New Science and Engineering Blog!

A series of miscellaneous articles, both curated and original covering various STEM topics.

The blog's editor Eugene Brennan is a qualified engineer with a BSc(Eng) degree in electrical, electronic, control and instrumentation engineering from Dublin Institute of Technology and FETAC certified in industrial automation (mechatronics and pneumatics). He has worked on the development of SCADA systems and data loggers, designing instrumentation electronics and developing telemetry software. He's also passionate about gardening and DIY. 

You can view the blog here.

How to Get Your Home Ready for Winter

 

There are lots of ways to prepare your home for winter's freezing temperatures. © Eugene Brennan

Winter Is Coming!

This article gives you some common sense tips on keeping your home snug and warm in the winter. It also provides information on how to protect your home and yard from cold, wind, rain, and snow. 

What Is Insulation? 

Insulation is any material that reduces the rate of heat transfer. For instance, the handle on a saucepan is insulated so you don't burn your hand. Metal is good at transferring or conducting heat, so saucepan handles are usually made from wood or plastic to stop heat conduction.

In the context of a building structure, however, insulation is a material that is used to stop heat flowing out through the walls, ceiling and floor. Usually, this is in the form of boards with an insulating foam layer or layers of fleecy material such as fibre glass, rock wool or sheep's wool. If rooms are well insulated, once they're heated, they hold the heat for longer and it doesn't leak out so fast.

How to Keep the House Warm in Winter

There are numerous ways to keep the chill at bay when temperatures drop.

General Tips

• Single-glazed windows should be upgraded to double or triple-glazed units.
• Boilers should be serviced to ensure they are working correctly, the flue is clean, fuel is being burnt thoroughly and they are working at top efficiency. Circulating pumps can become stuck during the summer so this needs to be checked out.
• Chimneys of open fires need to be cleaned to remove soot and creosote deposits or leaves from overhanging trees. Guards should be fitted to the chimney pots to prevent birds setting up residence the following spring.

Insulation Upgrades

• If you can afford it, try to upgrade the insulation in the house. Most heat is lost up through the ceilings into the loft and out through the roof. The space between the joists should be insulated with 4 inches (preferably 8 inches) of fibreglass or rock wool insulation.
• Inner walls can be insulated with rock wool and finished with plasterboard (drywall), or plasterboard backed with foam insulation may be used.
• Cavity walls can be drilled and a foam insulation pumped into the intervening space.
• External insulation is also an option. Multilayer sandwich panels consisting of insulation, a water-permeable membrane and an outer painted finish can be retrofitted to exterior walls. Some contractors render the finished insulation when it is installed.

Exterior House Maintenance

• Gutters and downpipes need to be cleaned to ensure proper drainage from roofs, but wait until the leaves have fallen off all nearby trees or you will have to do the job again later!
• Remove any moss or leaves which accumulated in the valleys between apex roofs.
• Ensure all brackets, nails and screws holding the gutters are secure.
• Check your downpipes are not clogged.
• Drips from overflowing gutters in the winter can form large icicles.
• Check gulleys for blockages from leaves and other debris.

Gate Valve. © Eugene Brennan

 

 

 

 

 

 

Protecting Plumbing From Freezing

• Frozen and burst pipes are a common problem during freezing weather. All pipes which may be exposed to freezing temperatures should be lagged with insulation to prevent freezing. New pipe work should be buried deep enough in the ground to protect it from freezing.
• The cold water tank in the loft should be surrounded with a layer of insulation and the associated pipe work should be lagged. When the floor of the loft is insulated, this makes the loft colder and plumbing is more prone to freezing, so during extremely cold or snowy weather, the loft door should be left open to allow some heat from the rooms below to travel upwards.
• Ensure you know the location of all your gate valves/stop cocks inside and outside and their functions. Write their function on the wall behind them with a thick marker and obviously check they actually turn and aren’t seized. You don’t want to be trying to turn off a seized valve in an emergency when water is coming down through the ceiling!
• You can use pipe heating cable to stop pipes from freezing where pipes are exposed to really cold temperatures. This comes in the form of a tape or cable that you wrap around the pipe. The tape warms slightly when powered up. Newer versions of this tape are self-regulating so temperature doesn't become excessive.

Preparing for Ice and Snow

• Ensure you have adequate supplies of fuel. Oil, gas and electricity suppliers are competitive so shop around to get the best deal.
• Get a good quality snowblower, snow or grain shovel for clearing snow from pavements and driveways. A blade made from aluminium is lighter than a steel blade.
• Clean moss from pavements with a proprietary cleaner or power washer.
• Stock up with salt and grit for defrosting snow and ice on pavements.
• Gutters should have adequate brackets to support snow load as snow starts to thaw and slide down roofs.
• Drain hoses to prevent them freezing and bursting.
• During thunderstorms which can occur during blizzards, unplug all electrical appliances and landline equipment such as modems and phones and use your cell phone for communication.
• Stock up with torches and a camp stove in case there are power failures.
• Get some storage containers which can be used to hold water in case the water supply pipes freeze and the supply is interrupted.

Protecting Garden Plants From Frost

If possible, bring vulnerable plants in containers which could be damaged by frost, inside or into a frost-free shed. Wrap bubble wrap or straw around larger plants or plants in the ground.

Here are a few more ways to protect your plants from frost.

Coping With Electrical Power Outages

• If you have a generator, make sure it works properly, the oil level is ok and it starts up without difficulty. Test it under load to see if copes ok without struggling.
• A freezer will maintain low temperature for several hours if it is not constantly opened.
• A portable gas stove can be used for heating and cooking.
• The backup batteries in your alarm panel and bell/sounder have a limited lifespan so replace them at the required interval.

 

 

 

Faultfinding String Trimmers (Strimmers)

 Just created a basic troubleshooting checklist on the Medium website here:

Troubleshooting That Problem String Trimmer!

 

Why Doesn't My Power Tool Startup?

When a power tool won't power up there are various causes of failure. but troubleshooting should be done in a methodical order, the main thing though is to check the obvious first!

Equipment Needed:

Some screwdrivers, flat and Phillips head
Continuity meter or multimeter to trace continuity from the plug to the motor.

A non-contact voltage detector (optional). These devices glow when the tip is held close to a live cable

Important !!!

Remember to avoid shock, disconnect the tool from the mains supply before troubleshooting!!!

Troubleshooting: 

 ● It may be obvious but ensure the socket outlet isn't faulty, try the tool in another outlet to see if it works.

● Check whether the overload circuit breaker if fitted on the tool has activated. This happens e.g. on a table saw when the motor is stalled. To reset you need to press a button. The breaker may need a couple of minutes to cool down before resetting

● If plug is rewireable check for loose screws at plug pin terminals, loose fuses etc. 

● A common cause of failure especially with drills and other hand held tools is one or more broken wires in the power flex caused by metal fatigue in the cable (like when you break a paper clip by bending it backwards and forwards) , this usually happens where the cord leaves the plug or where the cord enters the tool. If you have a non-contact voltage detector, you can use it to trace the break from the plug to the tool. Plug in the tool and hold the tip of the detector at the plug, it will glow here but as it is moved down along the flex it will stop glowing after the break (If the break is in the live core of the cable)

● Sometimes it is possible to detect where a break is in a flex by stretching it, the flex will narrow in the region of the break

● If you still can't trace the fault, unplug the tool. Open it. Check the continuity from each pin of the plug to the switch in the tool.

● A faulty on / off switch can prevent the tool from working. Use the continuity tester to check this

● Loose spade terminals on switches may cause intermittent operation

● Tools with green and red start and stop buttons may have a faulty relay

● The brushes in the motor may have worn down

● The armature or field coils of motor may have gone open circuit. The field coils can be checked with the continuity meter

String Trimmer Line

This 0.095 inch diameter (2.4mm), 3 pound, 685 foot spool of professional trimming line manufactured by Oregon should last you years and years. It has a high strength inner core and an outer coating to prevent welding. In other words it is less likely to stick as it unwinds from the spool. The square edges also improve cutting efficiency compared to standard round profile type
Check your trimmer to see whether it is compatible with this diameter line.

Activities for Kids During the Covid-19 Lockdown: Sowing Seeds

Equipment

• Some trays, pots, yogurt containers or similar
• Spray bottle from shower or window cleaner
• Seed compost or multipurpose seed and potting compost
• Seeds

Time to sow

For annual and half-hardy annuals, February to April. Check the seed packet.

You can use any types of pots, boxes or proper seed trays

Steps

1. Fill the containers almost to the top with seed compost
2. Shake the seeds out onto your hand and scatter evenly over the compost
3. Don't cover very small seeds. Seeds a few mm in diameter can be covered with a sprinkling of compost. Larger seeds such as sunflower seeds should be pushed about 1/2 inches (12mm) below the surface.
4. Water with the spray bottle and keep the compost moist. Only water as needed, not everyday. You can use a watering can, but unless it has a fine sprinkler rose, it can flood the compost and wash away seedlings.
5. Keep the tray in a warm place and cover with a sheet of card to conserve moisture and keep the seeds dark until germination
6. Once the seeds germinate, remove the card and move to a bright place such as a window sill.
7. Transplant into pots once seedlings have their first pair of "true leaves" (the second pair of leaves to appear). Once the plants become large enough, transfer to their final location.

Fill tray with compost

Sprinkle seeds from your hand

Transplant seedlings once they're big enough and have two "true" leaves

Repairing a Heat Selection Knob on a Fan Heater

Well this was frustrating! The range selection knob on my fan heater was turning without doing anything. I decided to try and open the case to see what was wrong, but of course the manufacturer had used security fixings, relatively uncommon triangular ones too!

I have lots of shapes and sizes of Torx bits and screwdrivers, but they would be useless in this situation. Luckily I managed to undo two of four screws from the upper side of the heater using a large jeweler's screwdriver. This allowed me to pull the case apart just enough to remove the knob.

Part of the shaft of the knob had snapped off in the switch. Gluing, even with superglue wouldn't be a permanent fix because the resistance of the switch was such that a large torque was needed to change range.
First I removed the broken-off piece of shaft from the switch using a woodscrew. The piece was hollow as was the other piece of shaft remaining on the knob. I decided to attach the two pieces together using a rivet pin.

I hoard lots of scrap, and rivet pins are part of my collection, along with self tapping screws, springs, nuts, washers and all sorts of other miscellaneous items! Some of these pins were exactly the right diameter.

I dripped some super glue into the hollow interior of both sections and also on the broken surface, then joined the two pieces together. Some heat from another fan heater accelerated curing of the glue.

After trimming the pin, I replaced the switch, cost of repair? Zero!

How Do I Mix Fuel for My String Trimmer, Hedge Trimmer or Chainsaw?

These garden power tools generally have a two stroke engine (also known as a two cycle or 2T engine), and to make them lighter, they don't carry motor oil on board as in the case of a lawn mower or road vehicle. Instead oil is added and mixed with the petrol (gas) before use.
In general petrol/oil ratio for 2-stroke engines is 40:1 or 50:1 which is 2.5% or 2% oil. 50:1 is equivalent to 20ml in 1 litre or just over 2 1/2 US fluid ounces per US gallon. 40:1 is equivalent to 25ml in 1 litre or 3.2 US fluid ounces per US gallon. 
After adding oil, swirl the contents around to ensure it's thoroughly mixed.Consult the manual of the machine for details of the recommended ratio.

How to Stop Nails Splitting Timber

Flat or round nails can split timber, especially if they're used near the edge because the sloped tip acts as a wedge. An old tip is to shear the tips off wire nails to stop them doing this. The nail then shears and cuts through fibres rather than acting as a wedge, pushing them apart and splitting the timber.

Homemade Tools - Snow Rake

I put this together from scrap 2 x 1 and 3/8" (10mm) plywood. I used some pieces of waste wire from electric cable (string would be just as good) as ties to stop the board pulling off the end of the 2 x 1.