Thanks for contacting us. The Bridge City HG-4 Honing Guide is able to achieve a 20~35-degree angles so it wouldn't be capable of performing 12-degree angles. For this you would need either a third party jig or other guide that is designed for achieving 12-degree honing angles.
Please let us know if you have any questions on this or need any assistance in the meantime.
Thank you and have a great day!
HARVEY INDUSTRIES INTERNATIONAL, Inc.
888-211-0397 | 10832 Ada Ave., Montclair, CA 91763
Does Bridge city have a honing guide that can set the plane blade to 12 degrees for a low a low angle block plane?