Do i NEED 2" pipe for my air supply?

[XombieChow]

hey guys I built my forge with 1" piping for the air supply...it seems to do ok but am i missing out? Should I have gone with the 2"?

[Rob Browne]

As most blowers we use are volume and not pressure pumps the larger the diameter of the tubing the better (within reason). Many people set up with 3" tubing but I find 2" handles most "normal" forging that someone is likely to do in their back yard.

[XombieChow]

for now I am using a hairdryer as an air source...what are the advantages to using the 2"?

[Frosty]

2" is closer to the diameter of the hairdrier and will allow more air through.

So, yes, 2" is better.

Frosty

[XombieChow]

well it looks like i'll be making another trip to SGS tomorrow lol. Thanks for the info!

[Glenn]

The drawback I found with small pipe used for bottom blast twyere is that it fills quickly with ash. The small pipe can clog easily, closing off the air supply. This means you have to dump the ash it early and often.

If you use 2 inch pipe, you reduce the problems. If you use 3 inch pipe there is plenty of room for ash, reduces clogging, and transports ample air to the fire. The air to the fire is then only restricted by the size of the openings in the grate. You can use 3 inch aluminum drier vents flex duct as a connecting pipe from the air supply to the forge. Cost less than $5.

[matt87]

What design of forge are you using (side or botom blast) and what fuel? I've used 1" and under with side-blast forges using coke and charcoal, not ideal but they work. Many water-cooled back/side-blast forges use tues of under 1" diameter and they've been in widespread production use for over a century on all sorts of work. I've welded in a coke fire using a home-made duck's nest with 1" air hose because it's all I had to hand.

None of these were ideal and the blowers were typically squirrel-cage (high volume low pressure) designs -- again not ideal and the pipe certainly hindered things by choking the blast. However it just meant that each heat was a bit slower and I had to be a little more careful with fire management.

[XombieChow]

bottom blast with coal/charcoal for right now...i haven't been able to find a coal source yet...so it's bbq charcoal...not the briquetts the (excuse me because i"m not sure of the correct name) more natrual charcoal.

[Francis Trez Cole]

My last forge I used 4"X4" square tube with a dayton blower. works great for a grate I used 5/8" rebar. it gets real hot good thing I have a good damper.

[double_edge2]

2" is good for me for normal forging, unless you're planning to do big stuff.

[Avadon]

I use 1.5" black pipe with a hair dryer. Mine is bottom blast. The pipe area never fills up with ash because I have a grate + pan in it. Ash is never been much of a problem. Easy to dump too. 1" is a little small but try it and if it works fine i'd just ignore it personally.

[Oak Hill Forge]

The big reason to use a larger diameter pipe is velocity. The blower is going to generate a fixed volumn of air. If your pipe is 1" diameter, the velocity will be high which is not what you are trying to achieve. You want the air to "puff" into the firepot, not blow thru like a whirlwind (blowtorch). The slower the velocity the less hot spots you will have and the "softer" the fire. When using my rivet forge I have found toward the end of a forging session is when I always burn up a project. The reason turned out to be that as ash / clinker began to clog the air outlet to the forge (smaller pipe) the velocity increased to the point it became more like a blowtorch, making it more difficut to achieve an even heat.

[Jim L.]

I currently use a coffee can forge lined with refractory. Well actually the "Mk 2" used a can for the inner liner (burned away fairly quickly as expeted )that formed the fractory inside of a larger container.
Air is forced via low pressure compressor through a 1/2 in. pipe. I do need to modify for ash dump.

Jim L.