Timer for dynamic braking circuit.

Hi all
This is my first post so if I make any newbe errors please forgive me.
I am starting a dynamic braking system project for my metal turning lathe. and i require a timer to turn off the braking power to the motor after about 3 seconds. I intend to use a 555 timer for this job But the output is to low for the relay,I need 500ma 12v It seems I need a transistor to handle the extra power. and this is the limit of my knowlage.
So my problems are.
What transistor?
How to connect Do I need a base resistor ETC.

Thanks in advance. Brian.

Welcome to the forum, Brian.
Like this, perhaps?

The 2n2222 is a good choice, if you cant get one a bc337 is very similar (just a plastic package version).