PDA

View Full Version : Forge design ? OT



Boucher
06-24-2010, 04:32 PM
Long ago I took metal shop in the 9th grade. First project was to make a chisel. The furnace that we used for forging and heat treating was a natural gas fired and was about one cu-ft in size. There were 3 burners on 2 opposite sides facing one another. Here is a comercially avaliable 3 burner Propane forge.
http://i109.photobucket.com/albums/n50/boucherbyron/Burner%20and%20Forge/3BurnerForge.jpg

Anybody know why the burners are vertical?

oldbikerdude37
06-24-2010, 04:57 PM
Just a guess but maybe the heat would shoot down, rise and you could use it twice.:confused:
The olny time I used a deal like that was for branding cattle, you just wanted a good even heat. Our thing was a crude steel pipe with some pipes.

It will be interesting to see answers from people who know why they do that.

lazlo
06-24-2010, 05:35 PM
I took a bunch of pictures of a neat benchtop forge that my Blacksmithing instructor makes for friends (but won't sell, due to liability reasons). I uploaded them to my photobucket, but let me ask Will if I can post them here.

His venturi is horizontal, but enters at the same point.

The one in my Photobucket is a made from a piece of 6x6 Schedule 40 square tubing. The back is open with a set of bricks to close-off as much as you need, while still allowing for heating any ~5" section of a long iron.

john hobdeclipe
06-24-2010, 06:14 PM
My wild guess is that having the burners vertical keeps the forge balanced...not likely to tip over onto the side as it would be if the weight of the burners was off to one side. Another plus is that you're less likely to set your beer down on top of the forge and ruin it.

The beer, that is.

Forestgnome
06-24-2010, 06:20 PM
Probably just to save bench space.

jeremy13
06-24-2010, 06:33 PM
I would have to say to save space. And to heat a flat bar more evenly ( bigger target). The flat bar will more than likely be laying flat so the flame will hit the broad side and not the narrow side. But since heat rises and that includes spent air ( no oxygen). The burners might suck up the spent air and not want to burn efficiently. Cold air from the side would be much better.

Plain ol Bill
06-24-2010, 06:41 PM
I agree that the burners are vertical to save spave. I would not have this forge for the work I do personally. There is going to be a hot spot right under the burners. Burners should not point directly onto the work but should come in to create a vortex or swirling fire. Just my humble opinion but I use a forge about five days a week and have made all my own.

Tinkerer
06-24-2010, 08:33 PM
I agree that the burners are vertical to save spave. I would not have this forge for the work I do personally. There is going to be a hot spot right under the burners. Burners should not point directly onto the work but should come in to create a vortex or swirling fire. Just my humble opinion but I use a forge about five days a week and have made all my own.

Hi Bill... Ya got a camera? Hint...hint. ;)

Your Old Dog
06-24-2010, 08:48 PM
I wonder what kind of bricks are in this particular oven. The kind sold at Tractor Service Supply which are kind of heavy and very hard or the light bricks that are also a bit fragile in that you can scrape channels into them for heating wire?

The particular brick that TSC sells is the same as used in my wood burning stove for the house, that is, heavy and durable. Wonder if they would work for a heat treat oven?

Ries
06-24-2010, 09:14 PM
Cheap or good- pick one.

most relatively cheap commercial forges use vertical burners, cause its cheap and easy to build em that way.

this is a great book about forge design-
http://www.amazon.com/Gas-Burners-Forges-Furnaces-Kilns/dp/1879535203

and this is a great source of info-
Ron has designed a simple forge that hundreds, probably thousands, of smiths have built variations on.

http://ronreil.abana.org/Forge1.shtml

this guy sells premade burners-
http://www.hybridburners.com/

Chile make some nice little forges that use a round shape, with an offset burner, to induce a swirling pattern of heat.
http://www.chileforge.com/

I make my own forges, using castable refractory from Pryor Giggey- much better than bricks from Tractor Supply.
http://www.pryorgiggey.com/
I cast cylinders, using two pieces of sonotube for a mold.
Its a design a friend of mine worked out, you can make em any size or shape that way.
Castable refractory will last a long long time- and its the radiant heat from the heated up refractory, as much as if not more than, the direct heat from the flame, that makes a forge work.

Just came in, all hot and sweaty, from the forge ten minutes ago, after forging tapers and textures on about 50 pieces of stainless steel.

Dr Stan
06-24-2010, 09:26 PM
Here's a very good blacksmithing forum: http://www.anvilfire.com/

Lots of very helpful individuals and other sources of information.

Boucher
06-24-2010, 09:27 PM
It would certainly be interesting to see your different furnace configurations. I have allways admired the work of the old blacksmiths. Here are a couple of branding irons that I was able to aquire along with a furnace that I have been trying to get to work.
http://i109.photobucket.com/albums/n50/boucherbyron/Burner%20and%20Forge/IMG_0110Small.jpg
The old branding iron furnaces in this area were made using 6 to 8" steel well casing. As in any furnace the swirrell and heat pattern were important. I can remember that old metal shop furnace from many years ago but I can't remember details of the pipe furnaces other than they used a pear burner and they worked rather well.

My well drilling days came along after the cable tool era had closed in this area. This is hard rock country and that requirred forged bits. Building up bits with a welder just didn't work here. Standing over a white hot 6 to 8" bit and forging it back to size with sledge hammers was bad in the winter and worse in the summer. The cable tool engines ran off LPG and usually had 250 gal tanks. This was then also used to fuel the forge. I will go by my Ex FIL and see if I can get some photos to post of one of these. The furnace was also used to melt the babbitt to pour the wire rope sockets for the drill string.

Dunc
06-25-2010, 09:42 AM
Dave Gingery (of build your own lathe, mill, etc fame) has a plan. Likely at Lindsay books

Forestgnome
06-25-2010, 10:34 AM
I make my own forges, using castable refractory from Pryor Giggey- much better than bricks from Tractor Supply.
http://www.pryorgiggey.com/
I cast cylinders, using two pieces of sonotube for a mold.
Its a design a friend of mine worked out, you can make em any size or shape that way.
Castable refractory will last a long long time- and its the radiant heat from the heated up refractory, as much as if not more than, the direct heat from the flame, that makes a forge work.

I see there's several different castable refractories at Pryor Giggey. Which one do you use?

lazlo
06-25-2010, 12:49 PM
Here are a couple of branding irons that I was able to aquire along with a furnace that I have been trying to get to work.
http://i109.photobucket.com/albums/n50/boucherbyron/Burner%20and%20Forge/IMG_0110Small.jpg

Does that get hot enough to forge, or is it primarily to heat-up branding iron?
I've used a couple of shop-built forges that used firebrick, and they don't retain heat very well -- they're "cold".

The ABANA guys recommend Kaowool or castable refractory, preferably the former, but I'm just a beginner, so I don't know WTF I'm talking about :)

Ries: what stainless do you use for forging? Will has a piece of boat prop that he's willing to let me use to forge a knife. Boat props seem to be variants of 440C -- how hard is that to forge? I'm guessing the 300 series stainless are much easier to work?

PTSideshow
06-25-2010, 01:59 PM
A lot of them use the soft brick if they have to move the forge around a lot. With the soft brick they are also easier to damage.
As to burner placement. As with beer, Nascar drivers, cars/trucks and women or men it is a learned preference. Some will tell you all kind of stuff why they are in the angle of the dangle or on the left, right or top or bottom.

Some are angle in towards the back or not. As long as it is heating the metal you want to adjust. It probably won't make to much difference of the occasional forger ;)

Here is one current book on a light weight ceramic type insulation (http://bbs.homeshopmachinist.net/showpost.php?p=494154&postcount=139)

You do need to coat the ceramic insulation with a liquid type flame protection.

Again you can use anything from a 5 gallon paint can wrapped in fiberglass insulation. A very short term forge to mineral wool insulation, the same soft firebricks used in kilns for pottery. Have seen an old top loader kiln on it side. with the lid modified for a door.

And a hole drilled in the side for the burn assemble.

Here is an interesting book using clay as a teaching medium for blacksmithing (http://bbs.homeshopmachinist.net/showpost.php?p=494783&postcount=141)

Blacksmith projects (http://bbs.homeshopmachinist.net/showpost.php?p=497651&postcount=148)

Another on forging, annealing etc steel (http://bbs.homeshopmachinist.net/showpost.php?p=502848&postcount=154)

The hard fired firebricks tend to be a better, stronger brick they are also harder to cut, drill etc. The soft ones can be cut with a hand saw (old) and holes drilled with the standard cheap hole saws.
Fiberfax coatings (http://www.fiberfrax.com/#Fiberfrax-Coatings)

http:ITC/100 (http://www.anvilfire.com/sales/ITC/100_2.htm)

rock wool (http://www.roxul.com/stone+wool/fire-resistance)

more insulation (http://www.spi-co.com/)

There also might be some other books in my welding book list, as it contains welding, some machining, sheet metal, foundry, casting, jewelry, art patina's and lost wax and sculpture and general art metal work and other subjects for the home shopper!

Roofers torch/weed burner forge (http://www.bladeforums.com/forums/archive/index.php/t-253613.html)

Zeoller forge (http://www.geocities.com/zoellerforge/)

Building the new forge saga (http://ironringforge.com/NewForgeSaga/New_Forge_Saga.html)

Johnson gas forges (http://www.johnsongas.com/industrial/frn-forge.asp)
:D

wierdscience
06-25-2010, 02:27 PM
I just bought the Gingrey book on building an atmospheric furnace.

http://www.lindsaybks.com/dgjp/djgbk/ffurn/index.html

I buy my refractory cement and castable from a local boiler service company.The guy there confirms what Gingrey says in his book.3,000*f castable will work fine,but 5,000*f lasts longer.

The two gas forges I have used both had the burners at 90*vertical or 15* off vertical.Makes sense since the heat is being directed down onto the work piece.

One neat feature the Gingrey furnace has is a Pyrometer for temperature control.

Ries
06-28-2010, 12:35 PM
My castable was just Econocast, I think it was the 3000 degree stuff, but there is no number on the bag I have, so I am not sure.
Whatever it is, it holds up for 3 to 5 years of hard use.

I forge mostly 304, cause its the cheapest stainless available, and it works well for most things- it can be forged, welded, and, with a bit of tool breakage, machined.

hojpoj
06-28-2010, 01:10 PM
A lot of forge design carries over from furnace design (like seen at www.backyardmetalcasting.com/forums), the key differences being orientation, access, and heat distribution.

If you're using castable refractory, you've got some options. Higher-rated is always better, but then comes the question of dense, or insulating? Most forges I've seen greatly emphasize the insulative properties of the furnace in order to economize fuel consumption. You can achieve this by purchasing the lowest-density insulative castable you can get your mitts on- or as some in the casting community have done you can take the standard hotface (dense) castable and mix it with styrofoam beads in a 1:3 by volume castable/foam mix. The beads burn out cleanly, leaving small air pockets to create insulation. This is a pretty darn cheap way to go, as well. You can line a far greater volume using this method than using an equivalent (in cost) of soft firebrick. I made a styrofoam shredder to get me the necessary beads (http://themannook.info/styroshredder/styroshredder.htm). Still building the internal forms for my furnace (I'm starting into metalcasting... forging is a long ways down the road).

Plop a hardface shelf in the bottom for you to place your stuff and you'll be ready to rock n' roll. If you feel that you might bang stuff around inside (and damage the lining) you can trowel on a thin layer of the straight castable to withstand some of the abuse. This will increase the time for your furnace to get up to heat.

Kaowool is still the hands-down winner for insulating these things, though. Dealing with the fiber issues is the only real problem it has.

lazlo
06-28-2010, 01:47 PM
I forge mostly 304, cause its the cheapest stainless available, and it works well for most things- it can be forged, welded, and, with a bit of tool breakage, machined.

Thanks Ries -- I'll stop by Metals4U on the way to class today and pick up some cut-offs.


Kaowool is still the hands-down winner for insulating these things, though. Dealing with the fiber issues is the only real problem it has.

I'm hearing that from a lot of smiths. I just started building the 1/2" T-Rex burner from Mike Porter's book. I'm going to do a 6x6x9" Schedule 40 pipe (benchtop) forge.

I need to find a small(ish) anvil :)

By the way, I participated in the Balcone's Forge nail header demonstration on Saturday (making nail headers from HC railroad spikes). First time I forged with coal. Greasy/smokey -- I like gas forges better (but I'm a newbie...) :p

Boucher
06-28-2010, 08:39 PM
Robert,
Make the forge fit the anvil you have. I have plenty of pipe up to 30" dia X 3/8 wall.

Serously if you want larger round pipe I have some. I visited my XFIL this afternoon and was not able to find any photos of working Bit forges. They may be found as he is still looking.

The one piece of information that I gleaned from him was that their forges were using forced air. They went from cold to white hot on a 8" cable tool bit in 20 minutes. When gas was a nickle a gallon they were not concerned with the economics of the forge.

I have been playing with naturally aspirated burners for a while. Even with my background in rocket motor design I am not progressing very fast. I will probably purchase one of the avaliable designs to put on a small forge. Unless things take a turn for the better, I am going to a forced air design.

I ordered the book on furnace design and will probably get the one on burners also. I mostly want to heat and bend metal but the furnaces are sure interesting to me. Maybe I am a closet Pyro-maniac.

I would sure like to see some photos of furnaces and your use of them.

ulav8r
07-01-2010, 02:10 PM
In about 1962-63 saw a simple, easy to make forge. My dad was having a well drilled. The bits were about 5 inch diameter and the driller sharpened them by forging. He used a shovel to dig a trench about 8 inches deep and three feet long. At one end he placed a 2 inch diameter pipe from a blower. A pile of coal was poured over the end of the pipe and lit. The end of the bit was then placed intoo the center of the fire with the other end angling up out of the trench. There was a shield of some type over the top to protect the bit from the atmosphere. When the bit was up to temp, it was pulled out and hammered. I do not remember if there was an anvil used or not.

lazlo
07-02-2010, 06:00 PM
I found out last night, the hard way, why you'd need a triple-stack of burners: a single propane burner simply doesn't get hot enough to forge weld.

I tried to forge some bicycle chain Damascus, and it was a mess. Had to use a rose bud on an A/O torch to get it hot enough. Also the borax make a mess of the bottom of the forge -- the acid eats the firebrick.

I'm wondering if two burners with Kaowool insulation would be roughly the same heat as 3 burners with firebrick. Seems like the latter is going to burn a lot of propane.

Byron, I might take you up on that pipe -- maybe we can trade for some other forge components.