Part G : Methods and Materials

Instructions for Building a UV Radiation Chamber

I.   Appendix IV:  Instructions for Building a U.V.
     Radiation Chamber designed by David M. Hill,
     Physics, Kansas State University

     The radiation chamber used in the 1988-1991 NSF genetics workshops is an effective, economical, 
easy-to-operate piece of equipment. Microorganisms, seeds,insects, small plants and
 small vertebrates readily fit inside the box, and the exposure time to uv radiation 
is conveniently controlled by the hand-operated shutter. Valid experiments producing 
quantitative and qualitative results can be performed by Middle and High School students 
within a 50 minute class  period.  Thesequalities make the radiation chamber ideal equipment
 for middle school and secondary science teachers.

     As this equipment is not available as a commercialproduct, instructions for building
 this specialized boxare included for those persons needing another radiation
chamber.  This is an easy project that can beaccomplished with a minimal to moderate amount of
woodworking experience.  The materials needed are listedin Tables V-VII and the directions
 are outlined in steps A-J. 

     First, get all the wood pieces listed in Table V,the hardware listed in Table VII
 and have access to toolsand equipment listed in Table VI.  Remember that "Number
of boards" and "Number of items" are for 1 box only. Multiply these columns by the number
 of units you want to build.  If you are constructing several boxes at the same
time, a jig will prove helpful during the initial process.

                      Table V.  Wood Needed For Each Box
 Type of Wood              Size                 # of boards       Name of Item

 1/2" Plywood              20" x 11"                   2            Top & Bottom

                           19" x 10"                   1            Shutterplate

                           20" x 12 1/2"               1            Back

                           13 1/2" x 10 1/2"           2            Sides

                           18 15/16" x 9"              1            Door

3/4" Pine                  19 x 4 1/2"                 1            Front

                           8 1/2" x 3/4"               2            Reinforcements

                           3" x 1"                     1            Stop on

                           18 7/8" x 2"                1            Baffle

1/4" Round                 1/2" x 1/2" x 8 1/2"        2            Door

1/4" Masonite              10 x 11                     1            Shutter
* The shutter opening is another essential cut on thefront panel.  This cut should
 be a total of 10" in lengthand 9/32" deep, beginning 6" from the left side and
ending 3" from the right side.  See figure 18.

      Table VI.  Tools & Equipment for Building Box
Table saw - if cutting major pieces of wood yourself

Band saw - cutting shutter & fitting

Saber saw - Trimming aperture in shutter plate

Drill press - bit for shutter plate aperture - 3"
              bit for indicator plug - 1/4"

Hand-held drill, screwdriver, hammer, pliers and file,

         Table VII.  Hardware Needed for Each Box

            Screws 	    	 Size          # of items       Functions        
                                 #7 x 1/2"          4        2 - attach light fixtures
                                                             2 -attach door pulls

                                 #4 x 3/8"          8        attach hinges

                                 #7 x 1"            4        fasten top to rest of box

                                 #6 1 1/4" long     1        pivot point for shutter

                   Nails         4-penny finishing  26-30    holds the box together

                   Brads         #17 x 3/4" wire brads   14   fasaten 1/4-round and
                                                              reinforcements inside box

                   hinges        1" - 2"            2        attach door to
                                                             front panel

                   door pull     4 3/4"             1        facilitates raising door

                   magnetic      small              1        keeps door closed 
                   latch                                     during radiation

                   fluorescent   18 1/8" x 2 7/8"   1
                   light fixture
                   U.V. germicidal  15 watt G15T8   1        provides U.V. radiation
                   lamp             18" med. bipin  

                   Lucite rod    1/4" diameter,     1        indicates light
              1 1/4" long

In addition, use wood glue, wood putty, sand paper & black spray paint to construct and finish the box

   Step-by-Step Procedure for Building a Radiation Box

    A.   Attaching sides and back to bottom

         1.   Glue the back on the bottom keeping the
              edges straight and flush, then nail pieces
         2.   Glue each side to the bottom, aligning
              edges and nail.  Then attach each side to
              the back.
         3.   The corners will match if all edges have
              been straight.  The sides and back sit on
              the bottom giving a total height of 20"
              for the  sides and 19" for the back.  See figure 19.

    B.   Attaching door rests and reinforcements,
         starter holes for the magnetic
         1.   Place the  door rests  (1/4" round) on the inside
              surface of each side, 1/2" from the front edge 
              and 8 1/2" high from the bottom.  See figure 20.
         2.   Using glue and brads, attach the quarter
              round so that the round surface is turned
              toward the inside of the box. 

         3.   Draw a line across each side 8 1/2" from
              the bottom on the inside and 9" from the
              bottom on the outside.
         4.   Glue the reinforcements directly under the
              8 1/2" lines on the inside and secure the
              reinforcements by nailing brads under the
              9" line on the outside of the box.
         5.   Place the door against the rests and
              measure approximately where the magnetic
              latch will be attached.  
         6.   Drill 2 starter holes in the bottom to
              facilitate later installation.

    C.   Cutting and attaching the shutter to the
         front panel

         1.   Mark the masonite
              as indicated in the drawing.  See figure 21.  
              Saw along designated lines and trim rough edges
              with a sander.

         2.   Drill a
              hole for the screw 3/8" from the bottom
              and 3/8" from the left side.  See figure 22.

         3.   To check for fit, drill a hole (3/8" from
              the left side).

         4.   Insert the screw holding shutter the front panel
              and move shutter back and forth through the opening.
              See figure 23.  If some area fits too tightly, remove 
              the shutter and sand the area until movement through
              the opening is easy.  Do not forget to round the corner 
              nearest the pivot point.

    D.    Cutting shutter plate and attaching inside
          the box

         1.   Mark two dots on the shutter plate, each   8 1/2" from 
              the side edge and 5" from the front and back edges.  See figure 24.

         2.   Using a special bit, drill a 3" hole at each dot.
              See Figure 25.

         3.   Using a saber saw trim aperture to make a dome
              edged cylindrical opening, approx. 6"in length.
              See Figure 26.

         4.   Glue and nail shutter plate inside the box. 
              Reinforcements and door rest hold shutter
              plate at correct height.  Lines on the
              outside of box designate the bottom of the
              board and nails are used 1/4" above the

    E.   Attaching front panel, shutter stop and guide

         1.   Using glue and nails, attach the front
              panel with the shutter to the box.  Fit
              should be tight, use a hammer to align the
              edges of front panel with the sides of the

         2.   Close shutter and glue a stop on the
              shutter plate.  See figure 27 and figure 28. 
              This stop will prevent the shutter handle
              from being pushed inside the opening.
         3.   Pull the shutter out until the aperture is
              exposed then glue the guide on the shutter
              plate.  The guide helps keep the shutter
              in the proper place.

    F.   Preparing box to be painted

         1.   Using a punch, sink all nails and fill
              with putty.
         2.   Fill all major wood gaps with putty.
         3.   Sand all rough edges and putty filled
              holes until smooth.  Run your fingertips
              gently along sides and edges to check for
              unfinished edges.
         4.   Let the box sit over night allowing the
              glue to dry.

    II.  Preparing the top and the door
         1.   Glue and nail the baffle beam to the lid.  The baffle will be 1" from 
              back of the lid and placed to leave 9/16" to the edge of the lid on
              each side. See figure 29.  The 2" extending downward inside the box
              effectively blocks the U.V. light waves and the opening provides
              necessary ventilation.

         2.   Draw guide lines at 8" and 11" from one
              side of the door.  Glue and nail (use
              brads) the stop between these lines at the
              top of the door.  See figure 30.
        3.    Check the fit of the door.  Use a sander or joiner to trim the door 
              if necessary.  It must not fit too tight as wood can change size 
              depending on the humidity.
         4.   Putty all holes and sand edges until
              smooth.  Let the top and the door set

 A. Final preparation preceding painting

    1.   Using a course file about 1/4" wide, file a rectangular opening
         about 3/16" deep in the top of the left side of the box.  This
         opening holds the cord from the light fixture.  See figure 31.
         Placement may vary, but putting the hole at the center works well.

    2.   Remove the dowel pin and the shutter to
         facilitate painting.

 B. Painting the pieces

    1.   Use flat black paint on the inside to
         retard radiation and reflection.  Use two

    2.   Use two coats of paint on the outside of
         the box also.

 C. Finishing touches

    1.   Test light fixture using a fluorescent
         bulb.  Center the fixture on the inside of
         the lid and secure with screws.

    2.   Reattach the shutter with the screw.  

    3.   Pull the shutter out until the aperture is
         completely exposed and glue a stop on the
         shutter.  This stop indicates the aperture
         is completely open.

    4.   Place the lid on top, measure and mark
         screw sites and drill guide holes.  Screw
         lid firmly in place with 1" wood screws.

    5.   Using 1/4" bit drill a hole in the front
         panel about 4" from the left side and
         about 3" from the top.  Insert the 1/4"
         lucite plug light indicator with sanded
         end extending about 1/2" from panel.

    6.   Install the magnetic latch on the left
         side, using starter holes drilled in step

    7.   Attach door to front panel with hinges
         placed about 1" from outside edge.  See
         figure 32.

    8.   Center and attach door pull on the bottom
         of the door.  See figure 32.

    II.  The radiation chamber is complete
         after it has been plugged into an
         outlet and the light indicator
         confirms the u.v bulb functions.

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Last updated Friday July 11 1997