It seems to me Patrick that beside the bits you also need the guide box which usually comes with a dust extractor connector to attach a vacuum cleaner. Also angle grinders don't come with chucks but with a threaded spindle and two collets. You can get an adaptor which screws on to the A/G spindle and then the mortar bit screws into the adaptor. The whole thing is then shrouded in the guide box which both limits the spread of dust and protects the user from flying debris and ensures you don't stray from the joint into the brick. Suggest you Google images "mortar rake angle grinder" there's another version which uses a diamond disc which is much more like a regular angle grinder application but still needs an appropriate guide box. Without the latter you could be carving some pretty patterns in your brick work. You can also get mortar rake chisels for an SDS Hammer/drill which you use on the hammer function; they act like a conventional hammer and chisel.