By removing the base and devising a means to lift the unit up
increased air flow and a longer roast time can be controlled.
 
 

A small panel can be opened and closed to various levels to control air flow.
A screen is necessory to avoid chaff flowing into the heater.
 

Typically at room temperature 1st crack occurs about the 5 minute mark
with 2nd crack occuring at the 8 to 13 minute mark.