Chuck

In my life I've purchased two brand new fixed pitch props. The first
was a replacement for an overhauled O-300D and the second for my
present 1975 172M when it was new. Both were made by McCauley, both
were out of balance when new, and both were made to run smooth by
Kenny Maxwell (a local prop shop).

I don't know how he does it given the comparatively crude tools used,
but he did. They were not balanced on the engine afterwards either.

The second one I first verified by wrapping two layers of duct tape
around a randomly chosen blade near the hub. If it is off in static
balance, it either will run smoother or rougher. That tells you the
next step. I finished having to put several coats of paint on the
back side of the lighter blade to get it to run smooth, but thought it
a helluva way to make a new 172 run right. Cessna picked up the
repair under warranty. Those were the days.....

If course you could also have prop roughness from unequal blade pitch,
or from the blades not being directly opposite each other (i. e. bent
like a boomerang).

If you have a similar driveline as my 172, it is also possible that
your prop is indexed wrong with respect to the engine crank. The
proper orientation should be described in the aircraft service manual.
The proper orientation is specific and some mechanics may not know
that. On my 172 facing the front of the A/C, it is to be at TDC when
the prop axis is at the 1:30 - 7:30 orientation.

Find out what is causing your problem. You'll save a lot of long term
agony.