A MODEL ENGINEERING APPRENTICESHIP

Part four by David Carpenter

So you’re standing in the nice new shed, sorry, workshop. Small init? If you haven’t actually got your workshop yet, go to a shed shop and stand in some sheds of different sizes. Looks a lot different than an exercise on paper! Better still use the garage, suitably lined and lit. It’s the worse place to put a wet car, anyway.

What to put in it?

First thing is a bench. This is the most important part of the workshop and where you will spend most of your time. It must be substantial.

If you are handy with wood, make it to fit the available space from 4 x 4in timber for the legs and 4 x 2 for the top, and 6 x 1 for the frame. Cover the top with a slice of MDF to make it smooth. Then cover that with a layer of flooring vinyl or rubber sheet, or best of all a piece of old fashioned linoleum. Plain dark green is best – 12 BA nuts can be hard to find on a patterned surface. Use it for the floor as well, at least for the areas you stand on.

If you are not into carpentry, buy a pair of two-drawer-high filing cabinets for use as pedestals – more drawers is better but still effectively the height of a two-drawer unit. Place a suitable length of kitchen worktop on top of the cabinets and glue batons round the underside of the worktop to hold it in place. Voilla! Instant bench and storage. Lockable cabinets are a good idea.

Or take your cheque book to your local tooling supplier and buy a ready-made metal workbench of suitable size. Or create just what you want in a bench like Cherry Hill (below).


You should fit a vice to the bench. For most of us an engineer’s vice with 100mm wide jaws is the norm. Vices are available is all sizes and configurations for special needs, from vices that swivel to large blacksmith’s vices to tiny jeweller’s vices.

Your standard engineers’ 100mm bench vice can come in two main types, and here you will need to come to a decision whether you are a workshop perfectionist, or a practical metalworker. The main difference is in the material it is made from. Inexpensive vices are made from cast iron. The good ones are made from steel. Whether you want to invest in a top vice  and whether you are prepared to pay between five and twenty times the price of the inexpensive cast iron one (below) is up to you. Whichever type of vice you buy, make sure that its jaws are removable (usually held by two screws).

If you’ve ever used a quick release vice, you’ll never settle for anything less.


Your vice/bench combination should be arranged so that the top of the vice is about level with a file held in your ’natural’ hand with your upper arm vertical and lower arm horizontal.

If you save some money on your vice, spend it on your hand tools. Over the years, you will probably amass dozens of these, but to start with, here is a suggested selection to start with for general model engineering use.

Start shopping!


•Quality hacksaw designed to take 12in. blades. Blades of 18, 24, and 32 teeth per inch (or tpi) with plenty of spares unless you buy the bi-metal type from Bahco. Old style blades break very easily in the hands of a beginner. The two with the higher number of tpi are used for cutting thinner sheet metal, there should be at least three teeth always in touch with the metal being cut. A coping saw and a copious supply of blades will also come in handy for cutting curved shapes.

•Odd workshop calculations, such as what tpi blade to use, are made easier if you keep a jotter pad handy, or perhaps keep a black or white board in the workshop.

•Many models for which plans are available have been designed in inches, and you will have to decide whether you will work in metric or imperial units, or both. Fortunately, conversions from one to t’other are quite straight forward, and while thread sizes are not interchangeable, it is not too difficult to decide whether you can replace 1/4in. BSF threads on your project with M6 threads. Buy a basic set of metric drills, or inch drills, or both. Using metric threads will cost less.

Files. You will accumulate them along the way. Start off with 10in bastard cut hand file, 8in. hand second cut, and a 6in. hand
smooth cut. Also 8in. second cut files in various shapes, round, half round, triangular, and square. Do not buy cheap files. Vallorbe/Grobet from Switzerland are the sort of files you will find in a toolroom. Wooden file handles come in sizes to suit. To fit the handles heat up the tang of the file until it is red-hot using a blowtorch. Remove the flame, and hold the file at the cold end, upright on a solid surface. Locate the centre of the tang in the centre of the handle, and steadily push down until it reaches a position where just part of the tang can be seen protruding from the handle, and not right to the shoulder of the file. Be warned a lot of smoke will be generated. If the file is hot enough, not much pressure will be required. Leave it to cool, and it should stay put for years. If it is loose, saw off a short piece from the end of the tang, put the file back in its handle and bounce the end of the handle on the bench.

•Files must never be used without a handle. File your files in slots in a rack to protect them. Never keep files and other cutting tools jumbled in a drawer. It ruins them.

•File cleaning card. This is a metal brush specially for cleaning accumulated metal particles from file teeth, but does blunt the cutting edges. Much better, but slower, use a corner of a piece of thin brass sheet.

•Later on you will buy a second set of files – and keep one for steel and the newest one for brass.

•Set of Swiss needle files. These are high quality needle files that come in a variety of shapes useful for precision fitting of parts, and can be used without handles.

•At some stage, you might also find a need for a set of Warding files, which are smaller than normal files but larger than Swiss files, and particularly useful in a knife shape.

•If you are planning working on complex shapes, also investigate a set of Riffler files.

•To get a smooth finish after filing, you will also need some emery cloth. Buy several sheets in various grades, and they can be torn into manageable strips for use.

•A pair of 8in. tinman’s snips for cutting sheet metal.

•An 8 oz. Ball-peined hammer.


Now you are almost ready to make something. But first, you will need the wherewithal to mark it out to the desired shape and to locate holes. Here are a few more items for the shopping list:

•6in. flexible steel rule

•12in. rigid steel rule

• Scriber

•Centre punch

•Micrometer: either 0-1in. or 0-25mm, or a digital one will work in both.

•Vernier caliper either 6in. or 150mm, or a dual digital one.

•Bottle marking blue

•BS2 Slocombe centre drill

•Drilling machine

  1. Set of twist drills

•4in engineer’s square

•Pair of overalls (aka smock)

•Safety goggles or spectacles and safety shoes

•Broom, pan and brush plus an endless supply of cotton swabs

•First Aid Kit – make
this your first

purchase!

•Barrier cream and Swarfega


You can add other items to this basic list when the need arises.


When tempted to buy some really cheap tools, be aware that you get what you pay for. There are exceptions, of course, but some cheap small tooling is dire. Good brands are good value.


Part one here. Part two here Part three Part four part five


 
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