US1072543A

US1072543A - Countersink attachment for bits.

Info

Publication number: US1072543A
Application number: US57500510A
Authority: US
Inventors: John Whyte
Original assignee: Individual
Current assignee: Individual
Priority date: 1910-08-01
Filing date: 1910-08-01
Publication date: 1913-09-09
Anticipated expiration: 1930-09-09

Description

COUNTERSINK ATTACHMENT FOR BITS.

Specification of Letters Patent.

Patented Sept. 9, 1913.

Application filed August 1, 1910. Serial No. 575,005.

To all *wh0mit may concern:

Be it known that I, JOHN WI-IY'IE, a citizen of the United States, residing at Everett, State of Washington, have invented a new and useful Improvement in Counter- The object of my invention is, in general,

to improve and simplify such devices, and

in particular to provide a device of this character which will do smooth work without roughening or breaking the wood, and one also which will have sufficient resistance by the time it has made the desired depth of countersink, that it will overhaul the bit, that is, free the screw which serves to draw the bit into the wood.

In the drawings I have shown my invention in the form which is now preferred by me.

Figure 1 is an elevation or side view of my device. Fig. is an end view of the cutting end of the form of my device shown in Fig. 1. Figs. 3 and 4c are like views of my device having a modified form of cutting teeth.

In the countersunk attachments which have heretofore been generally employed,

one of the most serious objections is their tendency to roughen the surface of the board outside of the countersunk area. Another principal objection is that they will not, with certainty, free the bit from its in-drawing tendency, and, therefore, the bit and its attached countersink will keep on boring into the wood, and the countersunk area will often be made larger or deeper than is intended or desired. The result is invariably, countersinks of varying size and depth.

The common countersinks quite generally have their teeth so shaped that they are very small or almost reduced to nothing at the margin of the central bore which receives the bit.

It is one of my objects to so shape the teeth that they will have a pronounced tooth shape at this inner margin, whereby they will cleanly out the borings produced by the bit as well as cut the wood within the area of the countersink; this shape is clearly shown in Figs. 1 and 3. In these two figures no attempt has been made to show the outline of any teeth which lie in the rearmost half of the device, for to do so would complicate the drawing. thus be considered as being an elevation of the outer side of one half of the device, the plane of out being a central longitudinal one.

The device consists of a tubular body adapted to fit over a bit provided with cutting teeth upon one end which is beveled and forms the countersink. It is also provided with a set screw or other convenient means for securing it in place upon the bit,

The cylindrical body 1 has a central bore 10 of such size as, to fit over a bit of the size with which it is intended to use it. The lower or cutting end is beveled to form a cone having the same angle as that desired for the sides of the countersink. "in this conical end are formed the cutting teeth, these extending with their akes substantially parallel with the outer surf-aces of the cone. The outline shape of these teeth may be varied somewhat. have found that the best results are obtained when their depth is relatively considerable, and also prefer These figures may that their surfaces beat unequal angles for one side, '31, which is the advancing side of the teeth, at rather a sharp angle, approach- Ling a perpendicular to the plane, of reV.0l1ition. {The opposite side -30 is at a much flatter angle. This form makes of each tooth a chisel which will smoothly and cleanly out the wood, avoiding splintering or breaking out of particles extending byond the margin of the countersink.

I prefer that the straight sides of the body 1 be provided with channels 2 in line with the channels 3 in the conical end. These I have herein shown as having their sides at equal angles. Above the grooved or channeled sides I bore and thread the wall and insert a set screw 5, by which the device may be secured in place upon a bit.

In Figs. 3 and 4; I have shown a modified form of construction, the modification consisting in making the toothed end with two different slopes or cones, a cone 6 of sharper angle being interposed between the terminal cone and the cylindrical portion 1. This ingrooves 2. This modification is of value where it is desired to countersink to such depth that the head of the screw will be suf ficiently beneath the surface to perihit the insertion of a wooden plug, thereby the screw head. The upper cone 6 fornis a smooth walled recess of truly 1otat1ve surface, for which plugs may be made which tion above, being the cylindrical body section of Fig. 1 and the cone fru st1im 6 pf Fig. 3, the bottom of the channels 8 in the tip section extend upward into one; face of the section above, as is clearly seen in Figs. 1 and 3. The under side of the face thus formed at the lower end of the upper groove creates a, stop which, byimpeding the free escape of the cuttings, prevents further entrance of the bit or countersink into the wood.

I have found that a countersink having the form of teeth shown will out freely until it reaches a certain depth corresponding to that desired for the countersink, and will by this time pro1duce'a resistance or backward pull upon the bit sufficient to relieve or free the indrawing screw of the bit from its hold upon the wood, ,thus stopping the advance of the bit into the wood. It thus acts, a stop to limit the depth of the hole made by the bit.

What I claim as my invention is 1. Acount ei-sink for wood havinga ,coned 77 end provided with teeth having their advancing face at a relatively greater1'angle to the face of the countersink than their other face; the section of the countersink next above said coned end being toothed with the "outer points of the teeth matching 'w 'i'th the points of the cutting teeth of the coiie'cl end, the two faces of these upper teeth 'beingof,substantially like angle, the bottom angles of the teeth upon said coned end eX- tending into one face of the teeth above to form a shoulder. A v

ou ntersinl a r its cutc'el1edjand provided with teeth disposed. in two :Sec'ti01ll those in the section 11l3t-,tl1 n(l h ihg z rh'1a with their or cutting face maki ng a relatively sharp angle with the surface the countersink the teeth. upon the section adjoining having their a vancing face at a relatively flatter: angle with the surface "of the countersink, eurfa'ces of the teeth in both sec-' tions continuing as planes to intersections forming shoulders. I v 3 countersink attachment for bits havii1g its formed as two frustuins of cones, the end frustun1 having a greater angle with the axis than the section therefrom, bot-h sections bei1 1g provided with teeth having coincident outer edges, the teeth upon the end frustu n having their advancing face at a relatively shar per v a than those upon th e inner fru s tuin-,a1i with the inner end of this face extending into a side of a tooth of the section above.

v JOHN WHYIE. Witnesses S .1I ER D D. MIDISEKE.