Router Woodworking

Edge guide adjuster 1

Edge guide adjuster 2

Both of my edge guides (mortising jig and edge of stock guides) must be adjusted for each new application; an arbitrary setting is rarely right where you want it. The adjustment can translate the cutter pathway centerline, facilitate a pathway greater than the cutter diameter, or both. Translation of the cutter centerline can be done with a setting change of the edge guides or the guide rods can simply slide to a new location within the casting. In the latter case, the 2 hold down screws/knobs on the casting are loosened and the router is relocated a measured amount.
It is customary & essential to start an edge guide cut with a calibration cut. This is the case no matter what the edge guide design may be. From the calibration (test) cut you can determine how much the guide(s) or rods must be moved. If the guide(s) has to be moved it can be translated as follows (without the accessory below):

  1. Slide the edge guide against the work and clamp the router to the work. The router cannot move during the adjustment.
  2. Select a spacer of a thickness = desired translation. For example, if you'd like to move the cutter .25" away from you, put said spacer between the work and the loose edge guide. Then tighten the guide against the spacer. (A 1/4 drill, drill rod, gage block etc.)
  3. The cutter will now reach .25" from where it was.

If the goal was to produce a .50" dado from 1/4" cutter, you'd start with 2 edge guides against the work with a 1/4 spacer between the work & one of the edge guides.
In this case the cut will probably start very near .50" but its centerline may not be where you'd like it to be. In this event, we have to move the router on its rods without changing the distance between the edge guides.
To move the router (a measured amount) on its rods without disturbing the edge guides:

  1. Measure the distance between the subbase (or casting) & one of the edge guides (inside). Whilst an adjustable parallel* is the tool of choice here to get the inside measurement, a caliper or rule can suffice.
  2. Now loosen the casting screws to free the guide rods. Subtract or add width to the parallel or create a scrap cutoff equal in width to the change necessary (+ the initial gap) to translate the centerline. E.g., if the cutter requires a 3/8" translation and the initial measurement is 1.0" then the spacer has to be 1-3/8" or 5/8" depending on which direction you slide the tool.
  3. Move the bugger against the spacer and lock the casting screws.

Adjuster (Product)

The new edge guide adjuster is designed to assist in making the space adjustment between 2 edge guides for mortices, slots etc. It can also be used to translate the cutter centerline when only one edge guide is in play. Let's start with 2 edge guides snug against a parallel workpiece. To open the cutter pathway (of a mortise e.g.) you first measure the diameter of the cutter and subtract that number from the desired width of the intended cutter pathway. This number is duplicated with a spacer-feeler gage, adjustable parallel, gage block, drill rod, sheets of "Post-it" or whatever. Now you slide the acrylic adjuster up against one of the edge guides separated by the spacer.
Lock the adjuster, remove the spacer, unlock the edge guide block & slide it up against the adjuster. If you spent more than 1 minute on this adjustment you should report yourself to the metrology police for disposition immediately.
The cutter pathway will be opened precisely by the amount of the spacer. If the starting pathway is too wide, slide the adjuster against the edge guide block and lock the two intimately together. Now loosen the edge guide, place the spacer between the guide & adjuster, and lock the edge guide. This maneuver shrinks the cutter pathway exactly the amount of the spacer.

Tho not as sweet as an adjustable edge guide it is accurate to .001", fast, simple to use, and low tech, nuthin' to break. The 12mm Acrylic blank is fully machined, deburred, flat and contains 2 non-marring all brass set screws. It is sized to overlap your edge guide block and therefore will be easy to handle in use.
One size does not fit all,however; you must dictate router model number for the correct adjuster.


  1. 1 unit: $24
  2. 2 units: $40
  3. 1 unit with an edge guide or mortiser: $18
  4. 2 units with an edge guide or mortiser: $30
    (S&H inclusive with all 4 options.)

*The Starrett adjustable parallel is not part of this package.

Email pat@patwarner.com for questions or ordering information.
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Copyright © 2009 Pat Warner
Last modified: Tue Nov 11 07:06:37 PST 2014