This should be moved to Help/Repair/Maintenance.

+1

question i change the brass barrel of my solidoodle 2 now the heat bed hit the Extruder Hot End  how i can calibrate it please help and where i can buy a big  roll of Kapton Tape for the heat bed.

Hi tapout

If you look near the back of the printer, to the left of the Z-axis support rods, there's a little black screw attached to a piece of plastic mounted on the back wall of the printer. That is your Z-stop. If you want your bed to stop sooner, you need to lower that screw so it hits the button (you'll notice this button when you press Z-home) sooner.

That said, make sure you tightened the brass barrel well. It sounds like you may not have, if your assembly is now much lower.