Hi all, Ive just finished build a hog using butt joints but im not too happy with it so i have decided to router the sides to be more precise. Would a depth of 5mm be sufficient or is it 9mm to be half the thickness?

half the thickness is excessive. most routers I have used have had 3mm steps on the depth gauge so either 3mm or 6mm (though you would probably have to do two passes rather than 6mm in one go).

Thanks all :)

I guess it depends on the design but I've never had a problem with just butt joints and loads of screws and generous use of titebond 3. They are cubo subs though which are very well braced for their size.

Well that bit would work for edges of a sheet but if you are doing more than a few cuts (especially repeat cabinets) most people make a jig and then use a a collar fitted to the router to control the motion through the jig. There is no bearing on the cutting bit, it is just a straight cutter of appropriate diameter. This then takes care of all the external and internal rebates on a sheet with one pass. Typically you'd rebate both side panels and then slot the rest in + fix.

If you only have a few cuts to make I'd probably use a collar with a straight edge guide, or a straight edge clamped to the board that I could then run my router base down. Still a non-bearing straight cutting bit though.

Can anyone point me toward good guide for rebating out joint for speakers?