You can see a spearhead I forged back on Page 1..... It's loosely based on this Anvilfire Iforge demo:
http://www.anvilfire.com/iForge/tutor/atli_spear/index.htm
Mine:
I forged mine from a high carbon railroad spike. High carbon is relative with a railroad spike, but ones marked with H or HC on the head are actually about 1040 steel, which with a water quench become suitably hard for spear use. No temper needed. 1040 is also much easier to spread the socket on, it must be forged out very thin. The bottom of my sockets is typically under 1mm thick.
I start with the point in the tongs and the head in the fire, aiming for a high yellow heat. I forge the head back into the spike's body. I ALWAYS forge the tang or socket or handle first, and the blade last. This helps to avoid bending up a forged blade unnecessarily, and avoids too many heats to the blade's steel after it's shaped. Take pains to avoid folding the head into the body, just drive it in without folds.
Then using a cross pein or straight pein hammer, I forge the head end of the spike out laterally, to begin to form the socket. The steel will spread towards the flats of the pein on the hammer, so this helps spread the steel in the direction you'd like. After many heats, you'll have a very ugly piece that looks rather like a garden trowel with a roughly triangular blade... At the top of the socket, try to forge in a spine that goes down about 2-3" into the socket, to carry bending forces from the blade into the socket. Like the vein on a leaf.
Continue spreading the socket until you've got enough material to make the socket. I aim my spearheads for 1-1/8" shafts, so that requires 1.125" X 3.14, or about 3.5" wide "trowel", and the socket is usually about 6-7" long. I clean up my sockets by cutting off the rough edges with a hardie or cold chisel.
Now flip the work and forge the blade you desire. The socket is still a flat triangular plate.
Once the blade is shaped, coax the socket into a conical shape. A pointed steel bar can help to form it around. The edges of the socket should about meet, but not overlap. The socket is left unwelded.
Straighten, normalize, heat to medium red and quench in water (or appropriate medium for the steel you're using... I'm using 1040 RR spike)....
Taper the end of your spear shaft to match the socket. Ram the head onto the shaft. The unwelded socket will spread slightly and grip the shaft very firmly. Drill thru both the socket and shaft, near the base of the socket, and pin the head to the shaft.
The spearhead's OAL is about 13", 6" blade, 7" socket/tang.
While I have yet to make one, there should be a steel fitting on the base of the spear too. This can be made from a piece of iron pipe, forged to a point at one end. Provides a wear surface, and a striking/stabbing piece on the butt....
Here's the first one I made, for a friend.... It's a bit rough, but it turned out OK. Also, I've used the same technique to turn out arrow points from 1/4" music wire.... But that needs more careful heat treat. Fun to make, a challenge in hammer and heat control. The arrowheads are about 3" OAL, and fit 5/16 shafts.
Arrowhead:
J