YO3BN - Homemade Insulator for Antenna Guying

Last edited - 30th April 2017

Homemade Egg Insulators

I have decided to build my own strain insulators or egg insulators because I found very difficult to procure them at a reasonable price here, in Romania. Egg insulator is priced at 17-18 RON per unit at a local shop, while I managed to make my own insulators rated at 4-5 RON per piece, including all raw material and production process.

My idea was to use some kind of clay which can be molded, then hardened somehow. After all that, a protective coating should be applied against UV and moisture. So, after some research I found FIMO clay suitable for this task. A pack of FIMO Professional 85g costs about 10 RON. I managed to build four egg insulators from a single 85g FIMO packet. The protection paint becomes optional beacause FIMO clay hardens as a plastic mass not as a concrete as I thought.

Building process is quite simple, the steps are:

Modeling
Baking
Milling
Coating

Raw Materials

The raw materials are:

FIMO Professional White 85g
KOBER UV Protective Lacquer for Stone

The FIMO packs were bought from emag.ro priced at 10 RON (without shipping costs).
The KOBER lacquer was bought from Dedeman, priced at 13 RON (without shipping costs).

The Modeling

The modeling is the hardest part of the entire process. It will take up to 5 minutes for each insulator piece on average. First, the FIMO pack is cut into four equal pieces. Each chunk of FIMO should be warmed between palms before being molded. Warning, FIMO loves dirt and pet hair, therefore hands should be very clean. Then it must be molded as an egg with a bit of rectangular shape. I used two wire hooks in order to shape the holes and their channels through FIMO blob. Sometimes, at this point FIMO becomes sticky therefore it should be left to cool down several minutes with the two hooks into it. After the hooks are removed a final reshaping is done.

Cutting FIMO as 1/4 chunks:

Wire hooks:

Final shape:

Oven Baking

After that boring modeling comes the easiest part, but the most critical. FIMO must be cooked into oven at temperature 110 ℃, at least one half an hour. The baking time is not so critical but the temperature does. In general, the thicker the shape, the more baking time. You could easely under or over bake your FIMO shapes if the temperature or baking time is not correct. If the baked shape is crunchy and it breaks, is under baked. If the shape is darker than the original color or is melted it was over baked obviously.

My oven does not have a precise temperature control, otherwise it has an analog scale on which temperature was chosen somewhere in between 100 and 150 ℃, and baking time was 1h - 1.5h

NOTES:
During the baking process, fumes were produced, so the room must be well ventilated.
The white color changes to a creamy white-yellow one.

The Milling

Probably the fastest and nicest part of the entire process is to carve wide channels through cooked insulator. For this task, a mini drill with a grinding bit was used.

Coating

This task is a bit complicated, because the piece must pe coated entirely without virtually touching it. Shapes were hanged with sewing thread and they were coated with protective lacquer using a small brush. They were left to dry about 12 hours then another layer of lacquer was added.
Uncoated vs. Coated one:

The final result

Lifetime

I hope they last long enough. At this moment I have no information about how long they last, but I'll update this section accordingly.

73 de YO3BN