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Engineering

A Primer In Hydraulics

Now that you have a basic overview of some of the components that go into making up a hydraulic system, let’s take a look at a practical application. The wood splitter is a good example.
First you need to determine what you are trying to achieve. In the case of our log splitter :
* How much force is required to split the timber?
* How fast do you want to complete a full cycle i.e. ram full out and full return?
* How much horsepower is available to power the pump?
We will illustrate an example using a single-stage pump with a safety margin of 200 bar (pressure
in bar: 1 metric bar = 14.5 lb/in²).
It must be emphasised that an oil pump does not pump pressure, but flow. Pressure is created by the load on the actuator

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How to repair a thread

Damaged and pulled threads can be an annoying inconvenience, especially a stripped spark plug thread. They can also be expensive if the equipment you are working on is vital or difficult to replace. But there are now systems with which you can repair even completely destroyed threads quickly and at a reasonable cost, so saving time and money.
Existing undamaged threads can also be significantly strengthened using these types of repair systems.

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Video of a restored 1910 Atlas power hammer

One of our favourite sheddies here at the magazine is Rudi Buchanan Strewe whose engineering shed we featured in issue 102. When we visited Rudi, he was restoring a 1910 Atlas power hammer. Here it is, restored, and up and running as good as new.

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Milling Part 3, cutting, clogging, and cleaning

Once your component is securely clamped (see “Showing restraint” Part 2, www.the-shed.nz), ensure the cutting tool is held correctly in its chuck or collet holder, keeping tool overhang or stick-out to a minimum. Being rigid and stable applies as much to tooling as it does to the workpiece. Drill chucks are NOT designed to take side loads induced by milling and are exclusively for drills. Milling cutters should be held in a collet chuck or other suitable holder.

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Milling – showing restraint

In Part One of this series on the milling machine we put the milling machine in the workshop and had it levelled. Before you use the machine, it is important to check the alignment of the spindle. Then comes understanding the importance of preparing the workpiece. Work to be milled or drilled on the milling machine has to be set up so that it does not move during the job. This is one of the most important things you can do if you don’t want an important component or workpiece to end up as scrap because it moved.

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Time for a milling machine?

In a typical home engineering workshop progression, you buy a bench vise, some hand tools, and possibly a bench grinder. After you buy a small pillar drill then comes a big leap — buying a centre lathe.
Along the way you acquire more small tooling, drills, turning tools, etc. You make many useful items and produce a fair bit of scrap.
But then you find the lovely pieces you are turning out on your lathe require other features, especially holes more accurately positioned than you can mark out and drill on your pillar drill. As good as you have become with a file, that flat section needed on the shaft really needs to be machined. And how are you going to make a slot for that keyway?

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Build a portable barbeque

At home, I have a big barbecue in the backyard and a little barbecue upstairs on the balcony that I use when there are just two of us. This hibachi or portable barbecue would be ideal for just two although the grill rack is big enough for four or five steaks or chops and sausages. It can be made with scrap mild steel and a piece of cut pipe. You will find scrap bins at your local engineering works. Most pieces of metal under a metre seem to go in there. You could ask and many companies would be happy to help out, perhaps for a couple of beers.

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Spinning wheel

While we are rather spoilt these days for ready sources of energy, it was once a matter of harvesting what was available in the local environment. More often than not, what was available was a stream or river, and so the workshop was built on the riverbank and the harvesting was achieved by a water wheel.
I’ve always been rather taken by the concept of water wheels (and other mechanical devices that harvest energy from nature), and have been intending to make a small one of my own, even if it was just to be a garden ornamental feature.

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As tough as steel

The chemistry of steel determines why and how it should be tempered.
The potential hardness of a steel is determined by its carbon content. Adding small amounts of other elements to the mix can produce enormous improvements in strength, toughness, and
resistance to rust and the response of the steel to heat treatment.
Steels referred to as alloy steels have additional elements such as chromium, nickel, vanadium,
cobalt, manganese, molybdenum, silicon, and tungsten included.

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Assorted nuts

For our purposes, a nut is an internally threaded part which is rotated or screwed onto an externally threaded part such as a screw, bolt or stud. If you can pick it up in your hand and put it onto an externally threaded item and tighten it, it is a nut. There will be some exceptions to this which will become apparent.

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Hexagon head bolt or cheese head screw?

There are so many types and kinds of bolts and screws that when you ask for the one you need, it is best if you understand the characteristics of the particular fastener. Then you can ask exactly for what you want. These characteristics are:
* Head type;
* Size;
* Thread form;
* Tensile strength;
* Finish.

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Getting up to speed

As sheddies, we are known to cobble together machines from whatever we have at hand. More often than not these items are less than ideal and a motor of some sort may run at a different speed to what we need. If we are looking to make a spindle moulder, belt sander, garden chipper, wind generator, compressor or similar item then it is likely that some sort of gearing will be necessary to give the right RPM at the business end.
Calculating the sizes of gears, sprockets or pulleys is a relatively simple exercise.

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Making your own campervan

Converting an ordinary van into a campervan is a project I have been talking about for some time.
As a retired technical teacher, I felt I had the necessary skills, and when a 2005 Kia Pregio van in excellent condition became available I decided to take the plunge.
The van is a 2.7 litre diesel, manual, with 26,000 km on the clock and a cargo space of 2.8 metres x 1.65 metres. My plan was to fit the space with two beds, one on each side. They can be expanded to a full-width bed using the foam backs of the seats supported on shortboards between the sides of the seats.

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A mechanic turns to clocks

Ken England has been fixing clocks as a hobby in his Whakatane shed since the 90s.
Repairing a clock is not just a case of pulling it to bits, replacing parts then re-assembling, he tells me. “Everything works in sequence and has to be timed.”
He is a member of the New Zealand Horological Institute but was never a clockmaker by trade. What makes Ken “tick” and has given him the necessary clock-repair skills is the engineering know-how already in his background, a knowledge of how to machine parts, manufacture, and silver-solder.

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