Question: The project is to rotate a load using a motor with a varying speed between like *2000-10000 rpm*.

I'm using a **flange coupling** to attach the cylindrical tube to the motor. Since I will rotate it to high speed, I think I need to tightly and safely attach the load to the motor. 

Do you have any suggestion on what coupling or what is the best way to attach the cylindrical tube to the motor **safely**?

NOTE: the shaft and load are the same lines. this machine is about centrifugal electrospinning which is a machine to fabricate a nanofiber. 

[![enter image description here](https://i.stack.imgur.com/JsGkQ.jpg)](https://i.stack.imgur.com/JsGkQ.jpg)

Answer: 
The safest way to attach a non-symmetrical load (such as that shown in your photo) that spins that fast (up to 10,000rpm) will be to mount it to a solid base, using bearings or similar, such that its weight is supported separately from the motor shaft. This will minimise vibrations/oscillations of the load.

As a result, there will now be a slight misalignment between the vibrating motor, and the constrained load. Using a a semi-flexible coupling (jaw, Oldham, etc) to transfer the rotation will accomodate this misalignment safely without damaging the motor.

Your biggest worry should be wobble from any off-centre mass of the load, rather than the direct strength of the coupling, per se.
Normally, you would use two grub screws at 90 degrees to each other, to secure the load onto the motor shaft. I have done this to attach a stainless steel flywheel on a motor spinning at 6,000 rpm and it's holding just fine.

To give it extra strength, you can also use something like Loctite 638 to glue the flange coupling, or whatever coupling you should choose, to the shaft. This probably means the coupling needs to be metal, not plastic (although I'm sure there'll be other glues to bong plastic to metal). Note that Loctite 638 is pretty much permanent: once you've glued your coupling onto the shaft, it won't be coming off again (easily).