2020 T-Slot Extrusion Joining Plates

This is a set of joining plates for 2020 aluminum extrusions. You can buy them just about anywhere in aluminum, but printing them is a lot cheaper, so you can use more of them for more strength.

They’re a drop-in replacement for any comparable aluminum plate (Remember, however, that they are still plastic parts, and even at 100% infill, they still won’t be as strong as an aluminum part– but for most low-heat, low-torque applications, they should be fine).

I’ve modified the standard design of these plates for 3D printing. Their sides are filleted, so they won’t come off the printer with ringing, even with a direct drive printer. I’ve also given the top and bottom slight fillets so that if your initial layer height is slightly low, you won’t get bulging on the edges. This also makes the plates easier to get off the build plate. Before you print the ones you need, try just printing a single 2-hole plate to make sure your print settings are correct.

These plates are compatible with both button head and countersunk M5 screws. I used 8mm screws with no trouble, but I think 10mm might be preferable. You’ll also need some M5 T-nuts. The countersunk screws sat flush with the plates in my tests; try messing around in your slicer if they bulge out for you. If you’re using button head screws, attach them from the bottom (flat) side. Despite the chamfer on the opposite side, they should work fine. If your application applies too much pressure for them, you should probably be using metal joining plates anyway.

I’ve left the Fusion360 file if you want to modify them. If you find a problem with them, please let me know so I can update the Thing and credit you. 🙂