Pipe Forge assist

[deputyrpa]

Hi folks! I'm new to this forum, but I'm an experienced lurker here. I've read the stickies, and searched and read every relevant post the search engine delivered. As you may expect, I have assumed the info overload position.

I wish to get into making some knives and machetes as a hobby, because I have a few minutes left over after my day job and my farm life. Most likely I will be also making and repairing parts for farm equipment as needed. I fix and build a lot of things with my cutting and welding tools already, mainly keeping my neighbor's small dairy farm up and running with his old equipment. I also have equipment capable of threading up to 6" iron, machine vises, a stake vise and a 150# anvil from commercial plumbing days. There have been several times where it would have been faster and cheaper to make parts and either anneal or temper bent parts, instead of finding and buying new ones. A forge may come in handy, but mainly I want to make some knives.

I have a plan, but I can't pull the trigger because I'm unsure. I have obtained two schedule 40 pipes - one 10" o.d. x 5' long, and one 14" o.d. x 31" long for the construction of two forges. They were free cuts from my friend who works with the stuff every day. I'd need to build venturi forges, as I don't yet have a shop with power, as I'll be remanded to the metal shed for this type of work. I'd like them to be capable of welding temps, but I'd like the 14" to be able to heat treat with a pipe-in-a-pipe as well. However, I do have a gas-powered plumber's lead smelter with a hand-crank blower (I wish I could post a pic!). Would that achieve and maintain the proper temps for heat treating? What are my options for forge lengths and burner designs for the pipes? (2" of blanket in each one and ITC or Plistex of course) I like the T-Rex burner design and the ribbon burner design, but I can't drop the cash to buy them. Owning a damn fifedom has its drawbacks. I was looking at sidearm burners as a compromise, and can figure out how many I need one I settle on pipe volumes. Am I off course? Am I asking for too much flexibility out of venturi forges? Should I just build a small forge out of the 10" and see how I like it? Have at me!

 

[Willie71]

I would set up the small one with a sidearm burner, see how it runs for you, and design the second one to account for any shortcomings you find in your design. DO you have access to a generator to to make the forge a blown burner, or possibly run a PID? I just today abandoned the idea of using my forge for heat treatment, and ordered another PID for a 220v electric heat treat oven. Its not that the forge can't double as a heat treat oven, but the ramp/soak options in the electric oven open more future steel types to me, as well as stainless. I have all of my parts for my PID forge, excepting the solenoid valves. Hopefully this week. Its a lot to take in. Read and re-read the threads on the forge design, and PID controls. I bookmarked them for easy reference.

http://www.indiangeorgesknives.com/building_a_forge.html

http://www.bladeforums.com/forums/showthread.php/600318-PID-Controlled-Forge?highlight=PID

BTW, welcome!

 

[Stacy E. Apelt - Bladesmith]

Blowers can run on 12VDC, a small and cheap generator, or off an extension cord. The pipe will need to be cut down shorter for any realistic use. 24" is a very deep forge, 16-18" a good size one.
Use 2" of Kaowool ( or more), plus all the necessary refractory coatings, and a good blown burner ( or two) for welding heat in a big froge. A venturi will work OK for a general use forge.

BTW, welding heat is best done in the minimum size forge chamber needed. I would set up the 10" pipe for a welding forge, and the 14" for a general use forge. A 4"-6" chamber diameter is all most folks ever need. It might even work out best to put extra insulation in the forge to make the chamber smaller. This will also make the forge more efficient.

 

[Salem Straub]

To all of that good advice, I'll add the following: I do recommend Zoeller's sidearm burners- I built a forge with them that I used for a year or so, then sold. It was 16" long, two layer of kaowool in a 10" pipe, with two sidearm burners. I just ran one for normal forging, and with both going, I could get screaming welding heats that were great for welding cable. I have used Satanite, Plistix, and ITC 100- didn't care for Plistix, it broke up too soon, ITC is great but expensive, and satanite alone should be fine to coat the wool and achieve welding heats if you can't shell out for ITC.

A hand cranked blower would be terrible for a blown propane forge, but you could sure build a good coal forge with it.

I'm with Willie, build the smaller one first to get your feet wet.

My small horizontal venturi forge works well for HT with a pipe muffle inside- I run it real low, and babysit the blade the whole time with a magnet-stick. You'll still have to shift it around a bit as it heats.