Spin tool being weird.

I’m trying to bend a cylinder to form a smooth 90 degree angle by using the spin tool and I get this instead:

I thought I was just placing the cursor wrong, but the problem seems to scale up regardless of where I put it.

I just want to make a 90 degree bend like a pipe joint. So, what am I doing wrong?

You need to ensure that the scale for each axis of your object are all the same. You can see the scale value for each axis by opening the Properties panel (shortcut N) and look in the transform properties in object mode.
If you scale an object in object mode this will affect the scale value, if you scale in edit mode it won’t.

You can clear the axis scale by selecting your object in object mode and use Ctrl+A / Scale. If you now try to spin your object you should get the proper result.

Ah yes, thank you. That feels obvious now. Ehehe.