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The paper insert lists the pilot hole as the precision hole which can be used to precisely drill the non-precision hole. Our preference is to use a tapered reamer from the front side of the prop to avoid contact with the precision hole entirely.
Unfortunately, we are forced to gate the material in through the center of all axis's which necessitates a second operation of drilling out the sprue. For this reason the precision locating rings were adopted for electric propeller production.
It is our experience that most of the time some customers fail to read the instructions for properly mounting the propellers.