Fire place bricks

[Archie Otteson]

I have too many to count of these bricks in the yard that someone used as landscape edging. I have no idea how long they've been out there. Previous owner told me they came from an old house's fireplace.   They are softer than regular red brick and will mark on a concrete sidewalk.  How can I test if they are actually refractory bricks?  Does it really matter?  Should I even try to use them to build a gas forge? Is there a concern for being exposed to the elements for so long?  

 

[Frosty]

Ahhh, now we're easing into my territory!

Fire place brick is as far as I know won't survive in a propane forge. For the most part they're barely rated to more than maybe 900f. 

Testing them is pretty straight forward, make sure they are D R Y through. Time around a camp fire until a drop of water will sizzle on the side away from the fire. Next stack them close around the fire stoke it up and give it some forced air till they're high orange heat. 

I'd just test a couple, I doubt strongly they are suitable fire bricks but I'll bet they'd make a nice fire pit or if there are enough a nice masonry pit BBQ.

The blow pic is my no weld bolt together brick pile forge. It's made with Morgan Thermal Ceramics, K-26 insulating fire brick. IIRC 10 bricks a little flat stock and angle iron, some all thread, etc. The bricks are kiln washed with ITC 100, It's driven with a 1/2" T burner and welds easily. This pic is about 5 minutes after lighting, one of the guys stuck a piece of steel in it immediately, not wanting to wait.

Frosty The Lucky.

[Archie Otteson]

Thanks Frosty, That pretty much settles it for me.

On another subject you just mentioned, my T burner is in the works.

 

[Frosty]

Cool, please feel free to ask me any questions you have. I posted illustrated plans in the propane burner section, I believe it's even pinned.

Those forges and burners were part of a 2 day club, forge and burner build clinic. IIRC 32 forges got finished for a total cost of $104 ea. including regulator, hose and valve. That was one cool clinic, some of the guys had never hit hot steel and in two days were set to go to work. It started with guys not knowing which way to turn but by lunch it was going like a factory. Guys organized by skill and ability. We built the forges the 2nd. day and that day started with a group organized meeting to establish who did what.

All I had to do was fine tune a few burners and keep folks with zero shop skills from injuring themselves. Good times.

Frosty The Lucky.

[Archie Otteson]

Fantastic!!! I have some questions so please bear with me.  First let me say I have spent the last half of my truck mechanic career putting up with newby mechanic's questions and mistakes.   In my mind sharing knowledge is how we move the trade forward in a positive direction. I tip my hat to all who are willing to help out the new guys.  

I see the burner instructions calls for 3/4" black pipe. However, in the above post you reference using 1/2" pipe.  I think that is due to the internal dimensions of the forge being used.  I am using 3/4" black iron pipe only because that is what I have today.  Is there a formula or rule of thumb for internal forge size and burner requirements?

My stock of MIG weld tips is all .030".  They can be drilled out to .035" or whatever is needed for efficient burning, so there are options here. How much will that matter? Again is there a formula or rule?

I have seen in some websites guys are referencing a 50/50 mixture of Plaster of Paris and sand mixed to a clay like consistency for an insulating material.  What are your thoughts on that idea?

I built 2 burners this morning, not that I figure I need them today. More like having a spare in never a bad idea.  How big should the forge be to need two burners?

Thanks for your help.

 

 

 

 

 

 

[Frosty]

Breaking in new comers to a craft lets me engage in one of my favorite pursuits. Telling stories and making up answers to dumb questions. That's with the understanding that no honest question is a dumb question; no  matter how dumb it is. But yeah, I enjoy helping folks out. 

I wrote up the plans based on a 3/4" x 6" mixing tube and 0,035 mig tip. I developed the T burner to bring a forge between 300-350 cu/in to welding temp reliably. It settled out with a 0,035 mig tip gas jet because that's the largest one I could use without the burner back firing up the tube. I'm a greedy sort, I want my burners to put as much flammable mix per second in the forge as possible and remain stable.

Guys like 0.030 mig tips because they're easier to make, they naturally burn lean and need a choke to adjust for a neutral flame. You have to adjust them with psi changes. The way I build one takes more care and precision up front but I never have to mess with them they will burn neutral at any psi. and the flame has a low velocity at the nozzle so it stays in the forge longer transferring energy to the liner which radiates it as IR to heat the work. Smaller jets require higher pressure = velocity which means the flame blows out of the forge faster. 

A buddy of mine built a 1/2" T burner using roughly the same ratios as a 3/4". He just made the jet the same ratio to tube Dia as a 0.035 in a 3/4" and VIOLA! The one on the picture has a 0.025 mig tip.

Before you drill a 0.030 tip with a 0.035" bit, check the ID of the mig tip. They are "contact tips" for the wire Dia. The marked dim on the tip is the wire, NOT the tip ID. 

I have to sign off or I'll ramble all night. 

Jer

 

[dgr]

Frosty, I've seen that picture in a couple of posts.  I really like the look of that forge.  It appears that the Tee is a 1/2 rise  X 1/2 run.  Is that correct?