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CRB7 Universal Mortise, Hinge, Lock & Flute Jig

Micro Adjustable – Inc. CRB7 Side Fence


Please note: The CRB7 MHLF includes a CRB7 Side Fence

The CRB7 Combination Router Base greatly increases “on surface” routing stability and therefore provides a more precise routing pass. Combine this with the MHLF accessory – Mortise, Hinge, Lock + Flute and the CRB enters an entirely new level of machining accuracy; never before achieved with a hand held power-tool.

Until now a routers position has been entirely dependent on the operators technique and grip. This becomes especially critical when routing into the edge of a board from above. The narrow workpiece reduces the surface contact area between router base and workpiece to the point of dangerous instability.

The MHLF is a pair of micro adjustable precision machined jaws; these sit either side of the work piece re-establishing a safer level of surface contact between router and work piece. Allowing accurate Mortises or Hinge and Lock Rebates or flutes to be machined.



Work mortise length with uninterrupted on-board “Sight lines”

Cut centred and off centred mortises.

Cut hinge and lock rebates.

Repeat cut sets of flutes.

Edge molding Parallel to edge groove or channelling.


Quick fit:
The MHL has just 4 screws to fit it to the CRB baseplate; so it’s seriously fast and simple to set up in 3 different positions according to the width of stock that’s being worked.

Core Stability:
The main issue with routing into the edge of a board from above is that the router foot print is much greater in surface area than the surface area of the material being machined. However MHL’s unique design creates a stable platform through increasing the surface contact area between router and stock. This is achieved by a sizeable jaw of 270 x 20mm either side of the workpiece that securely holds the Router CRB assembly onto the work piece. Even narrow sections of stock can be mortised easily especially when auxiliary cheeks are fitted to the jaws (Fixings included) they add a further contact surface area increase of 2 x 12 x 1.1/2″ (300 x 35mm) maximising and further stabilizing the relationship between router and workpiece.

Heavy Duty Jaws:
The 2 Jaws are injection moulded in solid highly durable low co-efficient Nylon. Then to ensure a truly flat surface to run up against the work piece. Both Jaws are machined flat on a milling machine at our factory in the UK. That guarantees consistent jaw to work piece surface contact. Threaded inserts are fitted to the jaws so that auxiliary cheeks can be fitted to further enhance stability when working with very narrow stock.

Blunted Jaw Tips:
We’ve improved the profile of the Jaw Ends – Feedback from our MHLF beta testers led us to re-tool the injection molding suite of tools. Our panel found that when using clamp heads to control the length of a mortise; the jaws curved tips made for a small contact point for the clamp head to consistently butt up against. The curves have been replaced by cropped right-angle ends that have proven to be the solution.

Micro Adjustment:
Having established and we like to think perfected micro adjustment of cutter position. We’ve repeated the same design and included it with the positioning on the MHL Jaws. However on the MHL we centralized the adjuster between a pair of rods, pinch bolts and collars so that when positioned can be locked; ensuring that the jaws remain parallel to each other at all times.

Sight Line:
During a router cutting pass considerable amounts of dust and debris are created. Making it difficult to accurately see the position of a cutter spinning at high speeds . All this is hidden at the center of the most crowded part of the router. So gauging when to consistently end the cutting pass is difficult. The design of the MHL offers an alternative “Sight Line” solution; recessed indicators are positioned on the tips of both jaws and allow an uninterrupted view that allow greater control and accuracy of the mortise length.

Massive Range:
It’s no news that the router is the most versatile power tool available especially allied with the CRB 7. However what may not be fully apprciated is that extraordinary levels of accuracy can be achieved comparable with accuracy levels attained by serious floor mounted machines. Comparing The CRB7 MHL to floor mounted machinery seams foolish.
However we can’t think of many if any mortising jigs or mortising machines with the adjustability that can cope with the huge varity of stock width that the MHL can. Starting from effectively a zero width (not very useful) up to a maximum of 7″ (178mm) – the MHL can cope with any stock width in between.

Mighty Small:
If workshop space is limited or there’s a need to work “On site”, The MHL like its base unit The CRB7 is light and easy to carry or store. Small in size, large in heart. The MHL can create extraordinarily crisp precise repeatable mortises and rebates easily and quickly.

3 Year Guarantee:
We are so confident of the build quality of our new MHL accessory. That each jig is backed by a “no fuss” 3 year extended guarantee.


Centered and Off set Mortising:
There are many ways to cut a mortise – from traditionally chopping out by hand with a mortise chisel to industrial floor standing hollow chisel machines and the list of advantages and disadvantages to each method is as long; be it too time consuming by hand or too expensive and space consuming with a single function machine.
There are a number of jigs utilising “the world’s most versatile power tool – The Router”
The base unit CRB7 includes a pair of mortise pins. However M.POWER pride ourselves on listening to our customers and in the endless search of “continual improvement” can now offer The MHL a truly stable accurate method of cutting a huge variety of different sizes of mortise.

Cutting in Hinges:
It’s impossible to consistently cut accurate hinge recesses without stability, Which is the main downfall of marching hinge recesses into the edge of doors. The average thickness of a door is less than 2″, which only increases the issue of a small surface contact area between the base of the router or any power tool and the worksurface. The MHL jaws fitted further with Auxiliary cheeks overcome this issue by shifting and increasing the surface contact areas onto the sides of the workpiece. The MHL assures stability allowing quick , repeatable hinge recesses.

Fitting Locks:
Again the main issue with cutting out a rebate for a lock in a door is that of stability. One way to improve the situation is to fit a temporary platform onto the door edge, which the router can then run on. However these jigs or platforms only have this one function, are expensive and take up valuable room especially when working “on-site”. The MHL doesn’t need to run on any platform rather gaining stability through for want of a better description two large adjustable edge guides.

Fluting a board:
Sets of decorative fluting can be the perfect finish to a piece of furniture or larger woodworking projects, such as Newel posts on a set of stairs. The MHLs micro adjust jaw settings combined with the same Micro adjustment on the CRB for the router cutter. Provides the perfect set up to machine sets of precise decorative mouldings with real accuracy, quickly and with a maximum board width of 7″ allowing every conceivable task to be undertaken.

Dado-ing/trenching in:
Traditionally a routers edge guide or side fence is a stand alone, single function jig assembly that fits via a pair of rods to the router. It has a very limited range for dado-ing/trenching in from the board edge.
The CRB7 MHL edge guide is breathtakingly simple to fit and has a much greater depth range to penetrate in from the edge of the board up to 7.1/2″ (0 > 190mm).
The new edge guide also benefits from the accuracy of the CRB7’s micro adjuster which controls the distance between cutter and the edge of the board.

Either copying an existing architectural molding on a kick board/skirting board or putting the finishing touches to a piece of furniture.
Edge molding is an essential task in most woodworking projects in everything but rough stud work, framing and perhaps woodturning.
The CRB7 fitted with an Edge guide is one of the simplest set ups with which to perform a quick and easily repeatable edge mold. The CRB’s Micro Adjuster precisely controls how much of the cutter is presented to the board edge to be molded and with the auxillory cheeks fitted the cutter is couched into the edge guide to create a seamless support either side of the cutter. Keeping the routing pass smooth and reducing the chance of burn marks and deviations in the molding.


Fits the CRB7 Combination Router Base Mk1 – Mk2 – Mk3

FAQ, Hints & Tips

Additional Fixing Screws
There are 2x additional Fixings screws M4x8mm (SKU 50433) included in the MHL fixing kit.
Although not specifically referred to in the Instruction Manual  – These are extra screws that offer a different length option when fitting ablative /sacrificial cheeks to an MHL Jaw.

Narrow stock:
Although the MHL greatly increases the stability and accuracy when routing into the edge of stock. Narrow stock in particular working on door edges can be further improved by making and fitting a pair of auxiliary cheeks. This further stabilizes the CRB MHL set up giving better control and consistency.

Large Mortises:
If the mortise is large i.e requiring multiple cutting passes to cut the full width of the mortise. Try setting your first pass off centered so that if you cut from left to right down the workpiece, the second pass can be taken without adjustment by rotating the CRB MHLset up 180 degrees and running the next pass right to left. Effectively doubling the number of passing strokes without adjustment.

Machining on Multiple components and/or sides:
It sounds obvious but whenever multiple components require the same sets of mortises or sets of decorative flutes. Carry out all the routing passes with the same set up (same cutter position in relation to the same jaw positions) All in one go ‐ This reduces time taken and further improves accuracy.

Contents & Spares

Main Unit:
1 x Fixed Jaw Assembly (Side Fence)
1 x Fence v3
1 x Sight Line Sticker
1 x Adjuster Fence + Bridge Assembly

Accessory Screw Pack
4 x M4 x 20 Fixing Screws
4 x M4 x 10 Fixing Screws

1 x Instruction Manual

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Customer Reviews


superb, fast and easy transaction

Joseph E P – Rockler

Like it, worked great. Used it to make a slot in a drawer front to attache a drawer pull (hand made)

Terry Clingan – Rockler

I have used this for lots. making circles and trimming edge banding is a breeze.
The best feature is a sweet micro adjust.