Improving the Burrell Engine Flywheel from the original heavy design to a thinner elegant long spoked thin rim to match the 1890 drawing. I roughed out a flywheel yesterday, but then Steve (SGSengineering) rightly commented that the rim was heavy. So back to the workshop after some pondering of the design and options I had to improve it.
Lighter Flywheel Rim
In the previous post I machined the flywheel. However, Steve’s comment on the weight of the rim, along with a drawing of another traction engine flywheel for reference, made me think again. This made me realise the flywheel did look too heavy. Also, the drawing showed the section of the flywheel and it had a subtle chamfer on the inner edge of the rim. A way to make it look thinner, but at the same time keep some of the weight.
I pondered the design over night, looking at images of different Burrell traction engines to get some ideas,
The flywheel goes back into the Warco lathe. The new Soba 3 jaw chuck is running very true and so an easy setup.
I machined the rim down to a thickness of 3.5mm and then added a chamfer at 20°. The image shows the tool angled over and creating the chamfer.
Post lathe work, thinner rim and chamfer machined. Re-aligning the flywheel on the rotary table. Machining the rim again with an end mill. The roughed out lighter flywheel.
Smooth Spokes
The flywheel process beginning to end is shown in this short video.
A close up of the flywheel shows the profile of the rim. This chamfer creates a thinner look.
The spokes are now rounded and transition smoothly from hub to rim. This was done using my hand belt sanding (shown in the video). Lots of care needed to repeat the sanding multiple times on all of the spokes to get a consistent finish. What I’m saying is don’t rush this stage.
This flywheel is quite small with a diameter of 72mm and thickness of 9mm.
I was concerned that in thinning the rim down I would reduce the rotational inertia too much. This will give me problems with low speed running of the steam engine. However, I will have to test and try to establish if it is ok.
I finally had to pose the flywheel and tender together. Still lots to do though on this 1/20th scale Burrell traction engine.