I'm getting into turning with a lathe, starting small with some decent-used tools from the local ebay(trademe) and some janky chinese-grade tools. But I want to learn Best Practices. Right now I have one mag base/noga-style arm, and one dial indicator, and one test indicator.

How should I store a magnetic base and a dial indicator to prolong their life and retain accuracy?

From https://en.wikipedia.org/wiki/Magnetic_switchable_device
A magnetic base.

These have a circular core which can rotate 90 degrees. In the on position there's a solid magnetic field from the underside, to hold the base on a ferrous surface like a lathe, drill, mill, or similar Big Tool. When off, there is minimal magnetic attraction so the unit can fall over, but it won't attract metal chips and filings.


  • do I store the mag base in the ON position, clamped to a metal surface? Or do I store it OFF?
  • should the unit be vertical or horizontal or doesn't matter?
  • should I leave the dial indicator in the mag base permanently or return it to a shelf?

(mine are all sub $20 items, so the boxes aren't good for long-term storage.)

  • My lathe is so small and old it is completely aluminium and brass, so the mag base has nowhere to clamp to. I screwed a steel plate to the tabletop just in front of the lathe as a substitute, but its not even vaguely parallel to the ways.
    – Criggie
    Commented May 15, 2020 at 8:04

4 Answers 4


Storing the mag base "off" is equivalent to storing it "on" attached to a thick ferrous item - "off" is "magnetically attached to itself internally." Either is fine. This serves the same function as a "keeper" bar for a plain permanent magnet. A thin surface (sheet metal) is not as good, and "on" but not attached to anything risks weakening the magnet over time.

Orientation during storage does not matter.

Leaving the dial indicator out is going to vary with local hazards - are you likely to knock into it if it's just sitting there? - Then put it away. Putting it away is standard in a multiperson shop, but your home shop practices can vary with your level of care.


So one thing professional toolmakers have a lot of is toolchests - storing delicate instruments safely takes space...

Many look out for those custom old wood toolchests and even refurb them. Others buy them or make them, but those expensive small tools need looking after.


While you're obviously working with metal here, if you're into wood working at all, build yourself a small custom storage box for it. You can make custom sized channels for the different pieces to lay down in, line them with glued in felt, and put a lid on it.

They may be cheap, jankey stuff, but they'll look very professional and impress your mates when you pull it out of the custom box!

If you're not into working with wood, just bang together a simple box, throw some foam in the bottom and another piece on top and call it good. Make the foam thick enough that it just squeezes down to hold the pieces in place when the lid is closed & latched.


I have learned from an Abom79 video that best practice for a Noga arm is to leave it pointing upward in a straight line.

This decreases the likelyhood of it falling over, they fit better together, and vibration is less likely to affect it.

He is also seen turning on the magnet when putting the item down, on a lathe headstock for storage.

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