For Kapex, the straight 36mm hose is the best (most CFM, which is what you need).? You can use the 36 on a random orbit if you really want with a hose adapter like these:
The challenge with the bigger hoses is that they are heavier and stiffer.? It's harder to use a random orbit sander and ensure that the weight/stiffness of the hose does not pull/tilt the sander down.? Maneuverability is much more difficult.? The straight 27mm hose (or a 27/32) is much easier to handle for a random orbit.
If you wanted only one hose, the 36/32 hose is larger and has much higher CFM than the 27mm variants.? It tapers down to 32mm on the last third of the hose length and is more flexible/lighter than the straight 36mm, but still not as easy to use with a random orbit as the 27mm variants.? You can still use the adapter for connecting to a random orbit.
The 27mm variants all have the small diameter squeeze on connector on the end.? The 32 and 36 variants have a larger opening where you can attach different adapters if you need.
For random orbit, I generally run the Festool extractor at about 50-60%.?? If you are using a 400+ grit sandpaper, you will probably want to turn it down to 30-40% (as the 400 grit has a much tighter seal with the wood).
If I am using a Rotex sander in "Rotex mode", I generally want to turn up the extractor to 100% speed because you really need it at that point.? Since the rotex pad is spinning as well as orbiting, you don't have the suction problem with the wood that you do with a normal random orbit.
I have all 3 hoses in my collection and use all of them in different scenarios.
-Aaron
