What are these MT3 Arbors used for?

[Friendly non murdering Sword]

Along with a box full of other tooling, I also got these MT3 Arbors with my Mill. Does anyone know, on which machine type and what they are used for? There is no drawbar thread at the end and the OD is engraved on the shanks with high precision (in metric). My first thought would be some sort of test- or alignment bar, but what are the threads on the frontend for?

 

[sdelivery]

Mandrels. Put a finished bore on the correct size Mandrel. Tighten the nut to secure it. Now the part should run true the o.d. can be machined.

 

[Friendly non murdering Sword]

Mandrels. Put a finished bore on the correct size Mandrel. Tighten the nut to secure it. Now the part should run true the o.d. can be machined.

Alright that sheds some light! But on what type of machine would they be used? Since there is no drawbar thread there can't be heavy side loads which would put the mandrel at risk of being pulled out? Are they used in a cylindrical grinding setup?

 

[sdelivery]

Typically used on lathes and cylindrical Grinders for od grinding and light turning. The bore would be in a finished state.
A part would be in a semi finished state where concentricity is important

 

[extropic]

I think they are intended to be used in a vertical spindle machine (such as a drill press).

Probably a special purpose machine, not a general purpose drill press.

The machine spindle would have a nut attached (rotating but retained) with female threads to accept the male threads near the fat end of the arbor's Morse taper. Engaging the nut/arbor will retain the arbor in the spindle. The nut/spindle design will be such that unscrewing the nut from the arbor will push on the arbor and separate the mated taper.

Exactly what each arbor was intended to hold (opposite from the MT) is beyond the capacity of my crystal ball.