This bracket allows you to clamp the speed controller of your Sherline lathe (or mill i think) directly on the motor. Then you don't need the belt guard to hold this electronics box anymore.
I did this because the belt guard (at least on my Sherline lathe) makes it a pain to remove the belt & motor every time I need to switch between normal turning and thread cutting.
Of course it is more risky to run without the belt guard so you have to know what you do when you use this.

You will need to remove the plastic "hinge plate" (Sherline #43120), drill 2 countersunk holes for M3 in it (spaced 80mm), bolt the hinge plate on the top part of the bracket (the screws will self-thread in the plastic), and put back this assembly on the electronics controller. Then clamp the two halves on the motor (with nuts in the side cavities) and you're good to go!

I attached my SolidWorks 2014 source files.