Threaded rods are required for various projects. There are two main problems. First problem is of holding the rods and avoiding from turning while threading. Second problem is of starting the thread (in tap set a starting tap is provided by default).
CAUTION: Please use safety glasses when holding a metal rod in vertical position as shown in this step. It is risky to hold a metal rod in such a position without safety glasses as the metal rod may cause injury to eyes.
Problem of Holding
There are various ways of holding the metal rod on internet. All successfully addressed the issue of turning of metal rod due to excessive torque. Some held it in lathe spindle, some used sandpaper between vice for increasing friction, some used pipe vice for holding the rod. Somewhere I found a special attachment for bench vise for holding cylindrical objects. The methods work but are more complicated than expensive. Also they require some special tooling.
Sand paper worked for sometime and then it worn out. Test tube stand vice
(it has two screws for holding circular rods perpendicular to each other) was also tried but worked only for alumunium. In that too the holding screw made a goove and the rod slipped after sometime.
So the problem is of slipping due to excessive torque. Friction alone is insufficient. This problem can be solved by two components - a flat surface filed (or grounded) on the rod and an adjustable wrench. Vice bar is used for holding in offset arrangement
Problem of Starting
One of the bolts of the vice bar is removed.
The rod is inserted in that hole such that a convinient (or required) length is above the vice bar.
A flat surface is filed right above the hole (this flat surface acts as the flat surface of a nut). It should be atleast 2 mm deep.
The rod is held in position with an adjustable wrench using this flat surface (adjustable wrench is designed to withstand high torques).
The end of the wrench is clamped to the vice bar using C-clamp.
This problem can be solved by grinding a 45° chamfer at that end of the rod where the threading is to be started.
Scope for improvement
The flat surface is not aesthetically pleasing. It is avoided in case of full threaded rod where the excess rod is cut off. But in case threading is required on both sides of rod, the threading is limited by the flat surface. Also this flat surface is not aesthtically pleasing. In these cases flat surface is unavoidable. But there might be some way to avoid this flat surface.
The diameter of the rod is fixed by the diameter of the hole.