Shapeoko 2 belt clamp with tensioner

Belt tensioner to be used on a Shapeoko 2 with Makerslide.
Can be used with 6mm or 9mm GT2 belt.

The following parts are used:
* A 50mm m5 hexagon head screw for tensioning end.
[RVS Paleis](https://www.rvspaleis.nl/bouten/buitenzeskant/din-933/din-933-[-]-a2-[-]-per-stuk/933-2-5x50_1) (in dutch)
* For the connection to the rail I used an 8mm m5 hexagon socket bucket head screw.
[RVS Paleis](https://www.rvspaleis.nl/bouten/binnenzeskant/iso-7380/iso-7380-[-]-a2-[-]-per-stuk/7380-2-5x8_1)