All seemed well until I realized I had an interference with one of the knobs that hold both the stop and the rail to the fence. The four star knob would not allow my material to fit flush against the fence. It seems that Shopsmith had shipped my flip up stop with a different knob than is called out on the instruction sheet, knob 521622. The specified knob is a 1" round knob with a through hole that has a 5/16"-18tpi insert. What was shipped was a four star knob with a nominal diameter of 1-9/16". The following picture shows the difference between the correct knob (on the left, stolen from my fence mounted feather board) and the 'shipped' knob (two of which were included for the stop and the rail).
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As you can see, the star knob projects over the fence. There are obvious workarounds, and many folks probably will not be working with material this tall. However, if you received one of these stops in the past year or are ordering one under the current email special, you might want to check to see if they have 'fixed' the new knobs. These knobs could cause an interference on all fences (500 upgrade, 510, 520 and bandsaw) that have the t-slot.
Also note, that the original knobs are used on the utility light t-track mounting bracket and fence mounted feather boards. The original round knob part number, 521662, was removed from the website sometime after I contacted Shopsmith. Rockler sells an identical one to the round knob, Rocker item 34121, for $2.09 each.
Linda with Customer Service has been very helpful and conscientious on following up on this issue.
You still may want to check your fence mounted accessories as there still may be some bad apples, er knobs, in the bunch.
