Care to review my plan? (WC forge w/Frosty's T burner

[Nomad]

Well, I think I’ll try something new and try doing something the right way the first time and NOT waste a bunch of time and cash… To that end I am going to try to line out a materials list and put forth a couple questions I have been unable to answer scouring the forum here and the plans I have downloaded.

A little background on me, I’ve built a couple gassers that worked fairly well over the last few years but currently (multiple moves recently where some stuff just didn’t make it) don’t have a forge. I have a fair few tools of various qualities and a little experience in a lot of different stuff. Specific to this project I have a buzz box welder that my very limited skill set can make work.

My goal in this is to build a propane forge that will allow me to work basic techniques until…well I outgrow it. I’m a cheap/broke hobbyist so I don’t need anything commercial quality and I enjoy the building side almost as much as the using so I don’t want to buy a manufactured one. I use a fair bit of reclaimed steel so I want something large enough to get odd shaped pieces reformed to bars that I can use (think opening eyes in leaf springs). In a perfect world (and this seems reasonable) someday I will start doing some forge welding practice and this forge should allow me to start. I figure that about the time I need to reline the forge, I may consider a new design.

My intent is to use a 20# propane cylinder as the body and follow Wayne Coe’s design. I am currently planning on firing it with a pair of Frosty’s T burners run off a 100#er I have. I already have a regulator that I’ve used in the past with good results.

As I said, this post is to try to consolidate thoughts and pose a couple questions. I apologize beforehand if these have been answered elsewhere on the forums; I have literally reviewed them for hours. (I work a job where I have a lot of time on my hands to do so). Some of my questions are more… academic as I am stuck planning at the moment and am curious more than anything. 

Let’s start with the burners (parts to make 2)

• 1"x 3/4" black iron plumbing T (2)

• ¾" x 6" black iron nipple (2)

• 1/8" mpt x ¼" flare fitting (2)

• 0.035" Tweco mig contact tip (2)

• 1” x 3” black iron nipple/pipe (2)- I intend to use these to mount my burners to the forge body. I have had good luck in the past thinning the outside of my nipple and reaming out the inside of these to make a tight slip fitting. I will weld these to the body and tap them to take the ¼” x 2” bolts to lock the burner in place

• ¼” x 2” Bolt (6)

Only question I have on the burner is this: I have seen references to cutting down the Tweco. Is that to ensure the tip sits 0.5XD from the end of the burner tube? I assume I’ll need to decide if that is needed during tuning, correct?

I have a working idea for my gas supply plumbing that goes from each burner to a length of copper pipe, then the regulator or needle valve (my plan is to use one of each though I might have a second regulator in my stuff) then to a T, a shut off valve, then to my rubber supply line coming from the tank.

With regards to plumbing, is the needle valve adequate to isolate my second burner or do I need another valve? My thought was when running just one burner to use the one at the rear but should it be the one closer to the door? I had also planned on welding a support arm to the forge body to secure the plumbing to, well away from the body itself. Is this a terrible idea?

For the forge itself, I need:

• 20# propane cylinder for the body (1)

• Hinges (4)

• Ceramic blanket (planning to buy Inswool from Wayne)- If my math is correct, the inside circumference of this cylinder is 39” and should be around 20” long if you include the ends. Figuring extra for the bottom, (5 linear feet)

• Castable refractory (Kast-o-lite 3000 or what I can get locally) (15 pounds)

• IR reflective (Plistix or what I can get locally) (1 pint)
• Fire brick for floor and end closing (have several on hand)

 

Regarding the forge, should I expect 1 pint of IR coating to do this or do I need to plan for more? Once the lining is in place, how thick will the walls of this be? I am trying to get an idea of what my finished volume will be (Wayne mentions 583 for a forge this size but is that shell only or shell with liner in place?) Also, I don’t have an oven to ‘kiln dry’ the castable as Wayne suggest. I’m in the Portland, OR area so humidity is going to be high no matter what. My thought was a few days with a candle or two inside it well buttoned up then a long low run with one burner turned as low as I can get it for several hours. AM I setting myself up to fail or is this a reasonable solution?

With this setup, should I plan to be able to do basic forge work (not welding) with a single ¾” burner and just kick on the second for bigger stuff/welding or would I be better off installing a pair of 1” burners? I know this forge is probably on the larger side (isn’t that a requirement for us new guys, overbuild the forge?) but I figure I will add bricks if needs be to decrease the working volume.

I hope I am not being too redundant with this line of questioning but your seasoned input is appreciated.

And I also very much want to thank the guys around here that put so much time and effort into sharing their experience and knowledge with the rest of us.

 

 

[Frosty]

Hmmmmm. That's a boat load of questions. When you guys want to know if you have enough burners you need to provide the VOLUME of the chamber. Telling me the length, Diameter or the CIRCUMFERENCE? Isn't going to do you any good, I'm not figuring it out for you. I'm not picking you out Nomad, most guys asking me basic questions do exactly the same thing. . . .Well, not the CIRCUMFERENCE(?) so far you're the first on that one. Give yourself a cookie you cam in FIRST! (sorry, couldn't resist)

You've obviously read my illustrated directions to list the parts so completely, why ask now?

Okay to business. 1/4 turn ball valves to isolate burners NOT needle valves. Needle valves are to control flow and using one as a gate valve you'll have to adjust it every single time you want to turn that burner on. Another important factor is safety, 1/4 turn ball valves can be shut off almost instantly. If something goes wrong and you have flames shooting out of places that shouldn't have flames shooting out, you want to be able to shut the gas off right flipping NOW.

Running 2 burners I prefer to use a non-flammable fuel line at the burners themselves they can get really hot so rubber hoses aren't the best. If your burners are horizontal and mounted low on the forge they won't get so hot from the chimney effect. Copper line fuel line follows. Tank, regulator, gauge, rubber hose. (1/4 turn valve is optional but a good way to shut the whole thing off quickly) rubber hose to the manifold which can be pretty simple, hose to 1/4" nipple or female pipe fitting depending on your hose end fitting. Nipple to a 1/4" pipe T. 1/4" pipe to 1/4 turn ball valves to 1/8" pipe bushing or Bell reducer. 1/8" MPT x 1/4" flare fitting. 1/4" copper tubing length as needed to 1/4" flare x 1/4" MPT on the burner.

The length of the copper tube, fittings and hose provide enough volume in a plenum to keep the pressure even to both burners.

The reason the mig contact tip in the burners gets shortened is to tune the fuel air ratio. Typically a 0.035 mig tip provides more fuel than a 1"x3/4" T will provide air for a neutral burn. If however the end of the gas jet is farther back from the end of the burner tube it will induce more air. So shortening the mig tip makes the burner bur more lean.

If for some reason it burns too lean from the start you can buy a larger dia. mig tip OR a longer one.

Hopefully that doesn't confuse you worse but I didn't cover anything here that I didn't in the directions. Just remember I'm not going to do simple arithmetic or list how the gas fittings go together for you again. I will however answer questions so long as I don't have to repeat myself. I've had people ask the same question repeatedly and I'm not doing that anymore. Okay?

Frosty The Lucky.

[Nomad]

Frosty,

Thanks for the info.

I 100% understand the need to base burner on chamber volume but I am kinda stuck for data. Not being where I can measure the cylinder I am going to use for the chamber has left me resorting to Google which has been tremendously unhelpful when it comes to dimensions. I can extrapolate some on a guess but so…

If the cylinder is, (rough guestimate as the only functional dimension I can find online is diameter)

• R=6 ¼ ”

• H=rounded to 12” for simple math (list as about 18 overall so guessing 6 inches for rings)

Gives me about 1470 cubic inches.

Now, I am guessing I can subtract the diameter down….3 or so inches for lining, that gives me a volume of a bit over 360 cubic inches.

Wayne says his propane bottle forges have a volume of 583 cubic so my guess on how much space I am loosing to the lining is off

My number puts it at the top end of your recommendation for a single ¾” burner (300-350) and Wayne’s well above it.  For the life of me I cannot find the volume you say for 1” burners but it sounds like I should scale up, especially since my intention is to use one burner only the majority of the time.

Yeah, circumference is only useful when trying to plan how much ‘wool to wrap the body in…not so much for burner sizing.

Thank you for the plumbing info. I will draw that out so it makes more sense (I’m visual) and make sure to put a shut off valve to isolate that burner. Sorry to press for more but I would like a little clarification if you don’t mind. You are saying I should place the regulator near the tank before the manifold. Does that mean you then tune each burner with the downstream ¼ turn ball valves?

Again, thanks for the assistance and I am happy to do whatever I can from the information I have.

[Frosty]

Calculate burner output by it's cross sectional area. a 1" circle has 2x the area a 3/4" circle does. Gun (blown) burners can deliver more because a blower can force more air (over or super charge) through the same burner tube's volume so you can turn up the fuel. More air:fuel per second more BTUs per second.

A problem you run into by over charging a burner is the velocity can just blow the flame out of the chamber and you have to get into flame holders, etc. A ribbon burner does a really nice job of super charging without blowing heat out of the forge. Lots of little flames instead of one BIG one.

Frosty The Lucky.