[TheForge] Sidearm burners

[Steve Smith]

Thanks Jerry. I think you're making the other side of the same point 
(can a point have sides?) that Rick K. made--my mixture may be off in 
the sidearm burner. You go on to imply that my Reil burners may be 
already well tuned--I hadn't thought about the sidearm having the same 
performance when adjusted, I was expecting miracles. On the other hand, 
maybe both burners are out of tune equally...

Thanks for the help. I never did understand carburetors.

Steve

Jerry Frost wrote:

> From: "Steve Smith" <sos at alum.mit.edu>
>> I was pretty interested in sidearm burners when they were first 
>> discussed. I followed in Frosty's footsteps and experimented with a 4 
>> way pipe fitting instead of a sidearm. It was ok, but not as good as 
>> the Reil burners, which I chalked up to not having a smooth transition 
>> to the 3/4" body.
> 
> More likely you're trying to use the same size jet orifice as you do for 
> one of Ron's. Try stepping it down about 30%, a jet ejector type burner 
> is about a 30% more efficient inducer. Alignment is still critical, no 
> change there.
> 
> There isn't a significant difference in the transition from a Bell 
> reducer to a nipple than there is a "T" or Cross to a nipple.
> 
>> Then I saw that Larry Zoeller had added a sidearm 'kit' (all you have 
>> to do is tighten things up). I bought one of these. It came with a 
>> tapered mig tip for the gas jet, pretty nice setup and for not much 
>> more than the fittings would have cost me. I recently compared the 
>> performance of this sidearm burner to a Reil burner. Both are 3/4" 
>> body with Larry's stainless flares on the end. I measured with a 
>> thermocouple, both in the same, single burner forge.
>>
>> The sidearm was almost as good as the Reil burner. Final temp was 
>> maybe 100 degrees lower. This makes me think that the sidearm is just 
>> an easy way to put the same burner together, and less impressed with 
>> the mig tip. Sounds like this isn't correct--what am I doing wrong?
>>
> 
> If both are properly tuned there will be no significant difference in 
> performance, a neutral burn is ging to put out the same BTUs for the 
> same amount of fuel. Tuning a sidearm requires taking into account the 
> single air intake and how it deflects the propane jet. You need to 
> offset the jet slightly to make up for the single air intake.
> 
>> I'm at maybe 300' above sea level, neither burner has a choke. 
>> Pictures could be done if important to the plot.
>>
>> Thanks,
>> Steve
>>
> 
> A little (recent) history may be in order:
> 
> The "sidearm" configuration for a jet ejector was Robert Grauman's 
> innovation. The summer of 98 or 99 Robert and his wife were visiting 
> Alaska and stayed with us for a few days. Deb and I were in the middle 
> of building the house and I didn't have much of my smithing stuff 
> unpacked. Certainly not the propane forge, we had heaps and piles of 
> wood so that's what I was using for the little smithing I needed to do 
> while building.
> 
> Anyway I described the "T" jet without making sketches and Robert 
> misinterpreted the description. The first time I saw a picture I nearly 
> E-mailed a correction but reading further realized he'd made it work 
> just fine so I filed it in my "learn something every day" file. One of 
> Robert's casting buddies made a 1 1/4" bore sidearm and melts up to 
> 25lbs. of iron at a time with it.
> 
> Another good example of well tuned sidearm burners is Ralph Sproul's 
> variable volume forge. http://www.bearhillblacksmith.com/
> 
> Ron's criticism of the sidearm was about it's off center flame. This is 
> easy enough to correct by tweeking the mig tip towards the air intake a 
> LITTLE till the flame centers properly. It's a minor thing.
> 
> Then there's the whole mig tip for the jet thing. I'd given up on making 
> a linear inducer to my satisfaction. Oh, I'd made a couple but they took 
> more tinkering than I liked to get tuned properly so I tried a jet 
> ejector. The first "T" jet. I suppose I should call it a "T" intake but 
> what the hey. If I'd been smarter I would've gone ahead and spent the 
> time to hunt down a pipe cross but having a lathe I just used a pipe "T".
> 
> What I knew from the general information I have on inducers is; a jet 
> ejector will be about a 30% better inducer than a linear but I'm not 
> good enough at math to calculate the ratios. So instead of going to all 
> the headaches of drilling a bunch of pipe caps till I got it right, I 
> drilled and tapped one, 1/4"-28 and bought a handfull of mig tips. 
> that's when I learned a brass cap isn't thick enough for a mig tip to 
> thread into securely so I found a brass fitting with 1/8" FPT to 
> something with a hole smaller than I needed for a 1/4"-28 tap and chased 
> it out.
> 
> So, I spent about an hour lighting it up and changing mig tips till I 
> got my first "T" jet tuned to my satisfaction and called it good. I 
> still have a little baggie with half a dozen different mig tips. The one 
> that worked was a 0.045" Miller mig tip in a 1 1/4" x 1 1/4" x 1" pipe 
> "T" and I'm still using it some 12 years later.
> 
> Having met with acceptible success for such little hassle I haven't 
> bothered to replace it with a better one. I have made half a dozen since 
> and fine tuned the "design". I've shortened the mig tip considerably to 
> move the introduction of the gas jet higher in the intake's cross 
> section. This improves induction considerably so a simple 1" x 1" x 1" 
> pipe "T" works quite a bit better. This is how I made the burner for 
> Rich Fizzell, host of the first (now) annual ArtMetal Shindig.
> 
> What I didn't realize when I started using the mig tips for jets was 
> just what a genius I was. I thought I was doing it the easy way and it 
> wasn't until Mike Porter straightened me out that I realized I was using 
> the mig tips for something else entirely. <grin>
> 
> What Mikey uses the mig tips for is an "accelerator". Basically the same 
> thing as the nozzle on a hose. It "conditions" the propane into a 
> laminar stream which performs much better as it enters the burner's 
> induction zone. Being a smooth conical stream (rather than the turbulent 
> vortex a simple drilled hole causes) the propane expands smoothly and 
> enters the the throat of the tube uniformly. All this increases both the 
> device's induction and disperses the propane uniformly in the intake air 
> column. It also allows a natural vortex to form in the burner tube which 
> enhances mixing.
> 
> Here I thought I was being expedient (lazy) and all along I'd come up 
> with a simple solution for a complex problem. <grin>
> 
> So, there is a good reason for using mig tips though they don't have to 
> be full length. I've found 9/16" works just as well as full length and 
> I'm sure shorter will work as well though I don't know how short is too 
> short. I haven't had much time to experiment this winter like I'd planned.
> 
> It doesn't matter much which configuration you choose for a naturally 
> aspirated burner, tuning it is what counts. Some (jet ejectors) are 
> easier to tune by their nature but once tuned there won't be any 
> difference in heat output.
> 
> Tuning is where gun (blown) burners really shine, they're easy as 
> adjusting the gas valve till you like the fire. You have to retune every 
> time you turn it up or down but it's still very easy. Building a gun 
> burner is pretty easy if a lot more expensive. You simply plumb a 
> blower's output through at least 1 90* turn with a gas fitting either in 
> the elbow or just in front of it. Attach it to your forge as you like 
> and begin tuning.
> 
> A properly tuned naturally aspirated burner on the other hand needs no 
> further fiddling. The intake air is induced in a direct ratio with the 
> propane. Turn up the propane psi and the air induction rises with it. 
> The only time you might need to choke a properly tuned naturally 
> aspirated burner is for lighting. I simply put a palm over one of the 
> intakes on my "T" jet and it lights right off. It'll light anyway but it 
> sometimes blows the newspaper out of the forge before it lights. Like 
> THAT'S a big problem. <grin>
> 
> I haven't put an electronic igniter in it though one is on the board for 
> my next forge.
> 
> Frosty
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