A NEW OR IMPROVED UNIVERSAL MANDREL
Year: 1872

page_text: PROVISIONAL SPECIFICATION left by Egmont Feldtmann at the
Office of the Commissioners of Patents, with his Petition, on the
6th April 1872.-A communication from abroad by Nicolas Bolonin,
of St. Potersburg, in the Empire of Russia, a Second Captain of
the Horse Artillery of the Imperial Guard of Russia.
I, EGMONT FELDTMANN, of No. 16, Mark Lane, in the City of London,
Merchant, do hereby declare the nature of the said Invention for "A
NEW OR IMPROVED UNIVERSAL MANDREL," a communication from Nicolas
Bolonin, of St. Petersburg, in the Empire of Russia, a Second Captain
of the Horse Artillery of the Imperial Guard of Russia, to be as
follows:-
The object of this Invention will be best understood by the follow-
ing preliminary statement: In the different kinds of work to be
executed in turning cases occur in which the use of centres is insuffi-
cient. In such cases the parts to be turned must, instead, be fixed by
means of set pieces and universal mandrels which form a complicated
system. Amongst these latter the preference is given to such as offer
the best means of quickly and accurately fixing in their places objects of
different external diameters, as this condition is intimately connected
with the quantity of work done in turning within a given time, and'
consequently with the price returned, which is all the more profitable as
the means employed to execute the work are the more perfect.
.

page_text: Let us suppose, for example, that a system of mandrels for a lathe has
been found out that gives a quick travel at the cheapest rate, it is
evident that these qualities apply only to the lathe system under con-
sideration; but on the contrary let a given system of mandrels be
applied to any kind of lathe, it is clear that its importance and good
qualities must attain a far superior grade to that of the preceding case.
In other words the system discovered would satisfy the terms of the
formula, that the more the use of an object is general so much more
are its qualities superior.
The new system in contradistinction to the old ones can be applied
not only to turning but to drilling, and be made to take drills of any
possible diameter. This mandrel is composed of a body of iron having
three cavities in which are placed three steel dies hardened and tempered,
on each side of which are projections placed at a certain angle with
the shaft of the whole system. Slots on the sides of the recesses in the
body of the mandrel serve as guides for the projections on sides of the
dies. The lower surfaces of the dies are parallel to the mandrel shaft.
Two bolts as also the projections of the dies bring them either closer to
or further from the centre of mandrel shaft. These bolts produce a
pressure on the upper and projecting sides of the dies, and oblige them
to move in such a way that they either approach or retreat from one
another. It is understood, then, when one of these bolts is at work the
other must not cause a pressure on the dies, that is to say, that inas-
much as one of the bolts gives an advance motion the other must
unscrew itself to go in the same direction; this operation is easily and
quickly performed. To exert a strong pressure of the dies on the
surface of the pieces, or otherwise to disengage them from the mandrel,
a key or cotter is used, the projecting part of which enters the aperture
corresponding to the bolt,
:
To each of the mandrels two systems of dies can be adapted, one for
very small diameters the other for the largest. In the lathe mandrels
the first series of dies allows the fixing of pieces differing in their exterior
diameters from one-eighth to three-quarters of an inch, the second from
three-quarters to one and a quarter inches.
In the drilling machine mandrels with the first series of dies holes
can be drilled of from one-sixteenth to seven-sixteenths of an inch
diameter, and with the second of from seven-sixteenths to three-quarters
of an inch diameter.