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As part of trying to run to ground some velocity variations I am experiencing, I duplicated (or at least tried) what another CGN member did with a white plastic barrel to control how much sunlight reaches my chronograph. The hardest part was finding just the right piece of plastic. I found mine waiting on the shelf at OSH as a trash can, but I knew better:
It even works sideways!
Here is how I did it:
Set up the chrony on the tripod and set it at about head height. Put 2 of the arial rods in and then set the bucket on the top of the chrony and against the rods.
I then marked both top and bottom of the rods where they met the barrel. I then set the barrel on the bench and placed a level up against the marks. Making sure the line I drew was in line with the rod marks, I made a line from top to bottom of the barrel. 2 lines on the top and 2 lines on the bottom relative to where the barrel would sit on the chrony.
I then measured the distance between arial rods. I used that measurement to make the rod hole locations starting 3" from the end.
Lastly, I drilled the 8 holes straight through and then angled the bit towards where the rod would enter/exit on the other end. I got lucky and had all 8 holes line up the first time! I pushed through the rods and it all worked.
I now have some real good light control for the chrony. Here it is in action at the range this morning. I turned it 90 degrees away from the sun:
Hope this helps someone else.
.
It even works sideways!
Here is how I did it:
Set up the chrony on the tripod and set it at about head height. Put 2 of the arial rods in and then set the bucket on the top of the chrony and against the rods.
I then marked both top and bottom of the rods where they met the barrel. I then set the barrel on the bench and placed a level up against the marks. Making sure the line I drew was in line with the rod marks, I made a line from top to bottom of the barrel. 2 lines on the top and 2 lines on the bottom relative to where the barrel would sit on the chrony.
I then measured the distance between arial rods. I used that measurement to make the rod hole locations starting 3" from the end.
Lastly, I drilled the 8 holes straight through and then angled the bit towards where the rod would enter/exit on the other end. I got lucky and had all 8 holes line up the first time! I pushed through the rods and it all worked.
I now have some real good light control for the chrony. Here it is in action at the range this morning. I turned it 90 degrees away from the sun:
Hope this helps someone else.
.
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