XRF testing vintage vehicles

[swarfless]

In the early days (several decades) of light alloys in i.c. engine development a very popular alloy was Elektron, a magnesium alloy very good in many ways when young. Machined crisply, & cast well but didn't age well especially in damp conditions .. As I think has been mentioned Aluminium alloys were pretty dubious brews, or foundry 'stew' & also prone to aging problems, corrosion-wise and metallurgically.

 

[standardparts]

"Should auction houses be using XRF?"...was part of the OP...

Someone showing up with an XRF gun at an auction house (heaven forbid) would likely be branded a terrorist.

 

[standardparts]

I want to get back to the original question and Joe Michael's first comment. XRF guns as used in scrap yards are not even remotely precise enough to distinguish pre-atomic and post-atomic age materials. First off, they aren't even intended to distinguish isotopes of the same element, which is critical to the pre-/post-atomic analysis. Second, the typical handheld guns are not set up to recognize some important elements at all. Like Carbon. They cannot tell you if you are looking at 1018 or 1095, basically. Third, they are lucky to get +- 5% accuracy on the proportions of the elements they are calibrated for. So, essentially, they can tell you what general family of alloy you are dealing with, like 10xx vs 41xx vs 86xx for steels, or 60xx vs 70xx for aluminums. They are just not the right tool to do pre-/post-atomic analysis.
I cannot say if the XRF process, carried out in lab conditions with lab-grade gear, can provide the necessary data. But the handheld XRF guns aren't going to answer that question.

A few years ago I had a steel casting checked with an "XRF gun" (generic(?) term as there are different types-not all are created equal) and then later cut a section of the casting and sent it to a metallurgical lab.
The XRF results may have been good enough to determine kinda-sorta what the steel was for purposes of feeds-speeds-cutting tool but not nearly close enough for heat treat as the lab results provided.

In regards to super rare motorcycles where there are only a few examples I would guess that those involved in that area of collecting know who is putting stuff together and how they are doing it. Of course, as always....buyer beware.

Somewhat related: The original 1903 Wright Flyer crankcase was not 're-discovered' until 1985 and it appears the aluminum underwent analysis. Since motorcycles, same a powered aircraft were in their infancy no doubt little attention was paid at that time as to exact composition of the aluminum but what they came up with certainly worked for the application.

The First Aerospace Aluminum Alloy - The Wright Flyer Crankcase - Frank W. Gayle

pswscience.org

 

[markz]

Having owned an XRF for many years, it's a great tool. You can fairly accurately measure element content, mine handles any element above atomic number 16, might be 22. So will not pick up beryllium, oxygen, silicon. It is quick, non-destructive. Display accuracy is 2 decimal places, I suspect it is only accurate to 1 (i.e., 50.1%), also there can be variations in metal, in the same piece; molten metal is hard to mix properly. So yes, you could distinguish one 'pour batch" from another. Most of the older metallurgy, from 1880 through 1930, is surprisingly accurate; most shops employed an assayer or metallurgist who chemically determined alloys. Precious metals especially, the chemistry of the US mint, for example, is spot on, from 1860's on, if the silver says it coin silver, it is 90.00 %

 

[markz]

"Should auction houses be using XRF?"...was part of the OP...

Someone showing up with an XRF gun at an auction house (heaven forbid) would likely be branded a terrorist.

And yeah, I used to go to auctions with my XRF, once everyone figured out what I was doing, they would simply bid on whatever I was bidding on and add $50. Last auction I simply bid up a bunch of junk just to prank some of my competitors. They were not as amused as I was.

 

[standardparts]

And yeah, I used to go to auctions with my XRF, once everyone figured out what I was doing, they would simply bid on whatever I was bidding on and add $50. Last auction I simply bid up a bunch of junk just to prank some of my competitors. They were not as amused as I was.

Yeah, auctions can become contests of personality and often, the extablished players don't appreciate new "tricks" they don't understand--while they don't have any qualms about bamboozling buyers...heaven help the person who out bamboozles the bamboozlers.

 

[Dan from Oakland]

Given the fact that most all old alloy castings are notorious for containing significant amounts of impurities, my guess is that a reproduction crankcase or housing cast in 318 or 356 aluminum would look much different to an XRF gun compared to an old casting. If the XRF operator was familiar with the signature from old castings, it would seem that the difference comparing new casting would be pretty easy to detect.

 

[EmGo]

Given the fact that most all old alloy castings are notorious for containing significant amounts of impurities, my guess is that a reproduction crankcase or housing cast in 318 or 356 aluminum would look much different to an XRF gun compared to an old casting.

At the prices some of these things bring tho - a million dollars for a motorcycle ? - I could figure out how to throw some dirt into the aluminum at pour time

Not worth it for a run of the mill old bike but, say, a triple overhead cam single, might be.

 

[john.k]

If you talk to a TIG welder who repairs antique stuff.......the surprising fact is that modern /current castings are often near impossible to weld due to a large content of inclusions and trash ,resulting from the demand for recycling materials into new make.

 

[80cui]

Indian was the biggest manufacturer for a time, but the casting was done by Brown and Sharp, F&S (?) and Lynite. The last 2 did crank cases and they were crap compared to Harley.
> Im only familiar with Indian junk so Im only assuming HD was the better stuff. (surely!)

 

[john.k]

A while ago on one of the Euro fbook sites ,a person with access to a metals lab did an analysis of late 1920s JAP crankcases .......the race motor (KTOR) had a different analysis to a standard motor ........dont recall the exacts ,but basically the standard ally was aluminium and zinc ,the race motor was ally and copper ,no zinc ....A lot of the Eurozone collectors are really into British bikes of the 1920s ,lots of small enterprises making replacement parts that have been only available as hard to find NOS before now.

 

[Ries]

Seems like the most common junkyard identification problems are going to be copper alloys and aluminum alloys. Its pretty easy to tell whats steel. But the fine points on cast aluminum alloys, and things like chemical resistance, weldability, and so on, are probably also beyond the abilities of a common junkyard XRF gun.
Add to that, a lot of the original copper and aluminum alloys are not available, and, probably proven not to last enough to be better than current replacements with known compositions.
I know that often Alfa GT, posting here about his amazing reproductions and repairs of vintage vehicles, has often used better modern alloys that are close but not the same as some originals.

 

[JST]

For the vast majority of cases, it won't matter anyway. The issues come up when some rare (and thus presumably expensive) item, vehicle, etc appears at an auction.

People who might buy it are naturally going to pay more if it is "genuine", all original parts, not later reproductions. The rarity is in it being all original and in good condition (pretty obviously). A modern reproduction would not be worth anywhere near as much, and the market would not be collectors, as it would be for a genuine article. A genuine item which has some modern parts would be somewhere in the middle, possibly depending on the chances of ever finding "correct period parts".

Where lots of money is at stake, people will go to quite some lengths to create missing parts that look original, and are in condition compatible with the rest of the vehicle. In the world of regular antiques, lots of fakery has been used to try to pass off a recently made item as an antique several hundred years old.

In such cases, the XRF might serve as a useful "survey tool", but any real questions would have to be answered with better tools.

 

[john.k]

Some bikes like knuckleheads have had enough replica parts available to build complete bikes for over 25 years .......the answer to this is the original condition 'barn find' which can be worth 3x a restored bike.....There is definitely a cottage industry in Holland reproducing pre 1915 US sourced bikes ......there is a well known dealer there who seems to find one incredible rarity after another in US veteran and vintage bikes.....US made bikes is where the money is ,with a few exceptions.

 

[Ries]

If you talk to a TIG welder who repairs antique stuff.......the surprising fact is that modern /current castings are often near impossible to weld due to a large content of inclusions and trash ,resulting from the demand for recycling materials into new make.

I have been tigging a lot of different things since about 86. Own 3 tig machines right now. Never found “trash” in much of any casting or metal stock. Aluminum or copper alloy Castings, brand new or 100 years old, are hard to weld if they have zinc, lead, or other weird stuff alloyed in. Always. usually the cheap stuff, like atlas lathes or sears motorscooters, is the worst. Zamac was crap in the 40s, and its crap today. 360 brass can be of the highest quality, and the lead and zinc still make it tricky to deal with -I usually tig braze with a silicon bronze filler rod. Much more common problem with motorcycle and auto parts repair is oil absorption, which is common, stubborn, and hard to remove. Parts washers, solvents, ovens, sandblasting- and it still fucks up welds.

 

[JST]

............................Much more common problem with motorcycle and auto parts repair is oil absorption, which is common, stubborn, and hard to remove. Parts washers, solvents, ovens, sandblasting- and it still fucks up welds.

I've had some success with "cooking" out the oil, at least well enough to silver solder parts where that is applicable. Takes quite a while and is a royal pain to do.

Tig would be fussier. Don't know about the "Muggyweld" and "aluminum solder" type stuff for aluminum alloys.

 

[triumph406]

The only feasible way it would work at auction is if you had a good known genuine crankcase from the same era. But it would be almost impossible to prove the providence of that part back to when? The 1920's?

So you compare the crankcase in question, to one you "think" is genuine. Then what? Every pour is going to be different. What tolerance does some so called 'expert' asign to the results? What happens if there were two consecutive pours, and they were both very different, maybe one was very clean with the minimum of impurities, what would happen if the expert said "there's no way they could have poured that in the 1920's" but it had been?

 

[triumph406]

An interesting question would be whether parts for very rare motorcycles have been replicated. The answer is of course yes.

I knew a guy who was the US's foremost authority on boardtrack racers. and had a significant collection of such bikes. (before he got into collecting TZ750's)

He had a v-twin motorcycle, rare to the point there was only two known examples left in the world. He had one, and there was another in NZ. The one this guy had was missing the cylinders. So he talked to the guy in NZ as to whether he could borrow a cylinder and have it replicated. The guy in NZ agreed, on the proviso that only 4 cylinders would be cast, two for the guy in the US and two to go to NZ. and after casting the patterns were to be destroyed.

So the guy in the US found a retired pattern maker who made patterns to cast new cylinders. Apparently the the patterns were so good it was very difficult to find any differences between the original and repro cylinders. After four cylinders were cast the patterns were bandsawed into small pieces. The sad part is the retired pattern maker never lived long enough to see his work cast.

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Might as well walk around with an XRF gun and test every part to see what's genuine and not, And scrape off paint to make sure it's from the correct era.

And the air in the tires? make sure that's genuine too,

 

[Ries]

I've had some success with "cooking" out the oil, at least well enough to silver solder parts where that is applicable. Takes quite a while and is a royal pain to do.

Tig would be fussier. Don't know about the "Muggyweld" and "aluminum solder" type stuff for aluminum alloys.

I have had this problem on things like aluminum truck tranny bodies, where Muggy would not exactly be a good solution. Things that are such a pain to remove and replace you want once and done...
Any time I can, I do jobs where I buy new material and put things together, but inevitably, in 40 years, I have fixed all kinds of things for myself and friends.

 

[john.k]

Some 35-40 years ago there was a costly lawsuit in the UK over the 'provenance' of a Norton race bike that had been sold 'with a known history'....this is the first (and only) major legal action over the genuineness or otherwise of a bike I am aware of ...........I have no doubt in the world of vintage sports /race cars where prices start around $25M there have been many .