first gas forge/burner (modified mag-torch burner)

[Vykk]

Hi everyone I'm a newbie in gas burners and forges and I'm looking for advice. 

The forge is just a brick stack 3.5"x3.5"x9" held together with sheet metal but seems to retain heat well enough. The burner is a modified 1/2" T burner built onto the end of a mag-torch. using a .35 mig tip.

it runs off a 1lb propane camp tank currently so one thing i would like to fix is I was told that because of the torch valve i can't hook it to a regulator so has very low pressure when trying to run on the 5gal tank.

the other issue im seeing is an unsteady blue flame that sputters a lot when tuning.

my idea was to make a small portable forge i could take with me for smithing for a friends youth group as a demonstration. 

any tips or suggestions would be appreciated. 

[Vykk]

forgot to add the face on views.

[Latticino]

Hard firebrick or insulating firebrick?  When you say it "seems" to retain heat, how are you evaluating that (outside surface temperature of your forge)?

A couple of immediate suggestions:

1. Switch out the .35 mig tip for the smallest one you can source to increase velocity of the gas and entrain more air (flame looks heavily reducing)
2. Make sure your needle valve is rated for gas service (not sure why you have two needle valves in any case...)
3. Try to find a method for using a 20 gal propane tank with an adjustable regulator if possible
4. Pull the end of your burner back into the insulation further.  From the photos it is too close to the forge floor and the tip will burn up eventually if your forge ever gets really hot.

[Vykk]

Latticono Thanks for the suggestions. I've kind of got it Frankensteined together out of parts i had on hand and what I could grab on the cheap from home depot.

The bricks are insulated fire brick from a local fireplace store. they do keep the forge from getting super hot until i turn off the burner.

The mig tip is .035 my bad i typoed and didnt catch in the edit. i do also have a .025 i'll try.

Easy enough to pull the pipe back in a bit. how far would you suggest? flush with forge top or half way into the brick?

I'm looking to rebuild the topside to remove the connecting needle valve and replace it with a ball valve then run a pipe to connect to a pressure regulator so i can remove the mag-torch.

Any advice on parts would be greatly appreciated.  I'm still new working with gas and would prefer to not blow myself nor anything else up lol.

Thanks again!

[Irondragon Forge ClayWorks]

Welcome to IFI... I always suggest this thread to get the best out of the forum. https://www.iforgeiron.com/topic/53873-read-this-first/

 

[Mikey98118]

I think that is a darn cute little box forge, and well worth preserving. First lets get a couple of minor problems out of the way, and then I hope you will write up your great little forge in the Forges 101 thread. I assume you are a jeweler?

I see two observable problems and a third potential (probable) problem with the burner:

(1) You have the wrong "T" fitting, because the threaded opening that screws onto its mixing tube is the same size as the other two, which means that the incoming air doesn't encounter a restriction as it flows into the third opening. The result is that the incoming air will not swirl enough to properly mix with the propane; this will result in a weak flame, which is what you have. The best fix for this is to by the right pipe fitting; I know that could be very hard to come up with in that dinky size, so if you can't, use a reducer fitting to get the the next smaller size pipe, and use that smaller pipe for your mixing tube. Remember to smooth and round the threaded end of the reducer fitting on its inside, so that it doesn't interfere with the flow of incoming air.

(2) It looks like your gas jet isn't perfectly aligned to be axially true with the mixing tube; it can be bent a little to get around that. When you thread the reducer fitting into the "T" fitting will be the perfect time to look and see if the jet is centered, and adjust it.

(3) Judging from the tiny size of your burner the chance that your gas orifice is too large is likely; what size pipe is your mixing tube, and what size drill bit did you use to make an orifice?

I can only hope you stay with us and tough your way through any discouragement. Such a great little forge deserves to be finished

There are easier burner designs to miniaturize than a "T" burner, but none of them are as well suited for use in a box forge as Frosty's burner is.

 

[Latticino]

6 hours ago, Vykk said:

flush with forge top or half way into the brick

Normally I would suggest half way with a slightly stepped hole to protect the face of the burner, but it really depends on the flame length you get from your burner. Right now you are too close to the floor, and ruining the flame envelope which appears to be giving you an insufficient burn inside the forge with left over gas combustion outside. Personally I think these baby burners would benefit from a pretty pronounced flair (or stepped transition with a flame retention nozzle), as most I've seen appear to struggle with flame retention at their peak firing rate.  That or they have long, narrow flame jets that are like yours and impact too early in the size forge they are designed for.  Haven't done any testing,  but will have to play sometime.  Maybe I'll cast a baby multiport burner.

[Vykk]

Thanks Mikey.

Not a jeweler. I'm a 24hr cargiver for my 100% disabled veteran father but also hobby knifemaker/artist.

I did have a hard time finding the right T for the burner. The openings were all 3 at 1/2" but i did bore out the 2 cross with a grinder till smooth to no thread and to 3/4" also added 3 downard drilled vents to add a bit more air to try to stop the sputtering i thought it wasnt getting enough air.

which direction did it look like i needed to move the tip? 

lastly the mixing pipe is 1/2" × 4" long. Here are a few other pictures. of the burner. the opening orifice drilled into the top of the top brick was made with a 7/8" drill and then finished with a large round file. i welded a post to the top of the sheet metal and have a very solid mounting that is 1 screw to pull off the burner to let forge cool down while the bricks weep heat after the forge is off. i noticed after shut down it got 10 times hotter than in operation.

My next round of testing i'm going from a .035 mig tip to a .025 tip and pulling back burner up to be about 1/3to 1/2 way in rather than all the way down and I'll let you guys know if it helps. Haven't got to a 20lb tank yet either so I'm still firing out of the 1lb camp bottles and no regulator. I'm fairly certain that would go a long way towards being able to solve the problem.

 

 

[Mikey98118]

The "T" burner design has no lack of available incoming air from its two entrances. As designed by Frosty, it also has no lack of swirl in its air; reducing flames are fuel rich. Turning that description around, i\they might be described as air poor; usually incorrectly. "T" burners--as designed-- induce more air than mine do, which is why they can use larger gas orifices to give neutral flames than mine. However, A Frosty burner in a 1/2" size would need a .030" MIG tip (I think), where as mine can use no larger than a .023" tip at Maximum. So change out your tip for a .030" to begin with.

It is not a matter of you drilling the mounting hole for your gas assembly incorrectly, but if you look intently at the photo of your burner laying on its size, and allow your gaze to go back and forth between the axis of of the of the gas assemble, and the axis of the mixing tube, you will see that the two aren't parallel.

Furthermore, your latest photos show that the "T" fitting is cast out of square with itself. So your gas jet will be out of parallel with the mixing tube in two directions. None of this is your fault; it is a design limitation of burners that require pipe fittings, which increasingly are cheap imported junk; this wasn't your fault, but it is still your problem. I don't know whether or not the side holes will degrade the burner or not, but they are at best unnecessary. Frosty has repeatedly stated that getting rid of the threading from the two incoming air openings do not improve burner performance, and that he suspect it may actually degrade it.

Your best chance to correct your alignment problems with the gas jet, is to build a special fitting that will allow you to mount a water hose to the burner, in order to see where the jet of water ends up as it exits the burner. You can then partially fix the problem.

What I would suggest instead is that you go back to the hardware store, and buy another "T" fitting. This time, screw pipe nipples into all three openings to assist your inspection of them, before purchasing one. Out of a whole bin of fittings you should be able to find one that is good enough. I'm very sorry, but those are your choices

Frosty, do you concur?

Don't forget to pick up a reducer and 3/8" pipe for the mixing tube. Then you will need a .023" MIG tip to run your new 3/8" burner size with. You will probably be pleased to know that the smaller burner size will produce a shorter flame, and that a neutral flame is also shorter than a reducing flame, so your problem of the flame being to close to the work will likely vanish.

[Buzzkill]

FWIW, I've had good success with .023 mig tips in 1/2 inch T burners.   I've typically had to trim them back 1/8 inch or more to pull in enough air to make them slightly reducing.

One way to find the right spot on the T to drill the hole is to screw the mixing tube into the T, place the mixing tube on the slightly parted jaws of a vise or in a piece of angle iron oriented like a V (with the T over the edge so it doesn't raise the mixing tube up), and then use a felt tipped pen or marker fastened to something that won't move around and about the right height to draw a circle on the T as you rotate it.  The center of the circle is then centered on the mixing tube regardless of where that happens to be on the T.  Center punch the middle of your circle then screw the floor flange on the other end of the mixing tube and drill as outlined in Frosty's instructions.

[Vykk]

19 hours ago, Latticino said:

Normally I would suggest half way with a slightly stepped hole to protect the face of the burner, but it really depends on the flame length you get from your burner. Right now you are too close to the floor, and ruining the flame envelope which appears to be giving you an insufficient burn inside the forge with left over gas combustion outside. Personally I think these baby burners would benefit from a pretty pronounced flair (or stepped transition with a flame retention nozzle), as most I've seen appear to struggle with flame retention at their peak firing rate.  That or they have long, narrow flame jets that are like yours and impact too early in the size forge they are designed for.  Haven't done any testing,  but will have to play sometime.  Maybe I'll cast a baby multiport burner.

I just finished my first test after pulling back half way into the brick as you suggested and moving down to a smaller mig tip. this one is a .025.

[Latticino]

Well, now you are at least getting a hot spot on the floor in front of your flame. Don't like it lifting off the end of the burner. Have you tried running it for a while at lower, more stable press till the forge interior gets hot enough  then turning it up?

Weird bricks. Are you sure they are insulating fire brick, not hard fire brick?

[Vykk]

Called the guy at the fireplace store and he said they are ceramic fireplace brick rated to 2700 degrees and thats why they're half red half white. k-26? they were easy to hand saw to fit together.

haven't tried to light and heat fully yet. forge was on less than 5 minutes before recording and this was about 3/4 pressure on small bottle. will try more later when im back at home.

[Mikey98118]

Most of your burner problem went away with the MIG tip change. I would bet on the axial misalignment to be at the bottom of the flame"s instability. On the other hand, Latticino is correct that a heated forge may tolerate it just fine.

[Frosty]

Vykk: If you'll put your general location in the header you might be surprised how many members live within visiting distance. Also with 4,500 members in 150 countries it means many things common to me might not be available to you at all. Make sense?

Don't buy your plumbing from a big box store, they carry very little stock of the most common possible size and type as determined by the bean counters in corporate. Go to a real plumbing HVAC supply, you can call a plumber and ask where they buy supplies if you can't find one. Believe me plumbers don't go to Home Depot unless it's a serious emergency. In the USA 3/4" x 1/2" Ts are one of the most often used T fittings out there, almost as commonly used as 1" x 3/4" Ts. I've never been in a real plumbing supply that didn't have bins full of them and cases in back. 

Another trick to check alignment is to sight up the mixing tube while holding it at arm's length aimed at a light. Look for light shining through the jet orifice. It's easy to gauge center by eyeball this way. 

0.030 is way large for a 1/2" T, one of the guys in our club is really good at 1/2" Ts and he uses 0.023" mi tips. He found the hold back on the jet to be less than I recommend for the 3/4" T. He places the tip about 1/3 of the intake diameter back from the throat. The flame is jumping off the torch because the psi is too high but that's what is inducing enough combustion air to get that good a flame. Your's actually seems to be burning pretty well for such a large jet and high psi but its still not right.

A ball valve is a shut off valve NOT a control valve. Put the ball valve after the regulator and the needle valve before the jet. Any good sporting goods store will have a hand bottle to hose and tank fitting to adapt camp stoves, lanterns and plumbing torches for running off regular propane tanks. Heck, a real plumbing supply will carry them, you never see plumbers using a Bernzomatic torch do you? I use a Bernzmatic to light my forge if I don't have a dry scrap of paper handy. 

23 hours ago, Mikey98118 said:

Frosty, do you concur?

Yeah, I agree Mike, that's a wonky looking T. I'm never surprised when the the face of the screw joints aren't square but you don't usually see Ts with the threaded fittings out of square like that. Just pick three longish, say 6" long nipples at the plumbing supply and check to make sure all three are at 90* to each other. The Jet MUST be aimed as straight down the tube as you can get it. Use a lathe if you have one available but the floor flange on a drill press table trick works well enough.

If someone at the supply shop asks what you're doing tell him you're a blacksmith and you need good quality fittings for this project. I avoid telling them you're making a propane burner! They have liability issues helping anyone not a certified HVAC tech, especially one making his own propane burning appliance. If you tell them you're looking for something to use for a propane jet they'll show you propane jets and fittings and you're sunk till they go away. Been there, got the T shirt. The guys just point me at the row and bin when I ask them for something but I have them trained. Invited them to  a demo and showed them what I do with the plumbing.

I don't buy those being K-26 ceramic tiles, wrong texture but I could be wrong. Do they feel light or heavy?

More later. Frosty The Lucky.

[Vykk]

Thanks for all the help guys. its working far better already and im sure that after i can find better parts and work the peices out all will fall into place and this little guy will roast like a tiny dragon.

I'm not 100% on the type of brick but the hey are much lighter than they look, easy to cut and they guy at the fireplace shop did say they are 2700 degree ceramic firebrick he didn't say k-26. They do also retain heat for probably an hour or more after i shut off.and longest run time so far has been about 20 min.

i am considering rounding the brick joinings inside the forge with castable refactory then wraping the entire unit in kaowool then another metal case around that to hold more heat in. would that be a total waste of time or worth the effort? I'm making this little unit more for portability for demonstrations than anything else but i think I'm finding love the on/off firepower vs my usual method of coal and forced air so probably will upscale a bigger unit for maybe sword length in the future.

Frosty, thanks for the reply, and i hope all is well for you there with the rocking and a rolling in the area. My sister still lives in Anchorage and i heard of all the quakes. scary stuff stay safe!

edit: By the way My general location is Portland, Or.

[VainEnd84]

1 hour ago, Vykk said:

edit: By the way My general location is Portland, Or.

People won't remember that, you can put your general location in the header of your profile so when so.eone wants to know it's always there! 

Also your burner is looking pretty good!

[Mikey98118]

5 hours ago, Vykk said:

i am considering rounding the brick joinings inside the forge with castable refactory then wraping the entire unit in kaowool then another metal case around that to hold more heat in. would that be a total waste of time or worth the effort? I'm making this little unit more for portability for demonstrations than anything else but i think I'm finding love the on/off firepower vs my usual method of coal and forced air so probably will upscale a bigger unit for maybe sword length in the future.

I would look in the opposite direction for both fuel efficiency and and convenience. You have choices as to the form of fuel source you employ; canisters are highly portable, but D.O.T. fuel cylinders are way cheaper to use. The first step to having that choice comes from buying a special fuel hose assembly that is meant to allow 16 oz. fuel canisters to screw into one end will the other end, four feet away screws into the original bottle mount receiver, allowing your burner and fuel cylinder to be separated (much more convenient than mounting the canister directly onto your forge). There are also fittings that allow the a regular fuel cylinder to be attached in place of the canister, saving a whole lot of many in fuel costs. Last time I checked, this hose assembly could be purchased through Amazon.com's propane section for about $20; a lot less money than trying to super insulate your little forge

[HojPoj]

Looking at your bricks, is there a reason the ceiling brick has a groove cut in the middle of it?  In thinking about the propensity for the bricks to develop cracks in use, you've essentially created a stress riser that guarantees you're going to get a crack there.  If there's something 'hugging' everything together that I'm not seeing, then you're likely ok.  If the top brick isn't being pre-loaded then when it cracks through it may just fall into the middle of the forge.

[Mikey98118]

On 12/1/2018 at 8:52 AM, Frosty said:

I don't buy those being K-26 ceramic tiles, wrong texture but I could be wrong. Do they feel light or heavy?

I agree; they aren't K26; that being said they are certainly some kind of insulating refractory, how insulating and how tough, who knows? It's a whole new ball game out there.

[Vykk]

2 hours ago, HojPoj said:

Looking at your bricks, is there a reason the ceiling brick has a groove cut in the middle of it?  In thinking about the propensity for the bricks to develop cracks in use, you've essentially created a stress riser that guarantees you're going to get a crack there.  If there's something 'hugging' everything together that I'm not seeing, then you're likely ok.  If the top brick isn't being pre-loaded then when it cracks through it may just fall into the middle of the forge.

the reason for the groove was that the original model i made before the  burner came along had just a small hole with a bernzomatic torch poking in it. as soon as all the air in the forge got sucked into the flame it just puffed out. i was creating a vent at that time to deliver air to the torch. it was fine to make a few 3" construction nails into letter openers but nothing bigger.

i widened the hole for the burner but didnt replace the brick. the sheet metal is squeezing the bricks in pretty tight and i have screws holding the metal to the sides and top bricks so they cant wiggle around. 

You are right the brick on top will need to be changed eventually because there is a crack forming. Luckly it's not crumbling or gapping right now and the top still isn't getting too hot durring operation i check frequently as im still testing and haven't  yet forged out of it. After shutdown the heat starts building fast so as soon as i turn off the burner it comes out and is removed so its nothing but brick weeping heat at that point.

 How big of a safety risk is likely present from this?

In my next build of the forge space I intend to make a fix for this problem or use kaowool for the sides and top and use heavier plate welded together for the outter shell instead of just sheet metal.

Which would be the more efficient way to handle this problem?

Mikey i do have a hose that goes from the forge to the camp bottle so the bottle is not attached to the top. I've also got the one to hook a 5gal to that connection.  I have a problem of no pressure when i try to run that way the 1lb bottle has enough pressure without a regulator but the 5gal does not. i haven't found a connection that would allow a pressure regulator between the 5gal and 1lb bottle connection. Is such a connector even out there? 

[Mikey98118]

I just cut off the end of the hose assembly that the canisters normally goes into, and replace it with a hose barb so that it can then be attached to a regular torch hose. But there is a long list of threaded hose connectors that can be used to do the same trick. i go this way because I prefer a lot longer hose than just four feet between hot work and propane cylinders. I like my cylinders kept outside the shop, just like safety regulation insist on.

2 hours ago, Vykk said:

Which would be the more efficient way to handle this problem?

Nothing is easier than using a cheap import carbide encrusted hole saw to cut large holes through ceramic tile, brick, refractory, etc. High alumina kiln shelf can normally be purchased cheaper tan steel plate. The kiln shelf gives some insulation and is designed to carry moderate weight in kilns at several hundred degrees higher temperatures than a forge will get to. End of problem.

[HojPoj]

Unless you're piling combustibles on the forge after shutdown I don't see much in the way of safety issues.  If the concern is the burner getting too hot from chimney effect, then pull it out or cover the ports to slow the movement of hot gases.

As far as the shell goes, unless you're using it to support a lot of externally mounted stuff then thicker isn't necessarily better (unless weight if the forge is a metric for success).

[Vykk]

43 minutes ago, HojPoj said:

Unless you're piling combustibles on the forge after shutdown I don't see much in the way of safety issues.  If the concern is the burner getting too hot from chimney effect, then pull it out or cover the ports to slow the movement of hot gases.

As far as the shell goes, unless you're using it to support a lot of externally mounted stuff then thicker isn't necessarily better (unless weight if the forge is a metric for success).

Portability is a metric for success. However when i shutdown i remove all combustables from the forge for seperate storage.

My only concern would be while in operation if the top brick cracks through or if a lot of heat should make its way through. i do touch the mixing pipe bare handed every 5 to 10 minutes now to check pipe heat. so i guess the main safety question with cracking bricks should i do more to insulate above while operating?

[HojPoj]

If efficiency is one of the things you want from your forge, then more insulation is always better.  Keeping the cracks from opening up and creating gaps is all you need to mitigate.  The fracture planes are rough enough that if you keep the cracked bricks physically held together then there shouldn't be any real loss in insulation effectiveness.

You keep using the phrase 'heat making its way through', do you mean the outer part of the forge actually getting hot?  The heat energy will find its way out one way or another, it's just a matter of the paths and transfer mechanisms available.  What's the longest you've actually run this small unit?  Once it reaches steady-state operation (probably 45 minutes or more) you'll have a good idea of whether the conduction through the walls is the primary heat transfer mechanism or radiation/convection are what's causing more of your heat losses. 

The outer metal skin should really only be there to keep the insulating stuff from spilling out (much like skin does with our guts).  It's not supporting a significant load, so no real reason to make it really thick.