CAD practice

As previously mentioned I'm regaining an interest in CAD. A friend has asked me to fabricate some frames for his shed windows and that seemed and excellent opportunity to practice my welding and also some drawing (with welding symbols).

Following Paul Tracey's advice I selected my CAD system, in my case the key features were, export/save as DXF and image (so I can share drawings with others), low price, runs on Windows and I can work out how to use it. I looked at a few options and Draftsight was free and seemed as good as any so I installed that on my machine.

I did complete a 2 week course in drafting at Dowty and then we had a day or so using AutoCAD, however that was 20 years or so ago and I don't remember too much. I have dabbled with Turbocad a few years back but nothing serious. So it's taken me rather a long time to produce one drawing but here's my first results.



One tip I've worked out, to handle the inside dimensions. Simply add a construction line (just a line that will be deleted) between the points to measure, then use the smart dimension tool to add the dimension to that entity. Finally delete the construction line and you get the desired result.

Obviously as soon as I printed it out, I spotted some issues. The projection lines need trimming back as they join with the frame and tollerances need to be added. One that's not so obvious from the pic is the border does not line up with A4 paper so that also needs tweeking. If there is anything else wrong, please let me know.

Wrapped in Bronze-anodised Aluminium

In my previous wander around St James I spotted a metal clad building. I've taken some photos and found a few details.









66 St James's Street was designed by Rodney Gordon of Tripos Architects in 1979-82. The building was commissioned for Swiss Bank.

The distinctive exterior is not copper as I origionally thought but bronze-anodised aluminium. The current occupants are the Stern Pissarro Gallery who moved there in 2009.

Another photo of the 66 St James Street

Curious Pursuits

Some pictures of the opening night of Porter & Jenkinson's Curious Pursuits at the Portico Library and Gallery can be seen over on the Flea Circus Research Library Blog.

Boxing the flea chariot

The flea chariot is off for a month in an art gallery up in Manchester so I wanted to ensure it would survive the journey up there and back. I already had a wooden box in the style of a pair of books so that seemed like a good starting point for making something. I also had some insulation blocks left over from the workshopshed roof rebuild project so those were cut up and hollowed out to form the shapes of the dome and magnifying glass.





That was a bit of a messy job so I did some vacuuming to get rid of all of the little pieces. The covering was some burgandy coloured felt, sourced from kleins and glue to the foam. Kleins also supplied some webbing and a buckle to form a strap to hold the box shut.









The whole thing is to be packaged up with some postcards and yet more foam pieces to protect it from the couriers....

The Manufacturing Rotary Table 'vs' Their Shed Based Cousins

Thanks to Martin Power and Robert from Kitagawa Europe, I have another guest blog. Robert looks at rotary tables and how the small manual rotary table you might have for your drill press or milling table compairs with it's bigger brother in the industrial world. For the model engineer, the rotary table would be for cutting curved slots say for an expansion link or rounding the ends of con rods. In industry there is a much wider range of tasks for the rotary table.

The Manufacturing Rotary Table 'vs' Their Shed Based Cousins

Those of you that have converted your shed or garage into a workshop will probably already know what a rotary table is may even have installed one. Even if you haven’t got your own personal workshop; there is a good chance that you have at some time used or at least come into contact with a rotary table. This will most likely have occurred in the school environment when in a Design and Technology class – or similar subject. The rotary table is of course a clamping mechanism that is used in the shaping of metal parts or components, in conjunction with various machines, including lathes, drill presses and milling machines.



In its most basic operation a rotary table is used to hold the object piece firmly in position whilst holes are made in an evenly spaced fashion. The image above shows such a task being carried out on a rotary table which has been mounted on a drill press. There are however much more advanced rotary tables available on the market, which are used in various manufacturing industries.



The photo above shows Kitagawa’s popular GT200 model, which is ideal for heavy machining. The complexity, accuracy and performance levels of such machines make their shed based cousins look like mere toys.

Ensuring safety

The top end rotary tables are commonly used in the manufacture of components that are used in cars, trains, planes and boats. Every time you travel somewhere in a vehicle you will be making use of metal work that has been created by a rotary table. It is of course important that every component of a vehicle is made precisely to ensure the safety of those using it. In order to deliver this precision, computer numerically controlled (CNC) rotary tables are used in the manufacturing world.



Rather than positioning and turning the rotary table manually; a CNC driven model operates using pre-programmed commands which are entered into a control module such as the one above. The rotary table is also able to communicate with the other end of the metalworking machine that holds the shaping tools. As a result both are able to work in unison; bringing precision and safety.

Irregular objects

Whilst rotary tables play a key role in the manufacture of parts in the transport industry, it by no means the extent of their reach. Their usefulness stretches to many other areas of business, from construction to pipe laying. In order to fulfil their role in so many different environments it is important that rotary tables are both adaptable and available in various sizes and configurations.



In the example above we see a rotary table that has a huge through-hole capacity of 345mm. This allows long bar and tube shaped workpieces to be clamped effectively and is ideal for producing pipes to be used to move gas, water and oil. For such tasks, the standard three and four jawed chucks, such as the one below, are not suitable.



Such a clamping solution cannot deliver a suitable torque to hold the piece in place whilst it is being shaped. The result will be that shaping tools will deflect from their target, thus compromising the quality of the final component. Instead a collet chucks as shown below is more suitable for use when manufacturing pipes and bars.



The circular shape of the collet chuck allows pressure to be applied evenly to the outer surface of the workpiece. This allows larger gripping torque to be applied and also reduces the likelihood of surface damage to the workpiece that could otherwise be caused by standard jawed chucks. The clamping pressure is applied by tightening accompanying sleeve over the outside of the collet chuck.

Tilting capabilities

The final main difference between manufacturing rotary tables and those used in schools and hobby workshops centres on the ability to choose tilting options. Standard rotary tables allow for the workpiece to be positioned along 3 axis in relation to the shaping tool. In contrast many models used in manufacturing include a manual or CNC tilting device that enables the workpiece to be positioned on a 4th and 5th axis. The image below shows a rotary table with tilting capabilities being use alongside a drill press.



As you can see, the machining tool is now able to approach the workpiece from different angles than would otherwise be possible. This allows for more much complex items to be produced, such as flute shaped ones.

Many thanks to Robert at Kitagawa Europe.

Additional references:

1/14th scale rotary table for a miniature bridgeport
Example of a rotary table from a kit

Castings and kits
College Engineering
Hemmingway Kits
Lautard
Division Master

What to Look for in a CAD System

When you are just making stuff for yourself it's fine to just sketch things out on a pad and make them. However, if you are working with others it is good to have proper drawings that you can share and discuss. I have also used a 3d Graphics program to visualise some of my projects.



This year I'm looking at getting back in practice with using a CAD system so I can draw up some of my projects. I did have several weeks training with Dowty back in the 1990s on manual drafting and a little time was spent with their DOS based Autocad system but things have changed a bit since then. So I asked the CAD Expert Paul Tracey what his recomendations were.

What to Look for in a CAD System.

At the risk of stating the blatantly obvious, any CAD System is just a tool. So you need the one that’s right for you, normally not the most expensive or complicated. A hammer is a hammer, but I’m sure we all have several different ones in our tool box for obvious reasons. So when I’m asked advice concerning the best system for a client, my first question is – What do you need to do? I’m always happy to talk in detail about possibilities, but in terms of general rules, below are some pointers.

2D or 3D?

A lot of people still draw exclusively in 2D, although a young engineer entering the job market is not going to get far if they don’t understand 3D CAD. All modern engineers draw in 3D, once you understand how to do it, then it is easier and faster than 2D. Architects and Interior designers are in the same boat. Why draw three orthographic views when one 3D is quicker and easier to edit. The computer will turn the 3D drawing into orthographic views for you – and sort out your sections.
So 3D is the way forward for most, however I do understand that some want to stay with their 2D, which they understand and feel safe with. For these the choice goes from free, DoubleCAD, up to AutoCAD LT at about £1,200. Considering a rectangle is a rectangle in both packages and they use the same file formats and look the same, I can’t really see any reason for putting your hand in your pocket. There is a professional version of DoubleCAD that will take in 3D drawings and turn them into 2D.
The next stage up is the chap that says that they need to draw in 2D, but would like to get into 3D at some point. For these the choice is easy, TurboCAD Deluxe is inexpensive, enables you to do anything you’d want in 2D, but also has plenty of 3D functionality. It gives you the chance to learn the principles of drawing in 3D without having to dig deep in your pocket and there’s free training on YouTube and excellent training books available.



Training

Make sure that what you buy has training that you understand and need. Some people like books, some on-line films. Don’t just presume that you’ll work it out, these packages are not intuitive, you’ll need help at the start and when you’ll pulling your hair out because a line refuses to move where you want it to and the job’s got to be finished and sent that day, you need to feel safe that you have back-up. I’ve had people at their wits end call me after spending hours trying to sort something that I resolved for them in a few seconds.
And if you need to enroll on a course of evening classes, ask yourself why you need to take so long to learn it and remember – the bloke teaching the class didn’t want to come out on a winter’s evening either, I know – I’ve done it.

Support

Occasionally some people have technical problems with a computer crashing or unintelligible error messages turning up. Ensure there is someone who will resolve this for you for free. If the people publishing the package want a few hundred quid a year from you in case their software screws up, I’d walk. It’s a bit like the shop wanting you to take out insurance on a brand new washing machine in case it goes wrong – why should it.



Compatibility

Ensure that you package opens and saves in all the main CAD file formats, so DWG, DXF, 3DS, DAE and at least saves in PDF. You’ll at some point want to swap files, so you need to be able to talk these languages.

Lastly

Lastly there is the reality that some people learn quicker than others. For some of us computers came along in mid life, after years of working on a drawing board, for other they have always been around. So be careful that you don’t buy something that is going to be so hard for you to learn that you eventually give up and feel that you’ve wasted your money.
Generally speaking, when interior designers and fitters come to me needing to do planed layouts, but also wanting a 3D representation, then I recommend TurboCAD Deluxe and Google SketchUp Professional, neither cost much, are easy to learn and will produce results at the highest professional standard.
For an engineer I recommend TurboCAD Professional Platinum at less than a thousand pounds including training.



About the Author

Under the guise of PaulTheCAD, Paul Tracey, looks after all aspects of TurboCAD and Google SketchUp in the UK and much of Europe. He is also an artist, having exhibited paintings in capital cities throughout the world.
Paul runs the official distributer networks for these packages ensuring that both resellers and end users have up to date information on the packages, are fully aware of developments and advises on functionality matters. As well as this he runs training courses and writes articles for various magazines. He also organizes specialist help for companies working on projects where their expertise with the software is not fully developed.

www.paulthecad.co.uk
www.paultracey.net
Training films on YouTube at paulthecadtracey.

You can also see Paul later this month at the London Model Engineering Exhibition

Fred Dibnah's World of Steam

I received Fred Dibnah's World of Steam as a Christmas present, it's a follow on from the previous magbook "Fred Dibah, The Early Years". The Mag Book is a curious format, it's basically a magazine sized book with a thicker cover, it also has a selection of adverts for other books and DVDs that might be of interest.



The book is in the words of Fred and has been compiled by Paul Donoghue who also writes a great introduction. There is a variety of chapters, starting off Alison, Fred's Aveling and Porter #7632 steam roller. Fred describes the process of restoration and has amusing anecdotes about building the boiler, riveting and dealings with boiler certification and insurance. The book continues on with the next roller project, Aveling and Porter #7838.

In one of my favourite chapters Fred describes the stationary steam engine he uses to power his workshop and the overhead shaft that drives all his machines.

No book on Fred would be complete without a section on steeple jacking and this magbook devotes a chapter to this including some more amusing stories about a cat stuck on the top of a chimney and trouble with the fires Fred used to topple chimneys. This leads on to some of his TV work and discussions with a German TV company make Fred reminisce about his time in Germany on national service and how he managed to get out of peeling potatoes.

Although he enjoyed the TV work it did have drawbacks and fame meant that he got rather more visitors that he liked. It did however mean he had some generous fans, one who provided an old steam roller manual which is included in full in the book.

The penultimate chapter has a short history of the use of steam in the Bolton area, Fred's home town.

The book finishes up with a scrap book full of photos and letters collected over the years.

Don't expect to be able to become a steeplejack or build a steam driven workshop by reading this but do be prepared for an entertaining read in Fred's distinctive style.