Author Topic: Building a forge (Read 23119 times)

David R. Pennington · « **on:** March 02, 2014, 04:40:15 PM »

Has anyone any experience with forges using back blast air? This is the simple style forge like Lewis and Clark used, also like they have at Fort Boonesborough. The air come in directly at the back wall of the forge and you build your fire up against the air pipe. I need to replace my little rivet forge. It just does not have enough depth to get enough fire for welding heats. I struggled the other day to get a weld on some soft iron wire for some basket weave chest handles. I am thinking of building one that I can use as a portable for demonstrations that also would be a little more authentic for earlier time periods. I have seen some with a little round bellows mounted under the forge and this is the general style I'm leaning toward. I'm wondering how effective the back blast style is compared to the bottom blast. It would be easier/simpler to construct. I've seen Mr. Farmer (I think that is his name) doing light forging with charcoal at Boonesborough but wonder how it would work for heavier jobs and welding heats.

jrb · « **Reply #1 on:** March 02, 2014, 07:53:33 PM »

The advantage of a side blast forge is the clinker falls below the tuyere where it's out of the way of the air blast.
The bottom blast cast iron firepots we're familiar with in the U.S., i think must have been designed in the late 1800s? to be more portable, but they require clinkers to be dealt with more.
I played around with a side blast for a few years, like the type Tai Goo uses for knife making. It works VERY well with charcoal.
It was a hand cranked blower on a 2" diameter black pipe, entering a 2x2 foot sheetmetal box (open at the top), full of clean wood ashes, with a cone shaped ducks nest. The pipe was covered and insulated by these ashes. Before firing, i usually slightly wet with water and packed the ashes to the conical shape. As the charcoal heated up, the ashes would get a slight crust which helped keep the cone in shape and helped stop breathing ash dust, i hope, each session.
I only ever used charcoal in that set-up.
If you've used charcoal you are aware of the massive amount it uses to forge weld.
I've recently got one of the heavy 1 1/4" thick bottom blast firepots from Kayne & Son to forge weld in with coke. It'll probably last a lifetime, but i kinda would like to try a water cooled sideblast like Mark Aspery uses.

jrb · « **Reply #2 on:** March 02, 2014, 08:04:33 PM »

I don't know how big your rivet forge is, or your air supply, but the dvd on forge welding by Bob Patrick, the one on gun barrel welding by Jon Laubach, and one by Hershel House, all just stack up firebrick around the top of their firepots to get extra depth for welding.

David R. Pennington · « **Reply #3 on:** March 02, 2014, 09:01:05 PM »

My little forge is poorly designed (in my opinion) but works ok for small projects. It has a little hand crank blower mounted underneath. The problem is the air pipe comes in the bottom and extends about 2" ABOVE the floor of the forge. You can't pile coal up high enough to keep a layer of hot coke above the air blast without it falling off the sides. As you know if you ever do any forge welding you don't want a direct blast of air without any fire under it.
I just bought a real nice (used) Champion tuyre, heavy, lifetime for permanent installation in my brick hearth when I get there, but right now I need a portable outfit.

Jay Close · « **Reply #4 on:** March 02, 2014, 10:46:43 PM »

Yes, the "build up the fire depth with brick" trick is a good one.

When I worked at Colonial Williamsburg I worked from a side-blast forge for over 12 years. Those were based on old illustrations and amounted to nothing more than a cast backplate with a tapered hole through it. They were miserable forges for heavy work --- which probably means we did not know enough at the time about how to use that old technology.

Since I left in 1999, experimentation has continued and they pretty much solved their forge issues with a heavy, cast iron nozzle. This was based on a illustration in Diderot's circa 1760. The nozzle idea seems to also be reflected in the evolution of English side blast forges. Eventually, the cast backplate developed a nozzle which then became hollow and cooled by a water jacket. I think Glendale Forge in England still makes both water cooled and solid tuyere's for side blast forges.

In short, there is nothing inherently limiting about a side blast forge. They can work well with coal or charcoal.

David R. Pennington · « **Reply #5 on:** March 02, 2014, 11:22:33 PM »

Jay, could you elaborate on the nozzle principle? I don't want to build a "miserable" forge (that's what I have now), but then I won't be doing a lot of heavy work in a portable outfit. I would like to be able to get welding heats for smaller projects. Does the blast nozzle come in the side near the bottom of the hearth or elevated some?

Old Bob · « **Reply #6 on:** March 03, 2014, 01:39:26 AM »

Quote from: David R. on March 02, 2014, 09:01:05 PM

My little forge is poorly designed (in my opinion) but works ok for small projects. It has a little hand crank blower mounted underneath. The problem is the air pipe comes in the bottom and extends about 2" ABOVE the floor of the forge. You can't pile coal up high enough to keep a layer of hot coke above the air blast without it falling off the sides. As you know if you ever do any forge welding you don't want a direct blast of air without any fire under it.
I just bought a real nice (used) Champion tuyre, heavy, lifetime for permanent installation in my brick hearth when I get there, but right now I need a portable outfit.

Rick, you ought to cut that extra bit of pipe off. Then make a V shaped box open at the top and bottom, wide part at the top, that will straddle the pipe. Make this in a rectangular shape, whatever size will work for you. Make it however deep you need. This will allow you to have better control over the fire and a much deeper fire. You could also drill a hole through the air pipe and drill a piece of square or round iron lengthwise a little off-site and thread it. Line it up with the hole in the pipe and stick a piece of all thread rod through it and the pipe. Bend the long end of the rod into an L shape and viola! you have a clinker breaker. You can make the box out of steel plate or fire brick. If you use steel for the box or the clinker breaker I highly recommend putting a heavy coat of refractory cement on them, especially the box. If you have a piece of cast iron that will work, you won't need it.

David R. Pennington · « **Reply #7 on:** March 03, 2014, 05:51:28 AM »

There is no room for modification on this little outfit. It is what it is. Did you shoot yesterday? I had planned to come but ended up shovelling coal.

Old Bob · « **Reply #8 on:** March 03, 2014, 02:59:53 PM »

Yeah, a little. When I got there, Ike and Dave G. were there with a really nice smooth bore barrel that Dave had turned out of boiler tube mounted in an oak test bed. Then Bob W. and Dave F. showed up a little later. We proofed the barrel and took pictures and they left. Then we just stayed at the shed and shot a little. Bob was sighting in yet another new creation, Dave trying out a new gun with an original Dickert barrel and I was trying out a new patch lube.

It seems to me you ought to be able to at least make a firepot that would work. That is the problem with these portable rivet forges. The fire spreads too much. Mine is like that but I never got around to modifying it because I quit doing demos and it just sits in the corner. I want to get it out one of these days and fire it up again.

David R. Pennington · « **Reply #9 on:** March 03, 2014, 05:05:08 PM »

It's not that the fire spreads. You just simply can't get enough depth of fire because the air inlet sticks up above the floor plate. I suppose I could completely redesign it but with all that effort I'd rather build something better. I picked up a real nice Champion 400 Whirlwind Blast tuyre Saturday but it will have to wait till I can build my new shop. It's too big for a portable outfit.

Old Bob · « **Reply #10 on:** March 03, 2014, 05:45:52 PM »

If you got a piece of 6 or 8 inch pipe about the same length as the diameter you could just center it over the pipe and put your coke in it instead of making the box. Quick fix that should deepen the fire. When you build your forge, go with a side draft. I built one for a feller over in Lincoln Co. once and it drew better than the hood style I have. That Champion 400 is a good blower. I have one here that I used until I went electric. It needs an oil seal put in it, but really puts out the blast. I'd really like to have a bellows, but I don't have the room. The squirrel cage blower I have is wall mounted and is completely out of the way. I'm about done with this snow. No school so I'm heading out to the shop and get into something. I've started restoring and old chalk cat that used to belong to my Grandmother. Then maybe start on a range box. I'm on hold with the rifle. I got to measuring the stock blank and found that it's too narrow for me to have a cheek piece and cast-off. I'll save it for a fowler. You goin' to make it out Saturday?

Jay Close · « **Reply #11 on:** March 03, 2014, 07:39:13 PM »

David R:

While I made the initial technical sketch for the cast nozzles now used in Williamsburg, I never had the chance to use their redesigned forges before I left. Your best bet, barring a trip to the museum, is to write, call or email Ken Schwarz, the current master of the blacksmith shop. I'm sure he'd be pleased at your interest in the period technology.

David R. Pennington · « **Reply #12 on:** March 04, 2014, 12:42:45 AM »

Jay, do you have any contact info for Mr. Schwarz?

Canute Rex · « **Reply #13 on:** March 04, 2014, 07:34:07 PM »

David R: There is a reason that blacksmiths switched from side draft tuyeres to bottom draft- they just work better. There is nothing sticking into the fire so no need for water cooling or frequent replacement of the tuyere. Easier to get a thick reducing fire. Unless you are interested in being museum quality HC for a first person interp or reenactment, go with bottom draft.

Rivet forges are a pain. A couple of ideas:

Go to your local steel yard and see if you can find a short cut-off from the end of a piece of heavy wall square tube. Something 4 or 5 inches long and 6 or 8 inches square, or a similar rectangle. Maybe a 6 or 8 inch round pipe cut-off, although that's not as good. You can set that over your bumped up tuyere for a firepot.

Just get a few of those hard white refractory bricks and stack them around the tuyere. Cheap, quick, and dirty, bit I've made it work.

Best of luck and have fun.

Old Bob · « **Reply #14 on:** March 04, 2014, 08:07:24 PM »

There's a difference between a side draft forge and a side blast forge. Also, building a box to hold the fire was suggested above.

Dociron · « **Reply #15 on:** March 06, 2014, 03:42:04 AM »

Here is a link to a PDF by Mark Aspery on how to build a side blast forge. These are the common style in Britain and Mark is from there so he should know how to do it.

http://assets.calsmith.org/cba-cdn/412/Side_Blast_forge_original.pdf

heelerau · « **Reply #16 on:** March 07, 2014, 12:49:14 PM »

I too have a rivet forge, mostly for shoeing horses and some other minor smithing work. I recently had my big rectangular buffalo forge shipped over from interstate, I have negotiated with central works, at my work, to make up a new fire pot and tuyere iron, for the price of a carton off beer. and also make up the missing section of draft duct. The next major project is the blacksmith shop.
You could make up a forge from old bricks, and use an old vacuum cleaner to supply draft, and some heavy wall tube with an oblong vent as a tuyere iron. Coke is easier to use than charcoal, if you can get it in a fairly fine grade.

Cheers

Gordon

David R. Pennington · « **Reply #17 on:** March 08, 2014, 03:32:14 AM »

I have begun building a new portable forge. I had on hand an old steel commercial cabinet slated for the scrap yard. I began looking at that thing and it appears to not be galvanized but just powder coat finished (black) about 20 gauge. It's side dimension is about right for the base so I commenced cutting it apart. I removed all the modern hollow rivets and made some adjustments. Some of the other panels will work ok for the draft hood and sides. I bought some inch and a quarter fire brick to line the bottom. I will put a heavier piece of plate near fire pot. I am going to build the pot out of 1-1/4 black pipe and flanges. I aim to make a small bellows for air supply.
I had another session with the old rivet forge and we are not fond of each other any more. I finally got a weld done but it's not hardly worth the trouble.

Jay Close · « **Reply #18 on:** March 09, 2014, 12:34:09 AM »

Getting in touch with Ken Schwarz, master of the Anderson Blacksmith Shop at Colonial Williamsburg, is as simple as calling the central switch board and asking for Ken. A snail mail letter addressed to him c/o The Colonial Williamsburg Foundation, Williamsburg, VA will also get to him. Sorry I don't have more formal contact info' at hand.

heelerau · « **Reply #19 on:** March 15, 2014, 07:22:23 PM »

the boys at central works have down a great job of the firepot, tuyere iron etc, will post a photo when I fly home next. !

KentSmith · « **Reply #20 on:** March 18, 2014, 10:15:42 PM »

I looked into side draft and bottom draft forges when I built mine 12 years ago. I went to Ft. Boonesborough and watched them at work with their side draft and also Williamsburg but settled on a bottom draft which has done all I have asked of it for a dozen years. I bought an old Chamion hand cranked blower, some flexible aluminum 3" X 3' venting, a 12" section of 3" galvanized steel pipe, a 3" gal. steel T and an old kitchen cast iron enameled sink with one 3" drain hole in the bottom. I mounted the blower on a stand and the sink on a platform 3'x3' made of cinder block with the front open. I connected the flexible venting to the blower exhaust with an O ring. I connected the gal. pipe to the T and secured on leg of the T to the sink by drilling 4 3/8" holes with lag bolts. I then connected the flexible venting to the gal pipe and place a 1/4" thick 6" disc of hot rolled mild steel with holes drilled for the tuyere over the sink drain hole. I made a sliding sheet metal cover for the other leg of the T that I welded a foot long 1/4 round to so I can open up the ash dump when needed. I have to replace the tuyere every year or so, keep oil in the blower and the enamel is almost gone on the sink but it is going on a dozen years and I am still going strong. I burn coal. Oh, I lined it with 1" thick firebrick and fireclay so I could get a sloping firebox that is about 4" deep and 10" in diameter. I weld, work 1" round wrought iron down to size and forge up pistol barrels when I want to get some exercise. haven't done a rifle barrel yet as my apprentice left for the real world so have run out of sons. My son-in-law is sensitive to coal smoke so he's no help. I'd say useless but the daughter might contest that statement.

David R. Pennington · « **Reply #21 on:** March 19, 2014, 03:36:15 AM »

I got a pretty good start on my new forge on Saturday. I too have decided to use a bottom blast. I got all the pieces cut out for the pan and draft hood. Had to patch two pieces together for one side. I used a piece of inch flat bar as a fish plate and riveted them together. I have it temporarily put together. I didn't want to use modern fasteners so I ordered some square head bolts and square nuts and some more rivets from Blacksmith Bolts. When they arrive I'll put it all together and rig up a temporary air supply and try it out. I forged a stove pipe collar out of angle iron and riveted it on the draft hood as well.
I've already named it frankenforge. The stock is a little heavier than I thought, it gauges 17 ga.. My son is away at college but he wouldn't be an apprentice any way. My son in law is an accountant and not very handy with tools. So I don't have any prospects for helpers.

KentSmith · « **Reply #22 on:** March 19, 2014, 05:57:02 PM »

Go to a local "hammer in" and you will find plenty of apprentices there. I just need to get my schedule in line with them and get the wrought iron for a barrel. Most of those guys have plenty of experience at the anvil but have never forged a barrel so I can show them something and they can show me more. Am hoping to build a second forge soon when I clear workspace for it as I need to get a little more room for the extra help to maneuver.

David R. Pennington · « **Reply #23 on:** March 29, 2014, 06:15:48 AM »

Started building "Frankenforge".

heelerau · « **Reply #24 on:** March 31, 2014, 08:07:11 AM »

Gents,
a shot of my current but very temporary smithy, the car port. It has the rivet forge under an old tin wood stove fireplace come hood. The anvil is about 120lbs and of unknown make, a blacksmiths post vice and a buffalo forge post drill. The other photo is of my Buffalo Forge No 650 forge sporting a No 200 hand blower. I have just had a new fire pot made out of 6mm bis alloy plate and a new tuyere iron. The pot is not a tight fit into the pan to allow for expansion. We will be converting a lean too off the main workshop into a proper smithy with a stoop to shoe our horses underneath. My smaller rivet forge will be great for hardening small lock parts etc. Knife making and the like. I once knew an old Italian gunsmith and watched him forge and temper a new spring for a flintlock pistol I had at the time, just a few bits of charcoal, pretty amazing old chap. Ver poor english made it hard to talk to him unfortunately.

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Author Topic: Building a forge (Read 23119 times)

Old Bob

Old Bob

Old Bob

Old Bob

Dociron