If placing a TC ( thermocouple ) permanently in a gas forge, you will need a TC sheath, or the TC won't last very long. That requires around a 3/4" hole in most cases. I am not aware of any manufacturers of forges for knife/blacksmith work that pre-install a TC sheath. This is something that the user does if he needs it. I really doubt most new users need a TC in their forge to start with, as the only place it is has any real use is if the forge is built with a blown burner and PID control. The blade and the TC are also unlikely to be the same temperature as well as the hot spot issues with most commercial forges. Again, adding PID control is something the user does on the type of forges we are discussing. The stickies and many past threads have good discussions and information for installing PID control. Auberins has complete TC and controller kits with all the parts needed, and the installation is so simple a cave man can do it. Once a TC and the PID are installed it can be used to monitor the chamber temperature. Converting the unit to PID control requires adding an LP gas solenoid to the propane line at the burner. The stickies explain it all.
As to the NC whisper forges, their biggest advantage is their portability and ease of use. Many other commercial forges are better at this or that, but the NC knifemaker models are really easy to move around. The side door on the lowboy is great if you do blacksmithing and ornamental forging, too. Their knifemaker model is a good venturi forge for the money.
Commercial forges will be built in ways that allow shipping and manufacturing ease...not for the features a small group of folks like knifemakers desire. They will be more "universal" and certainly lean toward ornamental work in iron than knife work in steel.
The main reason people build their own forges is to have all the features they want in a forge. Round chamber, chamber size, blown burner, burner placement and alignment, PID control, ports, and other features....all the way you want them.
If a Mankel Knifemaker fits your budget and weight requirements, it is a great choice. They allow use in several configurations with merely the moving around of some firebricks. However, they are not what I would consider portable for daily use. It would be very easy to add the TC to a Mankel, as the firebrick is simple to make a hole through.
Just an FYI, but a full size forge can take several hours to cool down enough to move. Additionally, firebrick and cast refractory does not move about well.
http://mankelforge.com/index.html
Food for thought - If considering doing your own HT, then getting a general use forge for forging and a HT oven for doing the HT is far better. If your budget allows it, a Mankel round belly knifemaker's forge and a Paragon KM24 or Evenheat KO22.5 will make a great combination for most any requirement you have. A forge is for forging, and is a basic HT device at best. It is only as accurate as the experience of the user in HT....and limited to simple carbon steels. An oven is a dedicated HT device and can do spot-on HT for any steel a knifemaker wants to use by merely punching in the numbers. In the final decision, you will have to consider your knifemaking now and in the future when making the purchase.
Final comment - If you are just looking to get your feet wet and start learning how to forge.....and will be carrying everything in and out of the house.... then maybe a smaller forge, like the Atlas is what you need at this point. Add a HT oven and a larger forge as your skills grow. The Atlas will always have a place in your shop for smaller work and portable forging projects years later when you might live in a different home with a dedicated shop.
