Side Draft Hood ?

[Ron Hicks]

I want to make a side draft hood- Ive read that most use 10 in. dia. pipe so it
draws better.
I called a few places and all they have is 6in. and 8 in. pipe.

I will not have any help & wasnt wanting it to weigh a ton.
Is there like a tin walled pipe I can get from my local Iron & Metal Supply?

How thick of materail shoud I use for the hood- I will be using oxyacetylene to weld with. Thought maybe angle iron and sheet iron
Thanks Ron

[bruce wilcock]

the flue does not have to be round, sq is easier

[the_sandy_creek_forge]

Ron,
Check with your local home improvement superstore and ask if they can special order 10 or even 12 inch stack. I know that the local Menards (central Illinois) could special order 12 inch at one time. Luckily I work only a block away from Champion Manufacturing who makes 12 inch diameter in multiple lengths and guages. You might contact them and see about the shipping/cost etc. CHAMPION MANUFACTURING INDUSTRIES, INC.

As far as the hood goes it doesn't have to be extremely heavy. Mine is a...um..."modified" furnace housing from a scrapped out electric house furnace.
Made do with what I could get.
-Aaron @ the SCF

[Glenn]

I know of blacksmiths that have used the "pipe" from inside hot or cold water tanks that no longer work as water tanks. As Bruce says, it doesn't have to be round, just safe to use.

[primtechsmith]

What about the drain pipe the department of transportation uses to go under driveways for drainage? I have no idea what it is called but it looks spiraled...Maybe a local supplier has this stuff...it may work.

Peyton

[Ron Hicks]

I thought I may get some of the 6 in - take it apart using 2 to make one
might be more work than it worth.

Could a sheet metal shop make 10in pipe ?

[Glenn]

The take two and make one is a much overlooked solution. And they don't have to be the same size, you can mix and match to make what you need.

[rthibeau]

are you talking about stovepipe here to vent a coal forge?

[Ron Hicks]

I had some old crusty 6in pipe and gave it a try thats works ends up about 12in dia.
This is the forge I want to make the side draft for

The opening does it need to sit on the edge of the fire pot?
I have about 8in. on the right side .
I thought I would do a box with a smoke shelf
What do you think?
Ron

[Ted T]

Ron Hicks,
I believe you have brought an excellent topic about pipe (chimney) size.
When you mentioned “pipe size”, it automatically includes the consideration that must be given to include the combination ratios of other factors such as “Chimney Size v. Draw Efficiency v. Heat Protection v. Chimney Material v. Intake Design (hood v. side draft)”
I have a question: Do we “need” to use triple wall , or are we “required” to use a triple wall chimney pipe in the same way with a forge chimney as we would for a wood/ coal stove chimney? Or, what type of other chimney material could we use safely ?
I would bet Richard is about to answer this question when he said:
“are you talking about stovepipe here to vent a coal forge?”.
My observations and experience has left me with the impression that it would be worth the extra difficulty to obtain a larger diameter chimney pipe other than an 8 inch pipe.
I was taught that on a wood / coal stove pipe you can neck a chimney diameter down some as it goes up, but not open it up to a larger diameter as it goes up.
I know smiths who have rigged a blower on an 8” pipe just above the side draft intake.
It worked well. A forge does not create a powerful draft force like a wood or coal fire.
Here are some of my “Rules of Thumb” about what seems to assist draft.
a. If you can run your pipe straight up with out a bend, you will get the best draft possible.
b. If you have a larger diameter chimney pipe than 8 inches it seems to add to the efficiency of the draw.
c. If you provide an adequate air intake supply to the forge, equal to the air going through the forge, and then up the chimney pipe, it will aid in good drafting.
d. Do not block the top of your chimney pipe with a regular type chimney cap.
You must allow your pipe to free flow out of the top. It will aid in draft efficiency.
Note: To keep rain out of your chimney, use a larger size diameter pipe that is slipped over the end and sticks above the top of your chimney pipe. I cannot explain it well. So you will have to do your research to see what I mean. It’s based on the idea that rain seldom comes straight down.
e. The higher you can extend the chimney pipe the more efficient the draft.
Be safe, be safe!
Ted

[Ron Hicks]

I havent a problem with the the pipe gettin hot its going through a tin roof on a shed -no wood near where its going .
I thought I would make a box that sits beside the fire pot wide as the forge with a smoke shelf to help the draft.
Opening in front as wide as the fire pot sq.
Come off the top of the box straight up through the roof and above the ridge and make the box just deep enough for the pipe to fit over a collar.
Maybe tapper the sides in to the pipe some.

Thinking about making it free standing so if I could move it outside if I wnated to.

[Ted T]

Wind and Rain Shield for a Forge Chimney
Please forgive me up front. This is just a feeble attempt to try to explain how a rain shield looks
An example of how to build a wind and rain shield for the top of your forge chimney.
To give you an example of how the shield looks and works, try the following.
1. If you took a small can of soup that is about 4 inches high and about 2 ½ inches in diameter (across the top). Cut both ends out. Now you have a tube that will represent the size of your chimney pipe (a).
2. Then find a large can of tomatoes that is about 4 ½ inches high and about 4 inches in diameter. Now cut out both ends. That will represent the cap tube (.
3. Place the chimney pipe (a.) on the table.
4. Set the cap tube (b.) over the top of the chimney pipe (a.).
5. Look down from above and adjust the cap tube (b.) so it is equally spaced around the chimney pipe (a.). That is how it should be laterally spaced when it is installed. You would use spacers to keep this adjustment when installed.
6. Then raise the outer can (cap tube (b.) up so the bottom is about an inch below the top of the chimney pipe (a.). That is about how you want it to look for the vertical adjustment when you secure it with the spacers.
The principal of its operation is based on the idea that rain or snow rarely falls straight down. So, due to the slight angle of the rain drops that would normally flow down the chimney pipe, they will be intercepted by striking the higher outside pipe cap pipe (b.). The rain will just run down the outer cap tube (b.) and drip off onto the roof allowing the draft to flow free with out being blocked.
Note: You would have to calculate or test to determine exactly what the ratio of how high and how far below the chimney pipe top the cap pipe shield should be.
I tried !
Be safe, be safe!
Ted

[Leah]

I have 8" triple wall ss stove pipe on my forge. I have a sidedraft hood and the stovepipe goes straight up through the roof. I admit that I get a little smoke in the shop when I first light a fire, but I have done the same with a 12" pipe. Once I get a fire going, I don't have any trouble with it not drawing. I tried for a long time to find triple walled pipe in a larger size and could not. I thought about making it or having it made, but I decided to go with something that I could easily replace by going to the local hardware store. I know this is not supposed to work well, but for me it really does. My shop is an all metal building but my husband insisted that I use triple wall. I am glad I listened to him.

[Jymm Hoffman]

I used rectangular heating duck for several years in 3 different locations, some was discarded from a furnace change. First stuff was 8 x 12 and last one was 10 X 14 if I remember correctly. Worked fine. Last place had to be inspected. As long as I was a certain distance from wood and built in a flashing, it was approved. Check your local codes. I switched to gas in 1993 and have not had to worry about chimneys through roofs or walls (did both.)

[Gary]

Ted, that was a very clear explanation. I've seen a picture of that cap somewhere but can't find it now. The type I'm going to try soon is at this site. Forge Chimneys. There are several different hoods and a very good primer on chimneys. I hope to have a hood fabricated shortly and am looking for 10" pipe for it now. I've been looking at some building material recycling centers and scrapyards. New runs 150.00 for a 4' section new.

[Gary]

I found the picture I remembered here, link removed at the request of anvilfire with credit to Mr. Dempsey, etal. What Ted described so well they call a low loss stack cap. At the bottom is a link to a side draft hood page. I'm going to try the one on the left. It's all theory to me as yet but some say that a smoke shelf is not needed and I'm going that route. I will post pictures and results hopefully in a month or so as things develop.

[Jymm Hoffman]

The best side draft chimney's I have ever used were masonry. The first one was at Ohio Village in Columbus, Ohio. It has at least 12" square flue liners faced with brick with about a 12" square opening at the bottom, and that is it, no smoke shelf. I built a double forge that went into a single 12" liner, faced in brick, also worked great, a lot of work though. The best metal side draft I have used were built by Richard Shepherd and are used at Touchstone Center for Crafts. There are 12 there for student forges. The instructor's forge is masonry and works very well. Metal can work fine, but it depends on your budget, both in money and time. However, if you don't like blowing black dust from your nose, messing with a chimney, what to do with ash etc, you can build a gas forge and not worry about putting up chimney.

[Ron Hicks]

Gary
Thanks for the link
maybe I read it wrong - the smoke shelf helps with the draw and back drafts.
I think the main thing is to make sure the closed down opening of the smoke shelf is bigger than the flue opening to work right.
+ it speeds up the draft.

A gas forge indoors needs a hood or something to draw out the carbon monoxide so you wont turn beet red & die.
I have a gas forge even with windows & doors open with fan blowing it still bothers me.
Ron

[Jymm Hoffman]

If the gas is bothering you, is it burning completely? Do you have a CO detector? Your shop may also be too tight for a chimney as well. I have been using gas since 1993, maybe that is part of my problem?! :)

[Ron Hicks]

Ha Ha Ha
If you could just see my shop/shed/cobbled up thing with tin nailed on it.
It just barely keeps the rain off my head- Its not to tight - yes I have a CO detector- I guess I was runin it rich so not to scale as bad .

I went and bought some Heads and Tails today at the metal supply today
380 pounds 2 sheets. 1 sheet was 4ft. X 7 ft. maybe 7 ga. & 1 sheet 4ft. X 9ft.maybe 13 ga.
Heads & Tails are cut offs from the ends of rolls .25 cents a pound
New sheet 4X8 11 ga. was like $93.00 ea.

So much for making the hood light weight - Im going to do something right or worng.
I think I will do something like the ones in the links posted thanks again Gary
Looks like they work really good.
Ill try the rain pipe Ted thanks bet it works

Thanks everyone

Its nice everyone offering help
I for sure need it
Gota get to work now
Thanks Ron

[Ron Hicks]

Sorry to hassel every one
I was looking tring to find more on Side Drafts
looking at the I Forge Iron home page
blueprints December 5, 2006

If you missed the Blueprints, we made a made a vase holder, a look at a side draft forge hood, a drift from a kitchen knife sharpening steel and a way to set up a lathe for long stock. Thank you Irnsrgn for the donation of the door prize.

I cant seem to find anything about the side draft hood
I sure would like to see it
Thank You
Ron

[HWooldridge]

This one has a 12" round galvanized duct. The side draft is an old material hopper, turned upside down, with a cap welded to what was formerly the hopper top. I cut a U shaped slot in the hopper and put a very short lip at the top of the cutout, which helps channel smoke when the chimney is cold. There are a few fire bricks inside the hopper that also help draw after they heat up. This chimney does occasionally smoke at startup but most everything goes up the stack once it gets hot. I proved this one day by sweeping about an inch of very fine ash and coal dust from the inside of the box after a couple years of regular use. Apparently, there is a little vortex when the stack draws because most of the soot is on the left rear side.

This was cheap to make and works quite well. Many years ago, I started with 8 inch duct and worked my way up in 12 in - there is a definite difference in drawing ability so my advice is to get the biggest stack you can find.

[Glenn]

Blueprint BP0394 Side Draft Forge

Search the site and enter BP0394

[Ron Hicks]

HWooldrige
Thanks for the pic.
I think you are right about the big pipe
I like yours it doesnt have that big box
How big is the hopper?

I found some hoods here + the brick top table forges really caught my eye.
The hoods havent that much materail in them.
I may just make one with the hood and put my old forge away. Student Forges in the Shop of Donald Stanley

[HWooldridge]

Ron,

What used to be the top of the hopper is 30" in diameter but you don't need that much - it's just what I had laying around. A buddy of mine made a steel box 18x18x18/16 that he stuck on the bottom of a piece of 12" duct and it works like a champ. He has about the same size cutout as mine but the side that faces the fire is tilted forward a few degrees so the bottom of the box is 18x16 but the top that fastened to the duct is 18x18 - hope that makes sense.

IMHO, the important parts of good smoke elimination are a large stack (at least 12" diameter - square is better), a tall chimney to pull strongly (at least 2-3 feet higher than the roof peak) and getting the lower end near the fire. The other odds and ends to box design can be fairly flexible.