Costing m+r in operating budgets

I recently realised I haven’t surveyed anyone to see how cafe owners cost their maintenance and repairs. I’ve always thought it a good idea to designate a portion of the machine’s value to each quarter or month or whichever fiscal period a cafe owner chooses toward maintenance and repairs, and to expect that this cost is going to rise as the machinery ages. As cafe owner/operators, how do you set aside money so that you can afford the predicted and unpredicted costs of keeping your equipment running in top condition?