I use my personal home printer for a number of different klal projects I am involved with. I would estimate printing use to be 70% klal 30% personal. The printer seems to be on its last legs. If I need to purchase a new printer, am I allowed to use maaser money up to 70% of the cost?
Assuming that the klal work that you are doing is a “maaserable” cause, yes, you may use 70% of the cost from maaser. This is because you are using the printer for a significant amount of your own use. Therefore, split the cost with maaser.
Hashem should help you continue to help Klal Yisroel!