Here's the main component for the new tensioning mechanism:
![Image](https://c2.staticflickr.com/2/1605/24847262774_34925c8d02_b.jpg)
![Image](https://c2.staticflickr.com/2/1693/25537853885_df05976d0d_b.jpg)
Got some extra bolts, and replaced the tracking adjusting rod with a bolt and knob:
![Image](https://c2.staticflickr.com/2/1712/25242237740_8e4baeceaf_b.jpg)
The tensioning mechanism works real nice and I calculated that I can take up to a 50x1000mm sanding belt. So this sander can take belts that are 790-1000mm long, a span of 210mm.
![Image](https://c2.staticflickr.com/2/1536/25242247710_af56a9887f_b.jpg)
Because of this wide span of possible belt sizes, the upper and lower wheels will be in different positions depending on belt length. So I made the platen so it could be moved and adjusted for various belt lengths.
![Image](https://c2.staticflickr.com/2/1669/25537886545_2ae1b0cf2e_b.jpg)
Platen is made from a piece of angle iron that I literally found rusting under my deck this summer (some of the house builders must've left it behind) and had forgotten about. Now to paint it, I am thinking black and yellow.