Over the years I can't tell you how many people have come up to me and said "Hey I had that same idea", about our alignment tool. I am also sure they usally had that thought as they were pressing their thumb into the front spring as they tried to tighten down their back deck. Our alignment tool is very simple to use and every tattoo toolbox should have one.
The tool slides right into the tube slot in your machine, notched side up toward the a-bar.
You want to make sure the slot is lined up with the a-bar nipple, and the shelf is facing the front of the a-abar. As you can see in the illustration above, the a-bar will marry right into the alignment tool and create the perfect side to side and forward placement.
Then make sure the a-bar is both forward as far as it will go and seated in the down position. You want to make sure the a-bar is depressed when tightening the deck screw. If you don't depress the a-bar it will change the angle and you may not get the alignment you need to make sure your needlebar is square to the tube.
Then slide the tool out and you are good to go, simple easy alignment.