The valve spring retainers are referred to as “top washers” in Velo-speak. Although they are available off-the-shelf in steel I decided that I would make a pair of lightweight items in titanium for this project. There is plenty already written about titanium vs steel and I won’t repeat any of that here. Rather, I will just note a couple of points from my own experience.
Firstly, titanium must be machined with sharp tools, ideally new carbide tips or, if drilling, a sharp carbide or HSS drill. If a sharp tool is not used then the surface of the material work hardens and it can be difficult to restart the machining operation.
Secondly, the swarf can catch fire! The short movie below shows a near-completed valve spring retainer being parted off from its parent bar and the heat generated by the parting tool ignites the thin ribbon of swarf.
In practice, this did not cause a problem but it’s good to be aware if it.
With a few scallops on the milling machine the final items turned out well.
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