There's pine, and the there's pine. A lot of the stuff sold by the likes of B&Q (for American readers this is our equivalent of "the Borg" or Home Depot) is white pine - really meant only for wall studwork and rough carpentry and just not of joinery quality. What you need to use is joinery quality redwood (not the same as redwood in the USA, BTW), spruce, douglas fir or even alder (sold as a joinery pine replacement, but in fact a hardwood) all of which cut much more cleanly. If you persist in using non-joinery grade softwoods then the only other thing to try might be HSS cutters as opposed to TCT. HSS can take a far sharper edge than TCT and will often show less signs of tear-out on soft, stringy softwoopds = but beware, it burns easily and the edge is really short lived!
BTW if you rout a cross-grain trench (housing) that close to the edge then the short grain between the edge of the material and the groove wil invariably crumble away at the first sign of stress or loading. Try to groove in the direction of the grain and at least the same distance in from the edge that the groove os wide for better di=urability and smoother sliding of components (as it will be with the grain)
Last edited by Job and Knock; 06-28-2017 at 04:35 PM.