Issues with heating

[goat]

so i'm having issues with my fire pot. i use bitumonous coal from centar forge and i'm having all kinds of issues with getting a decent heat. my fire pot is home made and meassures 12 inches X 12 inches X 9 inches deep. i have a tuyere that is made from 4inch diameter steel pipe and my air supply is a hair dryer. im wondering if i made the fire pot too deep or my air supply just isn't moving enough air. 

[Jonnytait]

Would you be able to take a photo of it, so we can see what you are working with?

[goat]

I edited the post and added photos of what I'm working with

[Glenn]

4 inch air pipe seems overly large, The 9 inch depth would seem to be too deep, but would depend on how large a fire you need and what you were forging. You can easily reduce both as you try to get things working.

JABOD just a box of dirt uses a 3/4 to 1 inch pipe directly into the fire from the side, and about 3 inches above the floor of the forge. 

You can easily modify your forge as a test by filling it with 9 inches of dirt and laying a 3/4 to 1 inch pipe directly into the fire from the side.  Reduce the width of the fire pot to 6 inches with metal walls, brick or dirt.  Add fire and coal and see what happens.  This is for testing purposes and can be changed or removed later.

 

[goat]

fire pot might be too deep.... huh. ok i can cut a plate that sits in the fire pot to raise the bed up to a depth of 6 inches. think that might work?

[Daswulf]

Few things I see. Fire pot is too deep. Glen mentioned it depends on what you are forging but starting out that is most likely too deep.  The holes in the tuyere are too small and that is contributing to a lack of air to the fire as is your hair dryer is likely underpowered for that kind of setup. Also the 4" on the T is a bit excessive. 

So it is a combination of a couple issues that are keeping you from getting a good fire. 

 

I use a brake rotor as a fire pot. I prefer them 8-9" diameter and 2-3" deep. The rotors on the rear of vehicles that have the drum style E brake I've found to work great.  A 2" T pipe works well, and bigger holes in the tuyere. You want as little are restriction from the tuyere yet just enough there to keep the coal from falling down through. 

You could make a pot like you have but make it shallower. You can always easily build up the sides of the fire  or bank up the fuel but with a deep pot you'll have more trouble getting longer pieces down to the sweet spot of the fire.

A hair drier might be enough air without the other issues but if not that could be upgraded easily after you build a better setup. 

[ThomasPowers]

Also if the hot spot is too low in the firepot you could add slots on opposing sides to be able to place the workpiece into the hot spot. Of course you will need to lift the firepot higher so the bottom of the slot is over the forge table.

[goat]

i have a 3 foot bar of 2 1/2 inch 01 round stock and some fork lift tines that are 3 inch square (4140) that i want to make a few hammers from. my old bottom blast forge is the same design just with a smaller fire pot. the old forge meassures 5inches X 5 inches X 4 inches deep for doing rivets, small hair pins etc...

[Glenn]

Looking at your photos, the fire pot looks to be too deep. There are not enough small holes in the bottom of the fire pot to get much air into the fire. I have a forge with 2+ and 3 inch diameter pipe for the tuyere.   The grate is 2 ea 3/8 bolts welded in place across that 3 inch opening.  Fuel does not make a fire hot, air makes a fire hot.  That allows a LOT of air to get to the fire. Control the air and you then control the heat.  If you need more fuel you can always stack it on top of the fire.

We are running two discussions here. One on the side blast test modifications. and one on making modifications to your existing fire pot.  We much separate the two discussions and speak to only one at a time.  Cross linking them will not work. 

Your fire pot to JABOD:  Fill your present firepot with 9 (nine) inches of dirt, so the dirt is just 3 inches below the rim.  Put a 1 inch pipe horizontally 1/3 of the way across the fire pot.  Build walls about 4 inches deep for the fire to rest between. Start a fire and add air.

Mod your existing firepot:  Get a piece of auto exhaust pipe 8-9 inches long and put it over as many of the existing holes as you can, then pack clay, mud, or dirt to seal off the difference, and support the pipe from the walls.  Drill a couple of holes about 1 inch below the top of the exhaust pipe and insert 1/4 inch rod or nails into the holes for a grate.  Build a fire on top of the dirt and let the air come out of the pipe you inserted.

All this is a testing platform.  Nothing mentioned is permeant and can be changes as needed.

Where are you located?

 

 2 1/2 inch 01 round stock and 3 inch square stock will need a LOT of fire and heat to get up to forging temperature.  You current set up will not do that. 

[goat]

im in east texas. thanks for the advise. i'll raise the bed of the fire pot and see if that does the trick. thanks again

[Irondragon Forge ClayWorks]

I agree with the too deep and wrong style fire grate. It would be easy to modify your pot. Not to worry about the 12x12 top measurement. I started with a fire grate like yours and had not so good results with a Champion hand cranked blower. You might want to look at this one, which I have used many times and love it.

http://www.bamsite.org/firepot.html

We won't remember your location once leaving this post, hence the suggestion to edit your profile to show it.

[Glenn]

Many forges (the upper limit for some) can heat 1 inch square.  If you go to 3 inch square you are talking about going from 1x1 in cross section to 3x3 in or 9 times the cross section.  This means 9 times the heat needed to approach working temperature.  It means 9 times the coal used and 9 times everything else involved.  

2-1/2 inch diameter round is 17 pounds per foot or 51 pounds.  3x3 inch is 31 pounds per foot 3 feet long is 100 pounds.  You have a set of tongs that will grip onto that size material?  How do you plan on handling or moving that weight?  And you do realize that you need some heavy hitting BIG hammer, think industrial strength.

Cutting off a hammer head size piece of material will still mean heating that chunk of metal, tongs, a heavy hammer and the proper size drifts for the handle hole.

This is not to throw water on your project or idea, but to give you information for consideration.

[ThomasPowers]

Perhaps you need a bit more experience before working such large stock?   I have a forge that the previous owner burnt a piece of RR rail in two in.  It's still waiting on me getting my powerhammers running.

[Irondragon Forge ClayWorks]

1 hour ago, goat said:

bitumonous coal from centar forge

Just a thought, I have used their coal and it is excellent blacksmithing coal although a little expensive.  If you could find an ABANA affiliate club of blacksmith's in your area they usually have coal and if you join attend some meetings for hands on experience. here is one.

https://abana.org/affiliates/affiliate-map-list/#!biz/id/596ff30b9865a16110706efe/Contact

[goat]

i have a pair if heavy duty tongs made for the work. hense the large fire pot. and i have plenty of coal and a few fellas for strikers. it's just getting the material up to temp is the issue i'm having. i've cut out a plate to raise the bed of the fire pot so i'll have to test it.

[Irondragon Forge ClayWorks]

To test it I would just tack weld it in one little spot and if it works (which it should) make sure to cut out the drilled fire grate, so ash & clinker doesn't get trapped on it. I can see myself welding the new grate in solid then having to cut it out to remove the old grate. My fire pot is round so I bought a round fire grate and didn't remove the old drilled one, so I speak from experience. lucky for me mine is set in fire clay so it wasn't a job to lift it out and torch the old one out.

[goat]

thanks for the advise. i honestly don't know why i built the fire pot so deep. well lesson learned

[Daswulf]

A fellow smith and I forged a 3# hammer in my 8"diameter x2" deep fire pot. We built up the coal around the stock and it worked fine with good fire management. 

From the info given and your issue, you may want to start out with smaller projects and build up to that.  By the time you are ready you will know more about what you need in a fire, fire management and techniques to forge the project. 

Just a plate raising the fuel above what you have might not work as well. It would be better to rebuild with the suggestions given. 

It's fine to safely experiment tho. Please let us know how it goes, or if any of the suggestions helped. 

[anvil]

Here's some more advice. You have already been to Centaur website, so you know how to get there. Go there and look up their rectangular cast firepot with a clinker ball. The dimensions for their firepot are there. They are about 9"x14" x4" deep. Build a firepot to match and buy a clinker ball and handle from them. The difference in efficiency between a clinker ball setup vs a flat piece of steel with holes in it is like night and day. I've used their firepots for over 30 years. The dimensions are taken from good firepots of the past. You can heat anything you mentioned all the way down to a narrow trench fire for heat treating or knife making. Check the price for the whole setup, firepot, tuyere, and clinker ball. Either way you won't be disappointed. Peigh tools is another source. And there are some other good places that do great cast firepots. Sometimes saving a dime will cost you dollars in the long run.

For a good fire for basically any size steel you want 4" of coke underneath and about 3" on the top. Your iron should be parallel with the top of your firepot and easily slide across the top back and forth. Never  point your iron down. 

With the dimensions above, you can get about 4 lengths of 1" square stock and quite easily get an 8" long heat on them by moving them back and forth. You can get easily 8 lengths of half inch square and get the same length of heat. Learning fire control will make this possible. As a general rule of thumb, a 6" long heat will keep you pretty busy. 

Basically the dimensions I gave is a great size for a single man full time shop doing any size work you want from hammers to crafts fair limited production to gates, railings and any lighting you want. 

And a 3"-4" tuyere is fine. You want air volume, not velocity. The smaller the tuyere the higher the velocity to get proper volume. Too much velocity means burnt iron. A good hand cranked champion or candy Otto blower is sized to about that size. The same size tuyere applies for electric fans as well.