Projects often call for edge-to-edge joints on long boards, but long boards can be difficult to handle on a jointer. If you don’t get a good glue edge, you won’t have a good glue joint. An easier approach for jointing long stock is using a handheld router with a steel stud as a guide.
I prefer a 1/2 in. diameter spiral bit for this operation, but a straight bit would work fine. You’ll need a piece of sacrificial material you can cut into. It should be slightly wider and longer than the boards you want to joint. Spacers are required to lift the sacrificial board off the bench. 2 in. x 2 in. work great. Grab some clamps to secure the work.
The spacer blocks are critical for this process to work correctly. You need two that are slightly thinner than the diameter of the cutter you’re using. We’ll call these bit spacers. Because plywood tends to run undersized, 1/2 in. plywood works well with 1/2 in. bits. You need another set of spacers that are slightly (1/32 in.) wider than the distance from the edge of the cutter to the edge of the router base. We’ll call these base spacers.
Position the material to be jointed by clamping one board to the sacrificial board. Place the bit spacers against the clamped board and snug the second board up against the spacers.
Push the base spacers against the bit spacers (which should still be on edge between the two boards), and the steel stud against the base spacers. Clamp the stud to the sacrificial board, which also secures the second board you’re jointing. You may need to use filler blocks inside the stud in order to clamp it.
Remember that you’ll be climb cutting on one board, so you need to be sure to maintain good control of the router. It’s OK to make the cut in multiple passes with slight increases of depth on each pass. This approach will be especially important if the edges you’re starting with are very irregular. Eventually you need the depth of cut of your router bit to be slightly greater than the thickness of the material you’re working with.
Use a shop vacuum to clean up the dust created by the cut. Remove the clamps and slide the two boards together, checking the fit of the joint. If the edges are really crooked, you may need to make the cut twice, setting everything up again using the bit spacers and base spacers. You should be able to slide the joint closed with hand pressure.