Do-it-yourselfers know the problem: With wood connections - across corners, flat to flat, in a "T" or at an angle - an annoying screw head is often seen at the end.

The alternatives are wooden dowels and glue, but they are usually less stable.

Or you can use the “Undercover Jig Set” from Wolfcraft (from 29.95 euros including shipping costs).

In the green case there is a so-called drilling jig, a guide for the special drill with an extra-long screwdriver blade that is also included.


Jig set

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The approach of the “Undercover Jig Set”: drill diagonally through the boards to be connected, screw in and cover the hole with a wedge-like wooden dowel.


An application example: It is therefore important to create a T or corner connection on a shelf without screws being visible on the outside.

You set the drilling jig to the thickness of the shelf board (this goes from 12 to 38 millimeters) and fasten it with a screw clamp on the underside of the board - where the connection should be made.

The step drill provided is clamped in a drill, the depth stop is set up and the wood is drilled at an angle.

That works well with a cordless drill.

However, the holes are less likely to tear out if you work with a higher-speed 220 volt drill.

Either way: The drill guide is precisely specified by the drilling jig.

Be careful with soft wood

Two holes can be drilled neatly next to each other at a distance of 2.5 centimeters.

In the case of a shelf, the holes should be a little further apart.

The gauge must then be positioned two or three times.


The result: holes at the same distance from the board edge with the same angle.

The exit holes are on the center line of the board front edge.

The entry holes in the other board are just small.

Because the tip of the 9.5-millimeter step drill is strongly tapered so that the screw has something to grip later.

With the long screw bit, both boards can now be screwed together safely and firmly.

If you want it to be even more stable, you should also use wood glue.

Then you put the supplied, sharpened wooden dowels into the hole.

Small edges can be leveled with sandpaper.

If the dowels and the shelf are the same color, hardly anything can be seen of the connection.

The “Undercover Jig Set” still has room for improvement: the jig slides on the wood.

A braking surface would be helpful.

And the supplied screws are countersunk screws.

Anyone who fiddles too hard with the cordless screwdriver will quickly turn the screw completely.

With softer spruce or pine wood, this is faster than the do-it-yourselfer can say "hearing ear".

The hole can then no longer be used.

If you want to avoid the risk, it is better to use screws with a washer head.



The set is well suited for a quick wood connection where you shouldn't see the screws.

It is also the right tool for quick and clean repairs - for example with a rickety closet.

This is faster than with wooden dowels.

This article was first published in February 2021.