1" copper pipe to mount a crown race, does that work?
If it does, it means your crown race isn't fitted properly. There's a pretty big interference fit by design, so copper plumbing pipe is much too weak to set it properly. Also helps if the end of the pipe is truly square to set the race evenly. By the time you've got somebody with a lathe to square off the end of a piece of thick walled steel pipe and ream out the bore to clear the 26.4 or 27.0 collar on the steerer, you might as well have bought the right tool to start with.
If it does, it means your crown race isn't fitted properly. There's a pretty big interference fit by design, so copper plumbing pipe is much too weak to set it properly. Also helps if the end of the pipe is truly square to set the race evenly. By the time you've got somebody with a lathe to square off the end of a piece of thick walled steel pipe and ream out the bore to clear the 26.4 or 27.0 collar on the steerer, you might as well have bought the right tool to start with.