I'm often asked 'Can you find me a new spring for my Purdey?' A bit like 'Can you get me a new hammer to replace the one I lost on my 1871 Grant?'.
This link shows you what we have to start with to make a new spring. They all have to be made from scratch.
https://www.facebook.com/photo.php?fbid=...e=1&theater
Fantastic photo of that spring blank.
Now that could not be a blank for a single spring. They are going to wonderloaf it and make several from the slices or else they are a bunch of masochists.
Thanks for the picture Digg. How about that, looks like the bend is machined and cut out. I'd have guessed it would be forged. It does have the look like there's a bunch of steel to hog off.
Yes, Dig, most seem to think we've got boxes of springs just laying around ready to drop in their hand made gun. Unfortunately, such is not the case.
Do you have any more pictures of the Reilly round bar hammer gun that was in the photographs? I am restoring a .577 rifle with an action like that, and I have to make new hammers.
Why would anyone want to make a spring like this instead of using the traditional method of forging one spring? Doesn't proper forging leave the grain structure running longitudinally with the leaf? Perhaps the answer is the lack of skilled spring makers.
Who exactly is "we"? Have you or do you perform any of the work on these guns?
cast steel from which slices can be taken to make multiple springs from one piece?
If you look futher down the album there is a forend made from what seems a combination of subtactive technologies- EDM wire eroding and CNC machining, a combination I find rather clever.
The shock to some that bespoke guns utilise these technologies is understandable. But may be we should not confuse the product with the way it is made.
I still have my spring bending jig somewhere. Making and tempering a spring was a big deal. Then I found OMPS in Italy and got V springs semi finished. Nothing makes you like coil springs faster than making your own V springs. That big chunky "motherblock" for V springs in the pic shows that even the best makers have a hard time with V springs and try to solve the problem in innovative ways.
Why would anyone want to make a spring like this instead of using the traditional method of forging one spring? Doesn't proper forging leave the grain structure running longitudinally with the leaf? Perhaps the answer is the lack of skilled spring makers.
Why forge one spring at a time, when you can bend one large piece of stock and cut three blanks from it? That way you will have a spare when one of the two springs you need to make happens to break during shaping/heat treating..etc. Seems to me the worker making these springs is very skilled/experienced in doing this work.
The steel is cheap, but the time it would take to prepare a single spare blank down the road, is very expensive.
Mike - email me and I'll return you a load of photos.
Le Fusil, 'we' refers to anyone here asked to make a part for an old gun. The photos come from the Purdey factory in Acton, where I was last week. Each folded blank provides the material to make three springs.
I am not a gunmaker, nor do I ever pretend to be one. I do run a firm which employs gunmakers and project manages the restoration of guns. In this sense 'we' includes me, as I am often asked to solve this problem for people.
The subject came to mind as I have a Purdey in right now for a new mainspring. I will see they the client gets his gun back with a proper mainspring working perfectly. I do not file the springs up myself, but you knew that, I think you were just being confrontational, or did you have something constructive to add?
I like this forum but sometimes I wonder why it is not more collegiate and less mean spirited than it is occasionally.
If you look futher down the album there is a forend made from what seems a combination of subtactive technologies- EDM wire eroding and CNC machining, a combination I find rather clever.
The shock to some that bespoke guns utilise these technologies is understandable. But may be we should not confuse the product with the way it is made.
Good catch, that is a very interesting photo. Although, I would opine that the machine work we are seeing was all done on a rotary 4th axis mill.
The iron was made from a piece of round stock, and I can see the mounting bolts still attached to the back of the stock where it was mounted to the face plate of the rotary table. I don't see any operations that could not have been made on a 4th axis, but there still may be EDM work yet to do on it.
As a CAD enginneer, CNC programer/operator myself, I have to say this is a fine piece of work. It is more impressive when you appreciate how many scores of hours it takes to bring a project like that to completion.
I do agree with your statement about people need to understand that producing blank parts with these methods is not a negative. There are still many hours of hand work/finishing involved. Creating these semi-finished parts with CNC technology is simply replacing the many hours of wasted time with a hack saw and bastard files. The parts still have to be brought to final dimensions, and finished by skilled workers, like they always have been.
The one potential drawback I will point to, is that it does limit changes, or one of a kind parts. For example with this forend iron, there is a large investment in creating a CAD drawing, CNC program, testing/editing that program, special fixturing in setup if needed...etc. Once all of that is done, to actually make money on that process, there needs to be a certain quantity of parts made to make a profit, or the price of that one part is astronomical, especially when you then think of all the parts that go into the gun, that are made with this process. There is a chance that this can limit creativity on future designs, but that might yet remain to be seen.
But I digress...Thanks for the photos Dig.
Flintfan,
Nice to hear from one that knows, really knows the new technology.
Lately there is a lot of "information" regarding additive pocesses like 3D printing in metal. What I cannot get from these reports is how heat treatable would be, for example, a forend iron made by laser metal sintering. Seeing one single automatic pistol made this way does not answer the question.
If the additive process can yield equal quality parts, then we are in for a new phase. But it is a big if so far and often one gets the feeling that the reports are deliberately overenthusiastic.
As to the cost of CNC parts. It often is worth it simply because the alternative is more costly. At the B.Rizzini factory they were making triggers from the solid with CNC. I asked Moira Rizzini why not use investment casting, and the answer was that casting needs a 5000 piece minimum order, whereas CNC is cost effective for far smaller batches. At the level of totally bespoke items, the cost of the machining, amortization etc is probably weighed against the cost of bringing on apprentices etc. I am guessing that it probably is about equal.
"I like this forum but sometimes I wonder why it is not more collegiate and less mean spirited than it is occasionally."
I agree. Not just this forum, some internet commenters, here and elsewhere, wade in with insults for no apparent reason, often driven by total misapprehension of what was written.
Flintfan,
As to the cost of CNC parts. It often is worth it simply because the alternative is more costly.
That reminds me of one more thing I forgot to point out. If you look in the background of the photo of the spring blank, you will see the remnant of steel that two action blanks were cut from of using wire EDM. While wire EDM work is slow (probably cutting somewhere in the 30 square inches per hour rate) think of the alternative of forging out a action blank, then using a hack saw and files to get it to that same point, and level of accuracy.
As for the 3D printing, it is not at the level it needs to be at yet for most parts, but like everything else, it will evolve.
I have a vintage Purdey, 1888, that needed new springs. The action was sent to Purdey where they farmed the spring work out to another firm. I got it back and it was not right. Back a second time to Purdey where they did get it right themselves.
My point is that this is a very delicate and hard to forge/machine/file part and I would never attempt to make it myself, nor would my Purdey trained gunsmith, here in the US.
I like this forum but sometimes I wonder why it is not more collegiate and less mean spirited than it is occasionally.
Good point Dig!!! A lot of good people have left this Board or only post occasionally because of that.
Getting back to springs....I have attempted to make a v-spring and for the home gunsmith it seems a mixture of luck and pluck. The hardest part being tempering after the thing is shaped and partly finished. Hats off to those who can do it.
And a Purdey mainspring has a lot of work to do - it has to open the barrels, cock the tumbler and fire the lock.
I asked a question. It wasn't loaded. When I post, I usually do have something constructive to add. I did not know that you didn't file up the springs yourself, hence why I asked the question in the first place. You do say "we"a lot and in this country that usually means that you are actually involved in the work, not just acting as a subcontractor farming out the work to the trade. In that case we say things like "a client of mine has a broken gun, so I found a gunsmith to fix it."
Anyway thanks for posting the pics. It is interesting to see these springs made. I've seen Purdey mainsprings made by Alfi Galifent, they are beautiful and complicated. He used to make springs in batches too. Too much work to make just one. My friend here in the states has a small box of Alfis semi finished Purdey springs. I currently have a Lancaster body action with a broken mainspring. It's an extremely complicated devil with much milling involved. You could make it solely with hand tools, but it would be silly to. I would venture to say that the Lancaster mainspring might be just a hair more complicated than the Purdey.
Mike Rowe,
That is outstanding work. Thank you also for showing the thickness section of the Dickson spring, interesting to see that it is a little thicker in the middle than either end.
The original broke or did it tire out?
Thanks for the pictures Mike, and for walking it through to the fitting.
That's how I supposed the original Purdey spring would be made, from smaller stock with more bending and forging. I would not be surprised if that raw "V" starts off so big so it can be held for machining. It would be interesting to see how close it is to final dimensions after machining.
Thank you for the kind comments, gentlemen. And Dig, I hope I'm not hijacking your thread here - just trying to show everyone how things get done at bench level.
Both springs needed to be replaced on this trigger plate. The right hand one was a roughly made replacement, and the left one was the very early style held to the tumbler by a tiny screw. The ears had broken on the tumbler and spring, so the decision was made to modify it to the later style with the seat and roller (the right side was already modified). "Later" is a comparative term, judging by the early round actions I've worked on it would be sometime in 1884, still quite early in the scheme of things.
Just my take on the picture of the spring blank, but I'd say it was probably made from cutting a straight bar of about 3/8" rolled steel with grain direction lengthwise, then hot forged for the bend to give it the proper grain direction around the bend. I doubt the Purdey engineers missed anything. No castings here.
Chuck
I want to agree with you, forging is the start for a spring, so I was taught. But look at the inside of that V shaped piece. That surface looks mightily like the one my EDM collaborator gets. Forged surfaces tend to be a lot rougher than that.
Now it could be that the EDM process is used to clean up the forging, which would be a clever use of the technology. But if the end result is a durable spring, the how becomes a bit secondary.
I think you folks would know better. Looks to me like 3/4" or maybe 1" stock that has a saw slit down the middle. Then forged to open up the "V". It doesn't look like the "V" itself was forged 180* back on itself.
The inside of the "V" doesn't really look cleaned up too much. Maybe surface ground to true up the top and bottom. There does seem like some nasty inclusion down where it's being held. I'd bet as they were slabbing off springs, they might not want to use that area. Surprised it doesn't make the whole piece suspect, because not much is invested up to that point.
I think it's so bulky just to make sure the pattern of a spring fits in there without too much worry. Maybe, but that rough stock doesn't look like much advantage would be gained up to that point with EDM.
I just have hard time believing that a Purdey engineer would not get the grain right. The forming to that shape could easily done when hot and the first outward bends of the ears done in a pressbrake, the center bend started in the pressbrake, then closed by pinching the outside in the pressbrake. All done while hot, probably in less than a minute. I just don't see any reason to use machining or wire EDM to make that raw part. If they sawed it or used wire EDM, they sure lost me on the logic. But there's always a bunch of ways to make something.
Only interesting conversation Chuck, no big deal stuff. If that 180* were forged. I thought I'd see much more distortion like compression on the inside and stretching on the outside of the bend. It might be very difficult to maintain the same thickness of material around that bend.
Maybe, the loss of grain flow around the 180* could be made up for by using a known alloy steel and modern heat treat practices. Agreed, traditionally I'd think bends, curves and likely tapers were all rough forged to get it close and probably more sound. I think a couple more pictures downstream in the process would be interesting to see.
For the 180 bend area of the finished spring, if you knew it wasn't ideal grain direction, you'd simply make it thicker there so it doesn't flex in the 180. All the spring response is in the arm of the leaf anyway.
They are folded into the basic spring 'V'.
Thanks Digg, I never would have thought that by looking at the picture.