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1/4" micro burner "pocket rocket"


Trevor84

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Diaclaimer: Number one I can garuntee you that if I sound argumentative or like I am giving you attitude or dismissing you I am not I promise so please bare with me and trust it's a misunderstanding and that I am only trying to communicate nothing more. 

I've been dealing with stupid spinal cord damage in the neck. 20220407_222231.thumb.jpg.af1993e5bb7a4bbd0629b6e39d813d7e.jpg

I only bring this up because it affects my hands and I drop the phone and mistype a lot and I struggle tap on the spot to get the curser to fix a typo. I loose focus so I in one paragraph I may use fractions, decimals, even use metric smh. I will use rough approximations instead of specific terms or quoting because I will literally forget what I was thinking.

 

Here we go 6 yrs lurking here and  working on bigger burners I figured I'd try my hand at a cute little micro burner for coffee tin or maybe bench work.

Now at the risk of sounding like a newb...... I've borrowed concepts from the "Mikey", "Frosty T" and the "Oliver upwind" 

Hold up wait until the end, I know what you're thinking but this is still in tinker-tune stage...... 

 

1/8"mnpt-3/8"flare

.4mm 3d printer nozzle

1/4" X 6" pipe nipple threads removed

3/8" pipe nipple threads on one ende

3/8" merchant coupler 

Tap the back end  1/8" npt (straight) 

I tap the 1/8"npt jb quick weld in the 3d jet 

See the photos that will follow for current dimensions... 

Use my neato square file and cut 3 equal square notches, I stop just as I see the silhouette of an opening forming (like a thin sheet of foil) you don't even have to measure much just file until each cut out is square and almost touching. I used a carbide bit on a rotary tool (the tip of a smaller file or drill bit can punch the little sections out) I used the little diamond files to square up the edges. 

The nozzle is a section of 3/8" pipe threads on one end cleaned out with a 17/32" (9/16" would be better) and screwed into a straight thread "merchant coupler" (?), you could use a section of 1/2" pipe nipple cleaned out 

Outside the forge the nozzle has an over hang of about 1 1/4" apx, the flame does ignite inside the nozzle maybe 1/2" but after awhile the nozzle still hadn't turned red. There is a bit of an air gap between the nozzle sleeve and thee mixing tube, I assume that help cool the nozzle. The flame was quite stable and I was able to wave it around. 

Inside the forge I think it was still a bit soft and long but I think if I use 8x id 2" instead of 9x id 2 1/4"  from the bottom of the air openings (forward end?) that should be making a big difference..... Obviously we know that but dang the difference from 3" - 2 1/4" was a better representation than I've ever seen on the larger burners ;-) 

The forge is a coffee can forge made with ceramic wool a bit of dense castable and high temp morter to seal the ends. This definitely isn't finished and will still be getting an ITC top coat in tge end. (plistex and mtrikote are too pricey to get here), so definitely not finished! I will update with the forge build later but, I'm open to advice but please note I've only got the pics here to show the burners reaction inside a small space (44-55 cubic inch maybe) 

Hmmm, here we go the withought further adue the "pocket rocket" 

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https://youtu.be/pxj_f5O85CY

 

 

 

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Trevor84, your presentation is a bit technical for me: I will enjoy the challenge.  But let me just say, that my cervical vertebrae are growing spurs, which are impinging on my airway.  It has a tendency to make a me bit terse... Looking forward to grokking your setup...

Robert Taylor

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I will definitely try to keep simplifying it, to me tis one seems to be fairly straight forward. 

 

Tap the back end of the 1/4" nipple to take the the 1/8" mnpt. 

Tap the 1/8"mnpt to take the mig tip. 

You mark/divide the pipe into three faces/sections,  file a square notch on each face just shy of 1/2" X 1/2". Or until you see a rectangle form in the center of the notch as the steel thins (inner most wall). Each square notch if deep enough will almost touch each other to make an equalateral triangle that has rounded corners. 

Use an  awl, Dremel, drill tip of file to punch through that rectangle silhouette, that thin inner wall and clean the edges up with a small file or rotary tool. 

Use a larger file and taper/blend the backward edge of the intakes into a nice bevel towards the backend of the burner. 

 

Trim the pipe to 2 1/4" from forward end of air intakes

 

Take a short section of 3/8" pipe nipple, screw it into a 3/8" merchant coupler (straight thread). Use a file or drill to clean out the 3/8" so it can slide over the 1/4" mixing tube.

 

 

12 hours ago, Trevor84 said:

1/8"mnpt-3/8"flare

.4mm 3d printer nozzle

1/4" X 6" pipe nipple threads removed

3/8" pipe nipple threads on one ende

3/8" merchant coupler 

Tap the back end  of the 1/4" nipple to accept the 1/8" npt  make sure to tap straight. 

I tap the 1/8"npt jb quick weld in the 3d jet 

 

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I'm in awe Trevor, I'll be printing you posts and keeping them for future study. Is this something you've been experimenting with or did you just build it? I tinkered with the first T burner when I had time for a couple years and the current build instructions as posted on IFI are the result of probably 10-15 years of refining the build method for folk who don't have access to a lathe. 

If you just decided to make and then put your two burners together, I'm humbled, you're way better at this than I am.

I'm not surprised at the difference in performance between a 3" and 2 1/4" mixing tube, it's a significant change in ratio. 2 1/4" is 75% as long, that's a lot. 

I find it easier to visualize effects by thinking in ratios or %, straight dimensions isn't as intuitive. I build with dimension of course but think in %, it lets me do all the math on comp instead of in the shop.

Thank you for sharing.

Frosty The Lucky.

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  • 3 weeks later...

Hey I'm back soo sorry for the delay and geez thanks Jerry *blush* and that means a lot it really does and double because I know you don't just say what people want to hear.

 

When it comes to the length of time that this took me to come up with I don't know what to say..... Call it a love child between gut feeling with educated guessing and mixing plans whilst reinventing the wheel.

Seriously though I had made a version of a Mikey burner before with three air slots and the accelerator tip sitting just back from the throat/forward edge of the intake. They worked great and it didn't really matter where the tip of the jet sat but it was most stable where xwind could get at the gas stream ie near the forward edge.

So i was sitting there wondering how to get gas into a 3/8" nipple and fiddling with a pile of parts on my bench banging them against each other like a monkey and I randomly tried the 1/8"npt tap into the 1/4" pipe nipple instead and bam it fit. I couldn't deliver the fuel as deep as I could with the larger "Mikey" burner so I stole the concept of the fuel being delivered upstream or upwind like the "Oliver" and rely on a high psi stream to make it past the opening. The  nozzle I use is a mate between the Frosty straight thread coupler (not the pipe thread coupler) and Mikey's discussion on the step nozzle. 

So it's a mess of info jammed together but there was definitely educational type gutsumating (guesstimating with your gut) I always repeat to to beginners.... "build a few to known plans, do some reading, more reading then maybe try and wing it". 

I'll follow with a whole bunch more pics and what I hope to be more concise and simplified instructions or lay out. The only power tool used is a drill for reeming out the step nozzle and set screws in the choke and step nozzle and the rest with tap wrench, files and hacksaw. 

 

This is still in its beginning stages and there needs to be discussion on the dimensions I've chosen to start with and what might be better or worse. 

I am trying to work up ratios and relationships between dimensions like intake to mixing tube cross section is almost 3x but the top successful burners end up closer 1.5x intake to cross section area (I know it's not supposed to work like that but it's something I've been noticing as I work through different designs) 

 

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Dimensions I'm working with right now are from tip of jet/orifice to forward edge of air intakes is 1" the 3 air slot are measured back from there 3/8" and material removed to expose 3 equal openings that are 1/4"X3/8" with corners and edges filed crisp and square. 

The mixing tube ie forward edge of intake to the end of burner will be somewhere between 2" & 2 1/2" depending on application 

Nozzle is as above, a piece of 3/8" nipple reamed out and threaded into the coupler with a set screw or three. 

So far a choke is needed with the current dimension and distance of jet from intakes 

The choke is just a little piece of 3/8" reemed out with a set screw. 

 I do think I will be shortening the distance between the jet/orifice tip to forward edge of air intakes. 

 

I will upload photos as I get them resized and orginized.... I also filmed myself making a burner tube beginning to end that I have to edit.

Maybe tonight maybe a few days but not now, I got to go eat something now. 

 

 

 

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I just call them like I see them Trevor. Right now I'm thinking you shouldn't try making these things the way I do, ratios and %s I mean, you're doing too well your way. I'll be watching and reading more than trying to contribute here. 

Frosty The Lucky.

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On 4/11/2022 at 6:16 AM, Trevor84 said:

I will definitely try to keep simplifying it, to me this one seems to be fairly straight forward. 

Yes, your presentation is straightforward.  I, for one, have had a few too many blows to the head to read through this thread the way I want to.  I want to copy your design, but with a machined finish.  I have a kiln burner project I am already behind on, as well as several other commitments.  Overextending myself, as per usual...

Much Respect,

Robert Taylor

Edit: would love to see some Schlieren imaging at the inflow...

Edited by Anachronist58
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Holy Moly Robert, now you have me wanting to watch all aspects of burners with Schlieren imaging! I wonder what transparent material will withstand a propane burner flame at the output end. The ceramics they made the Shuttle windshields from will take extreme temps and it's available. 

Now you have my wheels REALLY spinning! Where's Mike? 

Frosty The Lucky.

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Mikey is perfectly happy to stand back and let others shine; especially when they feel inspired by very good ideas :D

11 hours ago, Frosty said:

The ceramics they made the Shuttle windshields from will take extreme temps and it's available. 

Frosty,

Where do I find out more about this?

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Oh MAN I don't know, Shuttle windscreen ceramics came right up in a web search 20 years ago when we bought our Jotul wood stove with the ceramic "glass" window in the door. It was advertised as the same stuff as shuttle windscreens and would take the thermal shock from 1,600f to drenching with water without breaking. 

Dang, now all I find is the windshields were triple pane glass, not a clear ceramic. Unless maybe the glass could be considered a ceramic? I don't find anything about it on the Jotul site either. 

So much for marketing "information" as real info or my memory. <sigh>

Dang, I  may have to dream about clear optical sapphire mixing tubes so I can take pics of flow patterns in a lit burner. <sigh> 

Frosty The Lucky.

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Perhaps, I don't know. I was struck by the moving imagery of the Schlieren imaging process and how much it reminded of my experiments with clear plastic pipe and injecting smoke or compressed air with smoke in the air intake stream. The smoke method was blurry and indistinct but told me enough to make some hypothesis of flow behavior and mixing in a burner.

Schlieren imaging of flow patterns would be like the difference between squinting at the stars and Hubble images. Even cold it'd be . . . epic to be able to actually SEE what's going on. 

Hmmm?

Frosty The Lucky.

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12 hours ago, Anachronist58 said:

hijack

No not at all, this is a fun twist for sure a tease but fun.

 

Aside from this super fact maging is there a free or low cost program or app that let's you simulate fluid flow? I've wanted to play with angles to see how it effects swirls and stuff. 

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Yes, there are Trevor but I don't know how applicable they are. A couple have been posted over the years but I've lost track. The one I remember playing with was more effective for air foil design, wings, propellers, etc. liquid or gas didn't matter but my skills weren't up to getting it to work for forge and burner. I can't maintain focus or stay on task well enough since the accident though.  

Hopefully someone on the forum remembers, saved, etc. it or more appropriate programs and will link us.

Frosty The Lucky.

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