EAA Sport Aviation

nuts & bolts
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Calibrating Your Iron
Optimizing your fabric-covering tools
FROM THE ARCHIVES
CLAUDIUS KLIMT, EAA 11845

“The Shrinking Art of Fabric Covering” can be read online in the EAA Sport Aviation archives by visiting the EAA Members Only page at http://members.EAA.org/home

Irecently watched the EAA Hints for Homebuilders video of the iron calibration of an iron for shrinking fabric. Though I am no expert, I did try several methods of calibrating my iron for the fabric work on my AirCam. Here is what I found:

• It is difficult to find an iron that does not have all sorts of fancy features like automatic shut-off and water-vapor injection. It would be useful for you to spell out exactly what model iron meets the fabric-covering needs best. I explored the guts of an inexpensive iron and removed all the automatic features, making it a simple iron with a rheostat to control the heat.

• If you use an infrared heat-measuring device, the iron should not have a reflective surface. Some irons have a shiny silver bottom; some have a dark surface. The heat-measuring devices will not work on a reflective silver surface.

• Most important of all, if you check the temperature of the surface of an iron with a heat-measuring device, the numbers are all over the place depending on where you point the measuring device on the iron. As I understand, in order not to weaken the fabric, you must never exceed 350 degrees. It is important to make sure the hottest part of the iron does not exceed 350 degrees. If you measure the coldest part of the iron it could be 350 degrees, while the hottest part is more than 400 degrees. The same goes for the silicone system. If you select the wrong part of the iron to measure, you could get the same wrong reading.

• An interesting thing is the range of temperatures the iron goes through as its thermostat cycles through its selected temperature range. If you leave an iron on a specific heat setting, the thermostat has to drop a given number of degrees before it will turn on again. The temperature range of the iron surface goes through a large range, depending on the iron. Fifty degrees is not unusual.

For example, it drops 50 degrees before it senses that it needs to heat up again. If you measure the temperature in the trough, the maximum temperature reached at that setting is 50 degrees higher before the iron shuts off.

I would appreciate specific guidance regarding which iron to use and exactly how to use the temperature-sensing devices to calibrate the iron correctly.

Info From Poly-Fiber

We find that the Black & Decker F63D Classic provides good value for your money with acceptable performance. When using a non-contact temperature sensor, move it in a circular pattern around the heat face, which also results in a reasonable average temperature.

Irons are inaccurate tools, as Mr. Klimt rightly points out. There are many varying heat spots on the heating face. We find that a smooth motion of the iron averages these spots out and results in satisfactory average temperatures.