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Comment by showerst | Hacker News Reader

For everyone saying this is a 5000 dollar ebay score from the 50s, here's the regulation -- https://www.govinfo.gov/content/pkg/FR-2018-10-24/pdf/2018-2...

The regulation appears to pertain to _Three or more axis_ CNC machine with a sub 1.1 micron repeatability on one or more axes. That's not a 50s manual jig borer, that's a very high end modern(ish) CNC machine.

The Canadian implementation (Obviously not US law but it's implementing the same treaty), is a little more readable. https://www.international.gc.ca/controls-controles/about-a_p...

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Ok, so the Moore #3 Grinder was only guaranteed to 2.3 microns, and 0.75 uM in any given inch, after 10 years.

http://vintagemachinery.org/pubs/9432/20263.pdf

To be fair... I did try to find the specific grinder, but it doesn't appear to be listen in any article. Also, I agree that having CNC, and all the other upgrades is nice.

Dan Gelbart says his is accurate to a micron

https://youtu.be/HWPYoE1SNnA?t=61

.75 microns? Bah, may as well be a clapped out bridgeport clone! =). In all seriousness manual jig borers feel a little like a Monarch 10ee -- an absolutely incredible machine that will never be built again due to how constraints have changed, that solves a problem that I will never actually have.

Though if I lived out in the country someplace with a huge garage...

Edit: to respond to your specific point it's the 3+ axis CNC that's the key thing, not the accuracy. They were that repeatable in the 50s, but not when interpolating a 3d spline! Can you even 'side mill' a #3 style jig borer without destroying it?

The 10ee was in large part made for the nuclear weapons industry, so it's a good comparison.

The document you link refers to an absolute accuracy spec of 2.3 microns. The repeatibility will necessarily be much better than the accuracy. In terms of repeatability it's almost certainly better than 1.1 microns on every axis (even after 10 years).

The new programmable CNC grinders they sell appear to have approximately the same accuracy. Today they don’t report “greatest error in any inch” as a metric.

See the accuracy specs for the 1280 series on page 2: https://mooretool.com/pdf/F-1690%20Rev.%20G%20-1280%20Series...

Here's a modern example of a Jig Grinder. https://mooretool.com/jig_grinders.html

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