I needed to join two rails and checked out connectors. Wow! $32 for a pair of metal bars with holes in them. You’ve got to be kidding. Profit margin must be over 90% on that thing <end of rant>.
I stopped by the hardware store to pick up a piece of metal about 12x6 mm. They didn’t carry that, but instead (as it turned out later fortunately) had one 12.7x3.2mm. I then realized I could do better than the stock part.
I often read complaints that joined rails don’t stay aligned together. Festool warns not to over tighten the screws, in fact, boasts flat heads to prevent just that. And the connectors are about only Festool item that has bad reviews on Amazon. No wonder they can’t be secured well; steel screws dig into soft aluminum rail.
My solution is to make the connector consisting of two thinner 3.2 mm parts (see picture). The top one has threaded holes with Allen screws (M6, 6mm long). The bottom one has non through (1/3 deep) cone shaped holes that align with the screws. These holes help to fully engage the threads and prevent lateral sliding of two parts. As you tighten the screws the two pieces are pushed apart and firmly press against inside of the slot distributing pressure over large area. You can tighten them very well.
While fitting the connectors I discovered that two t-slots of the guide rail have different width by about 0.3 mm and had to file the bars a bit :-(.
I tested the setup. After joining two rails I moved, rotated, flipped, lifted by one end, and kicked them around. Checked again with a straight edge – perfect.
P.S. Festool, if you like the idea e-mail me a thank you card attached to a banknote or a green tool of your choice :-)