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Two-Brick Forge Advice


twigg

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On 1/12/2021 at 1:36 PM, teenylittlemetalguy said:

 I use a hole saw to drill out the bricks, then I like to scrape out the middle for a bit of a belly (1/4" total or so) so it is a bigger diameter than the entrance/exits. This makes for a little back pressure and It helps everything to get hotter and reduces the dragons breath a little.  

I was rethinking what you said, Tristan, and I think I missed the point when I shaped the belly last night. I feel like you meant that I put a hard 90* shoulder going from 1/4" wider on the inside to smaller on the exits. I feel like a hard orifice-like shoulder gives more drag on the dragon's breath than a tapered belly like I did last night. I did a silly little sketch if it's not clear in words.

bellyshape.png.1a87bfa41ea0f760444d35abbf853890.png

Going to update the interior shape on this tomorrow night.

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I can't see the surface close enough, but I can tell you that K26 is just its thermal rating. Morgan's K26 is quite porous. Your brick doesn't look porous. HOWEVER, not to worry. For all we know your brick is fine; whether it is Morgan's Thermal Ceramics brick, or not. OEM's compete all the time...Morgan had an exclusive for about two years, which I never expected to last :)

Next year, we will all be scrambling to buy  3100F highly insulating high alumina sphere bricks; the latest thing in China this year :D

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They are to firebricks as Zircopax is to heat reflective coatings; the next generation. You can buy as little as four bricks at a time for $6 each. Unfortunately, you literally have to wait for a "slow boat from China"  to arrive with your order. However, that just takes patience. Next year the drop shippers will swarm all over the OEM, and you will get to pay $25 a brick and ridiculous "shipping fees."

Down to specifics: These bricks are highly insulating, but are likely mechanically tougher than Morgans K26 bricks; not to mention that they are good to 3100F and NOT porous, so they will be more flame tolerant. They are high alumina, so they retain good tolerance for welding chemicals.

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On 1/15/2021 at 2:06 PM, twigg said:

Frosty's concern that plistex does not bond well to smooth surfaces.

That is ONLY as a cement to bond two bricks together. It works pretty well for mending broken bricks. 

To avoid having to mice the drill table up and down and recenter the bit, use an assortment of nipples. However it may not be worth the hassle if you can drill the T without the bit wandering. If you have a lathe use the center drill.

On 1/15/2021 at 8:52 PM, twigg said:

I'm still figuring out how to hole saw my way through the 9" length of the bricks without wrecking them

A little bit at a time, I have a cheap hole saw set that makes short work of IFBs without damaging them if you take it slow and don't bottom it out in the hole. Drill the limit pull the saw and chip the slug if it didn't break loose when you stopped advancing the saw.

Frosty The Lucky.

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Thanks all! Last of the materials should be arriving this week. Just going to fix up the taper then.

And Mikey, out of curiosity, do you happen to know what's driving folks to spend the money on R&D for the 3100F IFBs? I'm definitely not trying to look a gift horse in the mouth I promise :D I'm just curious what industries have those needs. Materials science research?

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I made a couple this morning before work and found a T that perfectly illustrates why I totally ignore the mold lines. You can see the mold mark is not in the middle. I don't know how they manage to make them like this, but I see it in many of the cheap box store brand fittings. 

To drill this T it was screwed onto a pipe which is mounted in the lathe and center drilled, so I know it is in the center of the pipe and why I think it is best to find the middle of your tube and then attach the T to drill it out. 

 

20210120_055417.jpg

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On 1/18/2021 at 3:44 PM, twigg said:

And Mikey, out of curiosity, do you happen to know what's driving folks to spend the money on R&D for the 3100F IFBs? I'm definitely not trying to look a gift horse in the mouth I promise :D I'm just curious what industries have those needs. Materials science research?

Industry?!? I think not. What industrial concern doesn't have accountants to point out that these prices are absurd?

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Alrighty, I found the shop empty today, so I went nuts trying to get stuff done. Long story short: still not done! I underestimated the effect of altitude. I triple checked that I was using a 0.023" MIG tip and 3/4 x 1/2 plumbing tee, but I just couldn't get a proper burner flame until I unscrewed the fitting and held the MIG tip orifice all the way inside the tapped hole where I mounted the fitting, at the back of the tee!! I guess I need either a smaller orifice or larger air inlets. If that doesn't work, I'll hook up my 1/2" Mikey burner instead (was hoping to retire it because the set screws have stripped and the accelerator got loose).

I got the plistex coating on, and I held the burner at the right position for a few minutes to do a gentle first fire. At least that's done.

I also could finally throw some sparks so I cut out a little piece of SS sheet to hold the burner collar. I just messed up my hole placement a little, so tomorrow I need to get it fastened to the other bed rail, so it doesn't potato-chip away and misalign the burner. For tonight I used a pipe clamp.

IMG_20210121_193033.jpg.294d3ea969f11b781333d4e277595a25.jpg
(Note, I fixed the alignment of the burner before testing, I know it was crooked in this picture)

One last practical consideration for anyone thinking about building a 2-brick forge: you need a way to either take the strain off the hose or keep the forge from rolling over.

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Haha, sorry Mikey, I would've needed a third hand to take a picture while holding the mig tip at the right place. When it was screwed together, it was a very sad, low air low velocity flame because there was almost no induction. Same kinda flame I got on your burner with the choke almost fully closed.

I'm currently thinking through the pro/cons of smaller orifice vs bigger intake

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I really like that updraft design Tristan. It would be a snag for me to copy it though because I'd need a new portable workbench to accommodate the updraft (I work on borrowed space, nothing can stay put after I'm done). I like the trusses!

Mikey, I hear you haha. I'm still chewing on your advice on microburners on page 13.

Current state of confusion: I have a working Mikey burner with the same size orifice, and I saw MT Hammer's YAPBF thread with a standard Frosty tee that appears to be inducing air properly with the standard ratios at 5800ft and ~1/2" from the mixing tube with a 0.035" contact tip. This makes me think something else is wrong and that the orifice is capable of inducing enough air but isn't for some reason. Going to start the tuning over with a fresh mig tip.

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gas orifice diameters change with burner size; but they also change between some burner designs. A "T" burner has a softer flame than a Mikey burner. Thus the two burners have very different mixture flow characteristics. The "T" burner uses eight mixing tube diameters, while the Mikey burner uses nine diameters. I doubt that my flame retention nozzle would work all that well on a "T" burner. Mixture flow changes everything.

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Picture / Video heavy! Sorry!

Round two of testing today. Short and sweet of it is that a larger air intake doesn't help. Able to run the forge with my clapped out, loosey goosey Mikey burner. Got pictures and video for all you pyros.

Here's the Frosty T with a 1" tee for extra air intake:

IMG_20210122_210101.jpg.9f261d5d666ec67f56d750be4355f3f0.jpg

And here's with a (crudtastic build quality) Mikey burner:

IMG_20210122_211306.jpg.153bebe6181d86037b5b7d0b2c2b6d1b.jpg

 

Other discoveries:

-same thing happened when I held the mig tip in the threaded hole of the Frosty tee, I got a seemingly decent jet (I have no idea why this occurs for both 1" and 3/4" intakes! weird!)

-seems like the 1/2" frosty tee needs a smaller orifice to operate normally at my altitude? would love to hear if anyone can confirm this. I recall in Mikey's book it says that a 0.023" mig tip is already a large orifice for a 1/2" burner

-a 6 screw burner collar beats the heck out of a 3 screw collar

 

I ordered some EDM tubing in the range 0.4mm-0.6mm. Not sure what I'm doing yet but one day I'd like to try a smaller burner. Maybe for a two-bricker 2.0!

Bonus photo: the very sad Mikey burner (served me well, given the build quality)

IMG_20210122_211310.jpg.73232d74fe7c8d50020dcc2ac801e735.jpg

I'm gonna go sleep off the fabricating depression :D

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17 minutes ago, twigg said:

I recall in Mikey's book it says that a 0.023" mig tip is already a large orifice for a 1/2" burner

Yes, it does; but it is discussing Mikey burners. "T" burner have considerably larger gas orifices. Different flow dynamics create different particulars.

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I hear ya, I'll keep the two apart in my brain from now on.

Any thoughts why the jet started inducing when I held the mig tip inside the threaded hole for the fitting? I meant to take video, but I done goofed. Does it prefer to pull air from behind then from the sides?

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