Were the Arabic numerals used in pre-modern times on mechanical clock faces?
Is there a specific point in time when they started to replace Roman numerals?
Wikipedia article for Clock face claims "Clocks using only Arabic numerals first began to appear in the mid-18th century" with remark: citation needed.
Wikipedia article for Arabic numerals contains an image of a Woodcut showing the 16th century astronomical clock of Uppsala Cathedral, with two clockfaces, one with Arabic and one with Roman numerals. Not disproving the statement above as it contained "only"-clause. The clock in Uppsala also was not a time clock.