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THIS is a forum for questions and answers about blacksmithing and general metalworking. Ask the Guru any reasonable question and he or one of his helpers will answer your question, find someone that can, OR research the question for you.

This is an archive of posts from September 1 - 7, 2011 on the Guru's Den
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Riffling cutters : I have seen the rifling cutters at Old Salem, Old williamsburg and several other historic places and all used a small mutli tooth cutter that was in effect a small hunk of file. I would suspect that a single tooth tool would have some issues in chip clearance in that long a cut, since the cutting is on the pull. If pushed to cut the chip could roll up in front of the cutter.
   ptree - Thursday, 09/01/11 07:20:03 EDT

Fisher Norris Eagle Anvil : Hello, I have a 250lb Fisher Norris Eagle anvil from 1882. I have done some research and i have noticed now that the "fisher " stamp on mine is upside down. is there any significance to this ?

   chuck - Thursday, 09/01/11 10:36:46 EDT

Out of Position Logos : Chuck, I have seen a number of Fishers with crooked and sideways logos but this is the first I have heard of being upside down. I suspect this is just sloppy workmanship. Often these parts were embossed tin and held on by a few small nails or tacks. If a business was really cheap they would transfer these from one pattern to another over and over the nail holes getting looser and looser. In the anvil business they may have had 30 or more different patterns (one for each size) plus those in different styles. They would be run in batches with the logo transferred from one pattern to another.

The last owner of Eagle Anvils quit using the cast logo altogether and went with a paper label.

Eagle anvil Logo Photographed by Jock Dempsey and digitally restored
Eagle Anvil Paper Label - Digitally Repaired by Jock Dempsey


Note that the 1882 is a patent date, not a manufacturing date.
   - guru - Thursday, 09/01/11 11:41:30 EDT

ANVILS : I was lucky enough to find a Russian cast steel anvil when I started blacksmithing in pigeon forge TN now I need something bigger I am about ready buy a anvil originally I was going to buy a Habermann from oldworldanvils but now I'm considering either Peddinghaus #12 or the Nimba Centurion because of the wider face for the buck, I want to know which is the best between the three I'm apprehensive for peddinghaus because I bought a peddinghaus 1500g german hammer from centaurforge that shattered into three pieces literally out of the box but in a honest opinion what is the best out of the three. To help what I do is tool making IE.. logging tools, chains, garden tools etc...
any help in this matter would be greatly appreciated
   Tye Bledsoe - Thursday, 09/01/11 12:51:16 EDT

Tye, can you tell me the best vehicle for me to get? I won't tell you if I need to haul a ton of scrap metal or drive it 120 miles a day on interstates 5 days a week; or haul 6 kids around all the time but please tell me what is BEST for me!

If you tell us how you plan to use it we might be able to opine if one is better than another for your planned usage of it.

Rifling: didn't one of the Foxfire books have an article on old time rifling?
   Thomas P - Thursday, 09/01/11 13:12:34 EDT

The file verses single tooth logic doesn't fly. A half inch long eighth wide piece of coarse file has less chip space than a single cleared space in front of the cutter. Besides cutting on the outer edge the rifling cutter must cut on three edges or it would jamb in the cut.

I HAD detail photos of these years ago. . . Yes, pieces of file were commonly used but today I would use nothing less than a piece of top grade high alloy HSS steel such as a lathe cutter bit or an old tap.
   - guru - Thursday, 09/01/11 13:39:09 EDT

Peddinghaus and others :
There are no less than 3 Peddinghaus companies in Europe, all completely different entities. The one that makes the hand tools is a different company than the one that makes anvils (which has been owned by Ridge Tool for about 15 years). There is also a Peddinghaus machine company that make ironworkers among other things.

I've got a bunch of the Peddinghaus hammers and have never had any trouble with them. I hope you returned the one that broke.

There are pros and cons on a wide anvil face. Many people prefer a narrow face and some very large (over 600 pound) anvils have proportionately narrow faces.

The Mediterranean style Nimba is a great anvil in that it puts all the mass where it should be. The down side to many folks is the wide face. But I have always felt that you like what you learned on or are comfortable with due to use.

Both the Nimba and the Peddinghaus have relatively (or proportionally) short stubby horns. When you are used to the more slender English style horn you find them more difficult to use. However, you've been using that lousy Russian shape and I doubt that anything else will feel the same (or worse. . ).

IF I could buy any anvil I wanted I am still a forged tool snob and would go with the Peddinghaus even though I prefer other shapes. . .
   - guru - Thursday, 09/01/11 13:58:39 EDT

Thanks : Thanks for the help sir its greatly appreciated yeah it was either the russian or a cast iron anvil, but like you I had the opportunity to make something on a forged peddinghaus I loved it I said if I buy a anvil it would be that, but then I ran across nimba but as you said the center of mass it were it should be for what I do I need a wide face with a lot of mass in the center I think I have made my decision over you comments. again thank you so much sir...
   Tye Bledsoe - Thursday, 09/01/11 14:12:59 EDT

upside down fisher : this isnt a tin plate, it is actually stamped into the base of it.

also, it says on the anvil that the patent date is april of 1877. on the other side it says 1882.

please forgive my ignorance in this matter --- i was directed to you from another site .

   chuck - Thursday, 09/01/11 15:07:59 EDT

upside down fisher again : if you have an email i can send you some pics of it.
   chuck - Thursday, 09/01/11 15:12:54 EDT

Tye Bledsoe : What kind of forging do you do ? I live in NE Arkansas. If I came over that way and spent a day or two, could I watch you work and possibly get a few pointers.
   Mike T. - Thursday, 09/01/11 15:37:55 EDT

The tin plates for logos, lettering and such are attached to the wooden pattern that the sand mold is made from to cast the anvil. They are not part of the finished product. Also note that Fishers are a cast anvil made in a mold. Logos are part of the casting, not "stamped" in as they are on wrought (forged) anvils.

Click on my name (the underlined link) and you should be able to send me mail with an attachment.
   - guru - Thursday, 09/01/11 15:44:54 EDT

Nimba Wide Anvil Face : I have a Nimba Gladiator and love it. The wide face is frequently very handy and when I need a narrower face I simply work on the tapered flat heel - any width I need from 3/8" to 6" that way. Works very well for me.

The mass of the Nimba being so compact makes it work like a bigger anvil, as compared to a London or American pattern anvil of equal weight. I have various anvils from 100# up to the Gladiator at 450#, and the Gladiator is my primary working anvil. My secondary anvil is a worn old 200# wrought anvil with a face that has about a 3/16" swale in the sweet spot - handy for straightening things.
   Rich - Thursday, 09/01/11 15:55:46 EDT

upside down fisher : email with pics sent, thank you.
   chuck - Thursday, 09/01/11 17:10:08 EDT

Anvil Mystery :
upside Down Fisher Lettering

Chuck's Fisher is an old model with the Eagle in a square recess and the FISHER letters along the front of the foot cut IN not standing out. They are indeed upside down but I cannot figure out how unless it is some kind of loose piece in the pattern or mold. I am inclined to think it was a loose mold piece (a seperate piece of the sand mold) that got flipped upside down.

This anvil also has the Fisher Eagle recessed in a square on the side. This was done for a good while but most Fishers have the Eagle raised from the flat surface.
   - guru - Thursday, 09/01/11 17:45:22 EDT

Uhh Rich; before you leave for Quad-State could you attach a couple of *empty* propane tanks to your NIMBA and write on them with sharpie "If found please sent to Thomas Powers, Lemitar NM"; just as a favour...
   Thomas P - Thursday, 09/01/11 18:02:11 EDT

I've always kind of assumed that riffler files were originally used for rifling (or developed out of ones that were). Been wrong before, though.

The Fisher anvil could easily have been covered by two (or more) patents issued on different dates. But it does seem a little odd to put them on opposite sides of the anvil.
   Mike BR - Thursday, 09/01/11 18:53:19 EDT

Rifling : The video, "The Gunsmith of Williamsburg" shows rifling performed inside a flintlock barrel. It includes shimming with paper.
   Frank Turley - Thursday, 09/01/11 20:29:45 EDT

I am installing a barrel stove in my shop. I am wondering if i can run the vent for the stove into the side of my 12" forge vent? Thanks
   Kelly - Thursday, 09/01/11 21:00:08 EDT

Rifling Cutter : The multi toothed cutter does not need to fly, just work. The "chips" are not like chips from a keyway broach, shaper or planer, they are tiny little, fine filings. These are brushed off after each stroke with a brush wet with cutting oil. Due to the spring in the entire setup, it takes several passes through each of the grooves before the next Zig Zag paper shim is added. The cutter teeth act more a scraper type tools than modern chip making tools. Seeing is believing, You can go to Kempton next year and watch.
   - Dave Boyer - Thursday, 09/01/11 21:21:31 EDT

Dave Boyer said what I was getting at in my post, a single point tool making a chip vs a file making tiny little scrapings. I too have seen the "brush the cutter at the end of every stroke".
Dave you siad it much better than I.
   ptree - Friday, 09/02/11 07:29:01 EDT

rifling cutters : A couple of old guys near me(now gone)used to rerifle old muzzleloading barrels. They would make a sawtooth type cutter, about 5 or 6 tpi, for their rifling setup. They would also freshen old barrels with the same type of cutter. They would inlet the cutter into a wooden rod and pull it through each groove. Then add a bit of paper under the cutter and repeat the process until the grooves were as deep as they wanted them.

I have freshened the rifling in one old barrel by pouring a lead slug in the barrel and then inletting a small piece of a file into one of the rifling grooves in that lead slug. Then pushing the slug through the barrel cutting each groove in succession and adding a paper shim after each complete pass. It cut very well and like Dave said, removed very tiny filings each pass.
   - Bernard Tappel - Friday, 09/02/11 09:57:21 EDT

Combined Chimney Stacks and Wood Stoves :
Kelly, you CAN do this but it may reduce the efficiency of your forge venting. Ideally when two chimneys intersect the cross section should be the sum of the two areas OR grreater. Adding a 6" (28.27 sqin.) stack to a 12" (113 sqin) stack results in an area of 141.23 squin. or a 13-7/16" diameter stack. Not much difference, but a difference.

If you T in as high up as possible it will reduce the loss a bit. But turbulance at the joint may be an issue.

When the stove is in use it MAY increase the draft at the forge by adding hotter air to the stack. When not in use the stove should be shut tight so that cool (room temperature) air is not sucked up the stack, reducing the draw at the forge. On the other hand, the open forge vent may prevent the wood stove from drawing well.

A lot depends on the total height of the stack, local wind conditions, how tight the shop is. . . Too many variables to give an absolute answer.

Also note that wood stove vents can clog rapidly with creosote a condition you do not get with coal. A chimney fire (creasote deposits burning in the stack) is best controlled by closing the stove so that there is less air to feed the fire from the bottom. When stacks are joined this is not possible.
   - guru - Friday, 09/02/11 12:39:56 EDT

Guru, Thanks for the helpful information!
   Kelly - Friday, 09/02/11 18:31:01 EDT

Rifling : Thanks Guru and everyone else for the information. Could someone break a piece of a keyway broach off and cut the rifling ? I have e-mailed a company before about ordering rifling broaches but never got a reply, I got the feeling they only wanted large orders from barrel makers.
   Mike T. - Saturday, 09/03/11 04:04:20 EDT

rifling : I want your opinion on this. This is something I have thought about doing for a long time. McMaster Carr has military grade tubing. The only .5 inside diameter I can find is with the 4130 alloy. The wall thickness is .25 I was thinking about using this and having a round bar of 4130 drilled, threaded and screwing the tubing into it for extra strength. I want to make a simple rifling machine like you see in the Fox Fire book. Cut rifling in the tube, screwing the tube into the round bar, screw the nipple into the other end of the round bar. I have made drawings for everything else, it looks like the 4130 is annealed, it shows the yield strength to be 75,000 lb per sq inch, i'm thinking it should be safe to shoot black powder. I know everything can be bought from Dixie Arms, I just want to make something from scratch. What do yall think ?
   Mike T. - Saturday, 09/03/11 04:35:08 EDT

Broaches and Tubing : Mike, Commercial keyway broaches, even very small ones have a very deep gullet (for chip clearance) that would prevent cutting them down to make a rifling cutter. They also take a significant cut per tooth that requires a lot of force.

Mil Spec does not necessarily mean something is suitable for making arms. It means it meets a quality standard for the defined use.

DOM tubing comes in many odd dimensions. I've got some 2" OD tubing with approximately 3/4" bore. . . (7/8" wall). Great for a small cannon.

50 cal is pretty large bore. I would look at the specs for other similar devices and see if I was in the right range. The unhardened alloy steel is probably more than sufficient but I would do comparisons and the math as well.

I always thought that I would like to build a muzzle loader but also figured that if I wanted to make barrels I would short 12" or so pistol barrels first then a "sportster" short barrel THEN the long rifle barrel. A progression of difficulty levels.

The primary reasons to make an all wood rifling bench OR a manual boring machine is historical reenactment or study. These machines were mostly wood for economic and availability reasons. Today you could use all metal OR a mix of wood and metal parts to great advantage. Modern bearings and precision drawn key stock give us great advantages over primitive builders

   - guru - Saturday, 09/03/11 14:15:07 EDT

125 pound Milne anvil : I have a hair line crack in the top surface shaped like the letter "Y". Two of the legs in the letter are running toward the edge of the top surface. The crack is about 3/4 inch in each leg. Do I have a problem here?
   Robert J - Saturday, 09/03/11 20:37:55 EDT

MIlne Anvil Repair : Robert, Any crack in the face of an anvil is a problem. In a cast steel anvil such as a Milne it is more of a problem than in a steel faced wrought anvil. In a cast anvil the crack can propagate through the entire anvil and result in it breaking into two or more pieces.

What to do about it is the question. You could ignore it an hope it doesn't get any worse. This IS a possibility.

You could repair it. This may or may not be better than ignoring it.

To repair you need to grind out the cracks chasing them as far as they go. Generally when grinding out a crack you can see it due to the temper rainbow that forms along the edge of the crack from the grinding heat. Otherwise you would need to use a magnaflux test or dye penetrant to look for the crack. Both are likely to show more cracks than you can currently see.

The welding would start with a preheat to about 350°F (177°C). Weld with a 70 or greater series rod (E7024, E8024. . ). Peen between each pass. Peening reduces stress in the weld. When using coated rods you need to clean ALL the coating out between passes. A needle scaler and power wire brushes help. Grind out any pits with a die grinder between passes. Buildup until the weld is a bit proud of the finished surface. Grind flat. Look for pits and any new cracks. Grind them out and repair as above.

Optionally you could use hardfacing rod for the last pass but these abrasion resistant rods are generally harder than the anvil and you still end up with a hard-soft difference at the repair plus the color difference of the alloy rod.

With a good sound casting you should get good results. If the casting has micro cracks that you cannot see now they will open up and you will have more problems.

   - guru - Sunday, 09/04/11 09:54:40 EDT

Mike T - rifling : I don't think modern rifling is broached.

Black powder barrels don't need to be extra strong, they were made of wrought iron with a forge welded seam for hundreds of years.

If You want to rifle Your own, You want the most free machining stock You can find, B1112 or something like it.

A keyway broach is pretty far from the right cutter, the cutter is about 1/2" long and has teeth about .040-.050" apart [from memory]. If You hand hot cut the teeth with a chisel, they will not be equally spaced. This is good. If You grind the teeth with a cutter grinder or surface grinder, vary the spacing a little bit, it will lessen the chances of chatter. If You make the cutter from a file, You get what You get.

The rifling is usually 1 turn in the length of the barrel, or about 1 in 48". this is much slower than modern rifles.

Even really damn good gunsmiths usually buy barrels already rifled and partially finished on the outside.

I have a friend much like You [wants to build a blackpower rifle from scratch], who has been asking Me to build Him a fifling bench for years now. I suggested to Him to build a kit gun, then start building another exactly like it from scratch. When He gets to parts He can't build well enough, He can buy the kit parts to finish it. This removes the problem of designing the lock parts, which He probably won't get right on the first try. All He would need to do is duplicate them.
   - Dave Boyer - Sunday, 09/04/11 21:13:59 EDT

Robert J - Crack : If none of the legs of the crack go to an edge, I suspect that the crack is a casting flaw, and has probably always been there, but may not have been visible.

Where is the crack located on the anvil face? If over the body, I am even more likely to suspect a casting flaw.

I would measure it accurately, and check for growth in the crack from time to time. If stable or nearly stable, I would leave it alone.
   - Dave Boyer - Sunday, 09/04/11 21:28:15 EDT

Mike T : Read this:

http://firearmsid.com/Feature%20Articles/RifledBarrelManuf/BarrelManufacture.htm

Google is Your friend.
   - Dave Boyer - Sunday, 09/04/11 21:53:06 EDT

Gunsmithing From Scratch :
Anyone who wants to make a gun from scratch should have the skills to make all the tools. The tools are no more complex than the parts of the gun.

The Williamsburg Gunsmith is a great film albeit very time compressed. The smith bores the barrel to size on a hand turned wood framed boring bench and does the rifling on a similar bench. I makes the tap for the breach and hand makes the breach plug. Even the brass sheet for the patch box is forged by hand.

A modern gunsmith with a small lathe, modern drill press and HSS steel tools is miles ahead of the 18th Century Gunsmiths that made thousands of long rifles with their hand made tools and marginal steels. Add a few nifty widgets like modern abrasives, hand and bench grinders, and a die grinder or Dremel tool and the job is EASY compared to the way it was first done.

I've got photos I took many years ago of a WWII U.S. Army Armoury Rifling machine. It was designed by a Maj. J.G. Smithley in 1944. It is entirely shop fabricated from small castings and steel structurals. I'll post the photos. But don't get your hopes up. Its a complicated machine gearing wise and there are few details.
   - guru - Monday, 09/05/11 00:09:27 EDT

Maj. J.G. Smithley Rifling Machine
   - guru - Monday, 09/05/11 02:18:16 EDT

That rifling machine is kind of a mystery, isn't it? I do remember reading about resistance fighters in occupied Europe building Sten guns in small workshops. Perhaps the idea could have been to design a rifling machine that could be built without special tools and smuggle the plans to them.

Or maybe the good Major was stuck in a quiet garrison somewhere and just had too much time on his hands. Whatever the story may have been, it's a neat machine.
   Mike BR - Monday, 09/05/11 06:56:43 EDT

The fact is its loaded with small but very professionally made castings and precision machine work (collets or sockets for them have to be dead accurate). But it is also obviously built with economy in mind as the castings are only used where they were advantageous in a shop built machine.

The mechanical arrangement appears to be fairly unique thus raising the possibility that it is an inventors prototype.

We liked to think it might have been made for a super secret research Amroury making toys for 007 types. . . ;)

Pat got it in some sort of trade, the origin a bit mysterious.
   - guru - Monday, 09/05/11 08:19:05 EDT

Mike T - Rifling Broach& Other Methods : There are other articles that do mention broached rifling, and show the broach. That would be a rather expensive broach, doubt You would want to buy one.

The hook cutter and it's holder as shown with the 20th century rifling machines in the link I posted require a good bit of precision machining that the much earlier machines that I and others have been describing does not require, and would have been a problem to build in the 16-1700s.
   - Dave Boyer - Monday, 09/05/11 19:11:17 EDT

Gunsmithing from scratch : The friend I mentioned is a dreamer, and wants to do all kinds of stuff He doesn't have the skills for. He is 55 now, and could learn many of those skills, if He made a dedicated effort to do so, but the rest of life always seems to get in the way.
   - Dave Boyer - Monday, 09/05/11 19:16:25 EDT

Gunsmithing from scratch :
There are all kinds of modern alternatives to doing things the most primitive and "hard" way. Lots of octagon barrels have been drilled and milled to shape, breach plugs sawed from solid and milled and turned to shape. Many parts can be carved from solid but some brass parts need to be cast and the wood work is just as critical as the metal. Its a wide range of skills no matter how you do it.

I've known several folks that bought long rifle kits and when they were finished the gun was worth less than the kit. . . Kits generally do the technically difficult parts for you but leave the really picky work to you. Building a kit is a good place to start. If you don't have the patience to do a good job then doing the whole thing from scratch is way beyond your skills, desires, dreams. . .

I still recommend starting small. . .

   - guru - Monday, 09/05/11 21:03:02 EDT

Gunsmithing : I had suggested that He build a smoothbore pistol with a precussion cap lock, as that is about as simple as it gets, and the lathe He has is big enough for that. The lathe is in a storage room in the house, piled over so bad that it can't bee seen or even gotten close to. He needs to put up a shop building. He has started making a few knives last fall, but got back to work working 7 12s, and hasn't made any progress with them since. Altho He just got layed off, "Must Do" projects will probably make the hobby stuff take a back seat. Such is life.
   - Dave Boyer - Monday, 09/05/11 22:02:55 EDT

Rifling and Small guns : Even with a BIG shop building much of my machinery is hard to get to. . .

I would bet that with a little tinkering I could setup most any Engine lathe for rifling. My little 6" craftsman can drill/bore about 8 to 10" and might even be able to rifle 8". Could make a fair short barrel pistol.

The last rifling setup I saw used a piece of 1/4" key stock as both the tool and guide. It was twisted and was pulled through a stationary bushing with a square hole. The trick is the bore must be .354" or more. The little Craftsman has 60 holes in the bull gear for using the spindle for dividing. Easy to get 8,6,5 or 4 divisions.

A standard old fashioned wood rifling bench must be 3x + dead space longer than the barrel to be rifled. That means 10 feet for a 40" (1m) barrel plus another 5 feet of work space beyond the bench. 16 feet (~5m) or more total bench and work space.

One method to make a barrel by hand without forge welding it is to start with a drilled billet and then draw it out. The finished hole will be very rough but will be fairly well centered along the length of the barrel. The small rough hole acts as a guide for the drill and greatly reduces the pressure required and amount of chips to clear. Starting with a through hole also means you can force drill coolant from the far end (a gun drill is not needed). . . How do you think they get those holes (often 2) in the gun drill. . . forging.

Lots of tricks to skinning that cat. . .
   - guru - Monday, 09/05/11 23:45:04 EDT

Helix : "There are lots of ways to skin a cat, but not that same cat"

There are a whole lot of ways to lay out and to generate a helix, many of them are simple, at least in theory.

Cable wound around a drum on the spindle and attached to the carriage of a lathe with rigid mounted turning blocks would be pretty simple. I could do about 1 turn in 40" on My lathe, but could only make the master for a rifling bench about 30-36" long in one piece. I would cut a groove with a router, tool post grinder, die grinder, etc.

The master on the bench at Dixons has (4)hardwood splines attached to a wood cylinder about 4-5" in diameter that runs through a guide block. Working clearance on that large radius ammounts to squat when You get down to a .50 cal bore.

The boring bench and rifling bench [at Dixon's] do take up a lot of room, but they are simply constructed.
   - Dave Boyer - Tuesday, 09/06/11 00:29:44 EDT

Helix Continued : A helix is a triangle wrapped around a cylinder, so cutting one out of heavy paper, wrapping it around the cylinder and marking along the hypotenuse is a simple way to get lines to locate the splines on the cylinder. Choosing a nice piece of wood for the splines would go a long way towards getting them attached accurately.

The indexing pattern used to compensate for cutter wear is an important part, I forget exactly how it went. They are NOT cut sequentally around the bore.
   - Dave Boyer - Tuesday, 09/06/11 00:43:41 EDT

Just a thought about the rifling machine. You note on your page that it has indexes to change the number of lands in the bore. Could it be that the Army was looking for a machine that would produce different rifling patterns to test effectiveness? That sounds like the time period that the Army was doing a lot of their own original research, before all that stuff was outsourced.
   Bajajoaquin - Tuesday, 09/06/11 00:51:43 EDT

The way they turn out : "when they were finished the gun was worth less than the kit"

My uncle Norm has been building at a single shot cap & ball pistol kit for many years now, a little bit at a time. Norm was a truck mechanic, a reasonably good one, but He has been nearly blind for the last 30 years.

I have not seen this project, other than I turned down the ends of the ramrod, put the brass caps on them and pinned them in place for Him about a year ago.

This might turn out to be worth less than the kit price as Norm can't see at all out of one eye, and has limited periferal vision in the other from macular degeneration. I just hope He is carefull if He goes to shoot it.
   - Dave Boyer - Tuesday, 09/06/11 01:13:52 EDT

I've watched Brad Emig bore and rifle a welded wrought iron barrel, and it was a nifty process on the traditional wooden benches. Took a LONG time, though.

The two biggest custom black powder barrel makers use different steels. Getz uses 12L14, a leaded free-machining mild steel, and Ed Rayl uses mil-spec 4340.

And yep, Foxfire 5 shows how to build and use a rifling bench. "Gunsmiths of Appalachia" by John Rice Irwin has some good info as well.

When I built the rifle and pistol set for Paw Paw Wilson we discussed having me forge the barrels out of wrought, but we decided neither of us trusted my welds quite that much...
   Alan-L - Tuesday, 09/06/11 12:06:14 EDT

Smooth bore! Abjure this silly rifled stuff; surely just a passing fad soon to die away leaving the smoothbore once again king!

My falconette is smoothbore made from high pressure flow line pipe from the oilfield. I always though that a drill sub (adapter) would make a good mortar when I read the specs on some with 3+" walls and very good steel! (Having one fail downhole can quite easily be a million dollar failure...I just ran across my sample of "drill bit gravel" Saturday from a bit the tool pusher tried to run too long and ended up running the cones off and spending a couple of days recovering the remains)

   Thomas P - Tuesday, 09/06/11 16:42:51 EDT

Smooth bore. . . The last one of these I shot just happened to be in rare lighting conditions and I could see the ball as it passed through bright sunlight surrounded by shade. It followed a drunken corkscrew path about a foot across. . . Only by the most unimaginable odds and NOT aiming straight could you hit a target smaller than a foot across with that gun!
   - guru - Tuesday, 09/06/11 16:56:40 EDT

Forging Tolerances : My shop does not typically fabricate hand-forged steel items. However one of our shopworkers is a skilled blacksmith and we are working on a project where we are required to fabricate 3 new rails to match an existing 75 year-old hand-forged steel rail. Though the existing rail has components that differ in dimension by more than 1/8", the Architect is demanding that we keep dimensional tolerances of no more than 1/8". Are there standard dimensional tolerances for hand-forged components such as steel collars, baskets, volutes, buttons and hammered posts? Is there a standard published by a recognized industry authority? Thanks.
   Chris M - Tuesday, 09/06/11 17:32:32 EDT

Times are changing : I will be offline for who knows how long. Thanks to all who have helped and tolerated me. Geezers' Forge is still up, but a sale may be in the future. Will get word out somehow if it happens.
Luck to all.
   - Keith - Tuesday, 09/06/11 17:52:04 EDT

Keith, Sorry to hear that. Keep our Tailgate sales page in mind if you need to sell.
   - guru - Tuesday, 09/06/11 17:57:51 EDT

I will. Just got to figure how to contact. Will only have snail mail and maybe a phone.
   - Keith - Tuesday, 09/06/11 18:02:34 EDT

Well in the early 1800's a blacksmith could be expected to work to the "thickness of a worn shilling".

In modern times I would say the tolerance is dependent on how much they are willing to pay for it.
   Thomas P - Tuesday, 09/06/11 18:39:11 EDT

Forging Tolerances : Chris, The folks at NOMMA would know OR have written such an industry standard.

The other way to do it is to provide tolerances you are willing to live with and quote at that price, AND quote at the specified tolerance. If you have already quoted it OR the tolerance was not in the bid spec then both parties may have some serious discussions ahead.

Tolerances are usually scale and critical dependent. Stock sizes come in +/-.005" of nominal and should match that unless some very odd size stock was used. Tolerances of +/-.010 or less can be held resizing stock on a power hammer using a stop block. Small parts can be hand forged with a hand hammer to +/-1/32" or less and +/-1/16" would be hard to distinguish on two parts side by side. But on common scrolls, fluer dis'lis and components over 6" a tolerance of +/- 1/4" would be reasonable. However, those made on jigs should be identical. On parts as long as pickets I would be upset with a worker that made them more than +/- 1/16" in length. However, I have known smiths to insist on hand forging shoulders on both ends of pickets and having a hard time meeting +/- 1/8". Methods also make a difference.

I'm sure the architect is trying to obtain something visually indistinguishable from the old stuff and does not know how to define it other than via a tolerance that is too tight for some things and way off on others. Example, a 5/8" bar compared to a 1/2" bar or a 3/8" bar compared to a 1/4" bar both meet the +/-1/8" tolerance but are WAY off from a visual standpoint BUT meet the tolerance. . .

THEN there is the question of NEW safety standards verses old. Will a copy of the old rail meet new building codes? Maybe, but unlikely. You may have to change picket spacings several inches. . .
   - guru - Tuesday, 09/06/11 19:05:30 EDT

More on tolerances :
Part of what makes hand forged work look different than machine work IS the variations in dimensions. When you purchase machine made basket twists for a fabrication they are obviously machine made looking at them from any distance. Every aspect of them is identical. But hand made parts will have just enough variation that even though they may LOOK perfect they will not have that machine made look.

On a beautiful railing I saw made in the famous Samuel Yellin shops of Philadelphia (same era as the rail you are working on) every picket was terminateed with a simple dragon head. When you looked down the line they were all exactly the same height and depth and mouths opened the identical amount. But when you looked CLOSE every dragon had a slightly different expression. Frowns, smiles, eyes wide open and others nearly shut, some with surprised looks and others mean. The smith that made these could have made them all the same. But the ART is in the differences.

Due to distances between posts pickets are often spaced differently in adjacent sections and even opposite sides of a stair. This is necessary to make things come out even and LOOK like they are spaced the same when they are not. A discriminating smith will open up or tighten up decorative elements as necessary. If you have pickets on 8" centers and gaps between scrolls or fluer dis'lis of 1.5" and in the next section pickets on 7" centers the fluer dis'lis will nearly touch. To be correct AND look right the gaps must be scaled down with the picket spacing. So you may have a 6" wide element on one side of a post and a 5-1/4" wide element on the other. Using an overly rigid tolerance would prevent making this visually necessary adjustment.
   - guru - Tuesday, 09/06/11 19:31:28 EDT

Tolerances : Thanks for the responses. Very much appreciate the feedback
   Chris M - Wednesday, 09/07/11 10:04:45 EDT

tolerances : One thing I'm wondering is: did the architect supply a drawing or not? Either way, how was the tolerance specified? 1/8" tolerance is soooo general.
   Ty Murch - Wednesday, 09/07/11 17:38:27 EDT

Generally on big fabrications the tolerances are based on total size. A half inch part may have a very small tolerance but a 20 foot part may be +/- half an inch. However, structural steel tolerances are surprisingly tight. Squareness of flanges is measured in thousandths.

A lot depends on the number of parts. Each joint represents a place for a possible error. The more joints the larger the total error. In practice things should average out, plus here and minus there. BUT, any designer worth his salt will assume both wost cases. All the pluses and all the minuses. IF the total must be tighter than reasonable then an adjustment is put in (shims, spacers. . ).

A lot of so called designer, engineers and architects have no clue about tolerancing. As a rule you should never make a tolerance any tighter than necessary. But a lot of folks don't understand how to determine what is necessary. What is necessary usually is what is required that parts fit together. But when it comes to appearances it is a different thing. Hoods, trunk lids and doors on cars fit relative to each other in thousandths over significant distances to look correct. But on a dump truck +/- 1/8 would be acceptable but +/- 1/16 better for interchangeable parts and fixturing.

On our title block the standard tolerance for machine parts was:

Decimal dimensions +/- .005" Except as noted.
Fractional dimensions +/- 1/64 Except as noted.
Round all sharp corners.

Exceptions were common but the general rules covered a lot.
   - guru - Wednesday, 09/07/11 18:41:12 EDT

tolerences : At the Henry Vogt Machine Co the Valve and fitting shop had std print tolerance of decimals to 2 places +/- .005" 3 place were +/- .001 4 place were +/- 0.0005 fractions were +/- 1/16"
In the forge shop many forge tolerances in the thickness that ran in the direction of the hammer ram were +.090/-.060" Mismatch was often +/- 1/16 to +/-1/8" depending on size of the part. With the added tolerance for side too side mismatch you could get a really big stack-up of tolerance. Of course anything that was needed to fit anything else was machined and see the above valve and fitting spec:)

In the boiler shops, where the side frames used 24" wide flange structurals that were 75'+ long the straightness of the beam was pretty bad. We had to straighten them to use, and one of my projects was a portable 1000 ton press to do that job. In that same boiler shop, where every pressure weld had to be full penetration, we made steam headers from 12" heavy wall, and ran 2 or 3 lines of tube holes down the length to weld in the finned tubes. Now one row of holes drilled on center line is not hard to do, and 2 or three rows is not tooooo bad with the right drill jig. BUT, how to bevel the edge of the hole, on the round tube for a full penetration weld, that was a trick, and the holes and bevels were held to a tight tolerance that made grinding not doable. We beveled that up to 1.5 inch thick wall on thousands of headers a year making from 58 to 84 holes in each header, the smallest for a 1.5" tube to be welded into.

Now to the question of the architect's tolerance. Many folks making drawings and spec's have no clue. When CAD came out we started seeing dimensions like 0.0625, for dumb stuff. When queried, the engineers admitted that they had just been the default setting, they really needed 5/8"!
My suggestion is to gently ask, and maybe do a little education. Jock's nicely thought out and written item above would be a great starting point.

And last, remember, we have the RIGHT and RESPONSIBILITY to refuse work when it will cost us money, lead to work you can't live with or will be a danger.
   ptree - Wednesday, 09/07/11 21:04:40 EDT

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