Wednesday, February 19, 2014

I was wrong

About the increase in speed resulting from putting ball bearings on the AA #1 flier.

I expected, perhaps a 10% increase in speed.  Actual increase in speed was closer to 25%.
That includes changes in geometry to the Mother of All, changes to maidens to increase vibration damping, but still it made the effort worth while.  Really worth while. The cost was almost nothing - (new) bearings left over from other projects, bits of scrap wood, a couple of nights thinking about it, and a day in the shop, doing it.

When I first measured the bobbin speed, it was only 1600 rpm, and I could not understand it, and it took 5 minutes to remember that I had changed the geometry, thereby changing the drive tension, thereby allowing drive belt slip - you cannot see drive belt slip - that is why I have a tachometer.  I increased drivebelt tension and I had the 2,600 rpm that I had expected.  However, with some tweaking and run in, rpm drifted up to 3,000.  The bearing must have needed a bit of run-in, or maybe it is taking a while for the Royal Purple to penetrate into the sealed bearings.

The bottom line is that the working speed of this flier/bobbin assembly has gone from 2,200 rpm to 2,800 rpm without changing either the ratio or the DRS.

If you are buying a wheel, you need to ask your wheel maker some intelligent questions. 

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