What are these in my lathe chuck?

[Wongster]

Hi Folks,

I recently bought an ER32 collet chuck and am looking at making an adapter plate to mount it on my Proxxon PD400.  While inspecting my 3-jaw chucks to see how it is mounted, I saw 3 set screws at the back that aren't holding anything.

Are they there as alignment pins? If not, what purpose do they serve?

   

   

[Pete O]

Judging purely from their position, I would say they are retaining the key spindles. You may find that where you have removed one, the key now unwinds the spindle rather than adjusting the jaws.