War story...
Got a Harbor Freight (Central Machinery) dovetail jig as a gift about a year ago. Finally had a need to build some drawers. Use the jig! Open the box. Looks good. Template is heavy metal. Adjustments are a tad awkward, but ok.
The comb template has 1/2" spaces and 1/2" teeth. Instructions say to use a 7/16" guide bushing and "1/2 inch dovetail bit". I did this and ran some tests. Not even close. The pins are huge compared to the sockets.
Did the math. Turns out the 14 degree router bit I bought, is WRONG. An 8 degree bit will work correctly with the specified depth setting of
23/32" for 1/2" high pins. Or you can set the 14 degree bit depth to
17/32", but the pins will be only 1/4" high! Nice for, say, jewelry boxes of thin stock; not drawers.
Moral: If you buy the HF jig, get an 8 degree bit!
Hope this saves someone somewhere some hassle!
Cheers, Gene