Hi to help with the metal swarf flying around I Use a sacrificial play on top of the door and cut from both sides if possible.
If its a one off and you can't get a specific blade just use a smaller blade with the same bore just adjust the speed accordingly
I got some metal stuck in my eye last year from grinding and had to get it scraped out, It was then that I found out that I'm immune to the anesthetic they were using. (my wife nearly wet herself laughing at me squirming) Safety goggles are a must when working