It looks like Santa Rosa has some rather strict noise ordinances
Santa Rosa noise
17-16.040 Standards for determining violations.
Notwithstanding any other provision of this chapter, and in addition thereto, it is unlawful for any person to wilfully make or continue, or cause to be made or continued, any loud, unnecessary, or unusual noise which disturbs the peace or quiet of any neighborhood or which causes discomfort or annoyance to any reasonable person of normal sensitiveness residing in the area.
The standards which shall be considered in determining whether a violation of the provisions of this section exists shall include, but not be limited to the following:
(A) The level of noise;
(B) The intensity of the noise;
(C) Whether the nature of the noise is usual or unusual;
(D) Whether the origin of the noise is natural or unnatural;
(E) The level and intensity of the background noise, if any;
(F) The proximity of the noise to residential sleeping facilities;
(G) The nature and zoning of the area within which the noise emanates;
(H) The density of the inhabitation of the area within which the noise emanates;
(I) The time of the day or night the noise occurs;
(J) The duration of the noise;
(K) Whether the noise is recurrent, intermittent or constant;
(L) Whether the noise is produced by a commercial or noncommercial activity. (Prior code Ch. 27, Art. I, Div. 5)
Under special noise sources
It is unlawful for any person to operate any machinery, equipment, pump, fan, air-conditioning apparatus or similar mechanical device in any manner so as to create any noise which would cause the noise level at the property line of any property to exceed the ambient base noise level by more than five decibels. (Prior code § 27.20)
The city determines "ambient noise" in an R1/R2 residential area between 7am and 7pm as 55db, so your machinery can't be louder than 60db at the property line. Industrial is the loudest and rated at 70db.
It sounds like your neighbor is bored and wants to control the neighborhood, but tread lightly as it doesn't appear the city ordinances are in your favor.
This also makes me appreciate the two autoshops at the end of the block, any noise I make will be assumed to be coming from them. I have woken up to grinders at 7am.