# Gold plated industrial "probe pins"



## mpetter (Feb 16, 2013)

I was digging
through my "get to one day pile" and accidentally found a couple of
lbs of gold plated industrial probe pins:

http://goo.gl/LN56t

I decided to estimate their gold content.

I looked up online and found that typical gold plating is 50
microinches. So, I assumed that thickness, as these are very expensive
industrial pins.

50 microinches is appx. 0.001 millimeter.

I further assumed that the pins are 0.1mm thick wall (they are hollow
tubes inside, they are spring loaded so that the pin is moving inside on a
spring).

So, on a 0.1mm material, there is two layers (inner and outer) of
0.001mm gold plating.

That is 0.002mm, or 2% by volume.

Since gold is 3x heavier than other metals commonly used for those
pins, like iron and nickel, then the gold content is 6% by weight.

Am I way off base?


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## etack (Feb 16, 2013)

I think you might be over estimating pins at 50 micro inches. I would guesstimate 30 but lets say you are right and they are at 50 you need to find the surface area of the inside and out and put it into a calculator like Sams. then multiply it by the amount you have to see your expected yield. Some times the spring will also be plated.
http://goldnscrap.com/index.php?option=com_content&view=article&id=72:gold-plating-calculator&catid=49:calculators&Itemid=66

Eric


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## tek4g63 (Feb 16, 2013)

I did a large batch of those pins a while back when I was still learning. I mechanically removed all the steel springs. Very long process. They are very good material, but not quite on the level you are speaking of. 

I made a post that documented my journey through the process. Complete with how much gold I was able to recover. Here is the link to that post.

http://goldrefiningforum.com/phpBB3/viewtopic.php?f=37&t=14154&hilit=100+ounces+pins#p142060

I hope that this helps you.


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## mpetter (Feb 16, 2013)

Thanks, guys. I ripped one of those pins apart (remember that they are not solid, they are tubes with a spring loaded plunger). 

I found out that they are plated on the inside, as well as on the outside.


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## tek4g63 (Feb 16, 2013)

They sure are. And like Eric said, some of them have gold or silver plated springs too.

I made a little jig that held like 20 pins vertical and a steel bar that I used to fold all 20 pins over. This effectively snapped them in half and the spring would stick out. Then I'd pull the springs out and throw the pins in one container and springs in another. I can post a picture of this jig in action when I get home in the morning if you would like to see it.

Thad

PS. These pins are also referred to as " pogo pins ".


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## Geo (Feb 16, 2013)

the fact that they are plated on all exposed area is pretty much a given. the total weight must be calculated less than the springs and nickel balls.the unplated material needs to be weighed and counted. break open ten and remove the springs and balls and weigh them separately. then count the total number of pins. this will give you a total weight on all unplated material.weigh the pins and subtract this number. then you can calculate the percentage of gold by weight.without knowing how much the springs and balls weigh, any number you come up with will be overestimated.


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## mpetter (Feb 16, 2013)

Geo said:


> the fact that they are plated on all exposed area is pretty much a given. the total weight must be calculated less than the springs and nickel balls.the unplated material needs to be weighed and counted. break open ten and remove the springs and balls and weigh them separately. then count the total number of pins. this will give you a total weight on all unplated material.weigh the pins and subtract this number. then you can calculate the percentage of gold by weight.without knowing how much the springs and balls weigh, any number you come up with will be overestimated.



Hi, my initial attempt at calculating the *percentage* of gold is, in my opinion, a lot less error prone than trying to find surface area of various minuscule complex objects that are all somewhat different (the pins are not identical). 

All that is needed for a good estimate is 1) a guess of the thickness of gold plating and 2) A guess of thickness of the average tube wall.

I ripped one such tube up and the walls are approximately 0.12mm thick, which is close to my guess of 0.1mm.

This means that at 50 microinch plating, there is appx 5% of gold by weight. At 30 microinches, perhaps 3% of gold etc.


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## goldsilverpro (Feb 16, 2013)

At 6%, that's about $1500 per pound, which is absurd, in my experience. Two problems. The outer gold thickness is more likely 20-30 microinches, since that is fairly standard and anything thicker is not needed for this application. Second, the inner thickness is most probably much less, since there is no electroplating bath on the planet, that I know of, that will "throw" 30 microinches of plating inside of those tubes. Plating goes to the path of least resistance and to get into those holes is highly resistant. The plating inside is probably 1/10, or less, than the plating outside. At most, I would guess the value is 1% ($250/pound) and that is probably stretching it. In reality, it is likely half that, or about 0.5%. It is a common thing to stretch the expected value of our own material to the highest level. The only way to determine the value is to process the material and see what you get. Only that will stop the BS and the false dreams.

To electroplate evenly inside of a small tube, you would need to insert a wire through the tube that would act as an anode. The wire would have to be perfectly straight and perfectly positioned to prevent it from touching the tube and shorting out. Also, fresh solution would have to be continually pumped through the tube to replenish the depleted solution inside. There are "electroless" gold solutions that would eliminate the need for the wire anode, but the need for continual fresh solution inside the tube would still exist. I will guarantee that, for something as lo-tech as pins, no company is going to go to those very costly extremes.


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## tek4g63 (Feb 16, 2013)

Listen to GSP on this, he is the man when it comes to plating application knowledge!

Not to be rude, but have you even glanced at the link I posted? If you had, you would see that GSP is right on the money. When all was said and done I believe that .6 to .7 % by weight is what that type of pin is. Still high grade in my opinion.

I ran many, many more pounds of just that type of pin after that post and they were very predictable in final yield. I always just figured .5% of total weight with springs removed. And usually got just above that.

Geo.
Some of the different styles of those pins do not have a little ball in them, but the majority of the up to 18 different styles of them I tore down did have the ball. So thank you for adding that bit as I had forgotten. Usually the ball shoots out when you break them open the way I did. Probably still have some hiding in the cracks in the floor.


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## Marcel (Feb 17, 2013)

I am no expert on plating but I can say that a lot of these pins went trough my wrinkled hands and I have never seen any testing pins that yielded even 1%. They look great and juicy and most of them are 24k plated but expext well below 1%, maybe 0,5% at best. When buying such stuff never calculate more than 0,1%-0,2% to be on the safe side.


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## mpetter (Feb 17, 2013)

Thanks, guys, for your "voice of experience". I appreciate your input!


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