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I Forge Iron

Narb forge build


Erik Mendel

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WOW, you're REALLY following my build aren't you? For the couple first pics I thought you were reposting my pics. 

Have you fired them yet? That is a MUCH nicer forge than I put them in. It's looking great so far Erik. Keep us posted please.

It looks like he used colored crayons just like I did, Robert.

Frosty The Lucky. 

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  • 3 weeks later...

Yeah I did run them. First couple runs weren't amazing but after some fussing about I ended up running .30 migs at above 6 psi to prevent the back fire issues (5 hours). I found the .35 to let quite a bit of fuel out the doors. I have a fair amount more that I can pull the plenum further back so I might futz with that because I wouldn't mind being able to run it at temps below 2100 without backfire. I'm gonna running it all day tomorrow so I was thinking about blocking one of the nozzles on each burner and see if that helps to bring up the pressure per hole and cool the block a bit. I put 5 layers of hyb-uv on today so its possible that could help keep the burner block from heating up as much.

 

 

The hole diameters are 5/16 crayons I copied frostys build as close as I could. 

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I pulled both burners out until they are even with the end of the kast-o-lite30 and stuffed the stuffins out of it with ceramic blanket . They ran admirably for 3 hours at 6 psi. the same one that always backfires began to at this point and I ran them higher to avoid this and figure out if their was a balance point when it would end and I could run both without the issue. Having some experience with how much one of the burners heats in temp and area I abandoned this experiment when the close burner began to backfire at 8 psi. I suspect the whole forge to be in the 2100 area at this point (my forge design had very little consideration to the placement of the thermocouple and general shape/ growing experience with color leads me to believe that it is quite a bit warmer than the 1900 advertised temps). I have found scale to release much easier above 2100 while 2050 doesn't act the same and these characteristics where present. At this point we were making a hammer and were more focused on this aspect than the testing as any relevant solutions would require total cool down. We ran the forge for 3 more hours running 10 psi on one side and I believe we were getting above 2100 from color, work per hit and based on the pour placement of the thermocouple we judged it to be reading 200 deg low. I am extremely pleased with these results at this point for a couple of reasons. 10 Psi for one burner doesn't freeze the propane tanks nearly as quickly as 2x3/4 .23, the heat is much more even than before desirable for the hammer work and the refresh rate is much quicker obviously due to the higher thermal mass but I feel as though it is cheaper to run and that is where we operate mostly in stock size and temp. I ordered the fireboard don was talking about and will try some new burners with 100 1/8 holes only because I do want the ability to turn it down without backfiring after welding temps. I saw the 3/16 200 plus as well as the 90 -1/8 which has been reported to run well but haven't seen any further clarification of office size/psi or temperature. although I find my self extremely interested in something between the 123 that don has had good results on and pondered a few less holes. I do believe in my original interest that a modified side arm burner might be able to get the most efficiency and adjustment based on the amml burners and the early ron reil burner results. ultimately I find undeniable truth in frostys results that each inducer is not created equally and I figure that it is likely that each casting has a similar potential for differential.

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Before you get crazy and make another burner try blocking ONE hole in the center of the burner that back fires most often and run it like you have been. Block holes towards the center to maintain even heat in the forge, it's surrounded by other outlets so it's loss will make the least difference.

Fewer outlets means the fuel air mix will flow faster than it's rate of propagation at a higher temperature and not back fire into the plenum. A faster flow will also aid in cooling the burner block.

Maybe even enough. ;)

Frosty The Lucky.

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  • 9 months later...
On 3/30/2022 at 8:10 PM, Frosty said:

WOW, you're REALLY following my build aren't you? For the couple first pics I thought you were reposting my pics. 

Have you fired them yet? That is a MUCH nicer forge than I put them in. It's looking great so far Erik. Keep us posted please.

It looks like he used colored crayons just like I did, Robert.

Frosty The Lucky. 

How far out will your 3x8 size NARB heat from directly beneath it. I am planning on building a forge that is likely going to be 5 H x 6W x 15 L and after much time spent on this forum i would like to use the NARB but would it be able to heat the extra 3.5 inches on either side?

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