RMH forge?

So I'm thinking about making a rocket mass heater for my garage but I thought wouldn't it be cool if you could double the burn chamber as a forge I thought about this and considering i wasn't even trying to make an excessively hot rocket mass heater and my first one reaches temperatures the better part of two thousand degrees without even trying why not simply make a slightly modified batch box with a place to slide in some metal and an inlet for some forced air and use some either coal or pine and see what kind of temperatures are achieved.

I would like to hear some of your thoughts on the matter I'm sure someone has tried it

Hi Ryan;    
I haven't heard of this being done but that's not to say it can't be done.

I suggest you start by building a standard batchbox and see how well it does heating your garage.
After you have it up and running then I would experiment with your idea.

Is the extreme heat in the batch box area or in the chimney?  I'd think a spot somewhere just above the riser would be a good place to heat metal quickly...

Hi Ryan,    I remember in one of the wood burning stove 2.0 DVD's Ernie Wisner was experimenting with a J tube rocket stove to heat up some metal acting as a crude forge. In this case, the top of the heat riser was exposed (no barrel) so that he could hang some metal into the hottest part of the heat riser somewhere at its base.

Having this as a separate function rather than combining it with a full size system with a barrel and a mass may be the best way to go as metal blocking the gas flow I think would slow everything down and may start to clog up your system.

I would agree with Mike in that the burn box would not be ideally be the best place to try and heat steel very quickly.