- Screw holes are best pre-drilled with a pilot hole using an HSS or wood drill bit and Kedel always countersink for the best finished appearance on their own products.
- It is possible to get away with not doing this, but it makes screwing more difficult because of the schaf which may melt and build up under the piece being attached inhibiting closing of the gap underneath as also immediately under the screw head. The finish will also not be so aesthetically pleasing as the head is therefore likely to protrude a little.
- A low drilling speed is recommended to avoid melting which may inhibit the travel of the drill bit.
- Sharp tools are strongly recommended.
- Again, sharp tools are strongly recommended to avoid excessive build up of heat which could melt the recycled plastic and inhibit the travel of the blade. Handsaws, circular saws or chop saws (including cross-cut mitre saws) have all been used successfully on a daily basis both by our customers as well as our own workforce.
- Slow cutting speeds are best using a medium tooth blade, for example a 305mm 60 tooth TCT blade.
- If a slow cutting speed cannot be achieved it's advisable to reduce the number of teeth on the blade, for example a 305mm 40 tooth TCT blade, but our own workforce have generally managed with the 60 tooth blades most of the time even at slightly higher speeds.
- Keeping tool speeds low prevents material from melting on the surface of your tools/blades.
- Kedel occasionally apply a little WD40 to the blade to reduce friction and therefore prevent melting of the plastic onto the blade.
Rail Expansion and Contraction
- Plastic is subject to thermal linear expansion and contraction, hence it's importance to make allowances within the design of Kedel fencing installation.
- Expansion Gap - A gap should be left where the rails butt up
- Allow for maximum expansion with regard to temperature at the time of installation. The lower the temperature at the time of installation, the larger the maximum expansion will be. The higher the temperature at the time of installation, the smaller the maximum expansion will be.
Maximum expansion occurring per running meter per installation temperature:
|Expansion Table |
|Maximum expansion (contraction) occurring per running metre: |
|Temperature ||0°C ||5°C ||10°C ||15°C ||20°C ||25°C ||30°C ||35°C ||40°C |
|Max. Expansion ||+7mm ||+6.5mm ||+6mm ||+5.5mm ||+5mm ||+4.5mm ||+4mm ||+3.5mm ||+3mm |
|Max. Contraction ||(-2mm) ||(-2.5mm) ||(-3mm) ||(-3.5mm) ||(-4mm) ||(-4.5mm) ||(-5mm) ||(-5.5mm) ||(-6mm) |
Minimum temperature in Western Europe = -20°C; maximum temperature in the sun of e.g. black boards = 50°C. Assuming that the installation is normally done at a temperature between 10°C to 20°C, the maximum temperature difference will be in the region of +40°C (expansion) and in the region -40°C (contraction). This demonstrates the importance of taking into account the process of expansion/contraction.