customcutter

Finally starting my forge

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I've been trying to locate a freon bottle so that I could make both forges at the same time.  I didn't want to mix up Mizzou and have too much left, if I could use it in a second build, but that hasn't happened so I decided to go ahead with the 30# propane tank build.  I started out by marking the semi-circle around the carrying handle and cutting the tack welds off with a 4.5" grinder.  Then I used my plasma cutter to cut through the tank around the semi-circle (it was full of water and standing upright, so no fumes could fill the tank).  I cut straight across the open end of the semi-circle, thinking I would use that to build a shelf area later.

It got interesting when I tried to cut my 1" inswool and insert it through the hole.  It didn't fit, so being hard headed, and not cutting the hole out larger and circular, I decided to cut the inswool into 2 pieces.  I got that installed and intalled a second layer of 1" inswool for 2" thickness, and off set the gaps.  I forgot to rigidize the first layer, so I made up a little over 1/2 gallon of colloidal silica and sprayed the liner real well with my pump up sprayer.  Not having a burner built yet I realized I had a turkey fryer with a high pressure valve, turned the tank upside down on it and began to cook it off for several hours, just to make sure that I had driven off all the water and rigidized the silica.

Yesterday, I looked several places for a 6" sonic tube (cement form tube) to place in my forge so that I could cast the Mizzou around it into the inswool.  No luck there, so I decided to use a 4" dryer vent and wrap it with cardboard until I got up to the 6" desired.   I tried fitting that into the forge this morning and it would barely fit if I used a putty knife to hold the inswool back while trying to insert the tube.  I decided there was no way I was going to be able to insert the tube and then pour the Mizzou down past the inswool.  So I decided to use the plasma cutter to cut another 1/2" out all the way around the forge entrance.  Boy what a mess, I used the shop vac to clean a lot of it out of the inswool, and had to pick a lot out by hand.  Take it from me, go ahead and cut a nice 8" hole when you start, you will fight a lot less demons along the way.  I decided  to re-rigidize the liner.  Then per Frosty's instructions I covered the outside of my liner tube with aluminum foil, I didn't have any plastic wrap, to keep it from drawing too much moisture off of the Mizzou and affecting it's thermal qualities.   I was barely able to squeeze a transmission fluid funnel (long skinny) down between the tube and the inswool.  

I mixed up approximately half of my 55# bag of mizzou, to peanut butter consistency and place a layer about 1/2" think on the back, with the tank standing up.  I then mixed it to a very thick soup and tried to pour it down the funnel using a 1/2" rod trying push it through and it would not go.  I cut about 2" off the end of the funnel till I got a 3/4" opening and it still wanted to plug, so I finally added a little more water.  Finally it was able to flow as long as I would fill the funnel and ram rod it down the hole with the rod.  I know my tube got off center at the back, so I may have to address that issue, as it may only be about 1/4" thick on the bottom.  I tried to use the 1/2" rod and an 1/8 rod to poke down through it to release any air bubbles, hopefully I got all of the larger ones out.  Now to let it set for at least 24 hours or longer before pulling the tube.

I know this is a long post, but I hope it helps someone else.

Ken

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You need to cut yourself some more slack, this isn't a space shuttle. Next time give yourself some room. So where are the process pics? It's a nice story, rife with human interest and everything but without pics it's just a story. :P

Frosty The Lucky.

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Sorry, I'll try to take some using the tablet on the freon bottle build, from the beginning.  Just a comedy of errors on this one, starting with too small a hole.  Maybe I'll finish up with some pics from here, but it was nasty cutting that tank with the inswool already installed.  Definitely changed my mind about cutting my torch holes with the plasma cutter.  I'll have to run to Lowes tomorrow to pick up a hole saw.  

Any problem using a carbide tipped for the metal and cutting through the refractory?  I'm thinking 2" or is that too big?

thanks, Ken

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Empty freon tanks can be found at any HEating and AC shop.... especially this time of the year!  I walked into a large firm, asked for a freon tank and was walked to the loading dock where there were two roll off dumpsters full of empty freon tanks!  Told the dock manager what I wanted to make, showed him a screen capture of a forge, presented my cordless drill and told I would drill out the pressure relief valve in front of him (so it could not be used as a pressure vessel) and left with ten!  Large companies sell that as scrap,and may have contingent liability concerns over an illegal use or an illegal purpose.  Perhaps a small mom and pop shop would be more receptive or find a guy in his truck in the neighborhood and ask for one.

 

sorry about your experiences... the next will be easier!  

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Thanks, yes I have 3 friends in the HVAC business.  2 techs and 1 actually owns his own business.  I have reached out to them, but they don't have any empties on hand at this time.

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Check with shops that do automobile AC, perhaps? I don't know if they use a different kind of tank.

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Until the mizzou is fired it should be quite easy to cut.  A bimetallic hole saw should do it just fine, if I recall correctly.  You will have lots of dust.  In future builds I recommend that the mizzou for the burner port be formed around a removable plug.  That way you can more precisely design it to both provide a little protection for your burner, and potentially act as a bit of a flare as well.  Ideally I like to have the mizzou skin just about the size of the burner outlet and flaring along the thickness of the forge insulation at the standard 12 deg angle to the out let of the forge, but it may have to be different for your design.

I'm not completely sure, but I believe that you can radically reduce the strength of your mizzou if you mix it in too thin a consistency.  It is not really designed to flow thru a small opening.  What I've done in the past for thinner mizzou shells is either trowel it right up against the insulation in sections without an inner form (use a consistency like mortar and just trowel it into place for around 1/3 of the diameter of the forge then after drying rotate and repeat till done).  I have also cast rings on end, though more often than not thicker than 3/4" tubes.  In this latter case I just dumped the mizzou into the annular form with a garden trowel (stolen from SWMBO, and carefully cleaned before returning) then packed into the form on end using a piece of wood to tamp it down.  You can even cast the mizzou to form first, then wrap it in insulation before inserting the assemblage into your metal skin.  A bit of loose insulation packed between the two and you are good to go.

Another good source for smaller forge tanks are used helium bottles from helium balloon places.  These are usually thinner than propane tanks and helium is inert.

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Like JHCC mentioned, larger auto body shops go through refrigerant tanks and when they are empty they go in the scrap hopper so if you stop by some and ask nicely you should luck out. Now is the time, it's slower in fall and winter but they still do go through them with front end collisions. 

I actually have a few set by my toolbox to bring home.  

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I knew that if I just kept talking, someone who actually knows what they're talking about would eventually show up.

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Party stores seem to throw away the bright pink He tanks that are quite similar to the freon tanks.   I often find them at the scrap yard too and generally have a couple on hand to give to folks wanting to get into smithing---at 20 US cents a pound they are giveaway cheap!

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Thanks for the replies everyone.   The mizzou I bought is a gunnable type, The directions for regular mizzou are not to exceed 11% by weight, and recommends 5 pints per 55lb bag.  I hope my attempt to pour cast with it is not a total failure.   I think it can be saved, but I won't be using this method again.  I have complete voids where no mizzou flowed next to the inswool and  I have lots of visible air pockets.  Despite 15 to 20 minutes of probing with 2 different sized rods.  Also the cardboard I inserted to cast around was nice and round when I put it in, but somehow became semicircular, with one very sharp corner.  I'm going to mix another 5 to10lbs and try to patch what I have for now.  That will still leave about 15 lbs for the freon forge.

One other word of caution, don't use Al foil instead of plastic wrap.  Most of it came out fine, but now I have to deal with getting the rest out before I can try to patch it.

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While planning my next steps to take on lining the forge, I decided to get started on my burners.  Half a day in the garage with the lathe and some 3/4 & 1" stainless 316 scraps i picked up the other day and this is the results.  Lots of machining left to do, but this is a start.  

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On 9/1/2017 at 8:20 AM, Latticino said:

In future builds I recommend that the mizzou for the burner port be formed around a removable plug

I found that a pool noodle works well for this. We installed the burner port prior to the insulation and Mizzou or Satanite refractory. It worked like a charm.

 

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Customcutter,

Your stainless work, so far, looks like a good beginning for your burners.  The second photo shows two sets of stainless steel parts, which can be used as mixing tubes, air chokes, and (with further cutting) spacer rings for stepped flame nozzles; or you can try to build tapered flame nozzles from them.

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Yes, the chokes are 4" at present.   I figure I can cut 1 of them down, for the stepped flame nozzles.  I want to try tapering the chokes, and see how that goes before cutting any parts shorter though.  Today I tried milling the slots in the burner tube.  Man is 316 a pain, talk about something work hardening.  I started out with a titanium coated 3/8 bit with a mist coolant, and went to a carbide bit dry.  I'm not a machinist, but I need to do a little research before trying the second burner.  I fried both bits.

I patched the forge early this morning, and it came out reasonably well.  I put a 100 watt bulb in it and turned it upside down to heat for tonight.  We'll see how it looks tomorrow after Chruch.   Maybe a real heat lamp tomorrow.  I need to get some IR reflector ordered.

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Tapering the choke encourages the burner to run hot; but at the cost of easily fine tuning the flame atmosphere; there is no right or wrong choice here. But, it is best not to cross that bridge until you come to it. If the flame can't be brought up to full power, that is the right time to trot out that trick ; otherwise, why give up something desirable to gain something unneeded?

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