Spectrometer Fabrication


Personal Safety

The following personal safety items will be needed at various stages in the fabrication.


Only small hand tools are needed to make the Aruna-1 spectrometer components. The following list of tools are suggested. Consumable materials are given in the parts list.

Component Fabrication

Base Plate

Select the appropriate base plate length which is best suited to your near vision. Hold up a printed page close to your face, and find the closest distance at which the print is clearly in focus. Select the base plate length which is less than, but within two inches of your closest distance of near focus.

Cut the spectrometer base plate blank of appropriate length, 6", 8", or 10", from the stock material using a saw. A small handheld hacksaw works perfectly fine, and, with patience, you can make a very straight thin cut. The recommended wood product is a 2" x 36" x 1/4" baltic birch strip, however, any similar width and depth hardwood strip with a reasonably flat surface should work well. Once the blank is cut, check the edges using a carpenter's square. The front edge of the base plate to which the slit plate will attach should be flat and square with the edges. Use sand paper (150 grit) to make flat and square the front face of the base plate blank. It is not as crucial to square the back edge of the blank, but, for cosmetic purposes, you may want to clean up the back edge as well.

Examine the sides of the base plate blank to decide which side should be top, and which side should be the bottom. Select the better quality surface for the top side, the side on which the other components will mate. Once selected, we mark the orientation of the base plate blank by beveling the bottom back edge of the base plate using sand paper. Lightly sand the top and bottom faces, and the sides of the base plate blank using 150 grit sand paper, to obtain a smooth feel to the surface. Then, wipe the blank clean of dust using lint free cloth or paper. You are now ready to mark the drill pattern.

Obtain the appropriate drawing pages for your chosen length base plate. Using a ruler and pencil, mark the positions of all of the mounting holes shown on the drawing(s). Try to achieve about 1/32" accuracy in marking the hole positions. Once the hole positions are marked, you can punch a shallow guide hole using a sharp point, such as the end of a nail, and lightly tapping with a hammer. The guide hole helps to position the drill bit for drilling the initial pilot hole.

A marked 6" base plate blank, ready for drilling.

Place the marked base plate blank on a scrap wooden piece with a flat surface, such as a piece of 2"x6". Start with a 5/64 drill bit, and drill pilot holes for all of the marked holes. For the base plate, every hole on the top surface is a through hole, and the holes on the front end, for mounting the slit plate, should be drilled to at least 1/2" depth. Follow the drill table specifications for the hole diameter, given in terms of the drill bit size, and hole depth. The hole number in the drill table corresponds to the hole number on the corresponding drawing. From the 5/64 size, gradually increase the drill bit size to enlarge the hole in steps, until you have drilled the specified bit size.

After all holes have been drilled to the proper size and depth on the base plate, use very fine 220 grit sand paper to smooth all surfaces and remove any burrs from the base plate. Also use a thin round metal file to smooth any roughness inside and around the holes. Wipe the base plate clean with a lint-free cloth or paper. The base plate is ready for painting. We recommend fabricating all parts before painting, since several parts may be painted at the same time.

Grating Holder

The individual pieces for the grating holder. Clockwise from top left (refer to drawings): piece A, piece C, pieces D and E, and piece B. The finished pieces are ready to be glued together to make the holder.

Refer to the grating holder drawings. Using a small hacksaw, cut two pieces, 1 1/2" long from the same 2" wide wood stock from which the base plate was cut. These are pieces A and B of the grating holder. Sand the top and bottom edges (2" sides) of these two pieces, as needed, to obtain flat square edges. Use the carpenter's square to judge the flatness and corner angle with respect to the side edges. On piece A, choose the bottom edge as the one which has the best flatness and is square with respect to the sides, since this side will mate with the base plate. Mark the two mating holes on the bottom of piece A using a ruler and pencil, punch guide holes, and drill the holes to specified bit size and depth indicated on the drill table. Once again, start with a 5/64 bit to make a pilot hole. Small centering errors on the pilot holes may be corrected as the holes are enlarged to their final size.

The remaining pieces of the grating holder, C--E, are cut from the 1/8" x 1/2" x 24" wood strip: piece C is 2" long, and D--E are 1 1/2" long. Sand the edges of these pieces to remove any irregularities from the cuts. A picture of all five pieces, A--E are shown above. The pieces have been lightly sanded, and the outward facing edges have also been rounded, using sandpaper, for a nicer look and feel. The pieces are ready to be glued together as shown in the grating holder drawings, page 2.

Left to right: piece C is glued to piece A, then, piece B is glued to the other side of C. The side pieces, D--E, are then glued. A C-clamp applies pressure to the pieces while the glue is setting.

On piece A, draw a line on the inside edge, parallel to the bottom edge, and 1" above the bottom. This line will mark the edge of piece C, which is glued to A, as shown above. Ordinary glue, like Elmer's school glue works well, but if you want a stronger bond between the pieces, you may use a carpenter's wood glue. A 3" C-clamp, with flat wooden pads attached to the ends of the clamp using double-sided tape, is useful for holding the pieces together with a little pressure while the glue is setting, making for a stronger bond. After about one hour, remove the clamp and glue piece B to the other side of C, being sure to align the top and side edges of A and B. Clamp as shown above. Finally, the side pieces, D and E are glued and clamped to the grating holder. Center the side pieces on the edges, and flush with the top of the grating holer. Allow the glue to set for 24 hours. The completed grating holder is then ready for painting, as shown below.

The completed grating holder, ready for painting.

Slit Plate

Slit plate blank, 2" wide by 3 1/4" tall by 1/8" thick, cut from aluminum plate. The blank is ready for marking and drilling.

Mask Plate

Mask plate, marked with drill and cutout pattern.

Drilled and cut mask plate, ready for sanding and painting. The two mounting holes on the bottom of the mask plate are not visible in this picture.

Top Plate

Top plate, drilled, sanded, and ready for painting.

Hand Grip


Completed 6", 8", and 10" base plates, after painting.

Completed slit plate, after painting.