CRB7: Router Base Revolution
Words and photos: Raf Nathan
For the router aficionado this is a must. For the rest of us it is a great aftermarket router base offering a variety of functions. Because it is so innovative it is worth knowing that the original router compass concept was invented by Alan Hezzlewood and then further developed by UK company MPOWER’s development team, led by Tobias Cardew. In Australia this unit and accessories are available from Professional Woodworkers Supplies.
A large 4.8mm thick plastic plate holds an aluminium bridge to which attach twin 8 or 10mm diameter steel guides. Most routers will slide straight on using either of the guides that suit it. The position of the arms can be adjusted to different widths. Your router slides onto the arms through its standard fence holes and uses the existing thumbscrews to lock it in place. My DeWalt 621 slid on without any fuss.
Showing the micro-adjust thumbwheel. The router sits on the steel bars at the top right. Note the neat hole for the steel and brass pivot pin in the centre.
Moving the router along the guides gives you approximate positioning, whilst at the bridge fine adjustment is easy with
the micro-adjust thumbwheel. This has an index mark and locks with a 13mm nut (you need a spanner to do this). One turn of the thumbwheel equals 1.25mm. A stick-on rule can be attached to the router’s original base to enhance the micro-adjust.
There are many functions that can be performed in conjunction with the CRB, some of which of course you can already do with a standard router base and fence.
The base has many pre-drilled holes so it is easy to attach a shopmade wood fence to it for jobs like repetition grooving and trenching. Squaring up a tabletop was definitely easier with the plastic base, as opposed to the original base, running against a straightedge.
The supplied large knob can be quickly secured to offer an alternative holding position. This gives a lower centre of gravity for holding and helps in jobs like edging as well as routing on large panels. The knob does however foul with the router handle in certain positions so you can’t always use it.
Screwing the mortise pillars to the base allows you to plunge mortises. The pillars limit twist and align the cutter at centre. Recommended wood thickness is 50mm but 40mm thick wood was tested on.
Mortising is possible by screwing the two supplied mortise pillars into the base. Rest the assembly on the wood and the pillars centre the router cutter automatically with the micro-adjust used for fine-tuning the position of the mortise.
There are three optional places to fit these mortise pillars allowing material from 50mm to 219mm to be mortised. In fact I mortised wood 40mm thick so I assume the recommendations in the detailed instruction booklet are prudently understated.
An anti-tilt support leg fits to the underside and offers extended support if you are routing along an edge of a board. The rubber foot on the leg however is not smooth sliding so in use I found it not that effective.
Drill a hole and drop in the brass pin. The screw fixes to the pin through the base and the assembly pivots around this for circle cutting.
Circle cutting is a breath of fresh air. Drill a 6mm hole in the wood and fit the brass and steel pivot pin to the underside of the CRB. This pivot pin can be fitted in either of two positions offering circle radii from 19mm to 224mm. The router is then spun around the pivot pin and of course the micro-adjust can first tune in the circle diameter. The pivot pin is small and easily lost but when not in use it sits in a magnetic hole in the bridge. Nice.
With the hub and steel arms a compass is formed to cut large circles.
Positioning an aluminium ‘hub’ on the centrepoint makes large circles up to 1270mm. The hub has a hole and lock screw to accept a 10mm diameter steel guide acting as a compass. This guide screws securely into a hole at the bridge. You can adjust the desired circle diameter by sliding the guide through the hub and use, yes here it comes, the micro-adjust for tuning again.
Edge trim base pushes onto main base and includes a bearing to run along the edge of work to be trimmed.
Other accessories available are an Edging Trim Kit. This is an extra base plate that pushes on to the CRB. A ball bearing guide runs on the edge of the panel and the router sits on the face. This is an alternative way for flush trimming of edgebanding.
Worth getting is the 15mm thick acrylic Parallel Side Fence. This can be screwed on to the CRB in either of three positions giving parallel routing up to 190mm from the fence. You can screw on shopmade sub-fences to the acrylic fence using the pre-drilled and tapped holes. Alternately you can simply screw on a piece of wood to act as a fence.
The CRB7 is an intelligent router accessory. Compared to using a router with its standard base and fence the CRB7 offers much greater ease of use. Now that it is on my router it is staying there.
Available from Professional Woodworkers Supplies