle and crankpin holes into the wheel was a mistake. If the cast hole is slightly out then it could cause the drill to wander. Hopefully I'll be proved wrong, especially as I might be after a set for myself if possible!

    1. In retrospect you are probably right. The axle hole could have been drilled without the small pilot hole in the casting, and the the crankpin hole drilled at the right distance using a sensible spacer piece slotted over the axle, or just some sensible measuring. Fortunately updating the 3D model to remove the holes would only take a second. I'll drop you an e-mail about a set as I'm not sure which profile you'd want for EM.