Driver drawing

As I’m planning to print patterns for the wheels, I could no longer be satisfied with blank discs representing the wheels, even in OnShape.  They’re a bit of a challenging part to draw, but I think I’ve captured the look of this photo from the Parry Sound Public Library.  Possibly the hub is too small – what do you think?


To draw the model, I sketched the cross section (based on Fig 355 of Meyer, Modern Locomotive Construction), and rotated the spoke portion of the cross-section to form a flat cone.  Then I sketched the face of the wheel perpendicular to the cross-section, and used this sketch to cut the spaces between spokes.  The hub and counterweight were straightforward extrusions before rotating in the wheel rim and tyre.  Finally, I filleted the edges of the spokes and their connections to the rim.

I can’t wait to see how I solve the painting challenge on these wheels!  Good luck future-Rene!


5 thoughts on “Driver drawing

  1. Hi Rene,
    I find this very interesting and your 3D wheel model looks good…
    If I understand correctly, I think you will turn the metal rim/tire and resin cast the spokes. Sorry, if I have missed a posting, but have you considered making the whole wheel from sintered metal? Shapeways can provide a metal part in stainless steel (the sintered air spaces are infused with bronze, I think). Your wheel design could be made this way, leaving stock for reaming the axle bore and for turning the tread and flange. I believe that my early Broadway Limited Imports Hudson drivers are made this way (I see copper wearing through on the tread faces). I’m not sure how strong the Shapeways part would be, and I see they recommend a minimum wall of 1.00mm[.040″], so this may not be fine enough for your project. Also, the resulting surface finish looks a bit rough – perhaps some stoning/paper could correct this. Since you have the 3D model, would it be worth a try to have one wheel made?
    Best Wishes
    Rick (Fillmore)

    1. Hi Rick, I actually did start down the path of getting the whole wheel printed. I had one made up and Andrew even tried machining it for me. You have more or less identified exactly what we found: the minimum wall thickness is too thick and the surface finish is too poor. On the positive side, they machined okay. I’ll see if I can find the post about it and link it here; I’m sure I wrote one.

  2. Hi Rene,

    Looks like you’re making good progress here. I wish I had the time to acquaint myself with 3D drawing and printing. I’m sure there would be some advantages for my project, but the learning curve would be almost like a precipice!

    One thought though – I notice you’ve included the balance weight in the 3D drawing. Is this wise? A number of locos from the UK and Europe had balance weights of different sizes and in different positions on each of the drive axles. I can’t see from the photos whether this is the case on 622. If they are different, best to get these etched and apply them to the finished wheels later.



    1. Thanks Geraint.

      The balance weights look the same on both sets of drivers to me. As these were moderately fancy engines, it’s conceivable that they’re different thicknesses behind.

      With respect to learning CAD, don’t sell yourself short! Parametric CAD like OnShape was so different, it was like starting from scratch. Even so, I don’t think I spent more than a couple of hours watching tutorials before I started being productive.

      Give it a whirl!


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