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"Finger Joints" can mean two things in woodworking because the media can't seem to standardize the names. To me, a finger joint is comprised of long tapered pins on the end of two boards that when assembled with glue, form a longer flat board. The other joint, to me, is square pins and equal sized square spaces between these pins, cut into the ends of two boards so that when they are assembled together they form a strong corner joint, as used in box building. In either joint, the cuts must be made with close tolerances so that the two pieces will fit together properly I'm asking which joint you are trying to make because the two joints are frequently called the same thing.
If trying to use a router bit in a router table to cut either of these it is frequently necessary to use feather boards to hold the stock against the fence and table so the cuts can be made accurately. Very careful positioning of the blade or bit as well as the wood is necessary when making the repeating cuts needed for longer joints.
Others will be along soon to also try to help. Your English is fine. I just need a better explanation or a picture to see better what you are trying to do. You should be able to post a picture if it's on your computer. Click on "Go Advanced" at the bottom of your post, then follow the instructions to add the picture from your computer to the end of your post.
Central North Carolina