Making a steering wheel mould for the miniature traction engine. Now I have a DRO on the Sieg SX2.7 I have the ability to mill to a high accuracy. But is this good enough to enable me to make a mould. In particular a metal mould. One thing to point out is that the overall diameter of this steering wheel is just 22mm.
I started by machining the blanks, not sure this is the best way round. With hindsight I would now machine the spigot in the centre of the wheel in each face and then use this to align the two parts of the mould.
However, I bolted the two pieces together with M3 bolts and then machined the faces all square. This means I can clamp these faces as I tighten the bolts and get the two halves accurately aligned.
I then laid the two halves side by side and accurately found the centre with the DRO. This then became my new reference. I made the machining slightly easier as the spokes are machined into just one half.
Testing the Mould
The first trial casting with machining wax. This doesn’t look bad for a first trial. The headers are a tad thin and the wheel spokes are too thin.
The central boss is not taking at all. Again for me this hits that the spokes are too thin and the wax is too viscous.
I heated the mould up before pouring the wax in and I pre-coated the inside of the mould with a wax spray polish.
This shows me that the steering wheel mould has been machined accurately. A great showcase for the Machine DRO install on the Sieg SX2.7 milling machine.
Not giving up, so I tried a different approach.
I pre-filled each half of the mould with wax. I then scraped the excess wax away and bolted the two halves together.
The mould was then heated with an open flame. The result was actually worse than the first go.
Conclusion
This mould has worked out reasonable for a first trial, however, a few improvements are required:
- Another runner needs adding as well as making existing ones larger.
- Release angles need looking at for the boss.
- Better temperature control required for the wax.
- Not sure this mould would work with a brass pour.
This might work well for casting accurate wax parts that can then be used for lost wax casting. Now there’s a thought.