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Gerhard Gerber

Small gas forge economy

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I'm guessing I'm after opinions more than facts.....

I was gifted a large dual burner gas forge, needs a bit of maintenance but I know it can reach welding temp, also know from its builder that it consumes a lot of gas.....

Then I have my DIY fire place brick effort forge.  Improvised burners and no refractory cement, just a mild steel frame holding bricks together.

I have steel left from another project, wanted to build a new forge but I've decided to modify the existing one.

It needs to be more or less square with a higher roof than currently, new single burner coming in from the side rather than top.

The current forge is such that once the little bricks are red hot, the work piece needs very little time in the fire before it's ready for the hammer....barely time to catch breath.

Economy is reasonable, not that I have much to compare to.

 

My question is this, would a refractory cement lining over the fire place bricks give a marked increase in performance or economy? 

The current forge is mostly used open at 2 ends, new one most likely the same. 

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My first forge was angle iron....light weight fire bricks.....and a weed burner. Never tried to put any refractory cement over it.....but I assume that the bricks will become brittle and break if you look at them wrong in time....at least mine did without the refractory.

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A hard surface forge is less efficient because the hard material is not an insulator, it a refractory.  A forge like that works best if it's running long hours with high throughput.  You are burning gas just to keep the bricks hot whether you are working or not.  A ceramic wool is an insulator, it's holding the heat in the forge where it does you some good.  In general, you burn less gas for the same work in wool forge than in the same sized brick forge.

Another point I feel like I should make, curved surfaces in the burn chamber are more effective.  A square box makes for "cold" corners.

OTOH, I know you're in Namibia, and I don't know what the availability of ceramic wool blankets is.  If you can't get the ceramic, then castable in a tube shape would be my next best advice.

 

Geoff

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I have a single burner propane forge. 1inch Kaowool with about 1/2 inch thick satanite coat and ITC100, a standard bbq propane tank lasts me easily 2-3 forging sessions over 4-6 hours each. 

seems much more efficient for me then my charcoal forge, although I am still in the process of tuning it to hit welding temps. 

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I've been sitting with a ceramic wool blanket for a while, problem was refractory cement.  My occasional partner in crime recently bought a bag while on holiday in Cape Town for almost exactly 10% of the local price.......problem is he couldn't fit 2 x 25Kg bags plus holiday luggage in the Volvo....

I might a able to bum a bit off him, but I have doubts it's worth the effort for a slightly improved forge I had in mind.

The bricks I used are 1" thick and the have surprised me time and again, I've used it a lot, it's traveled, and the bricks are still holding up.

I want to build small new burners and bring them in at an angle........but this is all just gut-feel and initial planning

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I did most of Saturday's work using what was left in a 9Kg gas bottle that was spluttering on the previous occasion, just put it in a bucket of water and got about an hour's burn out of it.

When I connected the new 18Kg gas bottle I almost too much heat.

After Saturday I'm considering building 2 identical smaller forges that can be joined end to end, using the same basic construction and materials.

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