Lollipop maybe?

Thank you Nicholas,

That just about confirms the vote for a magnifier. As they say, "nature abhors a void", so I've ordered a 2" magnifying glass to fill the void.

Thank you Michael,

I had considered length bars, but unlikely to find a 1.5" one. If I can't find the real thing, I'll try a 2" length bar and shift the zeroing point 0.5" upwards. Better than nothing, and a bit more fiddly, but hey ho. I presume 1.5" is because that's the bottom graduation on the imperial scale.

Well, I ordered a suitable magnifying glass from that well known auction site, and it arrived today. It was listed as "professional", although I'm not quite sure what that defines, with a glass lens. The lens doesn't appear to be glass, as it doesn't feel heavy enough. I do hate being hoodwinked, so, is there a "non-destructive" way of checking the lens material, before contacting the seller?

Plus. I tried looking to buy 1.00" & 0.50" individual slip gauges, but those I found were ludicrously expensive, so I'm still looking for a 1.50" height gauge setting block, if anyone can point me towards a source?

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It is usually sufficient to touch the lens to your lower lip ... a plastic lens feels warmer than a glass one.

MichaelG.

A steel scriber shouldn't be able to scratch glass at the edge of the rim where it won't show.

Make a block. If you have a normal mike, especially if you can check it against someone else's gauge block then you can measure your home made one. Although convenient if it is exactly a round figure it only has to be a figure you know,

Edited By Bazyle on 30/06/2020 17:34:17

You could make a round bar with finely faced ends, using a known accurate Micrometer or Vernier to measure the length. Silver steel?

(My Shardlow Height gauge has just such a Calibration block in the box ).

A 1.5 inch diameter Ball Race / Roller Bearing would be a bit large to store in the box, as a standard?

Howard