Holding The Workpiece
It is essential that the work is held securely before you start any routing operation, otherwise you will have great difficulty controlling the path of the cutter and risk damaging the work. At worst, it may be spun off violently with potentially disastrous consequences for you, the work, the cutter or the router itself.
There are literally dozens of ways of clamping the work, using a variety of strategies depending on the type of work and the cut you are trying to perform. You can use many of the traditional methods like G-cramps, bench dogs and vices, but also add to these a wide range of homemade devices such as folding wedges, cams and pegs or even a purpose made workboard. Sometimes you may have to combine several clamping methods for particularly awkward jobs.
Wherever you work you need a stable and rigid working surface, preferably quite high up, so you don’t need to stoop too much to see what is going on.
In the workshop this can be your normal workbench, or if space allows, you can make a dedicated router bench with that all-important extra height and built-in provision for a range of different holding devices
The aim is to get secure clamping but at the same time minimising any interference with the path of the router or side-fence, which is not always an easy compromise. You also want to be able to clamp quickly, particularly if there are lots of components to machine, so over-complicated set-ups are best avoided.
In many situations, the use of a special router mat will provide all the support you need. This has a specially designed rubbery consistency that resists slipping. Just lay it on the bench, drop on your work and away you go. Being so simple and effective, a router mat is always my first choice for holding small components, but it maybe less effective on bigger pieces.
You will find a dial caliper another invaluable aid for checking both inside and outside measurements. The dial type are not prone to subjective interpretation, you just read off the measurement. An expensive engineers type is not necessary, as you often only use comparative measurements rather than high precision ones.
A straight edge clamped across the workpiece is common practice for guiding the router, but even such basic technology can be improved on. Written by Gordon Warr - Established woodworking craftsman.
How many times have we all struggled when cutting large sheet material into smaller pieces, a batten in one hand, two cramps in the other and packing pieces so that we don't mark the surface!
Of course, that was the bad old days, now we have Clamp Guides, Bench Clamps and Pro Tracks.
All three are designed to make life a lot easier on-site, at home or in the workshop. Made up of an aluminium extrusion fitted with one sliding and one fixed jaw, they are infinitely adjustable along their length and lock tight with a flick of a toggle. Once pressure is applied, the work is held firmly, the simple cam lock offering two clamping pressures - tight and tighter.
For use as a straight edge or sash cramp, the Clamp Guide locks onto any square-edged, parallel-sided material, to act as a router or saw guide. Alternatively, they can be used for clamping several pieces together for machining or to supplement other cramps when glueing up. Available in three sizes 610mm (24 inches), 915mm (36 inches) and 1270mm (50 inches) between the jaws, the flat profile of the Clamp Guide (15mm high) minimises any risk of obstructing the power tool during the cutting operation.
The Clamp Guide can also be used as a general-purpose straight edge for marking out and in particular when scoring with a craft knife as the guide can be clamped to the workpiece or a cutting board beneath it, allowing your fingers to be kept away from the guide edge and knife blade.
In the workshop, you will soon find the Clamp Guide indispensable, as a supplementary long fence on band saws and saw tables, as a planning stop on a workbench and for a wide variety of other uses.
Using the Clamp Guide
Simply mark off the position of the cut, allowing for the base of the router or saw (that is the distance from the cutter or sawblade to the edge of the baseplate). Position the clamp and slide the jaws against the edges of the material. Lock the toggle to the first position and check with a try square that the guide is square to the edge of the workpiece. Set the toggle to the second position if you wish to tighten it. Soft facings are supplied with the Clamp Guide to protect the edges of delicate workpieces.
Similar in operation to the Clamp Guide, the Bench Clamp is designed to hold a flat workpiece to a work surface leaving the face of the workpiece unobstructed. The Bench Clamp is fitted with fixed and sliding jaws on both sides of the aluminium extrusions. One set is used to clamp it to a flat parallel-edged work surface, while the top jaws clamp to the workpiece. The lack of any protrusion above the surface allows total free access when freehand routing, sanding, hand planing and for many other machining and finishing operations.
The Bench Clamp is available in three sizes with capacities, between the jaws, of 460mm (18 inches), 915mm (36 inches) and 1270mm (50 inches).
Clamped to vertical rails fitted to the front or end of a workbench or across the legs, the Bench Clamp can also be used to hold workpieces vertically, ideal when squaring or doweling the ends of panels.
Although generally used in pairs, the Bench Clamp can be used on its own to hold small items. Again soft facings are supplied to avoid marking the edge of delicate work, while curved jaw blocks can be easily cut and fitted to hold curved or irregular edges.
The Bench Clamp can be fitted to most square edge surfaces including folding benches such as the 'Workmate'.
The Bench Clamp can be used in many similar ways to the Clamp Guide and can be used in conjunction with it, using the Bench Clamp to hold the workpiece to the bench and the Clamp Guide to guide the power tool across it.
Clamp Guide Pro Track
This is the most sophisticated of these three guide systems. Although similar in construction and materials to the other guides, the Pro Track has a 125mm (5 inch) wide extrusion to make it extremely rigid and is available in jaw opening capacities of 610mm (24 inches), 1220mm (48 inches) and 2440mm (96 inches).
Both edges of the Pro Track extrusion have a T-slot that engages the machined edge of one or two alternative carriage plates, allowing them to slide along the guide edge over the face of the workpiece.
One plate is designed to take a router, the other a circular saw. This allows straight cuts to be made across the work face with no risk of wandering away from the guide edge.
Power Tool Mounting
The carriage plates are made of nylon machined along one edge to fit into the T-slot as well as to extend over the top face of the extrusion. A second T-slot in the top face of the extrusion accepts a tee-bolt and thumb knob, fitted through the plate extension to stop the plate and power tool from tipping. This arrangement allows open frames as well as flush panels to be cut or routed, the power tool being supported on the plate as it is fed across the workpiece.
Both carriage plates are 19mm (3/4 inch) thick, the router plate having a circular recess of 190mm (7.5 inches) large enough to take most popular routers. To locate the router, the plate is pre-drilled to suit the table mounting holes in the router base on the Trend T10/T11 & T5 routers. For other routers, both the router and carriage plate can be drilled to take countersunk machine screws (ensuring that the screw heads do not protrude below the plate).
Alternatively, the router plate recess has a 30mm diameter centre hole that takes a 30mm outside diameter guide bush. With this size guide bush fitted, the router can be simply dropped into the recess, allowing the guide bush to both centre and locate it allowing the normal downforce to hold it in place while routing.
The carriage plate for the saw measures approximately 355 x 240mm (14 x 9.5 inches) with the same thickness as the router plate but no recess. The saw can be either fitted to the edge of the plate by drilling both and using countersunk screws, or by cutting a central slot with a router cutter wide enough to take the blade and blade guard (always fit the saw in such a way that the blade guard continues to operate as before). When fitting jigsaws, a small hole can be drilled to take the blade and the base plate either screwed or clamped (with homemade clamps) to the plate.
In order to limit the length or position of the cut, stop blocks to fit the Pro Track are available as an optional accessory. These simply engage in the track T-slot and can be locked with a T-nut as on the carriage plates.
Traditional bench vices are only suitable for holding pieces that can project clear of the jaws, but they are useful for edge work on large boards if you can provide some additional support to stop them pivoting.
A tail vice is the most versatile as you can use it in conjunction with a variety of bench dogs to hold flat work.
One very handy trick is to use a sash cramp gripped in a bench vice for holding a workpiece by its ends, but make up a couple of wooden saddles to support the work and stop it twisting over
Quick action clamps are probably a better option as you can adjust the clamping width in just a few seconds. They are also available in a huge range of sizes, up to really big ones for clamping doors and the like. I particularly favour the type that you can operate one handed, enabling the user to secure a guide batten onto the work at the same time.
End socket cramps are a great way to secure fences and stops but leaving the surface free of any obstruction.
However, you need to drill a 9mm hole to locate them and the minimum recommended material thickness is 18mm.
A standard G-cramp will often suffice if the wood has to be held flat on the bench, but you will need plenty of overhang on the bench top so you can locate it well clear of the routers path.
Although you can exert great pressure with a G-cramp, they are slow to use as their screw action takes some time to adjust to different openings.
Toggle clamps are available for either top or side clamping. They can be screwed directly to the bench or to a special workboard and are particularly useful for repetition jobs as they allow the work to be positioned quickly and then secured.
They will accommodate work up to 60 mm in thickness and their low profile means minimal interference. Quick release mounting plates for use with toggle clamps allow rapid repositioning of the clamp and often reduce the number of clamps required.
Workboards are the most convenient way of holding small pieces, and you can design one to take a range of different fences, stops and holding devices. They are easily made from pieces of MDF or laminate covered board and are secured by screwing a batten to the underside which can then be gripped in the vice. For extra versatility, drill holes in the board to take pegs or cams, or cut tee slots and fit toggle clamps. Cams or eccentric clamps are made up from scraps of timber and are best used in pairs.
Rubberised work support blocks
The use of non-slip rubber mats to hold a workpiece has been shown earlier but an extension of this idea are rubber surfaced blocks called Bench Cookies or Loc Blocks. Placing these Blocks under the four corners of the workpiece will secure small or medium sized workpieces to the bench and allow them to be routed or sanded without the need for clamps.
They also raise the workpiece from the bench by 25mm, which allows complete access to every edge, so making it ideal for painting or varnishing. The Trend Loc Blocks linkare a development of this idea and have interlocking edges that lock to each other so that different configurations of the blocks can be made. For example all four can be interlocked to form a square of 173mm per side, for supporting smaller items.
The top and bottom surfaces of the square blocks consist of anti-vibration, non-slip, non-marring rubber pads. They can be set-up in seconds and grip both workpiece and bench.
To set them up, the blocks are placed on a clean, non-polished surface and arranged according to the size and shape of the workpiece, which is then positioned on top of them. When used for router edge moulding, the blocks should be positioned as close to the edges of the workpiece as possible to prevent tipping, and the cut made in several light passes
Vacuum clamping provides a very effective method for holding and releasing the workpiece and is therefore ideally suited for repetitious batch work. It is generally used only in professional workshops where speed is vital, as it can prove an expensive option for the occasional user. However you can rig up suitable homemade devices that offer a very reliable method of holding while avoiding the need for separate clamps that can obstruct the routing operation or spoil the workpiece. Vacuum chucks are made using flat self-adhesive foam sealing material or round neoprene strip formed into individual cells. The workpiece itself then completes the sealed chamber from which the air is removed through an exhausts port built into the chuck.
To get the necessary suction you need to buy a dedicated vacuum pump or couple up to a domestic vacuum cleaner. This latter option is obviously more cost efficient for the home user, but only short periods of clamping are recommended as continuous restriction to the airflow will overheat and damage the unit.
Having created a vacuum beneath the workpiece, the external air pressure is sufficient to hold it firmly in place. Some vacuum clamping devices have multiple cell chucks, which are divided into several chambers that are shut off independently with automatic ball valves. This allows various sized workpieces to be held, as unused cells remain completely airtight.
Proprietary multiple cell chucks for use with a vacuum cleaner are readily available in a variety of sizes and these are ideal for the amateur user who is dealing with lots of small components. They can also be used for other jobs like holding work for sanding, etc.
However, for the chucks to work properly, it is essential that contact is made all round the seal, so bowed or warped pieces won’t normally hold. You can even make your own specially curved chucks contoured to a specific shape.
With any vacuum holding system, always check that the work is held down securely before you start cutting.
How does it work?
The top surface has a rubber gasket with a matrix of cells in two sizes which when used in combination provide maximum holding area for small or awkward shaped workpieces. The lower surface has a rubber gasket with one large vacuum cell which is used to clamp it to the workbench.
The timber is pushed down to activate the air valves in the cells to engage the vacuum. The vacuum suction then holds the workpiece securely onto the bed.
A red handle is used to release the vacuum.