Spun Steel Spinner Experts...

[sdennison]

So I am on to number two T-6 steel spinner project. This one is heavier gauge steel and was fabricated by metal spinning. Thus it retains the concentric tool marks of the process.

It appears to have been "plated" in some fashion but with the purpose of hiding the tool marks. This material is easily removed with a 3M buffing wheel. The brighter silver is the coating, the darker is the base material.

My question for the WIX brain is, does anyone know what this material is and how it was applied. See the couple not so good pictures for reference.

Thanks as always!

Last edited by sdennison on Sun Apr 22, 2012 4:01 pm, edited 1 time in total.

[AvroAvian]

Was it spun from a sheet of zinc anneal steel? Just a WAG...

[sdennison]

Might be but when the "plating" is removed, the texture definitely shows tooling marks. I would think if spun with zinc,it too would have the marks. Now that brings a good point, can you spin the part, showing the tooling marks and then bake to flow the zinc into the marks, then polish?

It does seem to come off like soft zinc might. I'm just not that smart, hence the WIX brain help.

[Enemy Ace]

IIRC you have to plate a spinner with Copper before plating the chrome. Otherwise the chrome will not adhere and comes off in big flakes. this is why the FAA outlawed chromed spinners, because too many people were cutting corners. There was concern especially with turbines that the chrome would come off in large enough pieces to get sucked into intakes and cause an unbalanced situation. I have also heard that spinners with patches of chrome missing also get patches of ice adhering to the un chromed areas, aggravating the out of balance situation. All of the above is just what I've heard over the years and is worth what you paid for it.
The stuff you are looking at on you spinner is the copper base remnant. My SNJ spinner looks exactly the same.
-Robert

[sdennison]

IIRC you have to plate a spinner with Copper before plating the chrome. Otherwise the chrome will not adhere and comes off in big flakes. this is why the FAA outlawed chromed spinners, because too many people were cutting corners. There was concern especially with turbines that the chrome would come off in large enough pieces to get sucked into intakes and cause an unbalanced situation. I have also heard that spinners with patches of chrome missing also get patches of ice adhering to the un chromed areas, aggravating the out of balance situation. All of the above is just what I've heard over the years and is worth what you paid for it.
The stuff you are looking at on you spinner is the copper base remnant. My SNJ spinner looks exactly the same.
-Robert

Thanks Robert, no chrome here at all. You are correct that chrome plating first involves copper, then nickel then the chrome. This is a very soft white metal of some sort and was used to fill in the tooling marks from spinning. I am looking for someone who may know the process and the material used.

[AndyG]

It's not body solder by any chance is it? Common in car restorations in pre-Bondo era.

You could check quite easily, with a hot iron tip inb a discrete location

[sdennison]

No need to be discreet, it is all coming off and hand working the rough stuff out then polishing.. I am just really curious how they did what they did. It could be old school fill but I think that was mostly lead and the weight would be too much.

In quest of the answer...

[flypa38]

It WAS lead that was used as automotive body filler long ago as you said. Well halfway anyhow. Some people used a mix of 50/50 lead/tin while others preferred 70/30. That's where the term "lead sled" came from for highly customized cars in the 40's-60's or thereabouts, by the way.
It is heavy, but in a layer that thin wouldn't the weight be sort of nominal?
Any idea when that coating was applied? Not sure when it was first used, but autobody suppliers have a lead free body solder available that is applied the same way as lead was.
No idea if that was useful in any way, but hopeful it was!

Johnny

[AG pilot]

Could it be straight nickel or silver? Firearms are nickel plated, and is pretty soft/easily scratched. No copper is used before hand.

[AndyG]

IF you are that keen to know, one way of discounting solder as a candidate is to touch a patch with a soldering iron.

[sdennison]

Thanks to all. I was mainly trying to educate myself to the process used in the era. My plan is to remove all of it and finish as polished steel. I have the time available that they certainly would not have had, thus driving them towards "hiding" the tooling marks rather than improving the finish of the steel base metal.

Still looking for an answer though, one I obviously do not have.