I am doing a belt drive conversion based off of some of the guys on this board and others, where they use the splined gear for the spindle and turn it upside down and press and weld in an extension. From what i can tell the piece that they press the extension onto is 1.376 Dia. and the piece that is being pressed on is 1.563 Dia. with a 1.563-18 Threaded end. My question is as follows. From what i can determine is that that will leave a wall thickness of .095", will that be enough meat to allow for a strong hold and resist the desire to fail under the torque of the motor turning the pulley? It is similar to the link i posted below.
http://www.cnccookbook.com/CCMillBeltDrive.html
http://www.cnccookbook.com/CCMillBeltDrive.html