I use charcoal only and if I wasn't careful when I first started I burned and melted the steel. I started with a smaller forge and now I have a larger one based off the 55 forge design. I started by chipping the wood and burning it that worked , but as said before there was to much ash. Make your own charcoal, I do it in 55 and 45 gal drums. I like the smaller drums better. I seive the charcoal to remove the fines and brake up the bigger chunks and reburn the few unburned chuncks in the next batch.
The old small forge
air turn down low air up higher
all on charcoal