Improvements in Twist Nails, Spikes, or Screws.
Year: 1886

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1.
Improvements in Twist Nails, Spikes, or Screws.
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I, THOMAS WALROND SMITH, of No. 5 Scarth Road, Barnes Common in the County
of Surrey, Civil Engineer, do hereby declare the nature of this invention to be as
follows
and
My invention relates to nails, spikes or screws which are twisted, and when driven
by a hammer are caused to rotate. I make such nails spikes or screws of metal of a
section which has two, three or more wings or ribs radiating from the centre where
there may be a circular core or not. By sloping the end of each rib backwards wholly
or in part, give it an edge such that, when the nail, spike or screw is driven into
wood or other comparatively soft material; the reaction of the material on the slope of
each edge causes or aids in causing the nail, spike or screw to rotate.
The slope of the edge may be uniform or varying as it recedes from the centre.
The front part of the edge may be square to the axis of the nail or spike or at an angle
with it, or curved. The part near the axis may be advanced or retired whilst there
may be a céntral projecting cone or not. The head may be of any form convenient
for driving or unscrewing.
Nails spikes or screws constructed as described can be driven by hammer causing
very little disturbance of the material, so that it is generally unnecessary to bore holes
for them.

page_text: I, THOMAS WALROND SMITH of No. 5 Scarth Road, Barnes Common in the County
of Surrey, Civil Engineer do hereby declare the nature of this invention and in what
manner the same is to be performed to be particularly described and ascertained in and
by the following statement :-
My invention relates to nails, spikes or screws which are twisted, and when driven
by a hammer are caused to rotate. I make such nails spikes or screws of metal of
a section which has two, three or more wings or ribs radiating from the centre where
there may be a circular core or not. By sloping the end of each rib backwards wholly
or in part, I give it an edge, such that, when the nail, spike or screw is driven into
wood or other comparatively soft material, the reaction of the material on the slope of
each edge causes or aids in causing the nail, spike or screw to rotate.
The slope of the edge may be uniform or varying as it recedes from the centre.
The front part of the edge may be square to the axis of the nail or spike or at an angle
with it or curved. The part near the axis may be advanced or retired, while there
may be a central projecting cone or point or not. The head may be of any form
convenient for driving or unscrewing.
Nails, spikes or screws constructed as described can be driven by a hammer, causing
very little disturbance of the material, so that it is generally unnecessary to bore holes
for them.
Fig. 1 shews in plan the general form of the metal bars which are to be twisted to
form twist nails, spikes or screws. The wings or ribs, two, three or more in number
radiate from a common centre and in some cases have a middle core as indicated by
the dotted circle a¹. The cutting edges are sloped backwards as from a to b either
wholly or in part so that when driven by a hammer or by pressure into any firm but
comparatively soft substance or material the reaction on these inclined surfaces causes
the implement to rotate, the advance due to the blow and the rotation due to the
reaction, being preferably made to correspond with the helical curve of the twist so
that the edges will cut out the exact form of groove for the twisted ribs or wings to
fit into.
The slope is sometimes uniform and sometimes varied as it approaches the centre.
A simple and effective section of bar is shewn in Fig. 2 which is a rectangle where
the width is considerably greater than the thickness, preferably three or four times
greater.
Figs. 3, 4 and 5 shew one form of edge, here illustrated for a section with two

page_text: radiating ribs or wings; c is part of a central cylinder of the same diameter as the
thickness of metal, terminated by a projecting cone or point or, if of a greater
thickness, it forms a core as shewn by dotted lines. A preferable method of varying
the slope of the cutting edges is illustrated in Fig. 6 where the slope at the outer
extremity d of the edge has half the ratio to the horizontal that the slope at e has when
the latter is situated half way towards the centre (see Fig. 5) and so in proportion
for the slopes at other points in the edge. In this way there is no drag on any
part of the edge as the combined advance and rotation correspond with the helical
curve of the twist at all points in the width of the wings or ribs.
Fig. 7 shews the same principle of edge as applied to a bar with two wings or ribs
but with the middle portion advanced to enable it to cut its way more readily owing to
the inclination of the edge.
Figs. 8 and 9 show a form of edge for two wings or ribs when there is no central
point, but the middle part is advanced and each edge sloped backwards, its front being
either straight or curved, and the back being either parallel to the front or inclined to
it as shown.
Figs. 10, 11 and 12 shew a modification of the edge for two wings or ribs when the
middle part of the edge is advanced or tapered both as regards its thickness as well as
its width, the edges being also sloped backwards from opposite corners.
Figs. 13 and 14 shew an edge for two wings or ribs with each half sloped uniformly
in opposite ways being an easy form to cut but not theoretically correct.
Figs. 15 and 16 show a modification of the last named figures when the middle
part is retired, the edges being also sloped backwards.
Figs. 17, 18, and 19 shew a form of edge, easy to cut, but not theoretically correct
and made by sloping the edges backwards from opposite corners.
Figs. 20 and 21 shew one form of the invention for driving into wood.
For small sizes they are made say 1 to 1 inches long of an inch wide and
about of an inch thick and twisted with from one to two complete turns in the
length.
Fig. 22 shews a modification of the form for penetrating earth, clay or chalk
where the width tapers downwards.
Figs. 3, 4, 5, and 7, shew the edges as they appear when the bar is twisted.
Figs. 6, and 8 to 19 inclusive shew the edges as they appear when the bar is
not twisted.
The edges are formed sometimes before and sometimes after twisting and may be
made by cutting or filing. The blanks may be twisted by hand or machine, and
when either hot or cold.
In the figures 3 to 7 and 10 to 12 illustrating the forms of edge two wings or
ribs are shewn but three or more may be used as explained with reference to Fig. 1.
Any metal or alloy may be used but preferably iron or steel. The implements are
driven by blows from a hammer or similar means and do not in general require a
hole to be bored; they may have any form of head suitable for driving or withdrawing
by unscrewing.
By this invention I find the implement cuts its way more easily when used with
wood so that it is less liable to lose its form under hammer blows, and also permits
of its being made with a sharper twist, thereby increasing its holding power.
Having now particularly described and ascertained the nature of this invention and
in what manner the same is to be performed I declare that what I claim is:
1. An improved manufacture of twist nails, spikes, or screws wherein the lower
edges of the wings or ribs are sloped backwards so as to cause rotation in the direction
of the twist, substantially as herein described.
2. Constructing twist nails, spikes or screws with sloped lower edges and a central
projecting point formed substantially as herein describel with reference to Figs. 3, 4
and 5, and to fig. 7 respectively.
3. Constructing twist nails, spikes, or screws with lower edges with varying slopes
substantially as herein described with reference to Fig. 6.

page_text: 4. Constructing twist nails, spikes or screws, with sloped lower, edges formed
substantially as herein described with reference to Figs. 8 and 9, and, to figs., 10, 11
and. 12 respectively. J.
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5. Constructing twist nails, spikes, or screws with sloped, lower edges formed
substantially as herein described. with reference, to: Figs. 13 and 14, and to Figs. 15
and 16 respectively. (
7.6.Constructing twist nails, spikes or, screws with, sloped. lower edges formed
substantially as herein described with reference to Figs. 17, 18, and 19.
Dated this 12th day of July 1887.
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ABEL & IMRAY,
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of bolni no LONDON Printed by DARLING AND SON.
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For Her Majesty's Stationery Office.
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144
1887.
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