Thursday, April 30, 2009

Forge Welding In Gas Forge

Forge Welding in a Gas Forge is Tricky

Propane gas forges are becoming common place for blacksmiths now. They offer versatility and ease of use, and the fuel is easily obtained. Mostly the gas forge is suited for forging smaller objects, as everything has to fit inside the box. Forge Welding can be done in many gas forges although not all.

The forge welding process requires sustained high heat to soak inot the bars that are being welded. These temperatures are near the top end for propane to support so we have to compensate with good insulation in the forge. Coal forges produce a much higher temperature so you can reach the forge welding temperature sooner.

The environment inside the forge is just as important as the temperature reached. If you have an excess of oxygen available you will find that your bar will scale up. Scale doesn't weld and will contaminate forge weld preventing it from sticking. We try to prevent scale build up with flux (Boric acid, Borax).

Flux will attack the insulation of most forges so you must be careful to have a drip pan of sheet steel to catch the drips. Or else you will end up replacing your forge insulation sooner than you would like.

The Forge Welding Process
  • Scarf your weld area (shape the bars so that they thin out on the edge and are upset in the meat of the weld area)
  • Bing up to a medium orange
  • Wire brush to remove all the scale
  • Coat with Borax while still showing color
  • Put at the entrance of the gas forge until flux melted
  • Put into the heart of the heat of the forge and take a full forge welding heat. This color is a lemon yellow or the color of melted butter.
  • Rotate your bar frequently to get an even heat
  • Pull the bar out of the gas forge and attempt the weld with solid penetrating hammer blows. This is not a really hard stroke as this can dislodge the pieces but more of a solid stroke.
  • You only have about 2 second to complete the weld. Do not Hesitate!
  • Repeat this process several times until you have a full and complete weld.

The Welding process is best learned in a coal forge then the techniques transfered over to gas forges. This is a skill that takes practice and patience.

The video below gives you some tips on building a gas forge and how I insulate it for forge welding.

<a href="">LinkedTube</a>

You will also find more information on my Blacksmithing website.



Mathew said...

Forge Welding Process Tips Was very Helpful us & our team... thankuu!!!

Midwest Metal said...

Forge w elding is really tricky!It is a welding job that needs 50-90% of the melting temperature is recommended. Utmost care must be taken to prevent overheating the metals.

Thanks for the tips!

-Andrei Smith
Midwest Metal Products
Follow me on

Anonymous said...

wow that video was very useful and thanks for the tips on Welding