GB2163995A

GB2163995A - Cutting apparatus

Info

Publication number: GB2163995A
Application number: GB08521738A
Authority: GB
Inventors: Walter Robin Potter
Original assignee: POTTER AUSTEN RICHARD
Current assignee: POTTER AUSTEN RICHARD
Priority date: 1984-09-01
Filing date: 1985-09-02
Publication date: 1986-03-12
Also published as: GB2163995B; GB8521738D0

Abstract

A portable clamp for workpieces (14) which are rounded, flat, square or angled, steel, brass, aluminium or wood enables accurate cutting by a hacksaw to any angle between 22.5 DEG and 90 DEG . By means of a protruding zone 13 of one jaw 1 it can be secured in a vice or clamped to a scaffold pole, or it can be used portably provided that the workpiece to be cut is rigidly supported. The clamp comprises shaped front- and backplates 6 and 1 with two handwheel screws 2, 15 to form a clamp. A vee block 3 with a metered quadrant aperture 5 and a locking handwheel 4 serves for clamping of rounded workpieces. The vee block 3 is removable to permit clamping of premarked flat, square, and by fitting a block inside the angle, angled workpieces. Two tensionable high speed hardened steel rubbing guide strips 7 are set in grooves 8 in the top edges of the front- and backplates 6 and 1 to prevent wear of the plates 6 and 1. <IMAGE>

Description

SPECIFICATION Cutting apparatus This invention relates to apparatus for use in cut ting a metal workpiece, in particularly for cutting the same accurately with hand-held hacksaw.

Cutting materials, such as round, flat, square or angled, steel, brass, aluminium or wood accurately by hand at various angles has always been a hit or miss affair invariably requiring filing or planing to the correct degree after sawing.

There are various machines which can perform such accurate cutting in a well provisioned tool room, but the average jobber, site worker, plant maintenance handyman, farm fitter, garage man, or D.l.Y. man, has no such machines.

According to the present invention, there is provided apparatus for use in cutting a metal workpiece, comprising first and second clamping jaws for clamping the workpiece therebetween, and hard metal guide surfaces arranged to guide a saw in cutting said workpiece.

In a preferred embodiment of the present invention there is a versatile and portable clamp comprising a backplate into which are screwed two studs, the purpose of which is to connect to a frontplate with the aid of two threaded handwheels. In the top of the backplate is a groove at one end of which is a fixed peg and at the other end a lever formed with a second peg for tensioning a hardened steel rubbing guide strip by means of a knurled jacking screw. The lower area of the backplate beneath the fixed peg is for securing the clamp in a vice or clamping to a scaffold pole, stanchion or another suitable support.

The frontplate has the same guide strip and tensioning arrangement as the backplate, but is of smaller area beneath its fixed peg. It also incorporates a metered quadrant aperture and a removable vee block mounted on a pivot pin and lockable by a handwheel.

The vee block is used when cutting rounded workpieces and is set to the required angle using the metered quadrant. Once set, repetition work can be done, without further adjustment of the vee block. For cutting flat stock, square of angled workpieces the vee block can be removed. The workpiece marked off to the required angle is then lined up to the strips on the clamp plates. Angled workpieces may require a wooden block set inside the angle for stability. The size of workpiece is governed by the amount to which the plates will open and the distance between the clamping studs.

A specific embodiment of the invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 is a top plan view of a backplate of a clamp for use in cutting a metal workpiece, with a guide strip in position and two fixed clamping studs, Figure 2 shows a front elevation of the same, Figure 3 shows a top plan view of a frontplate of the clamp, with a guide strip in position and a vee block in a 90 position, Figure 4 shows a front elevation of the same, but with the vee block omitted, and Figure 5 shows a perspective view of the clamp, with a length of pipe set for cutting at an angle of 22.50.

Referring to the drawings, in order to cut a pipe 14, the backplate 1 is secured in a vice or clamped to a suitable support. Then the two clamping handwheels 2 on their screws 15 and the frontplate 6 are extended to accept the pipe 14. The pipe is placed in the vee block 3 which has been set at the angle required by turning about a pivot pin 12 with respect to a metered quadrant aperture 5 and then tightening a locking handwheel 4. The frontplate 6 is now clamped to the backplate 1 by the two clamping handwheels 2, thereby holding the workpiece securely. This leaves the workman with both hands free to operate a hacksaw to-and-fro across hardened high speed steel rubbing guide strips 7 located in machined grooves 8 and tensioned between pegs 9. The hacksaw should be held slightly biased as if to cut into the strips 7, thereby maintaining contact on both sides.The vee block 3 can be set at any angle between 22.5 and 900 to the strips 7.

In order to cut flat stock, square or angled workpieces, the quadrant handwheel 4 and the vee block 3 may be removed from the frontplate 6 by releasing the swivel pin 12. The workpiece should be marked off to the required angle, then clamped in with the marked lines aligned with the strips 7.

For angled workpieces a wooden block should be placed inside the angle for stability. Otherwise, the procedure is as for round workpieces.

The strips 7, which may themselves be hacksaw blades, have slightly rounded edges to reduce wear on the sawing hacksaw blades and are set in the grooves 8 along the tops of both the frontplate 6 and the backplate 1. They are tensioned by adjusting knurled jacking screws 10 which extend two levers 11 which terminate in respective pegs 9. The area 13 is for securing in a vice or clamping to a suitable support. However, the clamp need not be supported if the workpiece to be cut is sufficiently rigidly sited.

1. Apparatus for use in cutting a metal workpiece, comprising first and second clamping jaws for clamping the workpiece therebetween, and hard metal guide surfaces are provided by hard metal guide strips carried by said jaws.

2. Apparatus as claimed in claim 1, wherein said guide surfaces are provided by hard metal guide strips carried by said jaws.

3. Apparatus as claimed in claim 2, wherein said strips are located in respective grooves in said jaws.

4. Apparatus as claimed in claim 2 or 3, wherein said strips are hacksaw blades.

5. Apparatus as claimed in claim 2, 3 or 4, wherein said strips are readily releasably carried by said jaws.

6. Apparatus as claimed in any one of claims 2

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Cutting apparatus This invention relates to apparatus for use in cut ting a metal workpiece, in particularly for cutting the same accurately with hand-held hacksaw. Cutting materials, such as round, flat, square or angled, steel, brass, aluminium or wood accurately by hand at various angles has always been a hit or miss affair invariably requiring filing or planing to the correct degree after sawing. There are various machines which can perform such accurate cutting in a well provisioned tool room, but the average jobber, site worker, plant maintenance handyman, farm fitter, garage man, or D.l.Y. man, has no such machines. According to the present invention, there is provided apparatus for use in cutting a metal workpiece, comprising first and second clamping jaws for clamping the workpiece therebetween, and hard metal guide surfaces arranged to guide a saw in cutting said workpiece. In a preferred embodiment of the present invention there is a versatile and portable clamp comprising a backplate into which are screwed two studs, the purpose of which is to connect to a frontplate with the aid of two threaded handwheels. In the top of the backplate is a groove at one end of which is a fixed peg and at the other end a lever formed with a second peg for tensioning a hardened steel rubbing guide strip by means of a knurled jacking screw. The lower area of the backplate beneath the fixed peg is for securing the clamp in a vice or clamping to a scaffold pole, stanchion or another suitable support. The frontplate has the same guide strip and tensioning arrangement as the backplate, but is of smaller area beneath its fixed peg. It also incorporates a metered quadrant aperture and a removable vee block mounted on a pivot pin and lockable by a handwheel. The vee block is used when cutting rounded workpieces and is set to the required angle using the metered quadrant. Once set, repetition work can be done, without further adjustment of the vee block. For cutting flat stock, square of angled workpieces the vee block can be removed. The workpiece marked off to the required angle is then lined up to the strips on the clamp plates. Angled workpieces may require a wooden block set inside the angle for stability. The size of workpiece is governed by the amount to which the plates will open and the distance between the clamping studs. A specific embodiment of the invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 is a top plan view of a backplate of a clamp for use in cutting a metal workpiece, with a guide strip in position and two fixed clamping studs, Figure 2 shows a front elevation of the same, Figure 3 shows a top plan view of a frontplate of the clamp, with a guide strip in position and a vee block in a 90 position, Figure 4 shows a front elevation of the same, but with the vee block omitted, and Figure 5 shows a perspective view of the clamp, with a length of pipe set for cutting at an angle of 22.50. Referring to the drawings, in order to cut a pipe 14, the backplate 1 is secured in a vice or clamped to a suitable support. Then the two clamping handwheels 2 on their screws 15 and the frontplate 6 are extended to accept the pipe 14. The pipe is placed in the vee block 3 which has been set at the angle required by turning about a pivot pin 12 with respect to a metered quadrant aperture 5 and then tightening a locking handwheel 4. The frontplate 6 is now clamped to the backplate 1 by the two clamping handwheels 2, thereby holding the workpiece securely. This leaves the workman with both hands free to operate a hacksaw to-and-fro across hardened high speed steel rubbing guide strips 7 located in machined grooves 8 and tensioned between pegs 9. The hacksaw should be held slightly biased as if to cut into the strips 7, thereby maintaining contact on both sides.The vee block 3 can be set at any angle between 22.5 and 900 to the strips 7. In order to cut flat stock, square or angled workpieces, the quadrant handwheel 4 and the vee block 3 may be removed from the frontplate 6 by releasing the swivel pin 12. The workpiece should be marked off to the required angle, then clamped in with the marked lines aligned with the strips 7. For angled workpieces a wooden block should be placed inside the angle for stability. Otherwise, the procedure is as for round workpieces. The strips 7, which may themselves be hacksaw blades, have slightly rounded edges to reduce wear on the sawing hacksaw blades and are set in the grooves 8 along the tops of both the frontplate 6 and the backplate 1. They are tensioned by adjusting knurled jacking screws 10 which extend two levers 11 which terminate in respective pegs 9. The area 13 is for securing in a vice or clamping to a suitable support. However, the clamp need not be supported if the workpiece to be cut is sufficiently rigidly sited. CLAIMS

6. Apparatus as claimed in any one of claims 2 to 5 and further comprising tensioning means for locating and tensioning the respective strips.

7. Apparatus as claimed in claim 6, wherein each tensioning means comprises a lever pivotally mounted on its jaw and engaging one end of its strip, and a screw arranged to act between the lever and the jaw to turn the lever to tension the strip.

8. Apparatus as claimed in claim 7, wherein said screw is turnably mounted in complementary threading on said lever.

9. Apparatus as claimed in any preceding claim, wherein said jaws comprise respective plates substantially parallel to each other.

10. Apparatus as claimed in any preceding claim, and further comprising first and second externally threaded elongate members each fixed in one jaw and extending with clearance through a bore through the other jaw, and first and second internally threaded handwheels encircling the respective elongate members and each releasably tightenable against the outside of said other jaw to clamp the workpiece between the jaws.

11. Apparatus as claimed in any preceding claim, wherein a block is pivotally mounted on the inside of the first jaw so as to be turnable parallelly to the inside of the first jaw for seating said workpiece and there is means for releasably setting said block at a desired orientation.

12. Apparatus as claimed in claim 11, wherein said block is arranged to be turnable over an angular scale indicating the orientation of said block.

13. Apparatus as claimed in claim 12, wherein said angular scale is associated with a metering aperture which is formed through one of said jaws and through which said block is visible.

14. Apparatus as claimed in claim 11, 12, or 13, wherein the setting means comprises a threaded handwheel releasably tightenable to set said block.

15. Apparatus as claimed in any one of claims 11 to 14, wherein said block is a vee block with its vee facing said second jaw for seating a rounded said workpiece in its vee and clamping that workpiece against said second jaw.

16. Apparatus as claimed in any preceding claim, wherein a portion of one of the jaws protrudes beyond the other jaw to facilitate clamping of said portion in a supporting device.

17. Apparatus for use in cutting a metal workpiece, substantially as hereinbefore described with reference to the accompanying drawings.