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Machining - Drawn

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On reading Gary Dabrowski's article in the latest Power Fibers about making deep drawn metal components, I noted that he infers that drawn ferrules are harder and stronger than ferrules machined from bar stock because of work-hardening.  I also recall A.J. saying that he had some concerns about machined ferrules and wondered if this is one of them.

Is there really a substantial difference in the strength and hardness of ferrules made from tubing vs. machined from rod?  Isn't nickel silver work-hardened to some extent when it's drawn or rolled into bar stock, or is bar stock annealed or that done at a high enough temperature that the metal gets annealed?  Has anyone had problems with excessive wear or deformation of machined ferrules?  (Robert Kope)

Yes there is. Given my absolute druthers, I would choose a well made drawn ferrule above all others. There is a noticeable difference in machined vs drawn, or drawn tubing ferrules. The problem is that there is no source for drawn ferrules that I know of, and the tooling costs for making them is prohibitive unless you can sell a few hundred thousand sets. Drawn tubing has the hardness, but I have had a few fail at the solder joints, which really upsets me.  Maybe the Loctite compound is the answer? I have used machined ferrules and like them, but do worry about wear.   Keep them clean, use a ferrule plug, and hope for the best. I think you could machine 1/2 hard bar stock OK, but have no idea where to get it. The bar stock available has been annealed, which is what mostly everybody else wants. Keep in mind that 10,000 pounds is a small order to the people who actually make the stuff. Everybody else just stocks it and sells it.  (Tom Smithwick)

If this work hardens like brass does, wouldn't it be a good idea to anneal NS while you work on it?  I anneal brass when I am working on it for a gun, and I also anneal NS when I am making parts out of it for guns.  Just wondering since this is one of the things I don't make yet.  (Bret Reiter)

Not for ferrules. You want the hardness for wear resistance. It makes a big difference. If you can, try filing some work hardened stuff and some annealed stuff. You will immediately see what I mean.  (Tom Smithwick)

Most of the sets that I machined from bar about 15 years ago are still in service. Most have had to be tightened up a couple of times. The ones that didn't hold up were the ones that didn’t receive much care (read: a lot). I have used a couple of commercial machined sets and was not too happy when I drilled for the pinning wire. Nothing wrong with the mechanical process, only the material itself. Fully drawn ferrules are most likely not going to happen very soon as the tooling cost is very high. Soldered from drawn tubing has been the compromise for 120 years (Bellinger, CSE). If drawn ferrules were available I would use them as a first choice but I WOULD anneal the bottom part around the ferrule leaves before I installed them.  (AJ Thramer)

I hope to be making a few ferrules from drawn tubing soon.  I checked the archives and found Dave LeClair's note on solder and flux.  He recommended Brownells Hi-Force Solder.  I found it on Brownells  web  site, but  there are two  different versions  of it - Hi-Force & High Temp Hi-Force.  Does anyone know which one Dave recommends or have other recommendations?  I assume the solder will be an important part of the ferrule, so I'd like to get it right the first time - or third, seventh or whatever it takes to make the first set of usable ferrules.  (David Bolin)

I use the lower temperature, hi-force solder most of the time.  (Dave LeClair)

One solder I have had luck with is the Stay-Brite solder.  Fairly easy to apply and the flux is provided. I think Brownells sells, or else find a jewelry supply place.  (Mark Babiy)

A while back I looked into the practicality of making drawn ferrules as an alternative to building them from tube.  I have a few friends in manufacturing businesses.  One of whom ran a stamping and drawing job shop at the time.  His tool design skills and experience was most helpful.  As a manufactured part, the ferrules we employ are among the most difficult to make.  The have a high aspect ratio, meaning that their length to diameter ratio is great.  While manufacturable, a typical #13 ferrule would require over eight stations and perhaps more in a transfer press.  This eight to ten station (tool group or punch station) press in not common in many firms.  Tooling would cost about three to five thousand per station depending on  designed run  rates and tool life expectations.  The other limiting factor is press stroke which in this case would need to be about two and a half times the ferrule length, needed to form and eject parts from dies.

Well designed and built tools will build good parts.  The advantage to drawing parts is general is the resultant grain orientation and the controlled work hardening of the NS resulting with strong parts at the end of the process.  Characteristics that are not available from anything made from the solid bar.

I've experimented a bit with my own OBI punch press that I use to make my drawn nickel silver and aluminum cups for reel seat parts.  Made a couple single station dies to test draw depth requirements. It's doable in single station, single operation tools but is the most tedious kind of work I've ever done.  In the end its easier to make ferrules from tube for the quantities I use each year.  (Gary Dabrowski)

I've been thinking a good deal about which types of ferrules are most durable.  Seems to me that in the past I've read hints that ferrules made from drawn tubing are harder, thus perhaps more durable, than those made from bar stock.  Is there any truth to this?  And if so, is the extra hardness from drawing the metal a big enough plus to make the tubing ferrules a plus?  (Harry Boyd)

This is an interesting issue.  This past summer on a fishing trip with some other builders the same subject came up and Tom Smithwick agreed that the N/S used for drawn ferrules is harder than the solid stock used for making ferrules.  However, he indicated that it make take years (10-20 possibly) to see the real effects of the differences.  Currently I think REC and Tony Young are the only ferrule producers I am aware of that are making there ferrules from solid stock, others all use tubing.

I was forced make a replacement ferrule last year and followed Tom Ausfeld's detailed instructions (which are included in the new Power Fibers issue) and the ferrule turned out great.  It wasn't as difficult as I though it would be, just like rodmaking.  Personally, I like the solid stock since I don't have to do any soldering.  As far as making my own ferrules, I may do it for quads but I'll probably continue to buy ferrules for hexes.  I have yet to try Rush River Rods ferrules but at $22 a set I'm sure I'll be ordering some to compare to the CSE and REC ferrules.  Also at $22 set it doesn't seem to practical to make your own from a time perspective.  At CSE and REC prices though it becomes a different issue.  (Bob Williams)

My "out loud" thinking is that they may possibly be different or the same.  That sure is not much help is it. The bar stock has been extruded and is solid while the tubing is also extruded but it will be a round tube. Now the extrusion process will work harden the metal, which means it should show slightly stronger strength properties on the surfaces of the metal where most of the plastic deformation occurs. After extrusion, the bar stock is machined and drilled. Depending on how this is done, this process may remove any work hardened properties from the material surface of the bar stock piece. It really also depends on how "hot" the material got from the cutting process work (how fast was the cutting and was a coolant used) as that could relieve the work hardening properties or induce more work hardening from the cutting process if it was done at high cutting speeds. I am not sure just which would end up being stronger. The ferrules may also be annealed which could change their strength properties.  (Frank Paul)

Nonferrous metals can be hardened by heating and letting them cool slowly.  It is the exact opposite of tempering iron or steel. If you heat and quench nickel silver (or sterling silver, or gold, etc.) it will anneal (soften) it. But, don't expect a dramatic difference as with hardening or annealing steel. There is a difference in heat hardening NS, but not as much as hardening steel.  (Darryl Hayashida)