I Think its more difficult with the tool. You have to disassemble the tool. Take the spindle housing apart. The tool slides over the spindle end. Then you lock it into a vice. And twist your chuck off. With a pipe wrench or a Allen key. I like the BIG HAMMER.
I have made some similar tools for the Bosch and Makita Drills. I take the guts out. Then weld the gear,
the spindle slides into.
On the end of a metal shaft. works great when you have a bad gearbox. I hope this makes sense. I failed English