Category: Orders and Procurement

This Monday morning saw the arrival of the electric motor, the gearbox, chain, cog wheels and the electronic controller. All this equipment is going into the Stair Lift unit to drive a moving platform system for our stairs. This device will help people and objects climb to the first floor and back again. We always wanted a stair lift design that is built into the fabric of the house, rather than a ugly bolt-on solution that virtually everyone else has to have. So we went for a flat-bed platform design as oppose to a chair, thus enabling a person in a wheelchair to have independent freedom to go upstairs at their own convenience and also allow the transport of larger and heavier items to be lifted up (or down) to the first floor.
To this aim, we designed and measured the power and torque needed to lift 250kg at a speed to give a journey time of 5 seconds. The weight has to include the mass of the platform and its support framework and wheels, we couldn’t design in the counter-balanced weights to cancel out the platform because there was not enough room to have another moving solid ballast hidden and safely out of the way of fingers etc. But the electric power to drive the combined load is only for an occasional use and the cost will be minimal in the long run.

The motor is a 3-phase AC 240V 1.1kW type that bolts into a heavy duty 15 to 1 ratio gearbox, a worm drive design that has the built-in advantage of providing a brake to hold the platform when electricity is lost to the motor but we do also have other safety measures incorporated into our design too. The gearbox will drive a 25mm thick shaft that will go out to the two cog wheels which in turn will drive the 11metres 3/8inch chain which in turn is attached to the platform.

The electronic controller, called a Variable Frequency Drive (VFD), which is a high voltage sine wave generator and produces three separate outputs to drive the motor, with a variable frequency range from 1Hz to 60Hz. This changes the rotation rate, whilst maintaining full torque.

We did some electrical tests but we discovered that the electrical filter design in these VFDs has a bad side-effect to the regular domestic RCD safety switches we have and kept tripping them. After some research on the web, learning about this design philosophy which is all to do with suppressing electrical noises being generated by the inverter and the motor, so unfortunately these industrial class of equipment needs a direct connection to the mains electricity on their own circuit and fuse breakers. We don’t have one of those which means we need to hire an electrician to come and add another consumer unit to our mains switchboard before we can carry on testing the motor etc.

We also been enquiring about prices for CLS timber, the 63mm by 38mm size, again to cash in before the prices goes up. We were lucky to find two of our local suppliers capable of offering a price of £1 per metre against £1.30 (on average) by other builders merchants. We snapped up all they had in stock (from Norwich and Great Yarmouth) and on Saturday and Tuesday, we had two deliveries, we now have another 630 4.8metre planks. The previous price we paid six months ago was 97p per metre so that is very good, especially in this climate of popular demands!

We have got the two pallets sitting alongside the Loke at the moment, in front of the house but it won’t be too long before we will need them all. In fact, that quantity will do the majority of all the internal structure of the ground and upper walls and floors. We may need a little bit more later on if we had generated more waste than we expected. But we are almost using every bit of timber everywhere, whether it is just 500mm long, right up to the full 4.8metres. We are planning to tongue and groove several lengths together when we are doing the horizontal framework which will allow us to use many of the cut-offs.
It is all about minimising waste, even if it costs more time. That is our philosophy…

On a few days from Friday 5th March to Thursday 11th March, we had the delivery of a load of sheet wood material of various types. All the material is earmarked for our internal structure of our house, doing walls and floors and a little bit of ceiling as well. We ordered it all now because there is several price increases coming because the world of timber is becoming too popular in building houses and high rises using wood instead of bricks and mortar? couldn’t they wait another year for us to get ours done first?? Phew!
So we ordered the following sheet materials ..

• 280 sheets of 18mm OSB 3 boards
•  30 sheets of 11mm OSB 3 boards
• 170 sheets of 22mm thick flooring grade ‘Tongue and Groove’ chipboards
• 150 sheets of 19mm thick flooring grade ‘Tongue and Groove’ chipboard

That is about 15 tons of wood stuff!
We organised the bottom of our site to store these eleven pallets into four main stacks, each one is covered over with tarpaulin. We had already several tarpaulin sheets but these were lightweight ones and we decided to invest in much heavier duty alternatives, deliberately paying out a premium ‘insurance’ price, to protect our money and our building material while we get on with the other structural jobs that needs to be done first before we can use these sheet materials.
Approximately, the chipboards will be used first, specifically the 19mm thick ones, to cover the first floor joists when we have finished building the framework on the ground floor and installed the first floor joists. Then once we got all the utility conduits mapped out and inserted, we can nail up the 18mm thick OSB boards to form the walls in all our rooms. Finally, the other thicker chipboards will be used to construct the suspended floors downstairs. The odd 11mm OSB will be used to cover up the roof rafters around in the storage triangular voids up on the first floor to hide away the insulation and rafters to make a neat finish.

We estimate that we will save about £1000 on the future price increases and we spent about £150 on the better quality tarpaulin for long-term weather protection thus a win-win for us!