8 



Constructing the LWI and Rain-intensity Pen Arms 



Materials 



(!) 30 cm flat strip of 0.5 mm x 6.0 mm brass stock (obtainable at 

 hobby shops) 



(1) 30 cm flat strip of 1.0 x 6.0 mm brass stock 



(2) Universal Series 39 disposable snap-on felt tip pens 

 (Graphic Controls Corporation, 2 Springdale Road, Cherry 

 Hill, New Jersey 08003, U.S.A.) 



(1) length of 18 gauge solid core copper wire 

 (4) screws 



Instructions (refer to Fig. 8) 



1. Fashioning the pen arms 



a. Cut an 8.5 cm length of the 0.5 mm x 6.0 mm brass stock to 

 fashion into a pen arm for the 12 V relay. 



b. Cut a 9.5 cm length of the 0.5 mm x 6.0 mm brass stock to 

 fashion a pen arm for the 6 V relay. 



c. Prepare each pen arm as follows: 



(1) From one end of the brass stock, twist a 1.5 cm length 

 90 degrees (a). 



(2) From the other end, use a file to narrow a 2.0 cm length 

 to 3.0 mm wide (b). 



(3) Crease the center of the remaining stock slightly to 

 add rigidity to the pen arm. 



2. Attaching the pen arms to the relays (c). 



a. Drill two 2 mm holes, spaced 4 mm apart, through the 

 twisted 1.5 cm end of the brass stock. 



b. Drill two corresponding holes in the metal plate of the 

 relay. 



c. Secure the pen arm onto the relay plate using two 2.0 mm 

 lengths of the 18 gauge solid core wire. 



d. Rivet the pen arm in position by flattening the wire 

 lengths into the holes with a hammer. 



3. Preparing the gap-adjustor bracket (repeat for each relay) 



a. Cut a 7.5 cm length of the 1.0 x 6.0 mm brass stock (d). 



b. Measure 4.0 mm from each end of the stock and mark. 



c. Drill a 2.0 mm hole at one mark and a 3.0 mm hole at the 

 other mark. 



d. From one end of the stock, mark-off 2.5 cm and 5.0 cm. At 

 each mark, bend the stock 90 degrees (e, f). 



e. The adjustor is attached to the relay by threading a screw 

 through the 3.0 mm hole to the bottom of the relay (e). 



