Alden really did tell me very emphaticly, several times that whorls, flyer and bobbin should be have "board cut grain". That did not stop him from making spindle turned bobbins as in
where he supplied me with bobbins with board cut grain and that were spindle turned.
Thus, since then, I ( mostly) made my spinning bobbins form glued up blanks so that the ends of the bobbins (the whorls) had board cut end grain.
This summer, I did some spinning on the patio, and noticed that over a period of weeks, the spinning bobbin which had been turned from old red oak salvaged from a kitchen remodel, had warped! I never had any problems with Alden's, or Ashford's board cut grain bobbin whorl's warping when I used them for spinning on the patio. I expect that I could have prevented the problem with a different finish. (The red oak had a Danish Oil finish.) (Also thicker whorls tend warp less.) (Also, black walnut tends to be more dimensionally stable than the red oak. )
This was not the first time that whorls had warped on me, but this time, I took action.
The new spinning bobbin for the AA#1 flier was spindle turned from a solid block of olive wood.
The bobbin above the flier is the oak bobbin that warped, The bobbin in the flyer is one turned in a few minutes. No making the parts, and gluing up a blank. Certainly it is too wasteful of wood for a commercial operation, but it can be done quickly, without planning. It good for repairs where a fast fix is needed. It is just a matter of having a big (2.5" x 2.5"x 4.2"), dry, block of wood around.
In the sun for a while, the diameter of the spindle turned whorls will change. For single drive, or DD with slippage that does not matter. For DRS, inserted twist can be adjusted by changing the flyer whorl. I have a graduated set of flyer whorls, so likewise change in bobbin whorl diameter is not a big problem. Nevertheless, the groove in this whorl is a little different than that of the old red oak whorl, and it took about 3 hours to get the new olive bobbin spinning 63 m/gram from fine long wool at about 200 m/hr (3+ gr/hr).
It works well, but it sure sounds like an old industrial sewing machine.