From the descriptions in primary texts and from other recreators we have something like this:
Source lost, my apologies!
It needs a bit of a point or a chisel tip to give accurate transfer of heat to the glass. It needs to be of thicker stock, however, to hold heat long enough to work.
I initially created one out of 1/4" stock, and hand filed a point on it. It didn't work very well! It was too thin to hold heat for very long. I consulted with other SCA glassworkers and was tipped off that that was likely my problem. One friend explained she uses large square stock and uses the corner of the square as her point. I couldn't find solid square stock around me, and time is of the essence. Instead I bought round stock that was 3/4" thick. I looked at it, looked at my hand file, and witnesses may or may not have later described something akin to "whimpering."
These tools are not intended to be entries on their own. That was never the intention. So, with the assistance of a friend we ground a stubby point onto two rods to give them a chisel tip without making the contact point too far away from the bulky, heat-holding chunk:
Spaarks. Pretty spaarks!
My two dividing irons. One is longer for fireplace/brazier work. One is short for torch heating at demos.
It does successfully work. It can be a tad hard to control, but it works. Its a pretty neat feeling when it does! I created two irons. One is just short of 1 foot long, and the other just over 2 feet (3' stock originally). I did this because iron/steel is a surprisingly poor conductor of heat. On the foot-long iron one end can be room temperature and the other red hot. The short one is intended for heating in a blow torch, which is useful at demos and events where an open fire is not an option. It also fits into a small round case I have for my period hand tools. The longer one will sit in a fireplace or brazier of coals.
A shot of an iron at work:
Edit: You can find VIDEO of the iron at work at the end of a later post found here.