Yes you have to declare them. Quarantine will look on an agricultural side of things, meaning are they clean, dirt/soil (which I doubt they will) attached, dust that sort of thing. Quarantine have many different types of treatments in Australia for cleaning (not just a steam clean). Regardless if they are panel beating tools I am sure if you give them a clean up they will be fine.
In regards to Customs however if you are bringing them under tools of trade you may (not 100% sure) have some customs duties & taxes to pay even if they are used, because it is not technically personal effects, they are tools of trade and you could be liable to pay some duties.
I dont know type of quantities you are bringing, but either way just check it out.
If you need contacts for moving companies over there that can assist, let me know.