Venting a 55 forge

[DennisL]

Is it a bad idea to tie my ventilation system for my 55 coal forge into the pre-existing ventilation I have in my shop for my gas heater?

I am almost done with the forge and am going to follow up with an additional 55 drum stacked on top with a large arch cut into the face and notches in the back for longer pieces. The location of my forge is almost directly under one of the two gas furnace heaters I have in my shop, which uses a 6" pipe. I'm going to run 6" off the top off the forge and tee into furnace exhaust. Everything I've read says to use 10 to 12", but that is not an option. I am going to put an electric inline blower fan just after the tee but before the pipe goes into the roof, as well as two dampers on each inlet (one on the forge exhaust pipe, one on the heater pipe) so I can open the dampener for which ever component I'm using and close what I'm not.

Any thoughts or suggestions on this matter would be much appreciated.

[Glenn]

Any photos of the coal forge and set up?

The quick answer is YES, a bad idea.

[Frosty]

Welcome aboard Dennis glad to have you. Now you've signed up with the gang here we'd like to keep you around, okay?

NO! Even if you have excellent home owners insurance it won't cover the house when it burns down! That is so far out of code anywhere I know of in the US. it's a major home fire hazard.

If you can't put in a 10-12" stack you should consider putting the forge elsewhere or perhaps trying a different kind of forge. Most indoor forges require exceptionally good ventilation, in and out for a number of reasons: First they use a LOT of oxygen. Secondly they put out a lot of exhaust, not the least of which is carbon monoxide, CO.

The only decent forge I know of that is reasonably safe to use in a closed shop is an electric induction forge. They're expensive up front but extremely efficient and as safe as anything that can make steel melt in your shop.

Frosty The Lucky.

 

[DennisL]

7 hours ago, Glenn said:

Any photos of the coal forge and set up?

The quick answer is YES, a bad idea.

 

[Charles R. Stevens]

The disconnect here is your dealing with a fire place, not a wood stove, or furnace. 

Look at fire place chimney flues, typicaly a 12 square peice of fired clay. So ask your self if you would install a Rumford style fire place like you are talking about? I dang sure wouldn't. A 12" flue works, and if you were trying to get code approval that's what you would be comparing it to (not a lot of NFSC or IBC codes for "forges") that or an indoor wood fired grill. Some have had luck with 10" but personaly, stay with a 12". 

Gas forges acualy produce more emissions (most are oversized for the work) and require some kind of mechanical exaust hood in an Inclosed shop. 

And then we have induction forges, with wich the only experiance I have had with is vicariously threw IFI. 

Lot note, typicaly if you work from the side, you don't need to cut a hole in the back wall of the hood

[Jim Coke]

Greetings Dennis,

          Just an old boys note on your forge. As pictured most of your coal will end up on the floor..  Take heed on others suggestions on proper venting.. 

Forge on and make beautiful things 

Jim

[Charles R. Stevens]

As the hight of the center of the fire ball should be about even with anvil hight (lifting stock up and down gets tiresome) cuting the bosom off your drum will be helpful and then you have a "pan" to set on top and hold your fuel. Cut the top down to atleast reach the center of the fire ball in atleast two apposing spots and do somthing about the sharp edges...

Lots of experiance here on IFI, most of it on how not to do it...

[DennisL]

As far as height, I was going to torch the drum off at the height I want, spilt the edges of the bottom section in a few spots and collar the top with the forge back on and down to the bottom section. I figure that will add to the structural integrity of the entire setup.

I have another 55 drum that I am going to cut a large arch out of the front of and stack on to what is pictured as a hood/flu, which up until now was going to be tied in to existing ventilation. What about piping it out a window? Is there no good way to have a coal forge inside without having to run all new, independent ventilation? I'm new at this and am not real keen on punching holes in my roof for a hobby I haven't ever tried out! I'm in Wyoming where it is freezing with strong winds over half the year, so putting the forge outside is not really appealing...? I'm about to scratch the whole top ventilation and just crack the door open!

[ThomasPowers]

Well Hofi had a nice side vent system that would work great with your window: http://www.iforgeiron.com/topic/23197-bp1048-side-draft-chimney/

 

[DennisL]

Okay, so I made it back over to my shop today. I haven't mounted my railroad rail to anything yet but it's my understanding that it's supposed to be right at knuckle height. The top of my 55 is just slightly above that (like an inch), so I'm scratching the idea of cutting it down for now.

I've got another 55 that I've cut the top off of. I'm going to invert it, cut an arch into it, leaving 2" or so on the bottom, which I will then stack onto my forge and weld at the seem.

I'm going to move the whole mess over next to my shop WINDOW where I can run ventilation out and up without issue. I'm thinking I'll just punch a 12" hole in the side of the hood right next to the top. I can then run the pipe at a slight declining angle out the window, put a drain hole in it right where I'll tie it into two 45 degree angles, then straight up the back of the shop and a few feet passed the top of the roof.

Okay... So... Will this work? (Fingers crossed...)

[Frosty]

Before you build a hood check out side draft hoods, Thomas linked you to one that works very well. As shown it's in a smithing school I believe. I like a side draft better than an overhead hood and stack running vertically. Check code locally but in general you want the top of the stack a minimum 4' above the highest obstruction within 10'. You want it higher if the stack is down wind most of the time. 

Don't mount your anvil permanently till you find out where YOU like it. The old books say knuckle height but they usually worked in teams with strikers and top tools. Most of us operate alone so a wrist high anvil face works better. Play around with it. Work on different heights long enough to develop muscle memory at that level. Even if you ultimately decide on a different height you will have trained your reflexes and eyes to work at the other one, it won't go away and I guarantee it'll come in handy down the road.

Frosty The Lucky.

[ThomasPowers]

Height of anvil was knuckle height back in the days when sledges, strikers and a lot of top tools were used. Nowadays most folks doing "fiddly work" want it higher; for bladesmithing I prefer wrist height.  Easy to tell, if you find yourself leaning over your work and your back  killing you after a day of smithing your anvil is too low!  Or you can put a piece of 3/4" wood on your anvil and see if you are canting the hammer to hit it flat, or leading the front of the hammer, (too low) or the back of the hammer (too high) when hammering "correctly"

[DennisL]

Almost done! All that is left is to plumb in the ventilation. You can see from the second photo the height of the hood next to the window I'm going to vent it out of. I'm thinking about just cutting a 12" hole just below the top of the hood and running the pipe out the window far enough out to clear the eve of the roof, then going up about 12'. I have a metal rack that I can put against the building and tie the pipe to, thereby making it temporary and eliminating any need to meet code, all the while NOT tieing into my existing duct work for my heater, violating every building code and potentially burning my shop down! Thanks for the advise guys. Tell me your thoughts please.

[C-1ToolSteel]

I like it. If you wanted to, you could even cut a hole through the back for heating the middle of longer pieces.

[DennisL]

That is the plan eventually. I also thought I read somewhere on this forum that I should pack some clay into the space between the rotor and the outside edge of the barrel. It would only be about 1/2" deep with clay... Not sure what the reason is for doing that though?

[NoName]

Hey DL,

   Any hints with cutting the vents on the disk.

  N.N.F.           Beautiful.               Manchester.         Michigan.           USA  

[DennisL]

1 hour ago, NoName said:

Hey DL,

   Any hints with cutting the vents on the disk.

  N.N.F.           Beautiful.               Manchester.         Michigan.           USA  

An oxy/act torch and a six pack of your favorite beer. I started with my 4 1/2" grinder with a cutting wheel but it wouldn't reach the middle with the guard on and was taking forever anyway. I also torched the ring off the hub that had the lug bolts. I then placed my black iron flange on the bottom of the rotor, put the ring in place, welded it to the rotor and laid a butt load of weld on the inside of the hub ring, thereby sandwitching the flange in place and filling the holes in the rotor all at once! Attached is a picture of the backside of the rotor. (Please cut me some slack on the "hammered owl xxxx" welds as I haven't picked up a welder since high school! It will hold, that's all I care about.)

[Glenn]

The original design was for the top of 55 opening to be 4 inches below the second ring on the drum because this is where I could stand and see the back of the fire pot. The width of the original was way to wide and was then reduced as I found what was comfortable to work through. Turns out to be 16 inches wide or less. The opening was then further reduced by making the top of the opening arched. Used a dog bowl to draw the arch, it was handy.

A 12 inch pipe, the pipe has an area of 113 square inches. Measure the opening of the drum and then reduce the opening to come close to the area of the pipe. Concept is good but does not translate in real life. You have to see what you are doing in the fire.

2 hours ago, DennisL said:

I also thought I read somewhere on this forum that I should pack some clay into the space between the rotor and the outside edge of the barrel. Not sure what the reason is for doing that though?

For some projects the 24 inch diameter pan with a fire pot in the middle was too large. The modification was to put a row or two of house bricks around the circumference of the drum to reduce the size, as well as to add depth to the fire. CLAY was used only to smooth out the inside surface of the bricks. The fire pot is usually a bit taller than the bottom of the drum and this area will fill with ash soon enough, making a smooth and level bottom.

If you use a brake rotor, just fill the holes between the two rotor disks with mud. Otherwise the fire may want to exit through these holes and out of  the fire pot.

Now that you have the reason for the numbers, you can modify the design to fit your needs.

[DennisL]

Glenn, I had an idea... Have you ever tried dropping in the rotor with the rotor vents still in place (not butchering them like I did), and welding an additional "doughnut" of steel (say, the lid cut off another drum) from the top outside edge of the rotor extending to the drum edge. You weld the whole mess solid so you have effectively created a double layer drum top with a gap the depth of your rotor. Then you put your forced air inlet directly into the space you created, which will blow on the coal through the rotor vents... Think 360 degree side blast with the center hole in the rotor for ash and clinker only... Thoughts?

[Glenn]

Try it.

I would suggest that it will not work as well as a bottom blast design as the holes will plug up and the air is not reaching the fire at the right level.

The original 55 Forge design was so anyone in any third world country could make a working forge with minimal tools, cost, and effort. Once the first forge is made and used, you can then modify it to suit your needs. It went from original pan bottom blast, to side blast, to adding a brake drum or rotor, to adding a second drum as a chimney. Each is a bit different and gives a bit different fire. All work. The modifications continue with simple being the primary consideration.

Do not try to overengineer simple. You want a forge. You have to deal with smoke from that solid fuel forge. You do not want to collect and store smoke, you want to get it out of the work area as quickly and completely as possible. Study chimneys and how and why they work. Build one, try it, and then modify it to make it better.

[ThomasPowers]

Another thought: instead of cutting a hole in the back for long pieces, do two on the sides as the back may be fairly close to the wall and long pieces may be *long*!