I'm mulling over some home brew designs of clamp-on test indicator assemblies for my mill. Something like these but without all the knobs & arms or Ikea hex wrench screwing around. I'd like to incorporate a Noga-style indicator arm with single action lock knob. Looks like most of the Nogas have a M6 or M8 thread so I was going to accommodate that on the clamp. Then I got thinking, if the clamp was made of steel, I could use the mini-mag DTI base as is. But I thought I read somewhere, magnets around spindle quills is not a good thing - it can attract swarf to the outside and/or partially magnetize the bearing races inside? Maybe this is the real reason they either aluminum bodies or don't involve magnets? What do you think?