Improvements in Electric Soldering Irons.
Year: 1891

page_text: COMPLETE SPECIFICATION.
Improvements in Electric Soldering Irons.
I, WILLIS MITCHELL, of Malden, in the County of Middlesex, and State of
Massachusetts, United States of North America, Electrician, do hereby declare
the nature of my invention and in what manner the same is to be performed
to be particularly described and ascertained in and by the following statement
and accompanying drawing, that-is to say:—
The object of this invention is to provide an-improved soldering iron, heated by
electricity, the same being compact and easily handled, yet having the wires coiled
in successive concentric insulated layers, which are located in a hollow shell at or
near the point, the electric connections being all internal and protected.
In the accompanying drawings,
Figure 1 represents a side elevation of a soldering iron-embodying my invention;
Figure 2 represents a longitudinal section of the same;
Figure 3 represents in detail perspective the point and the screw-threaded part to
which it is normally attached, the two being shown slightly separated;
Figure 4 represents a detail rear elevation of the hollow point;
Figure 5 represents the heating coils and insulating strips in detail perspective;
and
may
Its
be
Figure 6 represents the casing for enclosing and protecting the same.
A designates the handle of the tool having a central longitudinal passage a.
B designates a tubular stem set into the forward end of this
C designates
passage.
a metallic stiffening and connecting rod attached to said handle within said passage
and extending forward through the same and through said tubular stem.
forward end fits into a recess d'in the rear end of a stem or rod D; which
solid, as shown, or tubular, and is aligned with the tubular stem B so as to constitute
in effect an extension thereof. The contiguous ends of the said parts C and D may
be welded or otherwise permanently secured together as indicated, or screw-
threaded and thus: fastened if preferred. The other end of rod D has a screw D¹
formed on it, which is adapted to take into a screw-tapped recess e in the tip of the
hollow point E, the screw entering said recess from within said point. The corners
at the base of the latter are provided with eyes e¹ corresponding in position to eyes
or holes in a flat front plate F', formed with or rigidly attached to a cylindrical
casing F, which is sleeved on the rod or stem D. The office of this casing is to
enclose the wire coils or helices G, which are wound concentrically about said stem
or rod with strips of slate or other insulating material H between them. These
coils or helices are continuous, being formed by winding a single wire first about
the rod D, then back outside of a row or layer of said insulating strips, then
forward again outside of another layer of them and so on until a sufficient number
of helices have thus been formed, one outside of another. This winding practically
forms a heating cylinder, which is in an electric circuit, the wire being led backward
from it in two parallel lines which are insulated from each other and enclosed in a
cord I. This cord is carried back through the tubular part B and the handle A, it
being side by side with the rod C. Thus all parts of the wire are enclosed in the
soldering iron except from the point where it extends out in cord I at the rear end
of the handle A and thence to the source of electricity.
The operation is as follows: The current of electricity passing about the rod D
near the point E in the successive coils or helices G will generate sufficient heat,
owing to the resistance of the wire and perhaps to other and less familiar causes to
raise the temperature of the point E sufficiently for soldering. The iron is then
med like any other tool of the same general kind.
The wire of the coils or helices G is wound so as to leave a slight interval

page_text: between each two, thus preventing short circuiting and securing the best results
whether the wire be coated with insulating material or not. I prefer to have it
naked, as shown,
"
.
Having thus described my invention, what I claim as new and desire to secure by
Letters Patent is :
1st. In an electric soldering iron, the combination of a wire forming part of an
electric circuit and wound in concentric helices which are separated by strips of
insulating material with an enclosing casing for said helices and a soldering point
in proximity thereto so as to be heated thereby substantially as set forth.
.
2nd. In combination with handle A having passage a, the tubular stem B fitted
into said passage, the rod or stem D in alignment therewith, a fastening for said
parts B, D, a casing F sleeved on said rod D, a heating cylinder composed of coils
or hélices of wire wound on insulating material and arranged within said casing,
and a cord enclosing the wire leading from the beginning and end of said cylinder,
the said cord extending out through said tool so that all parts of the wire are
⚫protected and the said wire being made to form part of an electric circuit for the
purpose set forth.
3rd. A wire forming part of an electric circuit and wound into a series of helices
constituting a heating cylinder, in combination with a soldering iron constructed
with tubular parts enclosing the said wire, and a central rod connected to the point
and the handle, substantially as set forth.
4th. In combination with the casing F having a front plate F¹, an electric heater
enclosed in the said casing, a point E bolted to said plate and internally screw-
tapped as shown, a rod screwed into said head, a handle, connections between said
handle and rod, and wires running from said heater to a source of electricity,
substantially as set forth.
Dated this Eleventh day of September
EDWARDS & Co.,
35, Southampton Buildings, London, Agents for the Applicant.