Photo 1 above shows trap off, snake disconnected from machine and hanging out of drain.
Photo 2 shows new tool [boot] installed. Snake cable is inside and the drain is now sealed. Ready to fill other bowl and check to see if open.
Photo 3 note the support pipe to cabinet floor.
From a previous page I showed a jet assist tool... Now suppose your snaking a drain, you have taken the trap apart and have run in 3 cables should be enough footage per the piping layout. The photos below. Show a new tool I made on 1/28/2011. This tool allows you to seal off the open drain outlet leaving the snake inside. Filling the other bowl and draining to see if open properly. If not working properly, open the boot, couple on another cable and go in [down stream] further. Boot it again and try it. If open properly run water down the drain a couple of times from the second bowl. Result automatic snake washing. Note: the trap was only taken off and put back once. A little more difficult when you don't have the 2nd bowl, but you could connect a hose to the boiler drain to try the drain and wash the snake. Again this is not a tool for a stupid users !!! These tools are meant for the trade not for the inexperienced. Take notice to the support pipe, the boot does get heavy when filled.