Johnson Gas Appliance Forge Restore

mrjbinok

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Restoring old tools and machines is addictive! I recently picked up this Bench Top Johnson Gas Appliance Model 70B Forge from a local Craigslist with the hope of putting it back into service as a heat treating furnace. The model 70 is a scaled down version of the model 120 with the difference being the size of the actual fire box.

Some of the parts are still available from the manufacturer, but prices are extremely high. My forge is currently set up for natural gas and was configured with two forced air burners. Everything I have read about these forges is that they are fuel hogs, so I decided to convert it to more efficient hybrid propane burners.

There are several options for the burners, ranging from DIY plumbing parts to commercially manufactured Burners. I have decided to go with two of the 1/2" Shorty burners from Hybridburners.com. They have a few different models to choose from and after working with Jerod we decided that the 1/2" Shorty would give me the best combination of effectiveness and efficiency.

Here is a look at the initial teardown:









 
The original insulating fire brick liner were custom cast and according to the Johnson website > $2000.00 for the reline kit. I decided to build my own with ceramic insulated fire bricks that measure 9"x 6 3/4" x 3" rated at 3000 degrees F. I got luck and found these on Craigslist in Coffeyville Ks, which is about 45 minutes away. I have a hunch that the original didn't have a 3000 degree rating!
 
Still working on shaping the new fire brick into the cabinet and it is a slow process for me. I have a pair of the Shorty burners mentioned above and have almost everything I need now for hooking up the PID controlled setup. One thing I am having trouble with is the solenoid used to turn the gas on and off.

I have looked at several knife making sites and different setups for the PID controllers but the part numbers they list for the redhat solenoids are not available anywhere I can find. Has anyone on HM had any luck setting up a PID forge, that can point me in the right direction?


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