Thursday, August 2, 2018

Stepped Axles

Having assembled the basic chassis the next step is to figure out the wheels. Unfortunately as the prototype is a cartoon character there aren't any wheel sets I can just buy off the shelf. The only suggestion in the instructions is to use "Ultrascale or Markits 5'3" 16 spoke wheels with 8 spokes removed". Having looked at both of these options I wasn't happy with either, as even with the extra spokes removed I didn't think they really matched up with those you see in the cartoons. In the end the only thing I could think of was to make my own wheels. Clearly this isn't going to be a quick and simple process so it's likely to go on for quit a few posts as I detail the different steps and experiments. In this post I'm going to concentrate on the axles.

As I mentioned previously the kit is designed for use with axles with a diameter of 1/8". The wheels on Ivor don't have a huge central boss, and certainly not something big enough to accommodate a 1/8" (or bigger for an insulating bush) hole so my plan is to use stepped axles. Most wheels seems to use steel for axles so I've bought some 1/8" diameter silver steel rod (from Eileens Emporium) but having never tried to turn anything other than soft brass rod (CZ121 brass to be precise) I had no idea how well this would work.


For a quick experiment I've turned down a short length of the silver steel rod to take one of the OO gauge wheels I used to build the Clayton. These wheels fitted on a 2mm axle so I had to remove roughly 1.25mm from the diameter of the rod. I actually found machining the silver steel possibly easier than brass and the turnings come off as long thing ribbons rather than lots of dust. All told (including setting up the lathe) this took about 10 minutes. Now obviously machining steps on both ends of an axle and getting the back-to-back correct is going to be more time consuming but at least now I know I can work with the materials I've got, and I've 26" of rod (minus the short test piece) to play with and I only need two short (approximately 19mm) axles.
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3 comments:

  1. Adrian WardAugust 2, 2018 at 11:52 AM

    Excellent. Have you got collets for the lathe? My work flow would be have a little bit of the bar stock sticking out. Face and chamfer it then centre drill. Pull out the full axle length plus a bit and reduce one end with a tailstock centre in. I would mark up first with a felt tip pen.Part off then reverse the job and repeat to finish. If you get tool chatter you will have to face and centre this end as well. A dab of cutting fluid usually improves things no end. If you are fitting the parts then finish with emery tape. Use either a tiny bit or a long length that you can let go of if it grabs.

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    1. MarkAugust 2, 2018 at 11:59 AM

      Yes, I've got a set of cheap, but accurate seeming, ER16 collets (have a look at this post for a photo) which I used to hold the bar stock. I think I can probably get away with just a short piece sticking out from the collet so I can probably get away without the need for the tailstock centre to keep it stable, so yes I think markup the rod, turn and face one end, then switch it around and do the other end will be the plan, but we'll see how well it goes when I try and do a complete axle.

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    2. Adrian WardAugust 2, 2018 at 12:13 PM

      I don't know whether you are awareof them but we got some stuff...carbide tooling from Banggood
      It is reasonable quality and very cheap. Never tried it in the CNCs but it is fine for normal turning.

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