Shaft coupling

[Dauph]

Hi all,
I'm attempting to build a drum sander using an old drill. I attached the drill to the drum shaft using an aluminium flexible coupler. It snapped on the first test with barely any load on it.
It was cheap, and did mention 3D printers as a use, so I guess it wasn't up for the speed/torque of my plan.
I found this on Amazon https://shorturl.at/am5Wf It has no reviews but is potentially a better design that what's mostly available on Amazon
I found one that is described as "high torque" but, again, no reviews, and pricey.
Any thoughts/suggestion?
Edit: Photo is of the test set up and broken coupler

 

[ChaiLatte]

Take a photo of your setup showing the failed coupler in place.

You provide insufficient concrete information in your post to make any suggestion any better than consulting tea leaves.

 

[Dauph]

Take a photo of your setup showing the failed coupler in place.

You provide insufficient concrete information in your post to make any suggestion any better than consulting tea leaves.

Done. Please see above. Ta!

 

[Amplidyne]

Try amazon and search "Small Universal joint" Sourcing map have 10 and 12mm joints on there. Should be stronger than the spring type I would think.

 

[Phill05]

I don't think you need a coupler for that direct in the chuck as you show should be fine.