A cheap (or free) and easy solar finder

[gregl]

Here’s a quick and cheap solar finder for the annular eclipse next week and next year’s total eclipse. I made this with some foam core poster board from the dollar store that I already had in my workshop. To make one for yourself all you need is a sharp utility knife or Xacto knife to cut the board, a combination square to mark out and cut the board, a hot glue gun, and something like a scriber or awl to poke a small hole in the board.

The solar finder is self-aligning and sits on top of the OTA, held in place with masking tape.

The first step was to cut two pieces of foam core into 2-inch wide strips. The longer you make them the more accurate your first alignment will be. Mine were 9 inches long. Glue them together along the long edges with the hot glue gun, setting them at right angles to each other to form a V shape.
All cuts should be as accurate as you can make them as this will affect the accuracy of the finder.

Be careful with the apex of the V, don’t let the ends get dented as you’ll need this edge later when aligning the two sighting pieces.

[gregl]

Next you want to make a couple of pieces to fit inside the V at each end to add some strength to the V assembly. Stick them in place with hot glue.

The two end pieces need to be cut and marked as accurately as you can. The dimensions aren’t critical as long as both are the same. I marked out two pieces like the one in the photo; mine were 2 inches wide and 3 inches tall. The pencil marks were vertical along the center line, and 1 inch from the top.

I then took a scriber and poked a hole in one of the end pieces right at the intersection of the vertical and horizontal lines. This is the end that is toward the sun.

These pieces need to be glued to the ends with the vertical line aligning exactly at the apex of the V pieces. Do this by setting the V assembly on a flat surface and also setting the bottom edge of the vertical sighting piece on the same surface. You can see how I sighted along the V to accomplish this.

[gregl]

Then you’ll need to whittle away the bottom of the foam core of the end pieces so they’ll clear the arc of the scope tube.

Then I set the assembly on the scope tube and gently held it down so it would find its own alignment with the tube. A little masking tape holds it in place.

If you’re lucky when you aim the scope at the sun the dot of light that comes through the front hole will hit the cross lines at the back piece, and your scope tube should be aligned with the sun. I wasn’t that lucky but I was close. I was able to slew the scope so the sun was centered in the eyepiece and then marked the final position on the back piece of the foam core finder. I was right on vertically but a little off horizontally.

I’ve removed and re-set this foam core finder several times and by being gentle with it it has landed in the same way each time. I also discovered that taping it only midway along it’s length was a better way to insure that it settled down straight on the scope tube, giving me a free and easy solar finder.

[messier 111]

I like the ingenious side, thx.