Is working for non-Muslims, cleaning carpentry machines and factory floors, considered humiliating and degrading?

It is permissible, according to the generality of scholars, for a Muslim to hire himself out to a non-Muslim, as long as it is not for personal service. It has been narrated from Imam Ahmad that it is permissible for work other than personal service. Scholars have cited the action of Ali ibn Abi Talib (may Allah be pleased with him) as evidence for its permissibility, as he hired himself out to a Jew to draw water for him in exchange for dates, and similarly, an Ansari. Furthermore, the Permanent Committee for Scholarly Research and Ifta has issued a fatwa permitting a Muslim to hire himself out to a non-Muslim if the work is permissible.

Accordingly, the work described in the question is permissible.