Iron Hinges

[jacon4]

I'd like to discuss forged butterfly hinges. I used to wonder why 18th century forged iron butterfly hinges on drop leaf tables rarely survive, i dont wonder anymore. In addition to being very thin/delicate, theres another problem. If you click the link, then the pic on the left, it will enlarge. Notice the right wing of hinge wraps around the barrel/pin of hinge and then is forge welded to the underside of hinge. What happens at some point is, that weld begins to separate and when that happens, that hinge aint long for this world. I wonder, can that weld be restored-rewelded without destroying the hinge, or no?

http://www.pbase.com/nwba_archive/002

[Frank Turley]

I confess ignorance about the survival rate of hinges on drop leaf tables. I think that Peter Ross prefers to call the butterfly hinges "dovetail hinges" but no matter. We're on the same page.

In the photo, I don't think the hinge is coming apart. The forge welded barrel has the "teardrop vanishing point" because of the way it is forge welded over the radius of the anvil edge. It is not a defect.

To redo a weld that may be opening, we get into the area of restoration. If clinch nails are used, it's going to be a booger to get them unclinched. I have done this on old chests and cabinets, and great care must be taken not to damage the wood unduly. Sometimes, a nail will break. Assuming the hinge is removed, you now have the problem of attempting to forge weld a leaf without damaging or welding the barrel with its knuckles. I saw Peter make this style of hinge, and the weld was made on the fully doubled leaf with the pin still in place! When the weld was completed, the quenched leaf was clamped in the vise, and the pin was driven out cold with a pin punch. Only then did the hacksawing and filing of the knuckles begin.

When the old, removed hinge has either end of the pin peened over, you're not going to be able to do the weld without the other leaf and knuckles getting in the way, especially in terms of taking heats. Also, when you hammer on the leaf, you'll displace metal, including the holes. My conclusion would be that to make a new hinge with matching nail holes would be easier than trying to reforge the old hinge.

When we think about strength, let us not forget that a standard Stanley 5-knuckle butt hinge is made of 16 gage metal with none of the barrel welded; it is just rolled and tucked. Yet nobody is returning to the building supply to complain about it's weakness.

The old New Mexico cowboys say, "I don't care how weak it is, as long as it's strong enough."

http://www.turleyforge.com Granddaddy of Blacksmith Schools

[jacon4]

Hey Frank,
I just used that pic as an example of an 18th century hinge, my hinges are still on the table, lol. Yeah, i see what you mean about other leaf getting in the way. Thing is, its an american 18th century william & mary gate leg table and i really wanted to keep the old hinges, its a collector type thing where original hardware is kinda a big deal. Thanks for your reply

[John B]

If you wish to retain the old hinges, but the weld has deteriorated to the point where the action may fail, could you not carefully silver solder or braze the area to make it secure,

This way you are keeping the integrity of its heritage, but not replacing the part with a newer substitute.

Acceptable as a restoration, and still using techniques that were available to the original makers, although it may not have been oxy/acet or other 'modern' gasses they used.

[Bentiron1946]

I have seen a couple of demos of traditional brazing in the forge, an interesting take over what we now consider brazing with gas. First the demonstrator used a file to make a pile and I mean a pile of brass shavings, next he packed this around the join with borax for a flux and tied it with iron binding wire and then into the fire to melt the brass. He showed a lot of different types of joins one could make by brazing. :blink:

[John B]

It is also possible to focus the heat required for brazing in an open forge by using a thick plate with a hole of a suitable size through.

Place this plate on the top of the forge and the effect will be comparable to a 'bunsen' type burner, giving a narrow focused heat source.

[arftist]

I restored well over a hundred hinges last year, two seperate jobs in a very historical town.

They were mostly wrought iron, had been made by different smiths, and some were welded from multiple pieces or even layers of metal.

Many of them needed missing metal replaced.

Because the finnish was hot dipped zinc, followed by epoxy primer and automotive topcoat, I mig welded the damaged areas.

Just for the sake of providing information, I made a new pintal mount for each hinge (colonial style strap hinges)

with a stainless steel pin, and machined and pressfit bronze hat bushings into each strap.

[Frank Turley]

I see that keeping the original hardware could be considered a big deal. I also see that if you're a good smith, if you have some wrought iron, if you understand some of the subtleties of the forged hinge construction, then your piece will be just as authentic as the early piece. There is the possibility that yours may even be better in quality and strength.

By subtleties, I mean for example the knuckle length. The central knuckle of a three knuckle Colonial hinge is often just slightly longer than the two end knuckles. Say the barrel length is 3", then if each end knuckle is 15/16" long, the central one is 1 1/8". Nowadays, however, we tend to think that there should be as much "meat" on one leaf as the other...meaning the end knuckles are 3/4" and the central is 1 1/2". Another sublety may be the peening of the hinge pin. I think that very little was left protruding either end of the barrel for the cold upsets. Each upset became somewhat flattened and could even be burnished a little with light finishing blows. Something that Peter Ross did that surprised me at first; he cold punched the nail holes. The finished holes were spaced properly, but they were a little crude in appearance. There was some burr cleanup. Peter explained that this was an expedient method for a Colonial smith, and that the nail head would cover the slight irregularity of the holes.

http://www.turleyforge.com Granddaddy of Blacksmith Schools

[eric sprado]

I see that keeping the original hardware could be considered a big deal. I also see that if you're a good smith, if you have some wrought iron, if you understand some of the subtleties of the forged hinge construction, then your piece will be just as authentic as the early piece. There is the possibility that yours may even be better in quality and strength.

By subtleties, I mean for example the knuckle length. The central knuckle of a three knuckle Colonial hinge is often just slightly longer than the two end knuckles. Say the barrel length is 3", then if each end knuckle is 15/16" long, the central one is 1 1/8". Nowadays, however, we tend to think that there should be as much "meat" on one leaf as the other...meaning the end knuckles are 3/4" and the central is 1 1/2". Another sublety may be the peening of the hinge pin. I think that very little was left protruding either end of the barrel for the cold upsets. Each upset became somewhat flattened and could even be burnished a little with light finishing blows. Something that Peter Ross did that surprised me at first; he cold punched the nail holes. The finished holes were spaced properly, but they were a little crude in appearance. There was some burr cleanup. Peter explained that this was an expedient method for a Colonial smith, and that the nail head would cover the slight irregularity of the holes.

http://www.turleyforge.com Granddaddy of Blacksmith Schools

[eric sprado]

Somehow I pushed wrong button(story of my life)and copied Franks post instead of adding new. Sorry. Frank:I found your hinge article in Anvil Magazine,but it seems like I saw an actual video online somewhere of you making that hinge? Do you know where?
Brief aside-We met somewhere around 1964(?) when I was learning to shoe jumpers in Southern Cal.. Now I"m a crippled up old retired shoer who is trying to learn to be a blacksmith and having a hard time of it.Maybe I need to get out of my tracks,swallow pride, and come down to your school for a session..... Eric Sprado. Deadwood Oregon

[John B]

They were mostly wrought iron, had been made by different smiths, and some were welded from multiple pieces or even layers of metal.

Because the finnish was hot dipped zinc, followed by epoxy primer and automotive topcoat, I mig welded the damaged areas.

Galvanizing and wrought iron do not always make good bedfellows, A colleague who was restoring an old sailing vessal had the wrought iron plates holding the mast shrouds galvanised, 12 months later, they had corroded through, this may be due to the maritime location,(electrolosis ?) but something to bear in mind if you think you may be improving the corrosion resistance of the wrought iron by galvanising.

[Frank Turley]

Eric Sprado, In the olden days, I shod horses in Salem for about one year. On my site, http://www.turleyforge.com under Links and scrolling down, there are sequential photos of me welding up a strap hinge barrel. I normally send out hard copy school brochures, so a postal address left via my website would be the route to go.

Best,
Frank Turley

[arftist]

Galvanizing and wrought iron do not always make good bedfellows, A colleague who was restoring an old sailing vessal had the wrought iron plates holding the mast shrouds galvanised, 12 months later, they had corroded through, this may be due to the maritime location,(electrolosis ?) but something to bear in mind if you think you may be improving the corrosion resistance of the wrought iron by galvanising.

Galvanized iron (or steel) can work well on a vessal. Conversely I have seen all manner of metals from 316 stainless to cupronickel fail due to uncontrolled electrolitic corrosion.

Without doubt, epoxy coated galvanized iron or steel is a good thing in an architechural setting.

This is how I always finnish my hinges, and the finnish is garranteed for twenty years by the zinc dipper.

[John B]

Galvanized iron (or steel) can work well on a vessal. Conversely I have seen all manner of metals from 316 stainless to cupronickel fail due to uncontrolled electrolitic corrosion.

Without doubt, epoxy coated galvanized iron or steel is a good thing in an architechural setting.

This is how I always finnish my hinges, and the finnish is garranteed for twenty years by the zinc dipper.

But in a maritime situation we attach sacrificial zinc blocks to a vessals hull to help prevent corrosion by electrolisis, architectural situations are a completely different ball park, all I am saying is make sure of the situation before taking 'appropriate' action. In the situation mentioned, the wrought iron had been in situ for in excess of 100 years without being too adversely effected, only after it had been galvanised did it fail,

[jacon4]

So i gather from the replies that brazing the separation of the weld would be the way to go, correct?

[Frank Turley]

Yes, no, and maybe. If you're careful and skilled with a torch, you might get a clean looking braze where only a thin line of brass would show. If you're forge brazing, it is more difficult to control the flow of the brass. In either case, I would use the proprietary brazing rod, because it's alloyed to melt at about 1600ºF. Some old-timey brazing and horseshoe calk brazing was done using pure copper as the solder, but although resulting in a strong braze, copper melts at 1981ºF, so it may be more difficult to work with compared to brass. The iron must be in close contact with no gaps or daylight, so that the brass can run between the surfaces by capillary action. The iron will be at a good cherry red heat when the braze takes place.

No matter what you do, if you don't charge enough, this job will eat your lunch. You must also ask yourself, am I skilled enough to take this on this class of work? Can I forge new nails if necessary? Can I install without wrecking the table?

[pkrankow]

. Something that Peter Ross did that surprised me at first; he cold punched the nail holes. The finished holes were spaced properly, but they were a little crude in appearance. There was some burr cleanup. Peter explained that this was an expedient method for a Colonial smith, and that the nail head would cover the slight irregularity of the holes.

http://www.turleyforge.com Granddaddy of Blacksmith Schools

I tried this on a bracket I needed to hang. WOW neat trick. There was a "hanging chad" on all the holes, but twisted off neat with pliers. I did not even have a good backing, just a small punch and a 1/2 inch pritchel. The metal was heavy sheet metal, but less than 1/16 inch.

Impressed my dad too, who was still looking for a drill bit of reasonable size, etc. by the time I was done, especially since my workbench was organized at the time.
Phil