Large Forstner bits tend to wander on me when I use them on a cordless drill. As a result, I prefer to use them on the drill press.
In this case I wanted to install two sets of 1-inch diameter rare earth magnets on the upright legs and on the folding legs of this Prie Dieu (prayer kneeler). Although the 1-inch magnets are quite strong if aligned properly, their effectiveness is reduced when misaligned. Layout of their location is critical, to get the best holding power. Therefore, I prefer to wait until I can do a complete dry fit of the upright assembly to accurately lay out the locations for the magnets.
The steps involved in properly doing the layout are simple:
- Decide how far the magnet edge will be from the folding legs’ front edge, and add the radius of the magnet. This is where the layout starts (the first photo, above).
- Using a square, draw a line on both sets of legs.
- On matching faces, measure from the edge to the point where the center of the magnets will be located (photos 2 and 3).
- Mark accurately the location on both pieces.
- Using a 1-inch Forstner bit, drill a recess 0.130″ deep.
- Voilá – the magnets will be perfectly aligned.
The magnets are 1/8-inch thick (0.125″). By drilling a little deep I can use epoxy and not worry about them protruding above the surface of the wood.