Monday, 21 May 2018

Greenhouse escape cat flap

All of our outbuilding have ways to let cats out so they cannot get accidentally shut inside.

The greenhouse is no exception.

I could have added an off the shelf  cat flap but they tend to be chunky and I thought they would look out of place on a delicate greenhouse.

I used a 4mm polycarbonate sheet as the base with a grey acrylic surround.

The double thickness was mainly to give it strength where the bolts pass through. I deliberately used a contrasting colour so that the cats would be able to easily identify the place they can get through the otherwise clear panels.

The acrylic is glued to the polycarbonate with cynoacrylate (CA, Superglue).

I used a disposable brush to spread it thinly then sandwiched the sheets between layers of MDF clamped together. I only intended to leave it 10 minutes but I ended up going out so it got several hours to set. The joint is solid.

I used M6 bolts with large penny washers to spread the load to hold a large door hinge in place. The hinge only swings outwards. The idea is that it only lets the cats out not in, so they cannot get trapped.

I'm pleased with the result. It looks how I intended.

The polycarbonate flap is not quite heavy enough to always close so I might add a weight if it becomes a nuisance.


Sunday, 20 May 2018

Fix greenhouse sliding door

The design of aluminium greenhouses is very efficient. Someone has thought cleverly about how to hold the glass in and be able to assemble and disassemble quickly. However, the door on most of those that I have come across feels like an afterthought. The doors rarely slide well.

We reused a greenhouse from a friend and the door barely ran at all. I managed to sort that out. It's not perfect but as long as it is moved from the middle it slides open and closed easily.

The main problem, as I see it, was the runner at the bottom. On our's the door hung too low and the bottom rail of the door dragged in the runner. The trouble is there was insufficient height adjustment for the door.

Most people, myself included, don't find out that the door sticks until after having assembled the greenhouse. The most obvious thought was to slacken off some of the bolts and attempt to raise the height a fraction. This would require a lot of the glass to be removed for a minimal chance of success.

My solution was to file the holes, in the bottom rail of the door, in to slots.

There is no obvious way to easily remove the door. The two bolts holding the top runner to the door frame can easily be undone but that does not release it enough to remove the door! I found that if I slackened off two screws on the top rail, the runner for the door can be released and slid in-front of the door. This allows the two to be removed separately. Reassembly was the reverse.

I'm not sure if they were necessary but I fitted new rollers which came in the kit of door repair parts along with the lower plastic guides. It was the two guides I mainly needed from the kit as both of those were broken on my door.

There is a tiny bit of adjustment at the top of the door but that also needs some clearance or it sticks under the top runner. My modified screw slots in the bottom rail was what enabled me to get a good, perhaps 2mm, gap between the guide runner under the door and the lower rail. Luckily the glass still fitted in the now smaller aperture.

That fixed it.

Charging connector

Due to the short hops between jobs, that Shelley does in her Defender, it risks flattening the battery.

I thought about adding a bigger battery or dual batteries but all that does is delay the problem. The simplest solution is to monitor the battery and charge up before it becomes a problem.

I have ordered a dash mounted battery voltage monitor but that has not arrived yet. The job this weekend was to fit a charging socket to avoid having to take the passenger seat out to get to the battery each time it needs a charge.

This one is specific to the Ctek brand of battery chargers but as I like their chargers that is not a problem. It comes with a three colour indicator for a quick, peace of mind, check.

It was fairly easy to cut a hole in the battery box through to the passenger foot well, file the aluminium to size and push in the connector housing.

With a bit of bending the two eyelets fit the bolts on the battery terminals.

Now an overnight top up is as simple as plug in the charger.

Sunday, 13 May 2018

The greenhouse

Over a year ago we helped take down a friend's greenhouse and decided we would put it up in our garden. At long last I've got round to putting it up.

A few bits of the glass are broken or missing and the door is a bit stiff but they will be sorted as soon as the replacements and spare parts turn up.

Wednesday, 2 May 2018

Electric cars or not

For the last few months perhaps a couple of years the Diesel car has been hounded by some of the press and clean air pundits. Now the UK government is taking notice and setting policies for new cars to discourage further Diesel purchases.

This got me thinking about how practical it might be to run an electric car and can I get an electric Land Rover. It led to an idea which, I now know, others are already working on.

Everything EV

It's fairly openly stated that the pressure to move away from Diesel cars is more to do with air quality in cities than a more wider care for the environment. It's not mentioned very often but the increase in petrol cars will almost certainly add more greenhouse gases. Electric cars just move the air pollution to the point of generation. Until we get more wind, water and nuclear, power generation the total pot of electrical use still pollutes somewhere.

EV West

For the moment, to get cleaner air, the drive is towards electric cars. I am keen on electric cars. In most ways, an electric motor is a far more suitable power source for a car than an internal combustion engine. High torque at low revs, wide rev range, less complicated and therefore more reliable, virtually no environmentally unfriendly fluids to leak or be disposed of and no fumes. Even the freedom to position the motor at any angle and have multiple motors synchronised to work together are all ideally suited for cars.


If we ignore the currently very high cost of electric cars, the big technical disadvantage of electric vehicles, as everyone knows, is the battery. At the moment, the limitations of battery technology mean it is only suitable for smaller lighter weight vehicles which only need to travel a few hundred miles between long stop overs to recharge.
There is nothing stopping the scaling up of designs for longer ranges and larger vehicles but the already high costs become completely unaffordable.

Range Rover PHEV

As can be seen from my many other posts on this blog, I like my Land Rovers. These are not small vehicles and generally get worked hard. That could be carrying large families and friends, lugging lots of equipment, towing big and small trailers and, in our case, harrowing the fields, to name just a few uses.

I've done some research and there are a number of companies that will convert cars to electric. Usually only valuable classics because the costs range from £12,000 for a simple small car to £50,000 for a large 4x4 like a Range Rover.

It's obviously a large enough DIY market that the same companies sell kits of parts, starting at about £7,000 for a small vehicle.

Even if a car is converted, it will still suffer from a comparatively short range which gets dramatically shorter if you use any of the luxuries we have become used to, heating in the winter and air conditioning in the summer for example. Electric windows, stereo and any other gadget, like entertainment systems for the kids, all kill the utility of an electric vehicle.

I even thought the other day about what happens when we get those snarl ups on the roads, in the depths of winter, that last hours with queues of stationary cars and lorries. An internal combustion engine, at tick over, can keep the heating running for many hours and still drive home when the jam is cleared. An average electric car, from full charge, would leave the occupants frozen in less than two hours.

Land Rover

This is where hybrids step in. They have a smaller electric range but can swap to a normal combustion engine when the batteries get low. I think it is a disappointing solution to the problem. Either you are lugging a big hunk of metal alloy about all the time reducing your battery powered range or you are running on fuel which brings back the air pollution!

The question that occurred to me was, is there a lighter weight way to generate enough electricity directly from consuming fuel within the car without the need to have that heavy internal combustion engine?
It did not take me long to find that this is the same thing that many organisations have been thinking about for many years. On the face of it, fuel cell technology should be a good solution. This uses a chemical reaction, such as hydrogen and oxygen, to produce electricity. There appear to be lots of difficulties making this work for cars because it is not as widely touted as I would have expected.

It's clear from my limited research that a lot of people, a lot more knowledgeable then I, are already actively working on this. I hope they come up with a viable solution soon.


Reference links:


Saturday, 21 April 2018

Router stand

I wanted to be able to easily see the LED's on my router from where I normally sit. To do so, I needed it to stand on end.

A quick bit of modelling in Fusion 360 to produce an interlocking symmetrical stand.

Router Stand (STL)
Router Stand (Fusion360)
Licence attribution - small business exception

My designs on


Allotment canes

A quick project today. Canes to support runner beans and pumpkins.

Held together using cable ties.

Very easy to put together and the result is very sturdy.