Cast iron wheel spokes

[David Thompson]

I am building a 3.5" gauge "Marquess" by Martin Evans. I got the wheel castings from Reeves and I have turned all the drivers. I annealed them first in our solid fuel grate, to very little effect, and I grit blasted them at work with moderate effect, but I still have lots of hard knobbly bits on the spokes and a fair bit of uneven daylight between successive spokes. My files won't touch the hard bits, but I can Dremel them.

My question is, how far do folks go in smoothing off the spokes? I am afraid that any lumps and bumps will look awful under the paint but it is hard filthy work grinding them and a little slip with the tool can make a gash. I have found that once I get through the crust, I can file the iron (it turned beautifuly using WC tips).

I have to do some grinding anyway because a couple of the wheels have got a bit of the cast infill between the back of the spokes still showing as a ridge at the the rims.

Should I be aiming for a smooth bright finish round every spoke?

[baggo]

Hi David,

I had a similar problem with the loco that I am working on at the moment. The wheel castings were very poor and I had to spend hours cleaning them up. I started off with diamond burrs in a Dremel, but as you say, it's very easy to gouge a chunk out if you are not careful! I found that the bits tended to dig in and it was difficult to get a smooth finish. I eventually treated myself to a set of good quality diamond needle files and finished the job with those. As you've found out, the casting surface is like glass and ordinary files won't touch it. It is a dirty job and the dust gets everywhere! I did it a wheel at a time inbetween other jobs rather than tackle all of them (8) in one go

How far you go depends on how much of a perfectionist you are or if you want an exhibition quality finish. I just smoothed the sides of the spokes and inside the wheel rim to remove any lumps and flashing. Any holes can always be filled with P38 filler before you paint. Personally I'm more interested in having a loco that looks ok and runs well rather than a gold medal winner.

The quality of the castings available nowadays does seem to vary a lot. I've got a set of wheel castings for a 5" Black 5 ( original Don Young ) and they are superb and will take very little cleaning up. I also picked up a set of original Dave Goodwin wheel castings the same as the modern version I'm using on the present loco and the Goodwin castings are far better quality. It's a pity I didn't get those first!

John

[David Thompson]

Hi John,

Thanks for that suggestion and the moral support. It's good to know I am not the only one. Diamond needle files sound like a really good idea. I agree that working well is more important than looking good, but I don't want people pursing their lips and shaking their heads after I've spent ten years working on it.

Today I started turning the pony truck wheels and they are a much better pair of castings, also from Reeves. They run true in the three-jaw and the spokes are much smoother and come with gaps already between them.

[ivanj]

I have just completed a set of wheels for a King. The castings were OK but rough. I machined them all over using a rotary table - it is a lot of operations and takes a long time but it gives a good base for shaping the spokes. I then worked on each spoke with a file and a high speed burr, finishing with emery strip. I can say the the results are worth it especially as the wheels are one of the defining features of any engine. To finish I sprayed them with matt black plasticized paint from Wilco which does a fantastic job.

It really does depend on how much time you are prepared to invest.