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Drafting question


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Good Morning.  I have looked for this particular question but couldn't find an answer.  I am a worker bee part of a group that is in the process of outfitting a "demo" forge. The plan is to have two side-draft forges back to back. the table will be something akin to 4' by 8', with the chimneys in the center. My suggestion was to run two separate flues up through the roof, in a single chimney enclosure (for curb appeal and all that).  The option that is currently the plan is to have both flues connect to shared/common flue. 

I really don't like the idea of combining the flues - drafting issues, back-drafting, CO, and all that.  My problem is that I am a worker. educated maybe, but without credentials.  I have already sent a message to the head blacksmith at the JCC folk school, but am impatient (mostly due to time constraints).  Can anybody supply sound reasoning or documentation for the need for separate flues, or am I making a mountain out of a mole hill?

thanks, Paul

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Lowers the efficiency of the chimney immensely! If you are not using both at the same time then cold air will be pulled from the one not in use cooling the stack gasses and causing less chimney effect.  If you are using both at the same time then the crossectional areas per forge is halved decreasing the venting...

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20 minutes ago, ThomasPowers said:

Lowers the efficiency of the chimney immensely! If you are not using both at the same time then cold air will be pulled from the one not in use cooling the stack gasses and causing less chimney effect.  If you are using both at the same time then the crossectional areas per forge is halved decreasing the venting...

The cross section per forge may be reduced but the hot exhaust is doubled for a stronger draft. The cold forge drawing cold air is a factor though but an easy fit with dampers, like the one on a fire place. Two holes on the front edge of each side draft hood to stack transition and either a long hinge with handle or screws holding a square of light sheet steel.

A crank arm on one side of the stack would be clearly visible indicator of the damper's position. If using screws as short hinge points then a pull chain or trammel type prop takes care of opening and closing. The open position can be less than flush with the stack and act as a smoke shelf.

That's just a little noodling on my part though. What's your preference for a back to back multiple station forge Thomas?

Frosty The Lucky.

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With some of the folks I've shared a Demo with I'd prefer a "next county over" spacing!  Several aspects: can you field multiple demonstrators a lot of the time? if they both work off the rear then their demos will be interacting.  If they are to the sides then you have to move all the gear and put out the fire when you do not have a demo running of the off side but may later.

Actually the Abana affiliate in NM has a lovely demo trailer that is used for the state fair: on the side towards the crowd there are two complete forge set ups built into the trailer with a workbench between them with a door that goes into the back where there is a trailer long storage area hidden from the crowd and is a "safe" space. Each forge area has a door that opens out from the ends for a display area backdrop. The work bench/door area has a wall that opens up into a roof and is the sales area---folks forging are not expected to be selling or looking after stuff on display!  On the back end of the trailer is another door into the storage area so full sticks of steel can be loaded back there. The other side of the trailer was a wall with just ventilation openings---with iron bars....of course.  

Each forge has it's own chimney, hand crank blower,  Postvise and coal bin are in the work bench area and shared.

so |----Door----|--forge 1--|_workbench_|D|--forge 2--|----Door----|

Club Rule is that to sell at the State Fair you have to Demo at least one day.  I used to try to do it every year as it was a lot of fun with the group!

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That sounds like a nice set up. Are there  drawings, pics maybe, available? I'm not going to build one but I like well thought out things. In my simple thinking high tech means equipment, tools methods that do the job efficiently with as little effort as possible.

This trailer sounds like it has about everything I can think of covered and nicely.

Frosty The Lucky.

 

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That is one SLICK demo trailer Thomas, there are enough pics to get an idea of how it's set up. Folk working in it would almost have to try to get in each other's way. I like how it keeps the audience at a distance but allows good views from different angles. The work bench is sweet.

My only question is what the foundation for the anvils is. Are they on the trailer floor or is there something solid to the ground? If on the trailer floor are they solid enough?

At one time I was planning on rebuilding a step van for demos and was considering a number of different ways to provide a direct support between the anvil stand and the ground. Literally a jack stand type connection.

Frosty The Lucky.

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They are actually on "stumps"; for evening close up they can be moved to the door area IIRC.  The hand crank blowers demount and pile on the workbench for a temporary closeup. Shutting the large side doors deals with all the display items.  There is also a hand crank drill press; but it is "locked" to keep tourists from feeding their fingers into the gears...They always tend to have some inexpensive stuff for kids like horseshoe nail rings and a "puzzle" made from 2 inter locking nails.  Every year I've been at the fair with them we were set up along the street that leads to the horse and livestock exhibit; good crowd of 4H'rs and ranch kids. (whose parents have less irrational fears about risks---compared to Barrel Racing or bull riding blacksmithing is SAFE!)  We've had several that would come by every year to work in the forges and some even got their own set ups together. This will NEVER be a DYING CRAFT as long as we continue to teach the kids!

The club also has a MUCH smaller 1 forge demo trailer when the big one is not needed...

They're a talented group it's just a minimum of 4 hours each way for me to attend meetings...

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I can see the wood block anvil stands I was wondering what they are on. I tried working on my car hauler and noticed some effect from the suspension rigid as it is. I tried it with a bottle jack under the anvil block and it was like it was standing on the ground. I'm more curious if it's an issue and how you deal.

Frosty The Lucky.

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This is getting a little away from the "dual forges" question and more into the "portable smithy" aspects, but guru has a page about the portable forge he used for years and then passed on to Jim "Paw Paw" Wilson and the Historic Bethbara Park of Winston-Salem, NC. Google "ultimate portable blacksmith shop".

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On ‎8‎/‎23‎/‎2016 at 0:09 PM, ThomasPowers said:

You might want to write to the New Mexico Affiliate: http://www.nm-artist-blacksmiths.org/ and ask if they have any clear pictures of the trailer.  It will be coming out for the NM state fair soon and they may be willing to take pictures of it buttoned up, start of setting it up and fully open.

Thanks Thomas, I just sent Tod Amon a question to that effect.

we shall see.  When we do get the thing built, I will be sure and post pictures.

paul

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Is there any any reason you don't just build it like a standard double hearth? They seem to work fine with a single flue whether one or both fires are lit. You could always put a sheet / plate divider between the fires if you wanted to.

The old ogee shaped cast iron hooded Allays and Onions hearths were a much sought after prize over here. My Supreme Master Blacksmith neighbour Mike Roberts managed to find one and used it for 40 years with no problems. Many of you in the USA will know Mike for his brass forging expertise and his regular attendance at the ABANA conferences over the years...more recently his workshop/masterclass at the Memphis museum.

This is the modern fabricated equivalent available from Vaughans.

Alan

Screen Shot 2016-08-31 at 08.44.09.png

 

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