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'HOW TO MAKE STUFF' by Jessie the Jeep


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ZAP Zip Kicker - Zip Kicker is the best way to accelerate the cure time of all super glues. When sprayed directly on a glued joint it forces the immediate cure of the glue. Thick or slow glues form an instant hard outer shell when sprayed with ZIP KICKER, the catalytic action begins curing the remaining liquid CA at an accelerated rate from the outside in, creating a strong bond. This action allows the creation of fillets and the ability to fill large gaps. ZIP KICKER will not harm most materials making it perfect to use on wood as well as various plastics, metals, paints, and fabrics.

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ZAP Z-Poxy - Z-Poxy MINUTE Z-POXY is a premium two part epoxy adhesive, available in 5 minute and 30 minute cure times. The 5 minute cure time makes it ideal for fast building and repairs. Vibration resistant, this epoxy is perfect for many jobs, including the inevitable quick repair jobs. It does not get brittle with age and it’s easy to mix, just combine equal parts by volume. It is not advisable to use this product for major load bearing joints, for areas where greater strength is required; we recommend the use of 30 MINUTE Z-POXY.

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Fastglas - This is a polyester based resin which can be used in conjunction with fibreglass mat or cloth in mould making. It has a fast cure time of around 20 to 30 minutes. Epoxy and polyester resins are not compatible which has its benefits. Making a mould from Polyester resin, waxing it with an appropriate release wax and laying up the item in epoxy aids the release process from the mould.

 

Suppliers - Auto Spares & Repair Stores

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Glass Cloth and Mat - Woven glass cloth of various weights, is used by most professionals in mould and final product making. When combined with polyester or epoxy resins, it will produce a tough moulded waterproof article ( ie canoes ). In addition to making a complete item from glass cloth and resin, many model aircraft builders use it to skin over a wooden structure to give a smooth tough outer skin that will accept surface detail such as simulated panel lines and rivets.

 

For a novice to moulding, chopped strand mat is probably an easier form of glass to work with, but really only with polyester resins ( the chopped strands are held together by a wax that is dissolved by the polyster resin, but not so with epoxy ). Chopped mat once wetted out with resin will become very mouldable around complex shapes.

 

Glass Cloth Suppliers - Model Shops and moulding companies

Chopped Mat Suppliers - Auto Spares & Repair Stores

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Milliput - Milliput is an epoxy mixed with china clay if memory serves me correctly. It forms a mouldable putty which cures in about 4 hours. While set uncured, it can be moulded like clay and worked with water to form a shape, but will still cure under water and is heat resistant to 130°C. Once set can be sawn, carved, sanded, drilled, tapped, machined etc.

 

Suppliers - Model Shops and Art/Craft Suppliers -www.milliput.co.uk

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Styrene - Styrene is the plastic that model kits are made from. It is easily cut and sanded, can be heated to soften and bend, can be softened by heat and vacuum formed, and glued with a range of adhesives. It is best glue to itself with a solvent glue that dissolves the surface of each part forming a ‘weld’ between the two. I usually buy it in sheet form ranging from 0.5mm to 2mm for my uses. It can be obtained in a range of colours and clear, and in small sheets from model shops in textured forms.

 

Suppliers - Specialist Plastics Suppliers and Model Shops

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Wood – MDF, Pine, Ramin and Ply wood. Most of the boxes I’ve made, plus the Jeep doors were made from ordinary interior ply for a local hardware store. Sometimes when I’m looking for something with a smoother surface finish, or a long length without warps, I’ll use MDF ( Medium Density Fibre Board ) and it also has the advantage of no knots, no grain, and is easily cut and machined.

 

For something where the surface needs to be fairly smooth, having the stiffness of ply, will be more waterproof and will not de-laminate like MDF, I’ll use a good quality Birch plywood which has a nice tight grain. Quite often when making boxes, I’ll re-enforce the corners with small square sections of pine or ramin cut into strips on the band saw. However, most hardware stores will sell strip wood if you don’t have the facility to cut strip wood.

 

Suppliers - Hardware Stores, Timber Merchants

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MANUFACTURING TECHNIQUES

 

So how do I go about explaining how to make stuff? This section will cover understanding the form and ways to manufacture this.

 

Scaling

 

If you have some drawings for the object you are making, they may not be full size. Perhaps you have a square on photograph of the item, and you need to work out the position of a certain item on the picture. You need to establish a scale. To do this, you need a known dimension to work with.

 

Again, using my radio as an example, I knew from research that the real radio had an overall length of 18 inches. Taking a photograph I had of the radio, the length on the picture was 7.5 inches. So if I take the real size of 18, divided by the picture size of 7.5, it gives me an answer of 2.4, so that makes the scale of the picture 1:2.4. So now take any measurement on the picture and multiply it by 2.4, and it will give you the dimension of the full size.

 

The larger the first dimension you use to achieve the scale factor, the more accurate the scale will be. Obviously any photograph with some degree of perspective cannot be used for scaling, but a true square on picture can be used. In the past, I’ve used scale drawings, models and photographs to scale from to build models.

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Understanding the Shape

 

So, making stuff eh?!? The first step in reproducing an object is to study it, not as a radio, bayonet, a rifle etc, but as a series of shapes and forms. Looking back at my BC-348 radio, the main form of the object is a rectangular box 18 x 10 x 8 inches. On the surface of this box are other shapes and forms.

 

There are various knobs for adjusting volume etc, which are all cylindrical in form. Screw heads are all domed. Some like the dial are more complex, but again, this form is broken down into sub forms of rectangular and triangular sections and is built up in layers. Each different feature of the object is studied and broken down to its simplest forms and from there; it then becomes easier to begin to replicate the object.

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So to begin with, here are the basics of the box. The first part cut was the base, cut from ¼ ply to the true length and depth of the radio. The rest of the box would be built on top of this piece. Next to be cut were the front and back pieces, also made from ¼ ply. These were cut to the true length, but the height was cut less ¼ inch to allow for the thickness of the base, and less 1/16th inch to allow for the lid which was to be made from 1/16th inch aluminium sheet.

 

End pieces were last cut. The width was cut less ½ inch to allow for the thickness of the front and back, and height cut less the ¼ for the base and 1/16th for the lid. To strengthen the joints, I cut some 3/8th inch strips of pine on the bandsaw which would be glued along the joints to create a larger gluing area. The first piece to be added was the front.

bc348b7.jpg

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As previously mentioned under materials, PVA woodworking glue was used for most of the joints, but at each end, and a couple of places along the joint, I use some Cyanoacrylate glue. This instant bond glue holds the pieces together without clamping while the PVA cures. Along the back of the joint, I glue some of the 3/8th square section pine, again with a mix of PVA and Cyano, making sure that this reinforcing piece is short of the main piece to allow for the ends to fit.

 

This is repeated for the ends and then the rear of the box, each time adding the 3/8th inch strip wood to reinforce the joints. Once the basic box was together, it was left to dry fully. After it had dried, the edges were all sanded and it was skinned with 1mm styrene attached with ‘Cyano’ glue, to give a nice smooth final surface to work on without the need to fill the wood grain.

box1.jpg

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The tuning knob was basically a ½ inch thick cylinder. 1mm styrene was added to the top for a smooth surface, and a further 1mm styrene ring was added to that to create the slight lip to the front of the knob. The rear face was than marked out into eight segments which would form the centre lines for the scallops around the edge. A small ½ inch diameter sanding drum was then fitted in my mini drill to sand out the scallops. The small metal handle was turned on a lathe, with a small 1mm wire through the centre to hold it onto the main knob.

tuner1.jpg

tuner2.jpg

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The handles were made from ‘Chemiwood’. These were quite a complex shape, and so were made in stages. The first stage was to cut a ‘blank’ from the ‘Chemiwood’ which was the correct length and height, and twice the width needed. This would allow cutting of both handles basic shape at once which was done on the bandsaw. Here’s the first stage cut and the offcuts. The red dotted line shows where it will be divided.

handles1.jpg

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After the basic cut, the piece was sanded before it was then cut down its length to create two separate handles. The following picture shows them after the cut. The red dotted lines mark out the next cuts to create the correct plan form for the handles. Each one was cut separately on the bandsaw to leave me with two handles of approximately the correct shape, but squared off in section.

handles2.jpg

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The main frequency dial was probably the most complex shape to reproduce on the radio. Once more, the shape was studied and broken down into smaller, more easily managed pieces. The first picture shows many of the pieces and layers that go to making up the basic dial shape. A base of 1/8 ply, 1/8 clear styrene, triangle sections of pine etc. By keeping each piece a simple shape, the overall complex piece is easy to achieve, and a cock up on one piece does not scrap the whole item.

dial1.jpg

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Behind the clear part of the dial, the actual face of the dial is again built up in layers. The first with the curved slot is a piece of 1mm styrene. The slot was marked out with a pair of dividers scratching into the surface of the styrene, and then it was carved out with a scalpel to the score line. It is shown here with a first coat of black paint, prior to a light rub down and second coat.

 

A second layer was added behind, again painted black, but with the numbers added via white ‘Lettraset’. It was then glued to the rear of the first piece, with a small red painted pin trapped between for the marker on the dial.

dial2.jpg

dial3.jpg

dial4.jpg

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This piece was then glued to the back of the main wood/clear styrene piece. Because its overall size was smaller, other pieces of styrene were added to make up the thickness. These were then trimmed down flush with the basic shape prior to gluing to the 1/8 ply base.

 

The band switch was made from a piece of plastic tube glued to a larger styrene disc. Six pieces of 2mm styrene were then glued around the edge at 60 degree intervals and their corners lightly sanded round before painting. All styrene to styrene joints were done with plastic solvent glue, while ‘Cyano’ was used for styrene to wood joints.

dial5.jpg

dial6.jpg

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Where possible, details like screw heads were duplicated by using real screw heads, as it is easier than making them and the look more realistic than trying to paint something to look like metal. The toggle switch was bought rather than made. Apart from it being needed to function, it was simpler to fit a real switch than make one, though it could have been made turning aluminium on a lathe. Where ever possible, if a suitable item is available and not too expensive, I'll use it to save some money.

 

Once all the individual components were completed, it was a simple task to glue them in place. To plot the positions of the knobs and switches etc, a face on picture was found of a real BC-348 radio, and that was blown up and printed out at full size. The print out was placed over the front panel of the radio prior to painting, and the centres of all the switches etc, were drilled through the print out with a 1/16th inch drill into the surface of the styrene beneath. It was then an easy job to locate everything once painted.

bc348.jpg

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Markings and Lettering - All Lettering was added with off the shelf ‘Lettraset’. If you have more complex artwork to produce, there are companies that will make waterslide or rub down transfers from a master black and white image. This master image is usually produced at two or three times full size so that any errors in the graphic are reduced in the final artwork.

 

An example of custom graphics is shown below. This Ever Ready battery is one I made in university. It is five times full size, and stands approximately 10 inches tall. All the red and gold artwork is custom rub down transfers, costing £110 back in 1992. The second picture shows a real Ever Ready battery next to the model.

battery1.jpg

battery2.jpg

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Moulding

 

Some shapes that need to be made, especially if there is more than one identical part, may be better being moulded. Depending on the size, shape and complexity of the object, this dictates the mould type and moulding material that should be used. For the mould material, silicone rubber or glass fibre are options, and for the final item, casting resin or fibreglass?

 

Starting with fibreglass as a material for moulding and mould making, we’ll look at a few methods of production. Some shapes produce what is called an ‘undercut’, which if moulded in a one piece mould would trap the object being copied in the mould. See the picture below to see an example of an undercut. Because of the shape of the plug ( shown in green ), the moulded item ( shown in red ) is formed around parts of the plug preventing its release; this is an undercut. The choice of mould is often dictated by the shape of the item being copied.

moulding_trapped.jpg

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