I agree with Derek on using temp axes, but depending on your design intent, locating the helix along the shaft can also be done using a distance mate off the shaft end.
Or coincident between the shaft end and the outer vertex of the helix profile.
If you need to index the start of the helix to the "handle" portion of the shaft, try an angle/perpendicular/parallel mate between the helix profile face and a plane created by the temp axes of the two short cylinders on the handle (if they're not already on a plane, if so, use that plane).
Use the Sketch that you used to create the auger flighting, select the sketch circle and make it concentric with the shaft, then use a end vertex for your distance from the end of the shaft
You could also go to 'View' turn on 'Temporary Axis' and set the temporary axes to get the Concentric mate and use a plane perpendicular to the shaft to locate the screw along the shaft.
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