New forge - feedback on what you see

Z

zaph1

Active Member
New forge - new video uploaded 8-13

Hi all! I don't get around here much anymore, but thought I'd drop in and try to get some feedback. I'm working on a new forge, a bit bigger than the Atlas. It's an 8" steel tube with IFB for insulation. This is done by jigging up 2 bricks side by side and first drilling a 5" hole then an 8" hole. The two half circles are then stuffed into the tube.

Well, here's the first prototype. I'm happy with the 4" opening in the front, but not ecstatic about the rear oval. I really like how the legs turned out, and the two part front makes brick removal easy. I might end up with the front top stainless, depend on if the mild warps when heated.

It works, but a couple minor adjustments should help. It sputters badly when first starting. I don't know if this is normal, or I don't have enough back pressure. I do have some issues with the burner port. Cutting an angle and round is a bit difficult without an 8" wheel on the grinder. It was shooting tiny flames out around the port, which you can see in the video. I'll weld these for now, but think I know how to prevent it in the future. I don't like the back port. It shoots a LOT of heat out the back, far more than I'm used to with the Atlas. I'm thinking of reducing it to 3" x 1". Do you think this would be adequate, or would you want it larger?

The good:
Nice, even heating of the inside of the chamber with just a little hot spot.
The leg design is rock solid on the ground.
The flame, although tilted backwards, swirls nicely out the front
No more than 6" dragon's breath, and it was a nice blue.

Final dimensions
12" front to back, 12" to top of chamber, 13.5" to top of handle
5" diameter x 10" long chamber
1" front and rear, 1.5" side insulation
4" × 3" front port
4" × 2" rear port

[youtube]866u3raSm2c[/youtube]
 
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The main thing I saw that I would change is the intake end of the burner. It was only visible for a few seconds. but it looks like that is a straight piece of pipe....if so, thats where your "sputtering", and extra flame coming out the rear if from (it not getting enough air, and has a way rich burn)......rule of thumb on a venture is 3 to 1..... meaning that the air intake should be approx, 3x larger then the burner pipe diameter. That will increase air volume intake, allowing you to cut back on the gas pressure, and make it eaiser to adjust your fuel/air mixture.

Personally, I would also relocate the burner....bringing it further down the side O-- with enough downward tilt on the intake side to make if follow the interor contour of the forge. This gives a bit more fuel/air mix and a "smoother" burn.

While I suspect you wouldn't use the forge as it is in the video....make darn sure you don't leave that propane hose laying over the side/top of the forge. :)
 
Thanks for the feedback, Ed. The burner is already off-center, but no where near the angle I intended. It should be angled in about 1/2" below perpendicular to the chamber to give optimal swirl. It's about 1 1/2" below perpendicular now. It's also about 2" long now, but will be about 3/4" long on the next version. Do you like it positioned where it is in the top right, or would you move it down to the bottom right between the legs, giving it a clockwise swirl?

Once I go into production the holes and ports will likely be laser cut for a better swirl. Per Boss Dog's request, this is a larger version of the highly successful Atlas Mini Forge that he coaxed me into developing 4 years ago. We'll have a couple prototypes at the KD Hammer-in later this month.
 
I'm glad Ed said something about it. Seeing that propane hose laying on the side of the forge kind of scared me. Personally, I think that you're lucky that that mistake didn't bite you in the butt. Bringing the burner down a little more on the side as Ed suggested might discourage the user from doing this. If nothing else including a note in the assembly instructions might be in order.

Doug
 
I know the hose is bad. The forge was sitting on a BBQ grill and the hose wouldn't work from the other direction. I made sure the hose didn't actually touch the forge and it was only operating for about 30 seconds total. However, I don't like that it's even possible to position it that way. Expect it in a much different position on the next proto.

Charles
 
New video uploaded. A bit windy out, but still shows a better result. I still need to move the port to the bottom of the forge instead of the top.
[youtube]866u3raSm2c[/youtube]
 
Here's a video of the forge at the hammer-in last weekend. After about 12 hours it started to run out of propane, but held up very nicely for the first and second day.

TC showed 2300° F at the front and 2150° F at the rear, while running at 15-17 PSI producing about 80,000 BTU

[youtube]_MS6Ah1Ljq8[/youtube]
 
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