This is another model built with my
1930 red and green No.7 Meccano
set. The plans were published in 1928
as SML No.7 “Meccano Platform
Scales” and could be built with the
parts in the then current No.6 Outfit.
An earlier version of this model had
been published in the 1919 book of
instructions. Platform scales of this
type were a common item in railway
offices and on station platforms. See
picture of the Avery Scales taken from
the instruction leaflet below right.
Although the model is fairly
straightforward the mechanism was
fairly complicated and difficult to
assemble within the framework of the
model. This is part due to the none to
clear written instructions however my
patience prevailed and I finished the
model.
One major problem was the strip
coupling 63b the slot of which is
thinner than the width of a 25 hole
strip making it impossible to fit and
slide along its length. I had to
widened the strip coupling.
When completed and set up it does
work very well and will weigh from
light objects up to a few kilos.
This is one of very few Meccano
models that put the centre fork p/n 65
to good use, those I used on the
scales are much thinner and sharper
than the later version. The centre fork
is used as a knife-edge bearing
resting on two 19 tooth pinions and is
very effective I doubt the model would
work as well with the post war blunt
version of the centre fork.
Front page of original instructions.
Instructions of 1919 version of model
I made few changes to the model
including using an early ratchet/pawl
as the sliding pointer instead of one
cut out of card as suggested in the
instruction leaflet I also dispensed
with the card arrow and indicator to
show when the steel yard is level as I
thought this spoilt the look of the
scales and was not in any case
needed.
Page published November 23 2017 revised October 15 2023
Click on images to enlarge.
The model made a fresh appearance in the
October 1947 Meccano Magazine being described
as our “New model of the month.” This was a
revised version using flexible plates to fill in the
frame work but much of the model remained
much the same. The instructions though lack the
detail or print clarity of the original SML publication.
In July1962 the Meccano Magazine returned to
this model reproducing in full the illustrations from
SML No.7 with slightly amended text no mention
was made of its historic origins. Shown on the right
1947 version above