Jump to content
I Forge Iron

Newbie wants to make forced air mini forge


Recommended Posts

My son and I are wanting to make a small propane forge (paint bucket sized). Mainly we'll be heat treating steel knives and possibly forging a few odd items. Pattern welding may be fun, but that will come later after some experience and maybe if necessary a bigger forge. I've done all kinds of research, but due to the volume I've got more questions than answers. I have the paint bucket, more ceramic wool than I need, ceramic coating for the wool, a couple IFBs for the bottom. I am wanting to get a regulator and blower and go forced induction as I have heard you have more control and it's more efficient on fuel. However, is that possible/reasonable on a forge this small? I've not seen any paint bucket sized that use forced induction.

Recommendations?

Link to post
Share on other sites
8 minutes ago, makefire said:

I have heard you have more control and it's more efficient on fuel.

You have no more or less control, between fan-blown and naturally aspirated burners. Fan-blown is usually easier to build, and tune right, in the  forced place. Naturally aspirated burners are easier to change output levels on. Either kind of burner takes time to understand, and understanding your burner is the key to tuning it; not what kind of burner you are learning about.

All of this is beside the point for you, because you want to build a very small forge. Yes, it is possible to build a very small fan-built burner to mount in it, but why would anyone go to the bother?

The ideal burner for a one gallon size forge would a a 3/8" linear burner; the easiest burner for you to build, at this time, is a 1/2" "T" burner; it can be turned down low enough to work in your forge.

Link to post
Share on other sites

Welcome to the forum.  We always encourage people to put their location in their profile since the answers to some questions are location specific and it may turn out that another member is within visiting distance. 

It looks like you've done a little more homework than a lot of people who visit here, but I have a couple questions and suggestions.  What do you mean by ceramic coating for the wool?  If you mean something like Satanite or Kastolite you should be fine.  For the floor of the forge there are much better options than IFB.  You've probably noticed that they are a bit fragile, so they get damaged or destroyed fairly quickly from steel moving in and out of the forge.  Also, if you intend to forge weld then the flux will eat through them very quickly.  High alumina kiln shelf about a half to 3/4 inch thick works out pretty well or you can cast a floor out of something like Kastolite and it will be durable.

On to the forced air part:  First, it's a bit of a myth that forced air burners are more efficient than naturally aspirated burners.  If both are tuned right they will use the same amount of fuel and air to produce the same amount of heat.  Where some people get confused is that blown burners typically run at lower pressure, so they assume that means less fuel used. Naturally aspirated burners use a very small diameter hole for the fuel and higher pressure, while blown burners usually use a larger diameter fuel inlet and lower pressure, but the volume of fuel used is pretty much identical, again assuming both are tuned properly.

For a blown burner you want valves on both the fuel line and the air so you can adjust them independently of each other and fine tune the flame.  The down side is when you adjust one you have to adjust the other in order to keep the same type of atmosphere in your forge.  You can do this quickly when you get used to it, so it's not that big of an issue.  Of course you also need power to run one, unlike a NA burner. 

You should be able to make a blown burner that will work, but you may need to scale down to 3/4 inch or possibly even 1/2 diameter pipe for your final burner tube.

If fuel efficiency is your main concern and you have basic shop skills and tools I'd highly recommend taking a look at Frosty's T burner and going with a half inch diameter burner.

You can find the instructions here:

https://www.iforgeiron.com/topic/43976-t-burner-illustrated-directions/

 

Link to post
Share on other sites

All very good points, Buzzkill and Thomas.

This leads to your first bad news.  I am a fan of coffee-can and two brick forges; these tiny models push the envelope; that has always appealed to my inner maniac. Five gallon bucket forges were probably made popular, when Larry Zoller Forge did a tutorial on how to build them, But common sense stops at three gallon forges made from an empty Freon or or helium non-refillable bottle, or a half-muffler oval forge. All three containers can be acquired free, with a little work.

It will cost you more to make your five gallon paint can forge, as to build one of the recommended mini-forges. But the mini-forges are all made with blade smithing in mind, after you go through the trouble and expense to build it, that will make all the difference.

Link to post
Share on other sites
1 hour ago, Buzzkill said:

We always encourage people to put their location in their profile since the answers to some questions are location specific 

Done

Quote

What do you mean by ceramic coating for the wool?

According to the can the supply place I got it from it's mostly fireclay and aluminosilicate. It's supposed to form a firm protective layer on the blanket.
 

Quote

 

On to the forced air part:  First, it's a bit of a myth that forced air burners are more efficient than naturally aspirated burners.  If both are tuned right they will use the same amount of fuel and air to produce the same amount of heat.  Where some people get confused is that blown burners typically run at lower pressure, so they assume that means less fuel used. Naturally aspirated burners use a very small diameter hole for the fuel and higher pressure, while blown burners usually use a larger diameter fuel inlet and lower pressure, but the volume of fuel used is pretty much identical, again assuming both are tuned properly.

 . . . .
If fuel efficiency is your main concern and you have basic shop skills and tools I'd highly recommend taking a look at Frosty's T burner and going with a half inch diameter burner.

Good to know. I was confused on that point.

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...