FLUKI

spark plug in one hand with the engraver in the other, under a bright

ter on each side of the electrodes,

Eleva, Wl 54738

light. My engraver vibration frequency is adjustable and I thought I

chuck for two cutters. I drilled the hole for the 6-32 set

Anyone who cleans a lot of spark

would have to turn it way up from its normal engraving setting to make

plugs knows that a plug vibrator cleaner is the only way to go to

it work well but found that it was not necessary. It seems to melt the

screw all the way through the chuck because I didn't have a bottom-tap. It works out just as well because if

break up and clean out stubborn lead deposits. A spark plug abrasive air cleaner is great for the finish

deposits away just like the pro model. The only disadvantage to my design is that it only holds one

you damage the threads on one side you still have the other side as a back-up. I was amazed and pleased how well this gadget

cleaning but it just won't take care

cutter so you have to insert the cut-

works. I hope you will be too.

By ANDREW H. BITTINGER EAA 83801 W1515 Pine Rd.

one at a time. The pro model has a

of the large lead deposits found down around the plug porcelain. Out of frustration many mechanics and owners make their own clean-

ing tools (picks) out of welding rod to break up the lead deposits. It is better than nothing but it is time consuming, hard to clean the area

Drill #35 hole for 6 x 32 tap

6 x 32 screw

Cutter

directly under the electrodes and it

increases the risk of damaging or breaking the porcelain. It's not recommended. The Champion Plug vibrator Cleaner 2600A is one solution but at around $270 it is an expensive accessory for any shop.

The good news is that you can make a vibrator cleaner for a fraction of that cost. All you will need for this homemade version of the vibrator

#41 hole for cutter

1/2"

Make cutter holder out of 3/8" bar stock

Size shank to fit your engraver

cleaner is an electric engraving tool with a removable point. In place of the point you make a chuck that holds a Champion spark plug cutting tool. My 32 year old engraver

is still manufactured by Burgess (phone 315/737-7303). Wen, Dremel and Sears have models too, but not having tried any of the other brands I can't guarantee that they will have the right vibration frequency and other attributes to work properly. The Burgess V-74R engraver is marketed as a heavy duty engraver and does seem to have a more robust design than others that I have seen. The cutter blades can be purchased for about 45c each through any of the sources that handle the Champion Vibrator. I suppose you could make a stationary mount to hold the engraver in a horizontal position like the industrial model but I find it easier to hold the SPORT AVIATION 89

By MICHAEL E. WEED EAA 240875

509 Indiana Ave.

Nokomis, FL 34275

In the September 1992 column, a circuit was described for an avionics bus relay circuit. Although a single relay version of this circuit was mentioned, it was not shown. I thought the readers might like to see a simpler and cheaper version of this circuit which employs only a single

MAIN BUS

EMERGENCY RELAY BY-PASS SWJ.

relay and diode to accomplish the same function.

When the momentary pushbutton S1 is pressed (normally open), the relay is energized and power is supplied to the avionics bus. When this occurs, the avionics bus then keeps the relay energized via the diode D1. Diode D1 also keeps the momentary pushbutton switch from carrying the full avionics bus load when it is initially pressed to energize the relay. Again, a switch may be added as a safety backup in case of relay failure as well as a fuse or circuit breaker in series with the relay. The automotive relay specified in September is one of a number of remarkable units now available. Potter & Brumfield (P&B) offers ice cube sized relays capable of carrying 70 amps of DC current with a 240 amp inrush. P&B also has a DC motor reversing relay which seems ideal for such applications as flap motors, especially if you want to use small switches (HOTAS) to activate them. Perhaps one of the mail order aviation suppliers will start carrying these devices. Another item which may be of interest to experimental types for landing/taxi and recognition lights are the MR2 midget reflector 12 volt halogen lights. These lamps are used in department store display cases and such and are available in flood and spot styles. 50 watt units are commonly available at home improvement centers and I have also seen 75 watt units. The attraction of these units is that they are only 50 centimeters in diameter (about 2") making them ideal for wingtips and wheel wells in small aircraft. I have been experimenting with one on the workbench and car, but I don't currently have an aircraft to try it out on. My main concern would be how they handle the vibration. I would recommend the use of the corresponding porcelain connector or high temperature wire with these units, as the pins do dissipate a lot of heat. 90 DECEMBER 1992

1—| * J,.

OPT. FUSE OR CB

SW2 . . .

1 .CR1 L 1N4001

AVIONICS BUS

r~

.

rf^c\ vx iw i •

I ^ r

Readers are invited to submit entries to EAA's Hints For Homebuilders, Att: Golda Cox, P. O. Box 3086, Oshkosh,

Wl 54903-3086. Entries will be reviewed by a panel of EAA judges. Readers whose hints are published in any EAA magazine will be awarded a 3/8" Drive Socket Wrench Set. Aircraft Spruce & Specialty will also award a $25 gift certificate plus a current catalog. Members are also invited to submit hints of an electrical nature. Any hint used will receive a Fluke Model 23-2 Multimeter with Holster from the John Fluke Mfg. Co., Inc. The contest will run from August through July of each year with a Grand Prize being presented by both Snap-on Tools (KR657 Roll CAB and KR637 Top Chest) and Aircraft Spruce & Specialty ($250 gift certificate). A Grand Prize will also be awarded by the John Fluke Mfg. Co. These awards will be presented during the EAA Convention. Our thanks go to our sponsors for these awards.