Dear all

I am very new to working with extruded aluminium but can see the benefits of doing so. I have drawn up plans and designs for a number of updates to my joinery workshop. I am about to pull the trigger and place my order for all the required parts and components but there is something I simply cannot fathom and really have struggled to locate much online regarding this. Basically, where can I purchase a drilling guide for 4040 Bosch Rexroth extrusion. My projects are based upon joining the profiles using the drill and tap method but how on earth do I drill the access hole perfectly accurately without some form of jig or guide. I have found incredibly expensive ones on the net but was wondering if anyone had a tip or a link to where I can get one from. Unfortunately I don't own a 3d printer but happy to pay someone to print one for me if that's what it takes. I have a drill press but without a guide or jig I just cannot see how to drill mm perfect holes to ensure accuracy. Thank you