If you only occasionally work with flat dowels (e.g. Lamello) and therefore shy away from investing in a special biscuit joiner for this task, you can also cut the necessary grooves for the flat dowels with your router. The cutters used for this are essentially disc groove cutters, which we supply as sets. The flat dowel cutter sets also include the matching ball bearings (thrust rings) to adjust the cutting depth of the cutter to the three common Lamello sizes (0, 10, 20).
