If you only sew with waxed canvas occasionally, there is probably no need for any special maintenance of your equipment. However, if you get hooked on sewing with waxed canvas, the waxy finish of the fabric can begin to take its toll on your sewing machine and sewing supplies. Here are a few tips for keeping your equipment in good shape when working with waxed canvas:
1) Feed Dogs: Waxy residue can build up on feed dogs and reduce their ability to feed fabric through the machine. When wax builds up on my feed dogs, I remove as much as possible with a stiff-bristled paint brush. I use a small flathead screwdriver to remove any stubborn wax that remains, and then I wipe the feed dogs with a clean cloth.
2) Bobbin Case: After a particularly epic waxed canvas sewing session (yes, that's a thing), I noticed quite a bit of wax build up on my bobbin case. I simply removed it from the machine and wiped it carefully with a clean cloth until no residue remained. I dusted out the machine using my fluffy dusting stick (the technical term, I'm sure), then oiled my bobbin case and reinserted it into my machine.
3) Sole Plate: Wax can build up in the holes of the sole plate. Use a clean cloth to wipe the wax away. You may need to employ a pin or small screw driver to get at the bits of wax that cling to the holes of the sole plate.
4) Iron and ironing board: Use a press cloth any time you press waxed canvas and make sure that the press cloth protects your ironing board, iron, and any other fabrics you are working with in addition to your waxed canvas. You should have a press cloth that is dedicated to waxed canvas, since it will oily and waxy. I just use a large piece of muslin fabric. I generally try to avoid pressing waxed canvas since the heat causes some of the wax to melt, but it can be helpful in some cases. If you do get any gunk on your iron, you can probably get it off by just wiping the hot iron on your press cloth. You can also try iron cleaner-- I think the goo type works much better than the kind that comes in sheets.
I also recommend switching your needle after every bag making project, cleaning and oiling your machine after each project, covering your machine while not in use, and getting it serviced once a year. A well-maintained machine makes for pretty stitches and happy bag makers!