P.D.S.
Egg Pool Grader

P.D.S. egg scale from Australia

This egg scale was made by P.D.S. and most likely originates from Australia. I don't know the meaning of the abbreviation P.D.S. Also the location and production period are not known to me. The egg grader comes from someone who lived in Australia for forty years and had this scale 25 years in the kitchen. A search on the internet provided a couple of photos of P.D.S. egg graders. Based on those pictures I made the two missing text plates. The top of the wooden base now has the name of the scale P.D.S. Egg Pool Grader. Below this is the indication to place the egg upright in the holder. Also, there is PAT. APP. FOR, a patent application would have been made. I have not found any proof of it yet. Below this is a scale of seven egg weight values in ounces. These values correspond to the notches in the long brass bar of the egg scale. These values are: 1¼, 1½, 1¾, 17/8, 2, 2¼, and 2½. Rounded 35g, 43g, 50g, 53g, 57g, 64g, and 71 grams respectively.

other side of the egg grader

These egg sizes are outdated in Australia. The modern Australian egg sizes are: Medium 41.7g-49.9g (average 43g), Large 50.0g-58.2g (average 52g), Extra-Large 58.3-66.6g (average 60g), Jumbo 66.7g-71.6g (average 68g) en King-size 71.7g-78.5g (average 73g). In West-Australia on has the deviating Mega or XXXL class of 72g. The egg classes in New Zealand are of course not quite the same as those of Australia. The P.D.S. sizes scale still matches the current U.S. format, the following names and converted the following minimum weights per egg apply:
PeeWee 35.4g ~ 1.25oz
Small(S) 42.5g ~ 1.5oz
Medium(M) 49.6g ~ 1.75oz
Large(L) 56.7g ~ 2.0oz
Very Large or Extra-Large (XL) 63.8g ~ 2.25oz
Jumbo 70.9g ~ 2.5oz
The United States Department of Agriculture (USDA) has the US weight classes for consumer egg sizes system based on the minimum weight per dozen as follows:
Peewee 15 ounces
Small 18 ounces
Medium 21 ounces
Large 24 ounces
Extra Large 27 ounces
Jumbo 30 ounces
These are exactly the values on the scale of this egg grader.
At the bottom of the text plate are the weights of a dozen eggs of six egg classes, namely 15oz., 18oz., 21oz., 24oz., 27oz., and 30oz. (1 ounce = 28.35 grams).
I still don't know the meaning of the word Pool used on the scale. On the bottom of the purchased scale, only a small part of the directions was still present. I made the instructions plate "Directions" based on pictures found on the internet. One tunes this egg scale by first removing the weight and then moving the lead by rotating it. In the coreect setting, the long brass rod is in the middle of the ring at the end. When weighing an egg, you move the hanging weight away from pivot point of the weighing arm until a balance is reached. The nearest passed notch indicates the egg weight class.
Below some more pictures of this Australian egg grader.

[move pointer over the photo] animation: in balance without and with egg, by moving the counterweight to the left on the long brass weighing arm

the well-adjusted egg scale is exactly in balance without the counterweight

[move pointer over the photo] animation: the extreme positions of the fine adjustment lead weight

the well-adjusted egg scale is exactly in balance without the counterweight

the seven notches and the corresponding egg weight values in ounces

the factory plate copied by me, with the egg weight values in ounces per piece, and per dozen

the long bar is in the center of the ring	the egg holder seen from above	the weighing arm is in the center of the ring
on the bottom are the adjustment instructions	the adjustment instructions	the plate copied by me with the directions

the scale of the P.D.S. egg grader	the pivot seen from above	the egg grader in rest
in equilibrium with an egg of 71 grams (slightly above 2.5 ounces)	the egg is placed upright in the holder	the scale with egg seen from above
with egg slightly above 2.5 ounces	slightly above 2.5 ounces	in balance: the long bar is in the center of the ring

in balance

the long bar is in the center of the ring

equilibrium

in balance with an egg of 69 grams (slightly below 2.5 ounces)

in balance: the long bar is in the center of the ring