GB2257381A

GB2257381A - Arbor for hole saw.

Info

Publication number: GB2257381A
Application number: GB9213505A
Authority: GB
Inventors: John Rex Redman
Original assignee: ELDON TOOL Co Ltd
Current assignee: ELDON TOOL Co Ltd
Priority date: 1991-07-09
Filing date: 1992-06-25
Publication date: 1993-01-13
Also published as: GB9213505D0

Abstract

The arbor includes a spindle (10) with a screwthreaded end length (14) for threaded engagement in a screwthreaded hole (32) in a carrier plate part of the hole saw (26). So that the hole saw does not become tightly locked in position on the arbor, means provided for drivably connecting the hole saw to said spindle include at least one drive pin (34) extending through a clearance hole (36) in a fixed collar (18) and engaging a hole (38) in the carrier plate part of the hole saw. The drive pin (34) is carried by a collar (40) which is slidably mounted on a portion of the spindle (10), said collar being acted on by a coil compression spring (42) reacting against a washer (44) backed by a circlip (not shown). <IMAGE>

Description

Arbor for hole saw The invention relates to an arbor for a hole saw.

Hole saws are generally provided in sets for machining relatively large holes, that is to say holes of between 32 m.m. and 152 m.m. in diameter.

They are of particular use to plumbers and other workmen for machining access holes through, for example, plywood and blockboard panels or through floor boarding when installing lengths of pipework.

They are usually used in a pistol type electric drill. A hole saw of a selected size is connected to an arbor which can be held in the chuck of the electric drill, the arbor having a conventional twist drill extending axially therefrom. The twist drill acts as a steady for the hole saw by drilling a pilot hole in advance of said hole saw which is of hollow cylindrical shape with saw teeth at a projecting end thereof.

A conventional arbor for a hole saw has a screwthreaded spindle on which an end plate of the hole saw can be threaded to abut against a fixed shoulder. A particular problem with an arbor of this form is that, during use, the hole saw can become very tightly locked in position on the arbor so that, if the user wishes to change the hole saw for one of a different size, he may waste a considerable amount of time in trying to unscrew it from the arbor. Various attempts have been made to avoid this problem, for example by the fitment of a locknut which can be released by using a spanner, but even this is time consuming and not always a complete answer to the problem. The invention has for its object to provide an arbor for a hole saw by means of which this problem will be at least alleviated.

According to the invention, there is provided an arbor for a hole saw, the arbor including a spindle having an integral radially projecting member to one side of a screwthreaded end length for threaded engagement in a screwthreaded hole in a carrier plate part of the hole saw, means for a driving connection between the arbor and the carrier plate comprising at least one drive pin extending through a clearance hole in the integral radially projecting member for engagement with a hole in said carrier plate part of said hole saw.

The at least one drive pin may be carried by a collar slidably mounted on a plain cylindrical portion of the spindle and said collar may be acted on by a coil compression spring urging said at least one drive pin towards engagement with the hole in the carier plate part of the hole saw.

The means whereby the hole saw can be drivably connected to the arbor may be constituted by a pair of drive pins extending through respective clearance holes in said fixed collar, the carrier plate part of the hole saw having at least one pair of holes in which said pair of drive pins can be engaged.

A resilient washer may be located against the integral radially projecting member to one side of the screwthreaded end length of the spindle.

The screwthreaded end of the spindle may be provided with a bore for the reception of the shank of a drill, clamping screw means being provided for holding said twist drill captive.

In order that the invention may be fully understood and readily carried into effect, the same will now be described, by way of example only, with reference to the accompanying drawings, of which: Figure 1 is an exploded partly sectioned perspective view of the components of an arbor embodying the invention, and Figures 2 and 3 are views which illustate the steps in the assembly of the components.

Referring now to the drawings, the arbor there illustrated includes a spindle, generally indicated 10 provided at one end with a hexagonal drive shaft portion 12 which can be fitted in a drill chuck.

At its other end the spindle is provided with a screwthreaded length 14 which terminates in an integral radially projecting member, that is to say a shoulder 16 of a fixed collar 18. The screwthreaded end of the spindle is provided with a blind bore 20 for the reception of the shank of a conventional twist drill 22, this being capable of being held captive within the bore 20 by means of a grub screw 24.

One of a selection of hole saws of different sizes is indicated 26 in Figure 1. The hole saw is of hollow cylindrical shape with teeth 28 at a projecting end thereof and a carrier plate 30 at the other. The carrier plate has a central screwthreaded hole 32 whereby it can be threaded onto the screwthreaded length 14 of the spindle.

Means whereby the hole saw can be drivably connected to the arbor before the carrier plate, in being threaded onto the screwthreaded length 14 of the spindle, abuts against the shoulder 16, are constituted by a pair of drive pins 34,34 extending through clearance holes 36,36 in the fixed collar 18 and capable of being engaged with respective holes 38,38 in the carrier plate of the hole saw.

The drive pins 34,34 are carried by a collar 40 which is slidably mounted on a plain cylindrical portion of the spindle, said collar being acted on by a coil compression spring 42 reacting against a washer 44 backed by a circlip (not shown) located in a groove in said spindle, the spring urging the drive pins towards engagement with the holes in the carrier plate of the hole saw.

The arrangement is such that, as the hole saw is being threaded onto the screwthreaded length 14 of the spindle, the drive pins can be retracted by sliding the collar 40 against the force of the spring 42 as shown in Figure 2. The drive pins can be retracted so that their free ends do not protrude from the shoulder 16 of the fixed collar 18. Consequently, the hole saw can be threaded fully onto the screwthreaded length 14 of the spindle until it lightly abuts against the shoulder From that position the hole saw can be slightly backed off, away from said shoulder, through a distance of less than half a turn, to enable the drive pins to be advanced to engage the holes 38,38 in the carrier plate, as shown in Figure 3.

Thus there is provided an arbor for a hole saw which even after long use will not become tightly locked to the hole saw being used; a different size of hole saw will always be able to be fitted to it in a bare minimum of time. However. various modifications may be made. For example, the collar 40 could be provided with any convenient number of drive pins 34. The hole saws may each be provided with a plurality of holes 38 so that, in being connected to the arbor they do not require backing off very much, if at all, from the shoulder 16 when having been brought lightly against the shoulder.

A resilient washer placed against the shoulder 16 could provide a very light abutment pressure from which a further very small rotation could produce a very slightly increased, but still relatively light, abutment pressure to allow the engagement of the drive pins in the holes of the carrier plate of the hole saw.

Claims

CLAIMS:

1. An arbor for a hole saw, the arbor including a spindle having an integral radially projecting member to one side of a screwthreaded end length for threaded engagement in a screwthreaded hole in a carrier plate part of the hole saw, means for a driving connection between the arbor and the carrier plate comprising at least one drive pin extending through a clearance hole in the integral radially projecting member for engagement with a hole in said carrier plate part of said hole saw.

2. An arbor according to claim 1, in which the at least one drive pin is carried by a collar slidably mounted on a cylindrical portion of the spindle.

3. An arbor according to claim 2, in which the collar carrying the at least one drive pin is acted on by a coil compression spring urging said at least one drive pin towards engagement with the hole in the carrier plate part of the hole saw.

4. An arbor according to any one of the preceding claims, in which the means whereby the hole saw can be drivably connected to the arbor are constituted by a pair of drive pins extending through respective clearance holes in said fixed collar, the carrier plate part of the hole saw having at least one pair of holes in which said pair of drive pins can be engaged.

5. An arbor according to any one of the preceding claims, in which a resilient washer is located against the integral radially projecting member to one side of the screwthreaded end length of the spindle.

6. An arbor according to any one of the preceding claims, in which the screwthreaded end of the spindle is provided with a bore for the reception of the shank of a drill, clamping screw means being provided for holding said twist drill captive.

7. An arbor for a hole saw, said arbor being constructed, arranged and adapted to be used substantially as hereinbefore described with reference to and as illustated by the accompanying drawings.