The Content Of The Article:

Drilling holes in series at a constant spacing is a tedious exercise. Very simple to perform, this system will make you many services. A ripper, a clothespin, a few scraps of metal, and voila!

Text and Photos J. Petit-Jacquin

Practical advice

Ensure accurate centering and alignment during assembly, welding, and drilling. A small initial error will increase as the work progresses. Hence the need to resort to a martyr for soldering irons on the tubes. A circular clip ensures the transmission of the downward movement printed by the nose of the clamp to the vertical rod. His teeth are lodged in a groove machined on the steel rod.

Accessories intended to facilitate serial drilling are often imperfect. Main complaint: they do not allow to freely adjust the spacing between the holes (step).
● Our guide to mount on the soleplate of the router allows to accurately postpone a given step. You will be able to use the abundant hardware and accessories of furniture manufacturers kit for your personal projects. The adaptation also allows to choose at will the diameter of the holes and their spacing for any construction requiring perforations rigorously aligned with a constant pitch (the installation of adjustable shelves, for example).

The sliding cradle

At the rear of the machine, two steel rods (Ø 8 mm) 25 cm long fit into the holes in the soleplate, instead of the side guide slides. They support a cradle placed in the axis of the router. It is made with two parallel tubes (Ø 9 or 10 inside) 10 cm long, connected by two flat irons (15 x 3 mm) welded well square at the ends. These two legs support a wooden plate on which is fixed a spring lever device raising and lowering a steel rod of the same diameter as the mill (here 5 mm).
● Moving the cradle on the slides will set the pace, while the vertical rod will lock the system during drilling. Pressure on the back of the clamp raises the rod and moves the router. Sliding on the surface, and pushed by the spring, the rod automatically engages in the previous hole when it is exactly in line with the next hole. The machine is thus ready to perform the new drilling according to the determined step.

Precise landmarks

The use of this accessory does not pose any difficulty. Attach a ruler parallel to the drill line with clamps and bring the cutter over the point chosen for the first hole. Trace a pencil mark at the front of the router sole. Then mark with precision several marks spaced according to the step chosen for the spacing of the holes, axis in axis.
● Drill the first hole, then move the router to the next mark to drill the second, and so on until the first hole in the series is under the cradle.
● Stop the machine and lower the cutter into the last drilled hole. Slide the mobile cradle until the spring pushes the vertical rod into the nearest hole. Lock the two screws of the cradle on the slides: the step is set.
● The sequence of operations connects three movements: disengage the vertical rod; push the cradle-router assembly in the direction of work, until the rod engages in the next hole; finally, press the ripper to drill a new blind hole.

Deburring and aligning the tubes

Deburring and aligning the tubes

The tubes for sliding the cradle align themselves on the steel rods. It is necessary before deburring them carefully with the file "tail of rat" (round file).

Cut and adjust flat irons

Cut and adjust flat irons

Cut two flat irons and place their ends on the tubes. With the two slides locked in the soleplate of the machine, adjust the squareness of the flat bars on the tubes.

Weld the legs

Weld the legs

A press made with two drops of plywood tightened by four nuts allows the welding of the legs. It avoids modifying the alignment and spacing of the tubes.

Drill and tap holes

Drill and tap holes

In the working position, the irons are oriented downwards. Two holes (Ø 5 mm) are drilled and tapped in the middle of the tubes so that the accessory is blocked on the slides.

Drill the passage of the vertical rod

Drill the passage of the vertical rod

Locate the center of the cradle, in the axis of the cutter. Then point accurately before drilling the hole of passage of the vertical rod on one of the flat irons (Ø 5 mm).

Block the rod

Block the rod

The spring holds the half-clothespin on the wooden support. It is pierced at one end for the passage of the rod. Under the nose of the clamp, the locking clip of the rod.

Locking rod at rest

Locking rod at rest

On the underside of the cradle, the locking rod at rest is clearly visible. When moving the router, the nipple retracts into the thickness of the flat iron and wooden support.

Align the router perfectly with the guide ruler

Align the router perfectly with the guide ruler

When drilling holes (9 mm deep), the router must be perfectly pressed against the guide ruler to ensure hole alignment and even pitch.


Video Instruction: Mobile drill guide for perfect holes?