For those that have ever had trouble removing a lathe chuck from a threaded spindle, I wanted to tell what worked for me in case it might help someone:
I am making an ER40 chuck for a 1.5" X 8 spindle. It is 2" hex steel and I successfully (somewhat amazing for my lack of knowledge and experience) drilled, bored, internally relief cut, and threaded it. Anyway, once I was done with this process, I installed the chuck onto the spindle and began turning down the outer part of the hex for the ER40 nut to mate to. Turning a 2" steel hex into round is an unpleasant experience, at least on my machine, so I decided to mill down the hex peaks on my mill (which, by the way was the smart way to do and later worked fine)... BUT I couldn't get it off of the spindle, all of the interrupted cuts had hammered the chuck onto the spindle!
My first problem was that I had no wrench big enough to grab a 2" hex, then of course I had the often mentioned concern about breaking back gears. Well it was a simple matter of welding up a wrench with about a foot leverage, those of you with chucks, just chuck a piece of steel (wood would not be as good) about 1 foot long laterally. Then PUT A PIECE OF WOOD OVER THE WAYS FOR PROTECTION. Do not put the lathe in back gear, make sure it moves, but don't make it free wheeling, at least get the motor inertia involved. Then grab the spindle, the biggest gear you can grab or in any way just try to physically restrain the spindle. Then take the end of the one foot long "wrench" or other metal bar you have put into your chuck sideways....give it ONE SHARP INSTANTANEOUS WHACK ... AT THE END...with a metal hammer. The spindle inertia provides an instantaneous very large counter force to the very quick rotational impulse of the "WHACK". Just be careful, do a single, carefully controlled hit and if you have to try again re-position and repeat.
I am making an ER40 chuck for a 1.5" X 8 spindle. It is 2" hex steel and I successfully (somewhat amazing for my lack of knowledge and experience) drilled, bored, internally relief cut, and threaded it. Anyway, once I was done with this process, I installed the chuck onto the spindle and began turning down the outer part of the hex for the ER40 nut to mate to. Turning a 2" steel hex into round is an unpleasant experience, at least on my machine, so I decided to mill down the hex peaks on my mill (which, by the way was the smart way to do and later worked fine)... BUT I couldn't get it off of the spindle, all of the interrupted cuts had hammered the chuck onto the spindle!
My first problem was that I had no wrench big enough to grab a 2" hex, then of course I had the often mentioned concern about breaking back gears. Well it was a simple matter of welding up a wrench with about a foot leverage, those of you with chucks, just chuck a piece of steel (wood would not be as good) about 1 foot long laterally. Then PUT A PIECE OF WOOD OVER THE WAYS FOR PROTECTION. Do not put the lathe in back gear, make sure it moves, but don't make it free wheeling, at least get the motor inertia involved. Then grab the spindle, the biggest gear you can grab or in any way just try to physically restrain the spindle. Then take the end of the one foot long "wrench" or other metal bar you have put into your chuck sideways....give it ONE SHARP INSTANTANEOUS WHACK ... AT THE END...with a metal hammer. The spindle inertia provides an instantaneous very large counter force to the very quick rotational impulse of the "WHACK". Just be careful, do a single, carefully controlled hit and if you have to try again re-position and repeat.
