the gear to attach to the circular saw (West system or my homemade "clone") however have a disadvantage
They work fine only for sheet material of a thickness of typ. 8mm depending on the dia of the wheel.
I used this way for constructing stringers of laminated strips of 5mm ply, so I first scarfed the broad side of a whole panel, then cut it into strips. So they were immediately ready for glueing without further preparations
If you got sheet material, this tool is brilliant; if you got -say- strips of oak (I had 150 x 6mm for the keel), lay a few out on your table, clamp them with a thick plank, using additional wedges to fix the inner strips, cut it to same lenght and scarf it
Care must be taken not to drop the tool when reaching the edge; keep it horizontal until the wheel has clearly left the wood. I spoiled the first edges trusting my ears too much
OBS: my pictures had to move to http://www.dauda.at