GB2177959A - Helical guide machine tool attachment - Google Patents

Abstract

A machine tool attachment for marking and feeding an elongate workpiece onto a cutter blade of a router, lathe, drill, spindle moulder or any suitable machine or tool designed for cutting grooves in wood or similar materials in order to form helical grooves therein comprises an angled blade 12 which causes the workpiece to rotate in predetermined relationship with axial movement of the workpiece through the attachment. The workpiece maybe passed through the attachment a number of times until the desired number of helical cuts have been made. By using different cutter blades in the chosen machine, set at different depths, any number of designs may be made on the workpiece. By altering the angle of the blade 12 helical grooves of a different pitch can be marked and cut. Both left and right hand grooves may be cut if an adjustable blade holder is used. <IMAGE>

Description

SPECIFICATION Spiral guide machine tool attachment The invention relates to a machine tool attachment, in particular for attachment to a wood-working machine.

There are many instances where it is required to mark out and cut a helectical groove (spiral) in a workpiece. For example when producing ornate bedposts with helectical grooves cut into them to give a twisted appearance, orfor plant stands and other household furniture. The old way doing this was to markoutand cutthegrooves byhand, orto usevery expensive lathes with screw cutting capabilities.

According to the present invention, an attachment for a machine tool comprises of an elongate hollow bodywith meansforclampingastraightbladeele- ment at an angle to the longditudinal axis ofthe body.

The arrangement is such that when the attachment has been mounted on a machine tool an elongate workpiece can be passed through the hollow body, with its periphery in contact with the blade element, so that the workpiece is caused to rotate in timed relation to the rate of travel of the workpiecethrough the hollow body. It will be understood that what is required is relative movementoftheworkpiece, longditudinally, of the hollow body. Consequently, when the attachment has been mounted on the machine the attachment may be moved longditudinally, (by being mounted on a sliding saddle arrangement for example) or, alternatively, the attachment may be heldandtheworkpiececausedto be moved axially.

Theresultantlongditudinal movement causes the workpiece to be fed on to the machine cutters spirally, producing a helectical cut in the workpiece.

The elongate hollow body may be a tube in which the workpiece is rotatable. Alternatively, it may be in the form of an open-ended box provided with long ditudinallyspaced sets of rollers in which thework piece can rotate. Each set of rollers will, preferably, comprise of a pair of fixed rollers on whichthework- piece can rest, and a pair of rollers carried by a sliding plate capable of being located in a slot in the body.

There are numerous ways ofsubstituting the elongate hollow body. It will be sufficient to statethatany method of holding the workpiece so that it is restricted from lateral movement and is caused to come into contact with the blade element, whilst at the sametimeallowingtheworkpieceto rotate axially and travel longditudinally through the elongate body, as previously described, will suffice. Afew examples ofsubstitutesforthe elongate hollow body are ill ustrated in figures 7 to 12. Figure 8 shows blade element 12 lowered from normal operating position. The nor mal operating position of blade element 12 is to be located in one ofthefourslots in 31 figure 7.

The main object of the machine tool attachment is to both markout and feed that mark on theworkpiece onto the cutting tool of the machine so that a groove, orfancy profile, may be cut helically around the periphery of the workpiece. One or more passes of the workpiece through the attachment starting atdifferent settings around the circumference enable a largevarietyofdifferentdesignsto be cut around the workpiece. Figures 10 to 14 show drawings embody- ing the invention, by way of example only, of how by the addition of an additional sliding fence 33 (which incorporates straight blade element 12 and straight blade adjustable housing unit 31 to a standard roughtertable, is achieved.Figure 13 illustrates a straig ht blade element 1 2 which is to be secu red into a recess on 31,figure 14, by means of a threaded nut.

Element 32 is a standard sliding fence.

In orderthatthe invention may be fully understood, and readily carried into effect, embodiments thereof will now be described, by way of example only, with reference to the accompanying drawings, of which : Figure 1 is an end view of an attachment embodying the invention, Figure 2 is a plan viewthereof, Figure 3 is a perspective view of a somewhat differentform of attachment embodying the invention, Figure 4 is a plan viewthereof, Figure 5is an end view, and Figure 6is a view of a component partwhich will be referred to presently.

Referring now to Figures 1 and 2 of the drawings, the article there illustrated is an attachment for a machine tool and comprises an elongate metal tube 10 with a saw cut in which is located a straight blade element 12 (the blade illustrated being a bladefora 'Stanley' (RTM) knife). As shown in figure 2, the saw cut is setatan angleto a plane perpendiculartothe axis of the tube. The blade is secured in position by means of a pair of screws 14. The arrangement is such that when the attachment has been mounted on a machine tool, an elongate workpiece can be passed through the hollow tu be with its periphery in contact with the blade element.Depending on the angle of the blade, the workpiece will be caused to rotate rela tive to the metal tube 10 in timed relation to the rate of travel of the workpiece through the tube. The blade will thus describe a helical cut around the workpiece and along its entire length (if the set-up is such that the workpiece can be traversed entirlythrough the tube) or such shorter length as may be required.

It will be understood that the required relative movement between the illustrated attachment and the workpiece can be brought about in a number of ways. For example, if the attachment is located so that it is free to move axially, but is held against rotation, it can be located on a workpiece mounted, for example, between centres on a wood-working lathe. By turning the workpiece the attachment can then be caused to traverse to and fro along the part of the workpiece which it is required to groove or scribe with a helical cut.

Referring now to figures 3 to 6, the article there illustrated is an attachment for performing the same function as the attachment described above, but is rather differently constructed. The attachment in this case comprises an open-ended box 16 provided with Iongditudinally spaced sets of rollers in which aworkpiece can rotate. The sets of rollers each comprise a pair of fixed rollers 18 upstanding from a lowerwall of the box, on which the workpiece can rest, and a pair of rollers 20 carried by a sliding plate 22 capable of being located in the appropriate one of two transverse slots 24 in the box.

Intermediate to its ends, the box is provided with a slot 26 which, as best seen in figure 4, is inclined to a planeperpendiculartothelongitudinalaxisthrough the box. A straight blade element 12 is located in the slot 26.

As shown, the opposite ends of the slots 24 and the opposite ends of the slot 26 are flanked by pairs of flanges provided with screw holes 30 through which screws (not shown) can be fitted to retain the plates 22 (carrying the rollers 20) and the blade element 12 in their adjusted positions.

As stated above, this attachment may be used in the same way as the attachment first described, but being of rectangular cross sectional shape may be easierto secure in position on the saddle of a machine tool. It will also be understood that workpieces of different diameters may be mounted in the device by appropriate adjustments ofthe plates carrying rollers 20. However, in addition to being useable as an attachment to a machine tool, the device just described can be used for mounting a cylindrical wooden workpiece which can then be turned by hand to cause a helical grooveto be described along its length, or along part of its length.

Various modifications may be made. For example, it will be understood that the metal tube 10 ofthefirst described embodiment could be provided with two or more sawcuts at different angles in which the blade element 12 can be fitted selectively to produce helical cuts of different helix angles. Similarly, the openended box of the second embodiment could have two or more slots at different angles in which the straight blade element 12 could be fitted selectively. Indeed it would be quite possible to devise a simple mounting arrangement whereby the blade element could be angularly adjusted in a stepless manner so that infi- nite variation of the resultant helix angle of the groove or scribing on the workpiece would be possible.

Claims (9)

1. A spiral guide comprising a straight blade ele ment 12 fixed at a predetermined angle to the long ditudinal axis in a hollow body so that when an elon- gate piece of wood of the same diameter as the inter nal bore ofthe hollowtube is inserted into the end of the hollow tube, and brought into contact with the blade element. When the wood is twisted the blade element cuts into the wood and forces the wood to rotate in timed relation to the rate of travel of the workpiece through the hollow body. As the leading end ofthe wood comes through the end of the tube a cutwill be seen which is the mark left by the blade element. The attachment should then be adjusted so thatthe point of the cutting tool on the machine is just in contact with the cut made by the blade element.

Start the machine and move the attachment so asto bring the wood in contact with the cutter blade and set atthe required depth of cut. All that is then re quired is to continue twisting the workpiece which will, in turn, be forced onto the cutter blade, which will cut out a groove ofthe same profile as the cutter blade, spirally, along most of the length of the elongate piece of wood.

2. A spiral guide as in claim 1 whereacircular blade is used in place of the blade element 12 in claim 1.

3. A spiral guide as claimed in claim 1 or claim 2 wherein two or more blade elements 12 are mounted parallel.

4. A spiral guide as claimed in claim 1,2 or3 where the blade element is adjustable.

5. A spiral guide as claimed in claim 1,2,3 or4 where the elongate hollow body is replaced by the illustration in figures 3,4,5 and 6, which is an adjustable design.

6. A spiral guide as claimed in claim 1,2,3 or4 where the elongate hollow body is replaced with figures 7,8 and 9.

7. Aspiralguideasclaimedinclaim 1,2,3or4 where the elongate hollow body is replaced byfigures 10,11,12,13 or 1 4which incorporates two slid- ing fences and an adjustable straight blade element.

8. A spiral guide as claimed in claim 1,2,3 or4 where the elongate hollow tube is replaced byfigures 3,4 and 5, and without sliding rollers 22.

9. A spiral guide as substantially as described herein with reference to figures 1 - 14 ofthe accompanying drawings.