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[LL] Mysterious Starrett tools. What are they for?

 

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perhaps they were used for lapping ball seats ?

Diamond Charged Brass Balls

animal


On 4/29/25 10:11 PM, Miket_NYC via groups.io wrote:

I bought these recently in a thrift store in New Hampshire where I've bought many tools. They're made by Starrett and each consists of a ball on the end of a knurled shaft.?

The balls are very precise. The small one is 1 1/2 thousandths


smaller than 0.5" (an amount that could easily have been lost over the decades). But the small ends of both shafts are swollen and scarred from pounding, so these were apparently intended to be pounded into something with hammers.

I have both a modern Starrett catalog and a 1936 catalog, and I don't see these listed,? either under measuring tools or punches and similar things intended to be hit with hammers. Also, they don't have part numbers, like most small Starrett tools.

Initially, I thought a previous owner might have welded or brazed the balls onto Starrett punches or something like that, but that's apparently not true. It's clear, at least on the large ball, that each ball and shaft is turned from one piece of metal.

Any ideas? These gizmos were so cheap that I couldn't pass them up, but I'm flummoxed about what they are and what they could have been intended to be used for.

Mike Taglieri?
 

Something used as a lap must be able to "hold" the abrasive in a lapping compound or solution (which can be ludicrously fine diamonds such that the solution just looks like dirty water).? But the "lap" has to hold those particles which is why laps are usually softer metals with the hardest being maybe a nice grey cast iron like meehanite.

Charles E. "Chuck" Kinzer

On Tuesday, April 29, 2025 at 10:32:48 PM PDT, mike allen <animal@...> wrote:


perhaps they were used for lapping ball seats ?

Diamond Charged Brass Balls

animal


On 4/29/25 10:11 PM, Miket_NYC via groups.io wrote:
I bought these recently in a thrift store in New Hampshire where I've bought many tools. They're made by Starrett and each consists of a ball on the end of a knurled shaft.?

The balls are very precise. The small one is 1 1/2 thousandths


smaller than 0.5" (an amount that could easily have been lost over the decades). But the small ends of both shafts are swollen and scarred from pounding, so these were apparently intended to be pounded into something with hammers.

I have both a modern Starrett catalog and a 1936 catalog, and I don't see these listed,? either under measuring tools or punches and similar things intended to be hit with hammers. Also, they don't have part numbers, like most small Starrett tools.

Initially, I thought a previous owner might have welded or brazed the balls onto Starrett punches or something like that, but that's apparently not true. It's clear, at least on the large ball, that each ball and shaft is turned from one piece of metal.

Any ideas? These gizmos were so cheap that I couldn't pass them up, but I'm flummoxed about what they are and what they could have been intended to be used for.

Mike Taglieri?

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