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First Forge Build - Propane Venturi


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Posted (edited)

Hello All,

               So I have completed my first propane forge build and it's running pretty well i'd say. I haven't been able to run very much though due to weather conditions. I have it set up under my BBQ shack which has no walls. I do believe the wind is causing strange behavior in the burner. When it's not breezy it runs great. So I began the process of building a small forge house/barn. I nearly broke my back moving cement. Oh boy so the ER was 5/3. Today I'm ready to get back to building but I live in the swamp and it's been raining for nearly a week straight. Super bummer! I have a few blades I was working on and cant wait to get back at it.

 

I've obviously welded two 20lb propane tanks together and filled it with compactable refractory cement that I made from portland cement, sand, vermiculite and perlite. It's just about 2.25" thick. I have run several times for about an hour each time. I have a very small amount of cracking. The cracks are very small and do not seem to be causing a problem but I'll likely get them sealed up anyways here pretty soon.

 

Thank you for looking. So what do ya'll think of my first forge?!

 

Also, while I've been healing up here I've also been working on a little circuit build for a temp sensor. I'm using an ATMEGA328P chip and a MAX6675 chip with a K-Type thermocouple. I still have to make the schematic, draw up the board in eagle cad then export my gcode. I'll carve the circuit board on my CNC but dang it I completely forgot that I have recently upgraded my spindle motor so my 1/8" bits no longer fit as my new collet is 1/4". Waiting on a new one from Toledo. Should be here in a few days. I haven't looked into the cost of a digital temp sensor for kilns and forges but I'm guessing they're costly. I have about $5 wrapped up in this plus a few hours of figuring and programming. The rest will take the most time. The thermocouple and related MAX6675 chip are capable of readings up to about 1900°F. I need to be in the neighborhood of 1650°F so it should be perfect.

 

John

 

 

Breaking In The Propane Forge

 


 

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Edited by John Bumbino
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Your "refractory" is not really much of a refractory.  You would be money ahead to stop now and get rid of it and line your forge with 2" of ceramic wool.  you will get may better fuel efficiency that will pay for itself fast, plus your forge will get hotter, and do so faster.  There is a reason every propane forge build discussion on this forum says to use the ceramic wool, and it isn't because "Big Ceramic Wool" is paying us (but that would be pretty cool, so if the folks at Kaowool, Inswool, etc. see this hit me up, I'll take your money!).  And you will definitely want to be getting hotter than 1650F for forging, but maybe not for heat treating (depends on alloy).  

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Posted (edited)

Also, you have a very large forge.  Without a power hammer, hydraulic press, rolling mill or striker you will be hard pressed to use more than 6" of heated steel at a time.  Between poor insulation and oversized forge you will be using a lot of gas.  At least you didn't insulate with the Plaster of Paris and sand mix that some use.  Depending on vermiculite content yours may provide better insulation than that, and will certainly hold up better (though I don't know how well portland cement stands up to high heats.

 

Great initiative though, especially with the custom temperature sensors system.  In my experience a ceramic or SS shield will help it survive a lot longer, but a type K will wear out at the 2,300 deg. F forge temperatures most of us prefer pretty quickly.  Get the thickest wire type K you can find and use the correct thermocouple wire for accurate readings.

 

Your burners look like they are putting out decent flames.  How are they operating once the forge gets up to temperature?  Doors on your forge and a wind guard shield for the venturi burner inlets will do a lot to address wind concerns.  Note that the wind guard shield needs to be large enough to block the breeze while still not obstructing the air inlet.  6" diameter coffee cans work pretty well.

Edited by Dan Hertzson
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8 hours ago, Jerrod Miller said:

Your "refractory" is not really much of a refractory.  You would be money ahead to sto...... at Kaowool, Inswool, etc. see this hit me up, I'll take your money!).  And you will definitely want to be getting hotter than 1650F for forging, but maybe not for heat treating (depends on alloy).  

Hi Jerrod,

            I certainly appreciate the feedback. I should have prefaced with first not last forge. Also that I'm highly allergic to cancer and want nothing at all to do with kwool. I'll pay extra for propane the rest of my life to avoid that stuff. My reason for 1650 is that I have 14tons of steel that likes HT at 1650. I would love to do some stack welding stuff and this might do the trick. This all really came on quick for me. Like for example.. I just dug 25 post holes today for my new forge house/pole barn. Lots of pokers in the fire so to speak. lol. For efficiency it really could be a better, but I run at full blast for 30 minutes before the steel shell gets warm. My next will be of super thick hard fire brick and it'll be square. That tube was a pain in the ass.

 

Best, John

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2 minutes ago, John Bumbino said:

I would love to do some stack welding stuff and this might do the trick. 

 

I think you're talking about forge welding a pattern welded billet- aka damascus.

 

I'm gonna go out on a limb, and say not very likely with that John. 

 

Not trying to be rude...

 

As that was my goal for some time (damascus), I started with ceramic wool and a large area forge with a 2" dual forced air burner... I could not get forge welding temperatures no matter what I tried.

 

There's a good reason, like jerrod mentioned... that things are done a certain way. They work.

 

I get the cancer remark- which is why I "preach" about having the wool encapsulated in a forge.

 

Forging is dangerous by nature...

 

But, I'd dare say that standing next to a roaring 2,500 degree fire in a poorly constructed, possible bomb enclosure... would be secondary to a cancer worry.

 

Gravel, stones, additives in regular cement may explode at high temps... at the least, fail prematurely and be blown under the pressure from the forge. These extremely hot pieces and particles are now coming at you.

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7 hours ago, Dan Hertzson said:

Also, you have a very large forge.  Without a power hammer, hydraulic press ............. note that the wind guard shield needs to be large enough to block the breeze while still not obstructing the wind.  6" diameter coffee cans work pretty well.

 

Hey Dan,

               As soon as i get into welding and hammering I'm sure I'll build an auto hammer. City folks are gonna love it when they come up for some r&r. lol. I picked up this k type and matching IC years ago for my BBQ. Was gonna trick it out with push buttons, bluetooth, tft lcds, blowers n stuff. Then everyone started getting these electric traggers with pellet feed and i'm just like maaaan I changed my mind, I can't do it. I'm gonna continue as I've been for 10 years standing for 12 hours at a time in front of my offset wood burner. lol. Anyways - I priced some of them other type thermocouples and they aren't bad but i've got some work to do figuring out a new integrated circuit/chip and all of that. This was bing bang boom. I wrote like 20 lines.

 

I have seen a good many venturis with cans like that around them. Figured that's what they were there for so I used some tinfoil on the fly and it stopped all that nonsense. So I need walls! I should have a barn by the end of the week. Maybe by the end of next week, but i will have a barn!

 

I did make some forms and packed with refractory for use as doors. I use them when running and they work. A bit crumbly with all the handling but they're holding up. Once the doors are in place, the back hole about 2/3 closed and covers over venturis it runs well, but does still act up a little at times. Like the flame will occasionally "go hallow". The outer part is there but the blue tail is completely gone. Sometimes seems like air, sometimes like fuel, sometimes like wtf? Really thinking walls will help and only then will I really know how she's running.

 

Best, John

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25 minutes ago, John Bumbino said:

Also that I'm highly allergic to cancer and want nothing at all to do with kwool.

John,

 

I certainly get that, having spent 10+ years blowing glass with a glory hole lined with untreated ceramic wool fiber.  Had an MRI for a kidney stone and docs said,: "Surprise, you have significant scarring on your lungs, never been a smoker, right?".  Back then nobody ever mentioned that the fibers break down with heat and time then get airborne.  I'm just lucky I designed in a full enclosure for my glass furnace and glory hole, then used a 30,000 CFM exhaust fan to keep the breeze going the other way. I am a strong advocate for encapsulation as well.  My current forge has 2" of wool lined with a 3/4" thick Kastolite coating.

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3 minutes ago, Welsh joel said:

 

I think you're talking about forge welding a pattern welded billet- aka damascus .......  fail prematurely and be blown under the pressure from the forge. These extremely hot pieces and particles are now coming at you.

Hey Joel,

                  Yeah I just couldn't think of the names. I'm absolutely whooped working on this barn. I want to build forced air but worry about power outages as we have them here regularly. So I'd have to incorporate some type of electric fuel switch that closes on loss type of thing. Then if the power goes out in the middle of a run i'm gonna lose my mind. I know the chances are super slim but still..

 

I'm not knocking anyone for using anything. If you're comfortable with material, risk and maintenance go for it. Really. I know the black and white here tends to drop the tone from the conversation. I'm not being snarky in any way. If I blow up it's done pretty quick. If I get a crack in my kwool sealer, dont notice it (which I likely wouldn't) I could catch the big C and suffer to death for the rest of my life. lol ;)

 

Best,

John

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2 minutes ago, Dan Hertzson said:

John,

 

I certainly get that, having spent 10+ years blowing glass with a glory hole lined with untreated ceramic wool fiber.  Had an MRI for a kidney ...... has 2" of wool lined with a 3/4" thick Kastolite coating.

 

Dan,

       And if I were to seriously consider the big K, I'd need a big fan. In fact Big Ass Fans is mfg right up the road here about 40 minutes. lol. Joking aside I would only work with it behind a sucking fan then throw away painters suit i'd be wearing. Id make sure that even in winter here I had the exhaust fan pulling hard in the forge barn. Just scares the shit out of me. Man alive you can't see the enemy and it's real. 

 

Glad you didn't say they found something else...

 

Dude. You blow glass? That's awesome! I've always been intrigued by the art, but just never got into it. I'll tune into youtube and see what folks are creating. While i'll likely never really get into it, I do have some equipment here now, maybe i'll give it a shot some day.

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Well, I used to blow glass.  Can't afford to any longer, it is a full time occupation, not a pickup hobby (you have to keep the furnace going constantly, then turn out product to pay for the fuel costs...).  Try it sometime at Corning, Pittsburgh Glass, Haystack, Penland, Pilchuck or the like once things really open up again.  It's loads of fun, but watch out.  It can be at least as addictive as blacksmithing.

 

Here is a shot of one of my functional lines from back in the day:

 

multi-color optics.jpg

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I feel I need to mention again, Kaowool does not cause cancer.  Silicosis, yes. Cancer, no.  It is not asbestos and can't cause mesothelioma. 

 

But yeah, you do not want to be breathing the dust after firing. 

 

Dan, wow!  That's some awesome glasswork!

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If you are worried about a blown burner loosing power with a power outage put a ball valve in the gas line where you can get to it easily get to it while standing by your forge.  They're not a bad idea even if you don't have power problems.  If the power goes off you just give the valve a 90° turn and your gas is off.  A needle valve on the gas line is also a good thing to have for adjusting the gas flow.

 

Doug

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The classic method for protecting a blown burner system against a loss of power is to install a normally closed gas rated solenoid valve in the line.  Attach the solenoid valve to the same power source as the blower (or even better, in line with a supply side differential pressure switch) and on blower failure the gas will shut off.

 

Thanks for the positive feedback on my glass.  I certainly miss those days.

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52 minutes ago, Dan Hertzson said:

The classic method for protecting a blown burner system against a .... Thanks for the positive feedback on my glass.  I certainly miss those days.

Hey Dan,

             I looked into it a bit and that's exactly what I found. Blown burner has become an option! Thank you sirs. Headed out to pour some cement for the new barn.

 

John

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