What isnthe largest trackhoe i can use with a 12" bucket"
Well, I have seen 12" buckets custom made for Cat 245's and Komatsu 650's, so I would say it is entirely up to you and your imagination.
How deep are you going to dig with the bucket ? And how clean sided do you want the trench ? You can use a ripper on the arm to 900mm+ and just turn your ripper point up to use the attachment bracket to clear the trench,just a thought that on a 20 tonner.
I need to dig abojt 10 ft through some limestone but i need to waste as little material as possible but still be able to load trucks up with slabs of stone
I've seen Takeuchi 53 6ton excavator using Case 580 hoe buckets. Deere 110/120 maybe it, the bucket ears are 12" wide