Improvements in Dovetailing Machines.
Year: 1893

page_text: COMPLETE SPECIFICATION.
Improvements in Dovetailing Machines.
A communication from HERMANN FARCHMIN, of Gera, in the Empire of Germany,
Sculptor.
I, ALFRED JULIUS BOULT of 323 High Holborn in the County of Middlesex,
Chartered Patent Agent do hereby declare the nature of this invention and in
what manner the same is to be performed, to be particularly described and ascer-
tained in and by the following statement :—
The present invention has for its object to produce the saw-cuts which are
necessary for obtaining dovetails, in several boards at the same time which boards
are employed for manufacturing chests and boxes and the like with dovetailed
edges.
о
As manual labour can only be performed by skilled workmen while these
machines can be run by comparatively unskilled men much time and money will be
saved by using the new machine.
The machine which in its structure resembles a circular sawing machine is
provided with a horizontal shaft with removable cutting-tools (such as circular
saws, shaping discs, rabbet-saws) and with an adjustable table on which the work-
pieces which are put into clamps are reciprocated across the cutting-tools by means
of a guide. Two sets of cutting-tools are employed. In one set the tools are all
of the same diameter while in the other set the diameter of each succeeding shaping
disc or saw increases. The first set is employed when the table is worked parallel
to the shaft and incisions of equal depth are to be made, which enter the board
parallel to its axis but obliquely to its broad surface or face (see Figs. 8 and 9)
and take away what has been left between two of the oblique cuts (Fig. 7). The
second set serves for making grooves perpendicular to the face of the board but
oblique to its axis, (Figs. 5 and 6). In this case the table is obliquely adjusted
and the tools of different size make it possible to get incisions of equal depth.
There is a third form of incision, though it would be of no use in the common
dovetail joints viz. incisions which enter the board obliquely to both its axis and its
face. Also these incisions may be made by this machine, as it would be only
necessary to adjust the table obliquely as in Figure 5 and conduct the boards
obliquely across the cutting-tools as in Figure 8.
Figures 1-3 represent the machine with the device for putting the boards into
the frame and for guiding them.
Figure 1 is a front view partially in section.
Figure 2 is a side view partially in section.
Figure 3 is a plan.
In Figures 1 and 2 the table is obliquely adjusted.
I is the shaft which is carried in bearings 2 and 3, the journal carried by 3 is
less in diameter than the other part of the shaft so that the latter can easily be
removed towards the right hand in Figure 2. The cutting tools or saws 4 are
arranged side by side on the shaft I each tool being separated from the others by
collars 5; at one end the tools are held in place by an adjusting collar 6 and they
are adjusted with the intermediate collars 5 on the shaft by a nut 20 screwed on
the shaft. In this manner the tools of unequal size (Figures 1-3, 5 and 6) can
easily be removed and the tools of equal size (Figures 7-9) put in their place.
Care should be taken that by arranging thicker or thinner intermediate collars 5
the right distance between the shaping discs is always kept. It might be more
convenient to arrange the sets of tools at predetermined distances on a sleeve which
would be put on the shaft I so that only the sleeves need be removed when a new
set of tools is required.

page_text: The set of shaping discs of unequal diameter is of course only suitable for a
certain oblique position of the plate, but this will commonly be sufficient; in the
other case it is of course necessary to have two sets of discs. The cutting surfaces
of the tools of unequal size must, corresponding with the oblique position of the
board, be at an angle with the shaft (see Figure 11) which shows above the shaft
one of the shaping discs 4 of a set of unequal diameter and below it one of the
shaping discs 4 of a set of eqnal diameter.
The table 7 is provided at its under side with recesses which are entered by
screws 8 in such a manner that the table can not only be raised and lowered but
also adjusted obliquely to the shaft I. By the first adjustment the depth of the
cut is regulated; the second adjustment serves for regulating the obliqueness of
the cut according to Figures 5 and 6. Slotted quadrants 9 which are jointed to
the table 7 and wing-nutted screws 10 serve to fix the table in the required position.
The tools pass through openings in the table which when desired may be composed
of a series of bars or a grid so that narrow slits for the shaping discs are formed.
At this place it may be mentioned that the machine can also be employed as a
circular saw, in which case the opening in the table is covered in such a manner
that only a narrow slit for the saw-blade 11 is left (Figure 10).
The boards are put into a frame and guided in the following manner;-
12 (Figures 1-4) are long screw-clamps, into which several boards 13 to be cut
are put. Two pairs of such screw clamps are employed in such a manner that
each clamp is situated opposite the other in the same plane. The back of each
clamp is provided with a planed rib 14 which is preferably of a dovetailed cross
section (see Figure 2). By means of these ribs the clamps are guided in grooves
in the supports 15 which can be reciprocated on the table 7 and can be adjusted
by screws guided in slits 18. The boards 13 can be put into the clamps
rectangularly or obliquely to the back of the clamps 12 (Figures 3 and 4). It is
necessary to put them obliquely into the clamps when the boards are to be
conducted obliquely across the tools (Figures 8 and 9). In this case wedge-
pieces 19 are employed one of which is arranged in one corner of the clamps 121
while the other is operated by the set-screw.
The mode of operation of the machine is as follows;-
'A number of boards are screwed together by means of the screw-clamps 12, the
table 7 is obliquely adjusted and a set of tools 4 of unequal size is put on the
shaft I. The boards by means of the clamps 12 guided in the supports 15, are
then in the manner shown in Figures 5 and 6, moved twice across the tools, first
one end of the boards and then the other. By thus operating the cuts shown in
Figure. 6 are obtained. Then the tools of unequal size are removed and the tools
of equal size put in their place, and the table 7 is put straight. The boards are
then first guided in a straight line across the tools so that the latter take away the
material which has been left between the two cuts when broad incisions are made.
Then the boards which are to be joined to those operated upon as last described
are obliquely put into the clamps in the manner shown in Figure 4 and twice
guided across the tools as shown in Figures 8 and 9. Thus are obtained dovetails
which exactly fit each other.
Having now particularly described and ascertained the nature of the said inven-
tion as communicated to me by my foreign correspondent, and in what manner the
same is to be performed, I declare that what I claim is ;-
1. A machine for simultaneously making dovetails in several boards characterized
by a shaft I with removable cutting tools or saws 4 and a table 7 adjustable with 5
respect to the shaft on which table the boards put into screw-clamps are reciprocated
aeross the tools substantially as described and illustrated in the accompanying
drawings.
2. In combination with the machine characterized in Claim 1 a device for
clamping and guiding the boards in which a frame composed of two pairs of screw- 5
clamps such as 12 can be reciprocated in the guiding grooves of two supports I5

page_text: adjustable on the table 7 in which clamping device an oblique clamping of the
boards is made possible by putting wedge-pieces 19 into the corners of the clamps
the wedge-pieces determining the obliqueness of the boards.
3. The combination and arrangement of parts constituting the complete dove-
tailing apparatus substantially as described and illustrated in the accompanying
drawings.
Dated this 24th day of Max 1802
W. P. THOMPSON & BOULT,
Of London, Nottingham, Liverpool and Manchester,
Agents for the Applicant.