The original Tooke Gage is still in use

This information is provided for users who have the older microscopes that were marked in either (only) mils or millimeters. These old-style scopes have a green-anodized barrel, which is visible at the top of the gauge.

Measurements made using the Tooke Gage are a function of the cutting tip geometry (and not of the microscope). The usage of all three types of scope is the same; the cutting tips are the same; but the appearance of reticle divisions/hashmarks differ. You must know the measurement system of the reticle you are using, in order to calculate the depth of your coating.

To help identify your scope: the old-style scopes have a green barrel and a chrome eyepiece. The universal scopes have a black plastic collar, and a black metal top-optic. The new enhanced scopes will have a silver-colored barrel and eye piece.

The (old-style) English or metric microscope in the OG202 body: note the green scope barrel
The (old-style) English or metric microscope in the OG204 body

Principle: using the old-style microscope

The incised V-groove is observed vertically through an illuminated microscope bearing a measuring reticle (scale). Both the “English” (Imperial) version with the reticle marked in mils and the metric version with the reticle marked in microns, are not currently available. Micro-Metrics is working with an engineering design firm to have these scopes custom made.

The view through the old-style English microscope
view thru the OG202 microscope

English reticle (not currently available) specifications

Cutting
tip
Maximum
Coating
Thickness
Precision of
thickness
determinations
One division on
the reticle scale
represents:
1X100 mils± 0.25 mils1.0 mil
2X 20 mils  0.13 mils0.5 mil
10X1.0 mil  0.025 mils0.1 mil
An enlargment of the (English) reticle view showing the divisions
close-up of the view through the English reticle

English old-style scope
(not currently available)

Measurements made using the Tooke Gage are a function of the cutting tip geometry (and not of the microscope). This photo shows the view through the current "universal"microscope, which measures in millimeters. If you have the old-style scope marked in mils, your measurements will be as shown below the photo.

Photograph through the “universal” scope: remember, the actual units a reticle is
marked is doesn't affect the measurement: they do affect the calculations!
Thus, in the above photo, pretending the hashmarks belong to
an English-marked scope (0.001" per hashmark: 1 mil / “thou”),
the thickness measured for each tip equals:

1 X tip

  • “white primer” = 2 reticle/hashmark spaces = 4 mils
  • “blue topcoat” = 5 reticle/hashmark spaces = 10 mils

2X tip

  • “white primer” = 2 reticle/hashmark spaces = 2 mils
  • “blue topcoat” = 5 reticle/hashmark spaces = 5 mils

10X tip

  • “white primer” = 2 reticle/hashmark spaces = 0.1 mils
  • “blue topcoat” = 5 reticle/hashmark spaces = 0.5 mils

Metric old-style scope
(not currently available)

An enlargment of the (old-style metric) reticle view showing the divisions

Measurements made using the Tooke Gage are a function of the cutting tip geometry (and not of the microscope). The photo below shows the view through the current "universal"microscope, which measures in millimeters. If you have the old-style scope, which is also marked in millimeters but with a finer-measuring reticle (hashmarks closer together), your measurements will be as shown below the photo.

Photograph through the “universal” scope: remember, the actual units a reticle is
marked is doesn't affect the measurement: they do affect the calculations!
Thus, in the above photo, pretending the hashmarks belong to an
old-style metric-marked scope, the thickness measured for each tip equals:

1 X tip

  • “white primer” = 2 reticle/hashmark spaces = 40 µm
  • “blue topcoat” = 5 reticle/hashmark spaces = 100 µm

2X tip

  • “white primer” = 2 reticle/hashmark spaces = 20 µm
  • “blue topcoat” = 5 reticle/hashmark spaces = 50 µm

10X tip

  • “white primer” = 2 reticle/hashmark spaces = 4 µm
  • “blue topcoat” = 5 reticle/hashmark spaces = 10 µm

Old-style metric reticle (not currently available) specifications

Cutting
tip
Maximum
Coating
Thickness
Precision of
thickness
determinations
One division on
the reticle scale
represents:
1X2500 µm± 5 µm20 µm
2X500 µm  ± 2.5 µm10 µm
10X   75 µm  ± 0.5 µm2 µm

For comparision:
the current metric universal scope

View through the current “universal” scope
Thus, in this photo and using a metric-marked scope
the thickness measured for each tip equals:

1 X tip

  • “white primer” = 2 reticle/hashmark spaces = 80 µm
  • “blue topcoat” = 5 reticle/hashmark spaces = 200 µm

2X tip

  • “white primer” = 2 reticle/hashmark spaces = 40 µm
  • “blue topcoat” = 5 reticle/hashmark spaces = 100 µm

10X tip

  • “white primer” = 2 reticle/hashmark spaces = 2 µm
  • “blue topcoat” = 5 reticle/hashmark spaces = 10 µm

New enhanced scope

Micro-Metrics has been working for several years on the design and manufacture of custom reticles and scopes. (There is a light at the end of this tunnel, and it is NOT an oncoming train!) Production has been ordered, deposits paid, now the waiting on the actual production has begun. Track the progress on the blog!


The Technical Data Sheet for the OG202 Tooke Gage is available in a form that can be printed on 8-1/2" by 11" paper.
and
A detailed explanation of the geometry of the Tooke Gage called “Measuring: the Geometry of the Tooke Gage  is available
is currently being updated: sorry for the inconvenience!

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Contact Information

Mailing and Shipping Address:

Micro-Metrics Company
4450 Ansley Lane
CUMMING, GA 30040-5252

Telephone Number:

(678) 947–3723

Email:

Elenor2011 @
Micro-Metrics.com


(100% woman-owned business too.)