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I started out with what I think a lot of blacksmiths started out with: a 5$ hairdryer bellows, and charcoal. That worked pretty well, but it conked out on me a while back. One of my friends, as it turns out, used to own a bouncy castle, and still had the air blower for it. He was kind enough to let me have it, so I hooked it up to my bellows. It's much more powerful than the hairdryer, and has varied results. Sometimes it works great and gets really hot and powerful, sometimes it gets the inside of my forge glowing red, but there is no flame or heat at all (I can even put my hand over the top and it feels like a stove). My question is; is it possible to have a blower that puts in so much air that it's bad for the fire? or is this just an issue of me needing to build a better fire before turning it on?

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Well, yes, it is.  Obviously if were to blow coals out of the forge it would be too powerful, but I believe that you can have so much air that it actually cools the fire down.

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Hi Kyle.  I'm going to try to help you out before offering my ideas to help your problem.  Let me explain:

There are a number of highly knowledgeable people on this forum who will help you out whenever they can.  In fact they have spent countless hours online solving other people's problems and teaching them for free.  Problem is, they can get cranky.  Here is how to avoid falling prey to a curmudgeon attack....

1). Edit your profile and include your location.  Often times your location can seriously help someone answer your question.

2). Make sure you search the forums for possible answers for your problems.  Often using google and typing in your search terms plus iforgeiron is more effective than this site's search.  

3). Use more detail in your question.  The type/size of your forge, the diameter of your tuyere (ducting), the size of your fire pot.. etc...   All of these things will help us to answer you.

 

I reread your post and found that you mentioned charcoal at the beginning so I'm running with the belief you are still working with a solid fuel forge.  I hope you are using lump charcoal and not briquettes.  If not, problem solved partly.  Also, you should be using some method to control the air volume. An air gate like those used for shop dust systems.  You can also use a pvc "y" connector and use one leg of it with a gate to allow air to bleed out in a controlled way.

This will allow you to control the amount of air going into your fire.  When you start the fire you should start with a low volume of air.  It is possible that, running your blower on full blast, you are actually putting out your young fire.  It may work occasionally only because the size and compactness of your pile of charcoal puts enough back pressure on your blower and lowers the CFM's enough to get you a fire.  I imagine you get quite a lot of sparks!  As the fire becomes more stable you can increase the air to get it hotter.  This should set you in the right direction.

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Here's an idea for attaching your blower to your forge.  Get your hands on a junked old vacuum cleaner.  People toss them all the time but they are loaded with goodies.  You can steal its blower and take the nozzles and the hose.  The hose is smooth inside to reduce static pressure and it is flexible.  I got this idea last month when my wife announced that we need a new canister vacuum. I acted put out but in my head I was screaming, "SCORE!"

 

To test to see if I'm right simply back the blower away from its connection so there is a gap between your ducting and the outlet of the blower.  An inch will probably suffice.  This will reduce your air flow and you should notice the difference when lighting up the forge.  Good luck.  Do some searching on the forum for blowers and forges.  You will find more ideas.

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Is your forge side blast or bottom blast? Photos of your set up will help us understand the problem. 

Fuel does not make the fire hot, air makes the fire hot. I will suggest that you need less air and more solid fuel in your forge. A gentle breeze to start with just to get things going. Then adjust the air flow as needed to produce the heat you need.

The air pipe should be connected at the forge. The other end, where the air is generated (blower) can have an air gap between the air pipe and the blower. How much? You will have to play with the distance of the gap. I use 3 inch aluminum flexible dryer vent duct with a 3-4 inch air gap. Aim the air blast closer to the opening of the air pipe for more air flow, not so close for less air flow. Adjust the distance of the air gap as another variable.

The air flow is adjusted as needed, and is not a set it and forget it operation. 

Another variable is the size opening(s) where the air enters the fire. 3-4 holes 1/4 inch in diameter is just not enough to get air to the fire in my opinion. I like as much air as possible to be able to get to the fire. For a 2 to 2-1/2 inch twyere I use one 3/8 inch rod as a grate, for 3 inch twyere I use 2 of the 3/8 inch rods. No air restrictions there. And I can burn coal dust with this set up.

Lou, thank you for the suggestion on the sweeper hose. Great idea.

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Also, one of the quirks of charcoal is that it doesn't like too much air. A surprisingly gentle blast will give you plenty of heat, while an excessively strong blast will actually cool off the fire. 

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I'll be honest, Glen, I was assuming he was using a standard bottom blast.  So few people seem to use side blast forges.  That's why I feel like I'm flying blind learning how to master mine...  also, I'll be able to extract a check from my wife to send along for those shirts!

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  • 3 weeks later...

This is not helping Kyle today, (Kyle your location please) it is merely a comment.

I am using a Swedish cavalry field forge. They have a kind of valve in the bottom of the fire pot like a mushroom in a hole. A previous owner replaced the treadle with an electric motor that runs far to fast so the pressure from the fan is high. This means that I have the valve more or less closed at all times except when starting the kindle (which I do with the fan off).

The good thing with this is that I never get slag in the inlet. The air pressure keeps the opening free. The slag forms a doughnut that can be fished out of the fire. I cannot translate my inlet restrictions to hole diameter since it is an oval slit with slightly varying width. Nor have I measured the air pressure.

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