Originally Posted by St. Martin
I agree, Mark.
All my 3.17 stock adapters have been a easy slip-on, or sloppy fit. This is probably the reason for running un-true. I'm used to the WeMo adapters that had to be heated with a match or lighter, to get them on the motor shaft. The adapters I got from you were not that tight, but a very snug fit, on the HET shafts and the Mega's.
A possible reason for them going to 4 set screws? Interestingly, I have a few HK in runners, that will not accept a 3.17 adapter. Only the adapter that came with the fan. More of a 3.2 hole. Possibly, they don't know the diff between the two sizes, and they are using the wrong drill for the 3.17 adapters?
Yup, 3.17 four screw adapters are crap, and you will be lucky if you can make 'em run true. The idea there is some super secret offset drill process that purposely moves the bore off the centerline is just laughable on it's face, both on technical grounds, and also since this is obviously such a cheapo Chinese mass produced piece anyway.