New forge build...

[Savlaka]

So after a number of years without one, I'm finally getting around to building a new forge.  I'm doing a number of things differently this go around (different from how my last one was- not different from many other people's designs).

My old forge was a Brick monster - two layers of brick thick, with a cast tubular chamber... Impossible to move, and took forever to heat, but stayed hot for a long time.

This time I'm going much lighter in construction- steel body, ceramic wool insulation + coatings.

 

This is the main forge casing and test fitting the insulation to confirm my mental planed size is what I end up with. I still need to build the runners for the door, and the work rest, looking around for some more scrap steel... This has been entirely built from scraps so far, though I'll need to use new metal for the burners.

The internal size is 4.5 x 4.5 x 24" - I plan on using two 3/4” class burners, something along the lines of a hybrid style burner if I understand the terminology I've been reading on here correctly. Most of the time I'll really only use the front section for working the metals, the length is mostly for heat treating longer items.

I have a bunch of colloidal silica from my epoxy work (around 8 Oz by weight) to use for rigidizing the ceramic wool. I haven't worked with ceramic wool before so I did wonder if I can "paint" it on with a brush instead of a spray bottle? as the opening is long and narrow. Or if I can soak the silica mix into wool then install it into the casing then heat it?

After rigidizing I plan to coat with simond Heat guard refractory coating. I'm using this mostly since I have it, found a pail of it locally for cheap ($20 instead of the $45+ it normally goes for). I'm planning on about a 1/8 -1/4” layer over the inside and exposed faces of the insulation.

Then I will coat it with ITC100 - again using this since I got it at a discount ($25 a jar VS The $50+ it normally sells for) and I liked it last time I used it.

The burners are being made from common steel pipe, I'll acid wash off the galvanizing before I heat them up.

This is the initial stage of the burner build, air slots roughly cut out of the 1" pipe, and test fitting to the 3/4" mixing tube... Yes the tube is too long at this point, it'll get cut down eventually. The cut slots are around 2.5" long probably a bit under, I still need to file and grind them to their final shape. The choke will be a section of 1-1/4” pipe that slides up over the slots.

For a nozzle I'm looking at using 316 stainless sanitary weld on reducers. They look like they'll work well and are fairly reasonable in price. I picked up 3/4 to 1” and 1 to 1-1/4" along with a small section of 1" stainless pipe to make a bushing from if needed.

The Jet will be the Oh-so-common mig contact tip in the end of a section of 1/8” heavy wall brass pipe and secured through a 1" pipe plug. Not trying to re-invent the wheel here...

 

I'll add in updates as I get to finishing sections...

If someone sees a glaring issue with this build plan feel free to point it out.

[Frosty]

I don't see any "glaring" issues though I'm not a fan of using fire brick as the floor in a forge, there are better alternatives. I lay the hard refractory thicker on the floor but using kiln shelf is probably a better choice as it's higher temp more chemically resistant and easy to replace if it gets crudded up too badly.

Sure, you can apply the rigidizer before installing the ceramic blanket. I prefer to handle ceramic blanket wet to prevent fibers breaking loose and getting airborne. I wear a mask regardless. 

I don't know anything about Simond Heat Guard, it sounds like a kiln wash on their site though it has advice for applying it thicker than recommended. I couldn't find a MSDS without joining some sort of "service" and it wasn't actually listed so I declined. 

Mike will have better advice regarding your burner build. Their orientation in the forge will make a big difference in heat distribution. A chamber that long and narrow will want a strong swirl and good hang time for even heating.

Frosty The Lucky.

[Savlaka]

Thanks Frosty.

As to the Simond heat guard - from what I Saw it seems to work like a thin hard coat over the ceramic wool. I don't know if you call that a wash or what... I got it from someone local who bought more than they needed, his was used for a smelter he built. He mixed it with a bit less water than the instructions called for, and basically painted it on kinda thickly, then smoothed it out with a Plastic spreader (like for auto body work). He's been using his smelter for about 6 months now and there's very little damage to the coating despite the use - Even on the lid or the rim of the lower section where it gets bumped occasionally. And the ITC-100 he coated it with is still staying in place too. So I Figured it should do for my needs...  If not, well I can always redo the insulation and coat with a different product next time.

[ThomasPowers]

Smelter (making metal from ore) or Foundry Furnace (melting and casting metal)?

If they are really smelting I would like to get in contact with them!

[Frosty]

A forge is going to get more than ""bumped" occasionally, you're going to be poking and scraping it with cold sharp steel on an ongoing basis. 

Lifting tongs for a melter are typically round stock and curved to reach under the crucible so even a ham handed operator isn't going to beat up on the liner like a forge can expect every time you use it. 

The literature on the website reads like it's a kiln wash. ITC-100 is a kiln wash but has a whole different purpose than what a forge needs. It's mostly a release agent so melted . . . stuff doesn't stick to the inside of the furnace or kiln. It doesn't fire hard but if you don't rub on it it's almost indestructible, chemically it's pretty inert.

A forge needs a kiln wash that can take a beating while surviving the rapid thermal cycling a propane burner produces and some aggressive chemical erosion produced by propane combustion and welding fluxes.  Molten borax based flux dissolves Kaowool like hot water on cotton candy, common silica based fire brick lasts better than a sugar cube but not as well as rock candy in hot water. A good kiln wash will pay for itself pretty soon.

Were I using it as the hard inner liner / flame face I'd sure make it thicker than the web site calls for. 1/4" or less laid over a soft base like ceramic blanket, even rigidized it WILL flex, isn't going to stand up to much rough play.  3/8" might do it, I don't know, the only info I have at hand is on their site.

Frosty The Lucky.

[Savlaka]

Thomas - "smelter" is the term he uses but he mostly just melts and casts stuff. I never got into that side of metalworking.

Frosty - while I'd planned to use that Simond heat guard material for a base to apply the ITC100. I never actually expected it to make the forge as tough as a solid brick.

Whatever the castable type was that I used last time was super soft, I could gouge it with my fingernail. But with a little care that forge's tube lasted years anyway... I learned to set items into the tube, and to not drag them out but lift them out. I'm guessing it'll be the same with something like this...

It's only about $40-50 to fully replace the ceramic wool, so I figure I might as well try it out.

[ThomasPowers]

It's a common mistake---which is why I asked.  Unfortunately it indicates that they don't know the proper terminalogy for what they are trying to do and so folks may not want to share information that can be dangerous in the hands of people who haven't done their background learning.  I have done both foundry work and smelting of iron ore into real wrought iron and have friends who focus on only one of them. You learn fast that being able to use the jargon properly gets you clear specific answers to questions you have.

Looks like we will be doing a bloomery run out by my smithy sometime during the cool months; I've got to track down a local source of Goethite and start preprocessing it! 

[Mikey98118]

A high-alumina kiln shelf would make your best bet for a floor: the reason for that is that it is smooth and flat. If you want to save gas in such a long forge, you need to do more than shut down some burners, when hitting a part of the forge. You also need to add a movable baffle wall. That baffle needs a smooth flat surface to set on.

Remember to drill 1/8" holes in the bottom of the forge to allow steam and water to escape during drying. Remember to add some food coloring to the colloidal silica and water mix, so that you can see it soak the ceramic fiber completely through.

Did you remember to bevel the inside of the mixing tube, before pushing it into the pipe nipple?. You don't have to have a flame retention nozzle on a burner mounted in a forge. Bettery nothing than what you have in mind.

[Savlaka]

Mikey -

I hear you and frosty on the subject of a kiln shelf, what I'm running into is not being able to find anywhere local that sells High alumina type shelves, the one "store" (it's more of a school than store) I found only carries the carbide types and also told me that the next nearest place I might try is over 100mi north of me. the 3 online stores i tried are all charging an outrages amount to ship them -$52 in shipping $15 in packing for a $30 shelf that I might be able to cut to size. while firebricks might not last as long I can get a box of 6 hard type 1/2 thick or 4 insulating type full size 2700 degree rated bricks for under $40 delivered. I planed on needing to replace them occasionally, this doesn't bother me, and if I find a source for the shelf eventually I'll replace them with it.

i planned on using a hunk of insulating brick as a moveable wall to close off 1/2 the forge when I don't need the full length.

there's already a few holes in the casing metal, i can add a few more along it's length to vent the steam.

the upper edge of the 3/4" mixing tube is beveled, in that photo i was only friction fitting the parts together the final burner will be welded. 

The nozzle types I was looking at was  using the reducer I pictured as a starting point to hammer out a tapered nozzle. as i understood the sizing for a tapered nozzle it needed to go from outside the mixing tube to about the outside diameter of the next pipe size... 

I also have a straight piece of  1-1/4" SS pipe i can put over a small section of 1" SS pipe - as i understand it you call this a stepped nozzle...

and i do know i don't require one but my experience with the last one i built showed me it was a lot simpler to do most of the tuning outside the forge.

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This particular forge project was started with the goals of getting a working forge back in my shop (so my anvil can stop rusting away from lack of use) and addressing some of the specific issues i had with my last one - namely, 1: The ability to move the forge as needed; 2: shortening the heat up times; 3: the ability to heat treat longer Items. This is only the first new forge I plan to build. once I get this one up and running (and relearn how to work metal), I plan to build a second one along a more traditional shape. specifically for  blocky objects and small sized irregular shaped items (hammers, shelf brackets, ETC). and once that one is working I May try out building a set of ribbon burners to rebuild  this one with, as they look like they'd actually work better for heat treating (and a molten salt bath or electric heat treating oven is out of my price range)… But since I want something that'll work for now, and let me try and finish or fix a number of old projects that I still have sitting in a box. I'm building this one first.

[Mikey98118]

It seems to be that your mind is ticking over just fine. We all have to do the best we can. Half bricks are a good enough solution, until you can do better.

You would really be better off with a stepped nozzle, and they are a lot easier to deal with. You/re doing fine so far. Just keep truckin.

[Frosty]

Savlak: I mostly ditto Mike, you have the right attitude  for this stuff. Building something that'll work and planning your next one's mods while using #1 is just good technique.

There are always better ways and tweaks, I've never been "satisfied" with a burner or forge I've built though a couple have turned out WAY better than I expected. NARB was a lucky hit for me. 

Anyway, I really look forward to seeing what you come up with and will be around if I can answer questions.

Frosty The Lucky.

[Mikey98118]

What Frosty would probably like to say is that you should stick around and keep speaking your mind. I ditto Frosty on that

[Savlaka]

Got in a bit of work on the burner prototype during the evenings this week. It's a bit rough but should work... this is in line with figuring out my final design, I expect some problems with this first one and I'm hoping to figure out what construction methods will work best for me, and the tools I have.

The slots are still not pretty, the only drill press I have right now is a piece of crap 8" bench top type, with a lot of runout (visible amounts) and no way to fix it. It's fine for what I bought it for, woodworking, just kinda crap for any real precision work.

Speaking of Wood... I wondered if I could make the air intake and jet holder from Hardwood? That section of the burner should not be getting hot enough to damage something like IPE or Brazilian Cherry (very hard and dense wood types). I have a fairly good selection of woodworking tools to cut and shape it with... Hmm, I Might have to try that out...

I made two jet tubes, one for 1/4-27 (14T) sized tips and another for 6mm x 1.0 (11T) tips As I already had a pile of the 11T type tips for my welder.

I haven't put together the nozzle yet. And I need to get my tanks filled before I can test anything anyway. Perhaps this afternoon or evening I'll get a chance.

I think I'll be doing the two of these as I've been to get up and running, and then use what I've decided I liked to build a more finished product for the next forge. I finally found a metal supply store that will sell in small quantity's that's Semi- local (1hr drive) interestingly enough it's not 2 miles from the only actual Hardwood lumber yard I could find.

------------------

Mike, frosty,

I'll be around... I looked at a number of fourms before choosing to join this one, and you two were part of that decision. I respect the time and effort you both put into forge and burner design and I can see that your normal suggestions to people are good ones and based on plenty of experience...  I don't expect to always follow that advice, wether because I can't find the material, don't have the right tools or just want to try something I think will be better for me... Even if it turns out not to be.

Every craftsman has to work with the materials and tools they have, and also has a personal method to reaching an end product. What works for one, may be the most fustrating thing to the next one.

For small items like these burners, I'll build a rough version, play with it, then use what I learn to make a better version. My old Gas forge used a design based a 1" Reil burner, with a few things done different for my tools and materials, it worked fairly well though after reading through the information available now (the last one I built in 2003 I think) I can see I was running a bit lean with that one.

I've found that making a tool that works now but will only last so long, is better for me than trying to make the perfect tool that'll last me years the first time, often having a workable tool now helps me make that better version later...

[Mikey98118]

3 hours ago, Savlaka said:

Speaking of Wood... I wondered if I could make the air intake and jet holder from Hardwood? That section of the burner should not be getting hot enough to damage something like IPE or Brazilian Cherry (very hard and dense wood types). I have a fairly good selection of woodworking tools to cut and shape it with... Hmm, I Might have to try that out...

Another Frankenburner gets away with using plastic there, when trying new burner designs. However, I can't recommend it on a permanent basis, as it leaves the gas line vulnerable during a fire. Others might find that a minor point, but I'm pretty conservative on safety issues.

[Savlaka]

Tossed together a simple nozzle to run a few tests on the burner as it is:

I'm using an old fuel gas regulator for a torch set... This one works up to 25psi, while the regulator section is in good shape the Guage's are a bit worn out, so they don't read very well below 5psi.

This is running the .030 short type 11T mig tip.

My camera really brightens the colors a LOT... I had to edit the exposure to the minimum to get these remotely close to what they actually look like. At 5 psi visually it's dark transparent blue, and actually hard to see even with the lights off and the garage door only open about 24". But the camera really made it look bright blue/white before I edited the shot - that's what I get for a camera that works well in low light conditions... LoL.

Edited August 29, 2021 by Savlaka
Added size of tip

[Mikey98118]

If that is 3/4" pipe for the mixing tube, then I would suggest trying to find a 0.025" MIG contact tip; not a  0.023" tip.

[Savlaka]

I have .025 tips on order already, Along with the larger 1/4-27 thread size types. They're just not a size I normally kept for my welder, I had .023, .030, .035 and .045 in my welding box to test with. I tested .023, and .035 but it just didn't run right with the 0.23 one- had to choke it over 1/2 to work. For the .035 it was hard to not get a light blue with green inner flame at higher pressures, and it was definitely fuel rich with  much longer tongues of flame.

 

This version looked mostly useable to me, but I still planed to test the .025" tips.

Edited August 30, 2021 by Savlaka
Kept making typos

[Mikey98118]

When I started out, there were no .025" tips. I made .023" tips work by doing everything "just right" on the design. Using .025" tips are just a lot easier on people

I would have started suggesting the change last year, but so many sellers were pushing .023" tips off on folks as .025" that I thought my readers would just get frustrated; this problem seems to be settling down now, though.

[Savlaka]

Well, since my roughly built prototype burner more or less ran ok, I started work on the more refined version I'll actually be using... Still a hybrid type - same basic design, just putting more work into the refinement of the parts and the fit and Finnish of the final product this time.

This time the inner end of the 3/4” pipe mixing tube is getting a smooth transition ground in all the way to the edge, instead of the quick short bevel (maybe 30-45 degrees) I used in the prototype.

And yeah that's my wood lathe it's chucked into... Using files, a Dremel, and similar tools while it's turning at the lowest speed the lathe works at (375Rpm IIRC) to keep it concentric. Each of the parts will end up here to get cleaned up a bit.

I've ordered a better fitting tube for the choke to replace the sloppy fitting 1.25" pipe, and some 1" brass rod to make the gas jet holder from. Speaking of the gas jet, this time I'm using 8mm OD 1.5mm wall brass tube. This is a bit slimmer than the 1/8" pipe (0.315 vs .405) and already the right inner diameter to tap for the 6x1.0mm thread that the 11T type mig tips use. I could probably have gone all the way down to 7mm OD 1mm wall but I can still file this one down into a tapered end.

The intake chamber will get better made air slots this time around... I understand a square slot is better than round holes or ovals, but I wonder what the best geometry is for the sides of the slots themselves? Straight square edge, inner side beveled, outside beveled, both, rounded? From what I understand about fluid flows I'm guessing outside bevels. But I'm better with airflows for aircraft wings than for something like this. It might be some combination of straight and inside bevel to help establish a better suction or vortex for all I know.

[Mikey98118]

You have a Dremel rotary tool? Then, you may want look into some refinements that are being discussed on the 3D burner thread

[Savlaka]

I hadn't delved into that thread, as I don't own or have access to a 3D printer... there's some interesting shapes working well in there. I think I'll save anything that complex for another project. though he does show that an airfoil shape works, I might try and do a reversing bevel - inside in one side outside on the other to add a small amount of inward spiral effect to the slots...

[Mikey98118]

Every small improvement--in air swirl--at the burner's air entrance(s) gives an outsize improvement in the flame. Anyways that's how things have gone for me in the last 22 years

[Savlaka]

So I finally got time to finish up the 2nd version of this hybrid burner. I have a bit more testing and tuning to do, but it's looking good so far.

I tried a .025 tip, but the flames were definitely oxidizing at any setting. Super dark blue even at higher pressures. So I moved back to the .030 tip

With the .030 tip it looked much better. Especially once it heated up the nozzle a bit.

[Savlaka]

I also found a 94% alumina dense castable refractory rated to 3200 deg. I'm thinking it will work for making the floor out of seeing as I haven't found a good source for the kiln shelf. 

I'm thinking a 1/2" or so layer on top of a 3/4” thick chunk of insulating brick should work, and make it fairly flux proof.

I may also try it for making a ribbon burner at some point.

[Mikey98118]

1 hour ago, Savlaka said:

also found a 94% alumina dense castable refractory rated to 3200 deg. I'm thinking it will work for making the floor out of seeing as I haven't found a good source for the kiln shelf. 

That would certainly be up to snuff, in most ways.  What is missing is any background information about how well it holds up under the fast temperature changes that happen in gas forges. Most refractories with that high an alumina content are used in glass working equipment (which has sustained high temperatures and very slow heating and cooling cycles) ,  or for crucible in especially high heat foundry work. Mind you, the refractory might be just fine. I would love to here what brand it is. But, one of the reasons we keep recommending Kastolite 30, is that it is thoroughly well known to be satisfactory for use in gas forges. Having your refractory crack, is such a major downer