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?

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.

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.

Thank you for the advice on both my profile and my bellows. I am using lump charcoal, though I have used briquettes before. And yes, there is a lot of sparks.

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.

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.

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. 

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!

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.

 

As I saw new thread I will post question here

I have same problem here, higher velocity air blow out the fuel.

With smaller bellows and longer pipe I didnt had that problem.

I was thinking will longer pipe minimise air preassure. I thing I will raise mh bellows and put longer pipe

How about a counter weight so that the bellows closes slower?

What do you mean exactly ?

Well they will blow blast at upper stroke.

I was thinking if I made pipe 3 foot long bend and make two knees that I will minimise that preassure by creating bigger distance between bellows and forge.

Edit: I get it now that could work tying some weight and making fulcrum at top frame that will lift top board. I need to give it a try

Make the weight adjustable and you can get different speeds from the system---the inverse of tossing a hammer on the top board to make it blow harder.

What is the diameter of your tue pipe?  I think putting in a narrower section or even a valve in the middle of the length might be better than just longer pipe.

Welcome Kyle. I also have a single speed blower (that I should upgrade, the bouncy castle blower is a great they are designed to run for hours) but the solution is from: DF-in the shop youtube channel. It is a valve system that does not obstruct the air flow. It works for me I am very pleased with it.

https://www.youtube.com/watch?v=WLWupoLgOEs&list=FLVyDqFFEGLOBOwPoKrmco0w&index=3&t=115s

https://www.youtube.com/watch?v=epBHOViClBs&list=FLVyDqFFEGLOBOwPoKrmco0w&index=2&t=234s

 

54 minutes ago, ThomasPowers said:

Make the weight adjustable and you can get different speeds from the system---the inverse of tossing a hammer on the top board to make it blow harder.

What is the diameter of your tue pipe?  I think putting in a narrower section or even a valve in the middle of the length might be better than just longer pipe.

Well diametar is about two inches and it is narrowed to one inhes at end where tuyere meet fuel.

I cant put valve because I dont have weldor to weld it  I should drill pipe make weld some metal on rod and than where is hole to put that rod .

 

But I dont have material for that even if I did that there is realy small room.

Bellows are apart from forge like 10 inches or less.

So you can't hacksaw a slit in the pipe and have a piece of tight fitting sheet metal that slides in the slot? 

Well I could do that theoreticaly, but place where is pipe and where that will go is too short, and where tuyere meet forge.

And I dont think that will minimise preassure

Thomas has the right idea.

You prolly know this so consider it for others. You want volume not velocity.

Assuming yout top leaf falls and you lift for the return stroke, you need to control the speed of drop. 

A rope attached to the top leaf going thru a pully attached to the ceiling gives you an adjustable way of controling drop. That should be all you need.

If you still have too much volume than Thomas still has the correct solution.

To add to the above, then use a the gate to vent air to the outside. 

Example/ make your slide say half inch wide and cut the end on a diagional. Then the farther out you pull the slide, the larger the vent opening to the outside. The thickness i gave is just an example.

I will try with that even my bellows have loop for that where it should bee tied to make it work.

It will be easy to make counterweight.

Can you attach a T fitting between the bellows and the forge with a valve as a waste gate? 

I cant doo that because space is too short so I manage to do this like I saw jappanese smiths do , I restricted area where it could blow the fuel

If it works that's all that matters. If I turn my hand cranked blower too fast it blows all the charcoal out of the firepot also. I can't crank it more than about 8 rpm's or it's too much. 

Glad you got it sorted out. Is this the same bellows you was working on restoring back in the summer? 

Pnut

Yes they are the same bellows

Iam using charcoal for fuel and.this thing tend to.escape I mix it a litle bit with lignite so.it is packed.

Generaly I wont need bigger forge for swords etc, narrow hearth is what I saw in practical blacksmithing book too.

I think this should work fine. Just you have to use poker a litle bit so you can pack.your fuel.

I've noticed loose fuel can sometimes be a problem. I made a flat tool that fits in my trench to pack the charcoal down a bit. I've sat a brick on top of the fuel before too. I prefer packing it though. 

Let us know how it works after a few fires. 

Pnut

Well that could be tried too.

I for now on made two hooks for.bellows.

 

I will see if I will need to heat and bend pipe so.I can raise bellows and make one knee and than another kne so they will be like this.

 

But that is huge step and risky to do.

 

Something like this, this way if pipe is longer I guess preassure is lower but I wont consider it now.

 

Since I need forge to do all stuff for.example bend a pipe.