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Old 11-07-2017, 02:10 PM
Max Grossman Max Grossman is offline
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Homemade glory hole / forge / burner questions

Hi all, de-lurking to ask a safety question. Love reading every little bit of info on this forum, and I still appreciate the help with batching spruce pine years ago.

Past few years I've been getting into blacksmithing and toolmaking, making jacks shears tweezers etc, and recently I built a little homemade glory hole / forge in my backyard. I cast a burner out of mizzou, and the inside is frax with a half inch of mizzou on the surface. Been slowly curing the cement. Fired it up today for a bit of forging, but before I get any further I wanna make sure I'm not gonna blow myself up.

https://youtu.be/3kKDXqI4Dj4

https://youtu.be/6lPO3_VQxtA

Here's two videos of it, one of the burner head running and one of the whole thing right at startup. I'm using an old Eclipse Minimixer blower I got from Steven Correia here in LA (puts out 2.8 WC) which is designed to mix the gas and air in the blower. I'm running 1/2 inch PSI of house service natural gas, with nothing more than a needle valve to regulate. I'm worried about creating a bomb with all this gas and air mixed in the piping, and also about running a homemade ribbon burner with no regulator. I figured I didn't need it since the pressure is so low, but then again I barely crack open the needle valve.

I'm pretty sure I cast the holes way too big (used straws for bubble tea, so 13/32 I think) since the thing sounds loud! I'm trying to make it as quiet as possible. Also worried the big holes will allow more heat into the block. I know I need to shift the position of the burner so the flame is not boucing off the inside lip of the chamber - that I'm fixing today.

I'm worried about overheating the block and backburning - I barely use any of the air the blower puts out (have it stopped down with a quick and dirty baffle plate), and have the gas turned down pretty low - I have no idea what it's gonna take to get it to pre-ignite. I know the combustion has to overcome air velocity but I'm no rocket scientist. I didn't run it for more than an hour today because of that. The block is barely in the chamber, and is well sealed to keep the heat from hitting the outside, but I saw the holes start to glow and got scared.

So, am I worrying for nothing / should I cast a new or different block / should I go and buy a proper burner head made by someone who has already worked all this out? I've worked out of plenty of weird setups but this is my first time making something 100% from scratch for myself and it makes me nervous! Thanks in advance!

Last edited by Max Grossman; 11-07-2017 at 02:12 PM.
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Old 11-07-2017, 02:30 PM
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Pete VanderLaan Pete VanderLaan is offline
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Back when I did the 2012 color class, I inadvertently built a propane cannon mixing the propane about eight feet before it hit the ribbon burner which was a concession to people moving around on the trailer with two furnaces. When That particular burner cracked and when it burned back it was indeed a cannon which came out on the blower end. I don't introduce my gas into the forced air line now any more than about fifteen inches back from the burner.

It really was impressive and I was fortunate it didn't hurt anyone.

You can certainly make your own burners. Professionally made ones are very nice. Charlie Correll and Dudley Giberson make them. I use Dudley's for the most part and I do know how to make them. He does it a lot better.
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Old 11-07-2017, 02:48 PM
Jordan Kube Jordan Kube is offline
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I wouldn't sweat it too much. What you have looks fine. You might try something smaller for the burner holes. Hit me up if you want to remake it and I might be able to print you something out.
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Old 11-07-2017, 04:32 PM
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I did not look at the videos, I just reacted to the concept. It should be fine as a first generation. Mine would have fired golf balls at the moon.
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Old 11-08-2017, 12:54 AM
George Vidas George Vidas is offline
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Is there any upstream shutoff to the left of the yellow flex line? I can imagine a failure state where you get combustible gas coming out the air intake on your blower (power outage), and would like to be further away to turn it off.

I assume the blower is rated for combustible gas.

If you added the gas after the blower, but still a few feet of iron pipe away from the burner head, you would have something that looks more like an Alfred style burner, which based solely on familiarity would make me feel safer. This might be based on assuming that blowers should only move air.
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Old 11-08-2017, 03:35 AM
Eben Horton Eben Horton is offline
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Never never never mix your gas into a blower ! You need to make an Alfred mixer down stream of your blower. Sparks plus gas = BOOOOOOOOOOM
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Old 11-08-2017, 07:30 AM
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That blower looks like the maxon mini pre mix which was out and available in the early seventies. It was an expensive little blower. I did have several but never pre mixed the gas in it.

The whole thing about back fire is velocity. If it's high enough but it costs money. it won't happen but the downside in fine tuning is lowering the air and gas to save money and when the air is a bit too low, it will heat up the back of the burner and you get that preignition. If the mix is just right, you get a major backfire.
Pyronics used to make a mixer and I did try installing one at Pilchuck in '76 but it dragged the velocity down too much and caused a lot of angst. Nozzle mix is probably still the safest way to go but I continue to introduce the gas about 16 inches before the burner. It's also the case that if I turn it down too much, it will burn back in the tube damaging the cast burner sometimes. Keeping the burner body cool is really critical. I use a pretty cheesy Dayton squirrel cage on the furnace so I'm getting what I paid for.
Ward makes a cast iron burner head which looks a lot like the old Pyronics head but it burns back way too easily and I will not use it for anything. Propane is much more scary as compared to Nat gas.
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Old 11-08-2017, 11:15 AM
Max Grossman Max Grossman is offline
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Here's the info on the mixer -

http://www.eclipsenet.com/products/minimixers/

I guess pre-mix blowers are kinda common in industry, but not many artists using em. Don't get me wrong, the concept kinda scares me too.

Thanks everyone for the replies. Jordan, when / if I remake it I'll get in touch, thank you.

George, there's 2 shutoffs beyond that, one a few feet away and one 10 feet or so, so if power goes off I got plenty of ways to shut the gas down.

Appreciate all the advice. Makes me feel a bit better. Is there a magic temperature to keep the burner block from getting to? I'm not looking forward to the first time this burns back.

I have the option of switching where the gas is mixed - there's a plug you can see upstream of the blower where Correia had the gas coming in (with a Sticktite head on the train). That head was too loud for my tastes. But I can switch it back - he never ran the gas through the blower either.
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Old 11-08-2017, 11:32 AM
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Pete VanderLaan Pete VanderLaan is offline
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the placement of the burner is fine. The back of it can't really get hot from the gloryhole itself and anything above about 400F is going to invite some burnback. Keep in mind, velocity is key to the train staying cool.

I don't recall you talking about any orifice coming into the blower. It also does not have any gauge to register pressure of incoming gas which makes it much more exciting to turn on and also to get a desired temperature consistently. At .5 lb gas, it's a marginal system no matter what.

I would want an orifice, around a number 30 number drill and a decent gauge reading the back pressure from the gas source. I'm used to 2lb pressure and it may give you fits to try to choke down the incoming gas at all. I'm not sure of the sourcing of the needle valve but if Steve said it is one, I don't doubt it. The casting of the front looks like Mizzou but it's hard to tell. If it is, you might consider sticking some fiber on to it. Mizzou is not an insulating material.
Sticktites are indeed loud.
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Old 11-08-2017, 02:36 PM
Max Grossman Max Grossman is offline
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Ok cool. I think the next burner I make / buy will have smaller holes and metering tubes, so everything can stay cooler. I had read your cannon story a while back, which is the reason for this thread in the first place.

And yes, I would like to put a gauge on the line - I haven't found a suitable regulator / gauge combo for natural gas that goes from say, 14-7 WC.

I misspoke - actually a gate valve. Not sure about an orifice with natural gas - but never hurts to have a constant flow. It's regulated to 1/2inch PSI at the house, but who knows what it actually is at that outlet.

The front is 2 inchs of fibre in a ring shape covered in mizzou to keep the dust down, really the the whole thing is just 2 inches of fibre - I was trying to take a page out of the blacksmith forge building book and not deal with bricks or casting a retaining ring. Seems to get hot fast, but I'm sure it won't last long. Like you said, first generation.

I haven't heard back from Charlie in a month or so, but ideally I would have just bought one of his!

Edit: Just ran it for a couple hours and did some forging. Gets real hot, and towards the end of the session the refractory half of the exposed burner block was almost too hot to touch. Ran rich as it heated up, I just kept turning down the gas while keeping the air constant to keep velocity up. Methinks at the very least I need to add a good regulator.

Last edited by Max Grossman; 11-08-2017 at 04:38 PM.
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Old 11-08-2017, 05:03 PM
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Pete VanderLaan Pete VanderLaan is offline
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well if you don't run it rich starting up, it won't stay lit. It's no different with your lawn mower. Adjust it to lean when it gets hotter
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Old 11-08-2017, 06:57 PM
Marc Carmen Marc Carmen is offline
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Well having the blower impeller do the mixing is one nice way of having very well blended air/fuel, albeit a bit scary. The whole idea of an Alfred mixer being some distance upstream from the burner is to allow the air/fuel some time to mix. Since you don't have this issue, why not just mount the blower much closer to the burner? That way if you do end up creating a pipe bomb, its a pretty small one.

Also, bubble tea straws are huge, no? One cause of backburn is low velocity through the burner head. Im sure that blower can create enough pressure for decent velocity through 3/8" or even 5/16" burner holes.

Honestly though, I think you're fine. Backburn sounds way worse than it actually is and thats on the very rare occasion that it happens. I occasionally run an oxygen enriched gloryhole. Now THAT is backburn.
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Old 11-11-2017, 09:20 AM
Eben Horton Eben Horton is offline
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Quote:
Originally Posted by Max Grossman View Post
Ok cool. I think the next burner I make / buy will have smaller holes and metering tubes, so everything can stay cooler. I had read your cannon story a while back, which is the reason for this thread in the first place.

And yes, I would like to put a gauge on the line - I haven't found a suitable regulator / gauge combo for natural gas that goes from say, 14-7 WC.

I misspoke - actually a gate valve. Not sure about an orifice with natural gas - but never hurts to have a constant flow. It's regulated to 1/2inch PSI at the house, but who knows what it actually is at that outlet.

The front is 2 inchs of fibre in a ring shape covered in mizzou to keep the dust down, really the the whole thing is just 2 inches of fibre - I was trying to take a page out of the blacksmith forge building book and not deal with bricks or casting a retaining ring. Seems to get hot fast, but I'm sure it won't last long. Like you said, first generation.

I haven't heard back from Charlie in a month or so, but ideally I would have just bought one of his!

Edit: Just ran it for a couple hours and did some forging. Gets real hot, and towards the end of the session the refractory half of the exposed burner block was almost too hot to touch. Ran rich as it heated up, I just kept turning down the gas while keeping the air constant to keep velocity up. Methinks at the very least I need to add a good regulator.
If you do buy a new burner, allow me to recommend Wetdog's solid round burner head. Your great great grandkids will still be using it.
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Old 11-11-2017, 01:09 PM
Max Grossman Max Grossman is offline
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Pete: Totally! Trying to save some fuel and cut down on the radiant heat. Course, you need a rich environment for the steel.....I think all signs are pointing towards me building a much smaller forge, and using this as a glass gloryhole.

Marc : Thanks for the thoughts! Getting rid of some piping is a good idea. I think I'm ok too - the blower puts out a ton of air and I barely have it opened up.

Eben: Thanks for the rec! Might buy a small one and make a tiny forge with it. Are they quiet?

Thanks again everyone for the advice!
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Old 11-11-2017, 04:36 PM
Jordan Kube Jordan Kube is offline
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I also recommend wet dog burners. Spiral arts also makes the same style with a right angle pipe entry.
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