Jymm Hoffman Blown Burner search

[Caleb Schwenk]

Hello all,

I have been digging around for information on Mr. Hoffman's blown burner design and come up short. His profile shows he has not been active here since 2020 and all of the discussions with pictures of his build are old enough that the photos are unavailable. He does describe a build briefly in this discussion:

But I would like a bit more to go off of than that. Has anyone built or bought one of his blown burners? Or does anyone have access to the fabled "Hammer Down" article where he details his builds? As some background I have built a Frosty T-powered forge and have piddled with coal forges as well, but after a lot of life changes, including moving several times, that paused my blacksmithing, I'd like to jump in again and try something new and more refined (This is not to say that Frosty's burners themselves are unrefined, but that my previous builds and blacksmithing efforts were done in the backyard of my college residence in a 10x10 plastic shed). Forgive me if this topic has been covered, I promise I did a good bit of looking through the IFI forums. Any help in the right direction would be appreciated. If the answers simply aren't to be found or I need to do more homework, that's great too! 

Thanks in advance, and thanks to the IFI community for all of the information and support that have gotten me this far. As I alluded to, I've been gone a while and am sad to learn of the passing of some senior members who (indirectly) taught me a lot even as a lurker.

 

Caleb

[Caleb Schwenk]

PS

This page was not successfully archived in the Wayback Machine, so I was unable to retrieve any photos that way per the Feedback and Support discussion.

[Buzzkill]

Is there some particular feature of Hoffman's blown burner that interests you?   I've built and used a blown burner, but I'm not familiar with any design specifically attributed to Mr. Hoffman.

In general, forced air burners are rather simple to build and operate.  Also, since you can manually control the air and fuel independently there isn't the level of precision required for proper functioning that is needed for naturally aspirated burners.

 

[Mikey98118]

Yes, and furthermore, a lack of precision input leads to  a lack of precision output

In larger equipment; especially if burning natural gas; this is not necessarily a big deal. But the smaller the forge the more inconvenient that becomes.

[swedefiddle]

Good Morning,

The 'Hammers Blow' is an ABANA publication. You can pay your membership and look through the Archives, they are still available on-Line.

A Blown Burner is very simple to make by using an old Hair Blower as the Fan Motor. I use a reostat to control the fan speed. Make sure the Propane Regulator is adjustable and you can make anything happen.

Neil

[Caleb Schwenk]

Thanks for the replies, all.

Buzz,

I was just about to send you a PM because it looks like you may be close to me. I do understand all of the points you brought up, and I don't suppose there is anything earth shattering about Hoffman's design. What did pique my interest was reading posts from 10 or 15 years ago. It seemed to be described as a straightforward and reliable design that a lauded pro had used for years and others had copied. Just to clarify I have no problem designing and building my own stuff and after some more looking I'm gravitating toward a ribbon burner instead. The intent behind my question was hoping to save some R&D time by copying a 'tried and true'. 

Mikey,

I generally share that opinion. From what I could glean from the old forums, people had good things to say about Hoffman's forges in general as well as his burners so that's why I was curious.

Neil,

I saw that, but wanted to avoid spending the 90 bucks to dig through archives. Especially since these (admittedly very old) posts gave the impression the article was floating around somewhere not behind a paywall. I'd rather spend 90 dollars on new forge parts. I have messed with hair dryers, rheostats, Coleman mattress type pumps, etc. All the regulators I use are adjustable, so we are good to go on that front. I do appreciate you chiming in.

While I would still be interested in copies of the article or pictures of Hoffman's forges and blowers, I think I will change tack and spend more time digging in the Ribbon Burners discussions.

Thank you all for prompt and encouraging responses.

Caleb

[FlatLiner]

PM sent

[Latticino]

Options for blown burners from Giberson's site:

[Mikey98118]

Latticino,

back in 2000 I stumbled across Giberson, and bought his excellent little book. The only reason why I didn't buy his burners, was because he was into hot glass work, with much longer heating cycles. I had some doubts about how well his burner heads would hold up with repeated fast thermal cycling.

However, Kast-O-lite ribbon burners seem to be doing okay in forges. Eventually, I think something very like his burner heads will end up as the standard burner in forges. Perhaps, with a little tweaking of what refractory is used to make them.

[Latticino]

Mike,

I used his high alumina ceramic multi-port burner heads in hot glass glory holes (no joke intended) for years without any problems.  These warm up quickly from room temperature in the morning and ran typically for around 4-6 hours (until I ran out of steam) then were allowed to cool to room temperature.  Of course with blown burners I always ran air through them both in the pre-fire cycle and afterwards, during shutdown, so they may not have experienced  the same level of thermal shock.

[Mikey98118]

Thanks, Latticino; that was good information.

I used the unfortunate term "glory hole" just one time. The lady eventually got over it...and I never repeated that mistake! There comes a point when good manners trump politcally incorrect techncal terms

[Frosty]

Wouldn't running air through the burner after shut down speed the cooling, making a sharper thermal cycle? When I run a gun burner I always start the air before the propane and always run air after shut down till it's cool. 

Air first is a good way to prevent little gas explosions shooting those pesky flames out every opening.

And air on shut down keeps everything at an even temperature while cooling, none of those pings and squeaks cooling metal makes.

My point joining this little thread is I believe running air after shut down keeps everything the the same general temperature so differential in temp don't stress things. 

Giberson's burners were one of my inspirations for the NARB. I even knew NARB is just one type multi orifice burner long before I named it. I didn't try to "copy" a Giberson because it was way to complex for guys with basic shop skills and tools to pull off. 

There were a couple other multi port burners I paid close attention to as well but some of the resources were unavailable without splitting the cost several ways. The refractory used to make the burner heads was #1. 

On the upside I think I did an adequate job of evening out the fuel air flow across the outlets well enough for what they're for. My best NARB has uneven length flames but oddly enough the longest aren't closest to the inlet port nor at the very ends and it's consistent between the two. Happily though it's not uneven enough to try and correct.

Frosty The Lucky.

[Latticino]

Frosty,

I do the same as far as procedure.  The air gas mixture keeps the burner head cool while firing and the airflow keeps it similarly cool during forge cooldown when the retained radiant heat of the walls affects the burner.  My chambers had very little thermal mass (just a skim coat of Mizzou on the bottom and directly opposite the burner head), so the stored heat dissipated quickly.  I theorize that one reason his burner heads worked so well in turndown is that with less thermal mass in the delivery tubes from the mixing tube, preignition happens in a relatively smaller zone inside the burner head, so is less likely.  They did tend to get somewhat brittle over time for some reason (maybe caustic environment), but mine typically lasted me 5-10 years.  

[Frosty]

Oh good grief, I wasn't thinking about the heat of the forge heating the burner head up after it's shut down. All I can say in my defense is we haven't talked about these things in longer than my memory. <sigh>

While I don't use them much anymore, the NARBS seem unaffected so far.

Frosty The Lucky.

 

[Mikey98118]

Well, we need to talk about this subject more. Small naturally aspirated burners are my particular rabbit hole, but I think fan-blown multi-lame burners will become the main stream.

[Frosty]

Well YES, you and I like naturally aspirated burners because they offer lots of room to tinker, challenges, rewards and occasional pleasant surprises. 

Of course, gun (fan blown) burners will become the main stream, they're easy to make and tune. Multiple outlet versions only take slightly more understanding. What's not to love?  

Do you remember where we left off earlier? I know I was getting tied up in construction issues to up performance much. 

Frosty The Lucky.

[Mikey98118]

1 hour ago, Frosty said:

Do you remember where we left off earlier?

I only remember what was going through my head when the conversation fizzled out; that was fine control of the flames, and thougts about how to successfully use Kast-O-lite 30 for constructing burner heads similar to Gibson's.

That would take casting the heads in two parts, introducing vibration during the casting, to get smoother surfaces, and coating internal surfaces with Plistix 900 for final smoothing

I think fine flame control will require 12V to 24V fines, and speed control circuits.

"fines?" That should be fans.

[Frosty]

Okay, I remember that. I sifted the more coarse aggregate from some Kast-O-lite for the NARBs. The larger aggregate left too many flaws against the crayons making rough pitted outlets. 

I figured I'd do a thin coat of Plistex 900 against the crayons and flame face of the burner block, then fill it with Kastolite. Like Gel coating a mold before laying up the fiberglass plies.

I was following your ideas for fan control, waiting for experiments to throw in my $0.02 or decide.

Frosty The Lucky.

[Mikey98118]

What I have found to be the biggest surprise, is that too much airflow from fans screws things up far more often than too little flow.

[Frosty]

Too much air wants more fuel. A larger jet perhaps? From the start one of my targets for burners is to put as much flammable fuel air mix in the forge per second as possible. In the last few years I added the parameter, "at the lowest possible velocity," for the longest hang time in the forge. 

That brings up the flame front velocity as a lower limit AND it's a variable depending on temperature. Sooo, how about prolonging the flame path in the chamber?

Funner and funner, eh?

Frosty The Lucky.

[Mikey98118]

19 hours ago, Frosty said:

That brings up the flame front velocity as a lower limit AND it's a variable depending on temperature. Sooo, how about prolonging the flame path in the chamber?

Wherever we start from, creates its own particular path of limitations. I started from highest flame velocity, as a way to promote highest flame temperatures, without adding oxygen. So, increasing the length of the exhaust path was the obvious way to increase hang time. Then, I added multiple smaller burners, to hedge my bets; it worked well enough that, I have slowed exhaust gases down to the limit, which is the amount of exhaust gases generated. I see no way around that barrier...at present.

You started out with slower and larger flames, which did not need anywhere near as much breaking to meet the same goal; to lower exhaust losses to what is absolutely necessary.

Despite our different starting points, we have used the same strategies to attain the same goal; all the efficiency we can manage in our fuel bills, while attaining sufficient heat to do the job.

The final solution, no matter what burner design, will always be multi-flame burner heads, since the smaller each individual flame is, the faster it slows to a walk

Once this is perfected, hotter fuels and added oxygen are the only paths forward; but that is a ways down the road, and I am an old man. Someone else can go there.

[Frosty]

It's been an odd path, at one time we almost became adversaries but the instigators couldn't make it work because we started talking directly and it took what 2 posts of "I never said that" messages to become friends. Turned out almost all the conflict between guys making burners was stirred up by one bad actor who as far as I care has faded into obscurity.

Now the only "conflict" is between "Asian" companies marketing departments trying to make a version of your burner look new and improved. What surprised me is how many large manufacturers are selling "Frosty T" burners. I should maybe contact them about my % for using my name. The multiple intake jet ejector has been around since IIRC the 14th cent. and is fair game. 

I'm getting up there myself and don't spend much time in the shop at all anymore so I talk and coach guys.

Frosty The Lucky.

[Mikey98118]

Yeah; I spend most of my limited energy weeding the garden, these days