That shaft only looks to be about 3mm long so it will be difficult to mount the blade on the end.
I would always mount the blade around the outer case where it is between the bearings but that requires a large hole in the blade or mount see below.
that's the same motor i'm using for my spinner. aparently it gets good speed so quite a good one. i've been told that best way to mount the blade is to use a 3D printed mount. that shouldn't be too much of a problem if you have easy access to a 3D printer. good luck and remember to be careful, even when the blade isn't on spinners are still dangerous.
pre ant freeze update.
Are first test of moulding are own tyres have some how made there way on to the one the only Smart ant 1!
and wile we were at it we fixed it's major floor (other than my driving ) its speed.
smart ant 1 now has 50:1's from smart ant 2 ( which is now dead because of flail whale ) so it now has some speed to it to make uses of its powerful flipper
smart ant 3 is ready for ant freeze
we just got are motors for some nano's which will hopefully be done by aws 46
sfbb has got one of the gearboxes from sf (as one of sfbb's had broken) but needs its polycarb putting back on.
no advances on the spinner or any of the 5 other robots in the first phases of production.
Team RobotMad, home of the Smart robots, and very mean pots
Chris and Lincoln Barnes
we are putting the spinner on hold but building smart ant 4 which will be a 4 wheel drive pusher similar to smart ant 3
are nano is coming along nicely as well but it is a bit slow and because of the type of gearing in the motors we cant speed it up
so hopefully a new ant and maybe more by the aws (all nicely painted of course)
i wouldn't worry about the speed of the nanoweight. mine is very slow as are quite a few others. pushing power and/or weapon effectiveness tend to count for a lot more in a nanoweight battle at least that seems to be the case in my arena.