Vacuform models

[rickshaw]

I have made smaller vacuform models in the past and aren't overly deterred by the methods of how to build them.

I'd like to get some larger models, such as a C-133 in 1/72 but I am worried about how to sand the fuselage and wing halves evenly.

Does anybody know of any good tutorials on how to build these larger models?   I have also read about using expanding foam to fill the fuselage and wing halves to provide a solid and stronger item.  I suspect this would also make it easier to sand them down to the required thickness.   Has anybody used this method?

[PR19_Kit]

I used the foam-fill method to build a vacform model boat once, and it would give added bouyancy as well if the thing got swamped.

I didn't find it easy as it's difficult to figure out the correct amount of foam mix to pour in, and I ended up with having to saw off huge chunks of the stuff before I started the sanding down. That went OK so long as I kept on checking to ensure the joint line was a) straight and b) equal on both sides of the hull.

The sanded foam made TONS of dust though and I moved outside eventually as doing it in the model room would have meant wrcked paint jobs for weeks afterward.

[kitnut617]

There's a good book called 'Building and Improving Vacuum-Formed Model Aircraft' by E.Richard Staszak published by Kalmbach Books (ISBN: 0-89024-047-7), it has loads of very useful tips for building the models Brian.

For sanding the joints some say to glue wide strips of sandpaper to a very flat surface, like a mirror or glass table top (old disused ones of course   )
What I did was get a couple of sanding bars which you can buy at the RC model shops.  I've got two, one is about 10" long and the other is 22" long and you buy rolls of sanding paper of various grits which have a sticky back to them.

[rickshaw]

Thanks, I know about using tables/mirrors.  My concern has with the larger kits being able to make sure that I get even pressure on them as I sand, so that their edges sand evenly.  I can do that with smaller models, it's just the sheer size of these ones that worry me.   I'm worried that due to the flexibility of the plastic, the sanding will come out uneven.  I was wondering if using the expanding foam would prevent the plastic from flexing.

Would these sanding bars help with the problem?

[PR19_Kit]

Aeroclub used to sell a miniature version of those bar things, but I'm not sure if they still do. I have a set and find them invaluable in keeping the vacformed parts more rigid than they'd otherwise be during sanding. I use the trick of drawing round the bottom of the moulding with a thick felt-tip pen before cutting out, and that leaves a marker line so you can judge the level-ness or otherwise as you sand.

[Hobbes]

To make sure you're sanding the part evenly, you'll have to check frequently: place the part on a flat surface without applying any pressure. If the part is uneven, there will be a gap between the part and the flat surface.
Kit's method of marking the bottom of the moulding also helps.


I don't think the sanding bars would help if you use them as intended. But you could try using the bar as a handle: place the bar on top of the part, and fill the gaps between the part and the bar with e.g. silly putty or playdoh. Now the pressure you apply on the bar will be evenly distributed.

[kitnut617]

I think everyone is mis-understanding what these bars do, the rolled up sand paper are made to the same width as the aluminum bars, and you stick the paper to the bar's flat surface.  It then becomes a long flat sanding file.  The paper comes in various grits.  These bars are used by the RC bunch when building their flying models (or boats, or cars) and considering the size of many of my vacuforms they work in the same way.

[PR19_Kit]

The mini-Aeroclub versions of the bars are designed to work in both modes, and I use them like that but even the longest one is not really long enough to sand down a big model. My attempt at building Airmodel's vacform Seamaster failed because of that, the fuselage ending up with a warp all along its length.

[kitnut617]

I was using the 22" bar while sanding the edges of the 1/72 747 I started. It's still in the box where I had packed it away for the house move a few years ago ---

I've got a few projects to wrap up and then I'll get back to it, I want to build a few of these very big models I've bought recently, the 1/72 C-5 Galaxy is one I really want to get on with.

[Father Ennis]

I've used a sanding board made from.a large scrap of plexiglass with a full sheet of sandpaper attached. I also use a trick of my aircraft modeler friends who built many vacuform kits,back in the day. I spray paint the top side of the sheet. Then I cut out the individual pieces and sand them out of the backing. The paint allows you to get the best edge to the parts.  Size doesn't much matter with my setup. You can use one or both hands ,as required to sand. And, yes it generates LOTS of plastic dust,too. You can use the dust mixed with liquid glue as a great filler. 
       I have the book that was mentioned, I can also recommend it to you.  As for the use of expanding foam, my friends who have tried it have had mixed results. One used it in his 1/72 scale U-boat and all he will say is it split the hull and ruined it.  Others have used it with good results but nobody I know likes it.

[PR19_Kit]

One used it in his 1/72 scale U-boat and all he will say is it split the hull and ruined it.  Others have used it with good results but nobody I know likes it.

Using expanding foam to fill up an enclosed volume is NOT a good idea.

It's very difficult to work out how much you need to mix in the first place, unless you waste a load of it testing, and if you over-estimate the bursting situation is a very real possibility. I did do that once myself and the foam broke the deck off all the way round the hull. Luckily once I'd carved the foam down flat again the deck was repairable but it's not certain that will always be the case.

[rickshaw]

OK, Kitnut, I must admit then don't understand how you use those standing bars.

I learnt many years ago the way to prepare a vacuform kit was to draw a line around the piece on the sheet and then cut close to it with scissors/knife.  Then, with a sheet of wet-and-dry sandpaper taped to a flat surface you sanded the piece down until the line drawn disappeared, applying even pressure across the surface of the piece being sanded.

How do you use the sanding bar then?   As a replacement for the flat surface?

I can't see how you get an even sanding across the whole part, as mentioned above.

As I've said, I'm concerned about the large plastic fuselage/wing pieces of the big models flexing while I'm sanding, ending up with an uneven surface.   Which is why I was asking about the use of the foam, which I believed, if you used before you started sanding, would prevent the piece(s) from flexing and allow a large, flat mating surface, which was flat and even.   I wasn't intending to fill the model with foam after I'd assembled it (for the obvious reason as Kit has pointed out, it could well pop the seams).

[PR19_Kit]

How do you use the sanding bar then?   As a replacement for the flat surface?

I can't see how you get an even sanding across the whole part, as mentioned above.

In a word, yes.

When I used the mino-Aeroclub bars in that mode I held the moulding in one hand and slid the bar with the wet-and-dry attached along the surface that required sanding down. Because the bar is straight, and hopefully longer than the item being sanded, the warping is minimised. I used the felt-tip outline too as it still gives you a 'target' to aim at. I should imagine that Robert's longer bars work in exactly the same way on his (MUCH!) larger mouldings.

[kitnut617]

How do you use the sanding bar then?   As a replacement for the flat surface?

I can't see how you get an even sanding across the whole part, as mentioned above.

In a word, yes.

When I used the mino-Aeroclub bars in that mode I held the moulding in one hand and slid the bar with the wet-and-dry attached along the surface that required sanding down. Because the bar is straight, and hopefully longer than the item being sanded, the warping is minimised. I used the felt-tip outline too as it still gives you a 'target' to aim at. I should imagine that Robert's longer bars work in exactly the same way on his (MUCH!) larger mouldings.

You got it Kit, I've had no problem sanding long parts of the joining edge with the bar, in fact I've been using it on just about every model that I've kitbashed. The bar is quite ridgid so as long as you apply even pressure you get a nice straight edge.  I've tried the 'black' marker system but not had terrific results, I find it easier to cut all around the shape to sand but leaving about 2-3mm, then sand this down until the excess is reduced to wafer thin thickness.  Then I very carefully sand this until the wafer thin waste drops off naturally.

I posted this sometime ago but I can't find where I did, IIRC it was on another 'How to do vacuforms' thread.  This is how I do it which is explained in the book I mentioned.

[NARSES2]

Right I've not done any large vacforms, and only a couple of small ones, but these are the John Adams notes about using his T-Bar system.

I have a hard copy but I've nicked these off Brit Modeller. So credit goes to firstly John and secondly them.

Hope it helps

Chris

VACFORM MODELLING, a new approach?

by John W.Adams.

Models featuring the vacuum formed method of construction have been around for a long time. However, many people who consider themselves to be competent modellers, will still not attempt this form of construction.

Also I speak with an equal number of modellers who have had a go at vacuum forms and made (what appears to them) to be irredeemable mistakes and given up in disgust.

Why! Do they lack confidence, patience or skill? Perhaps the answer lies in the traditional techniques.

These vary slightly on the theme, "cut out and sand down parts using an abrasive covered board either wet or dry". Some advise modellers to leave a rim of waste plastic around the part. The theory here being that when this rim wears down to a thin membrane and breaks off, the correct thickness has been achieved. In fact, if the average wall thickness is 1mm and a rim of 2mm has to be sanded away, that to me spells 3 times the effort.

Let us look at the problems.
1. Vacforms are difficult to cut out.

2. I can't see how far to sand down.

3. My fuselages end up like bananas.

4. Parts are difficult to hold whilst sanding down.

And some common mistakes.

5. My trailing edges end up too thick and the wing appears flat.

6. I make a mess of cutting out cockpits and wheel wells.

7. I have taken to much plastic off.

Now let us look at some answers.

Start off with the right tool for the job, a good knife with a replacable blade is essential.
I always use a straight edged blade such as a Swann Morton 10A pointed blade with a No3 handle. (The No 11 blade is too fragile). This type of blade is good for most jobs, but knives such as Edding and Stanley are best for heavier work. Olfa and Scribe 'N' Cut, make tools who's primary purpose is scribing panel lines but can be used to score through very thick material. I use blades with a curved edge,only for scraping.

Hold the scalpel comfortably like a pen and angled away (about 45 deg) from the piece to be removed. Score all around the part using reasonable pressure.
1. The first myth to dispel, is that vacforms are not cut out by brute force, but merely scored around with a sharp blade.
Once the surface of most sheet material has been broken by a cut or score and that sheet is then stressed by bending so as to open the cut, the sheet will invariably break along the cut, no matter how wiggly the score line. Always take some cuts out to the edge of the sheet and start the break-out there. Practice on a piece of waste plastic.

2. Before scoring out the parts we must have a marker to show how much plastic will require removing by scraping or sanding (abrading) so the parts will fit together. We can use a fine (0.1) pointed marker pen, preferably permanent ink. A soft sharp B pencil will suffice. I find the best results are with a Rotring .25 (or similar make) drawing pen ideally filled with the type of ink specified for use on plastic drafting film (I use both Red and Black ink for contrast). Simply draw around each part where the part meets the backing sheet. This ink line shows us where we score and where we need to remove plastic. Be accurate. The ink line is King.

The part when broken out is then sanded down to the pen line.(more anon).

3. Fuselages end up like bananas, because, when using the traditional techniques any pressure on the centre of the fuselage will cause the part to bow, and as this is usually at the widest/deepest part, the wall plastic will be thinner. The waste plastic at the ends of a tapered fuselage, drop tank or nacelle or wing tip (where a mould cavity narrows) will be thicker . Consequently the centre edges of the part abrades away more quickly than the ends. Also slight 'moulded in' stresses can cause a part to bow when released from the constraints of the backing sheet.
Obey the ink line and the parts will straighten and fit, when taped together.

Paragraph 4. should provide a solution.

4. When using the traditional abrasive paper covered board the following formula applies. 'Finger ends tend to disappear at the same rate as the plastic', or when the water turns red , that's far enough! Also parts are slippery and tend not to want to move against the drag of the abrasive. There is nothing to grip, on such as tailplane halves or wheel halves.

We need some form of adhesive tape which is resistant to shear (drag) loads, and tacky enough to grip on a curved surface, and yet peel off easily when required. Also something to hold the part in comfort.

A method often employed to hold parts whilst sanding is to use some ordinary kind of sticky tape, either made into a loop or of the double sided variety, often using a piece of wood as a handle.

These tapes are not made for the job and are either too strong or too weak. The part keeps falling off or will not come off easily. Blu Tak is equally unco-operative when used for this purpose.

The answer is Sticky-pads and Tee-Al. (If this just sounds like a blatant advertisement , the simple truth is - they work)! Sticky-pads measure 12mm x 25mm and have a fabric base coated with a high-tack but highly peelable adhesive which is very resistant to side loads. Tee-Al is simply handy lengths of Tee section aluminium extrusion used as handles, other materials can of course be used.



When these two items are combined, handling of vacform parts becomes very easy. A suitable piece of Tee-Al has one or more Sticky-pads removed from the backing strip and positioned on the top face of the 'Tee' and then the protective wax paper is removed from the pad. The vacform part to be worked on is simply pressed into place and abrading or scraping can begin.

Even small curved or rounded parts can be secured by this method. In trials I have easily held and sanded down the mating surfaces of small difficult to hold parts such as drop tank and wheel halves. Highly curved parts like propeller spinners can be held by drilling a hole (in a piece of wood) and cover it with a Sticky- Pad, cut radial slits in the Pad and push in the spinner. A pair of wheel halves took a mere 3 minutes including cutting out.

Sanding down the parts.

For sanding (abrading) the parts I prefer to make my own handy sanders by affixing abrasive paper of the required grit (80!) to a piece of Tee-Al (or wood,even tube) with ordinary double sided tape (I recommend the new Selotape range). Thus a whole range of sanding tools can be created for little cost.
Alternatively you can use a Sandvik Handy Sander fitted with a medium Sandplate. Sandplates are rectangular metal self adesive plates (110x60 mm) with a pin point textured surface fitted to an orange plastic, comfortable handle. It is an excellent tool and widely available. Sandvik also produce a smaller tapered Hobby sander which has it's uses. Sandvik also make a larger type but beware as I have found the moulded plastic handles may have a slight curve, and so the plate is not truly flat, however the self adehsive plate (220x60mm) suitably mounted can be very useful (I have one on the bench top). I sometimes use a 10 inch single cut File (Farmers friend) of the type sold for sharpening lawn mowers (the handle is forged on the blade).

Leading and trailing edges can be reduced most effectively by scraping,using a heavy duty craft knife blade (Stanley knife). This is held almost at right angles to the surface and scraped to and fro along the wings inner surface. Use the curved type for single surface biplane wings. If you want to use two hands,then Tee-Al can be easily held in a small vice. Scraping is by far the best method and is a very fast way of removing material. You can scratch build wings this way.
When a Polyhedral wing (cranked or gull) is encountered, just treat the wing in separate stages.

There are other advantages to using this system. Work can be carried out at a convenient eye level thus enabling closer monitoring of the plastic removal. Parts such as wings are kept flat. You can work over a sink wet or dry so the dust can be washed away. Dust is the enemy of the tacky surface. Once adhered to a dry surface, Sticky-Pads will remain in place even under water. If water gets between the pad and the part, adhesion will cease, but can be reactivated by drying.

Trailing edges must be treated separately to the leading edges, which is the answer to problem no 5 (flat wings). If you draw a chord line through a section of vacform wing ( representing the flat abrasive board) it should be noticed that the leading edge meets this line at a much steeper angle, presenting a smaller area to the abrasive than the trailing edge. This means that more plastic will have to be removed from the latter. So if the old abrasive board method of sanding is employed, it's all to easy to take off too much of the leading edge whilst concentrating on the trailing edge, if both edges are in contact with the board at the same time.

Let us now take a look at cutting out waste areas such as wheel bays cockpits or windows.

As a general rule I do not remove waste areas until I have most of the mating surfaces sanded down, unless they project in some manner as to be a nuisance to progress. Whilst still in place, waste areas help with maintaining rigidity.

With a cockpit, or nosewheel, or gun position cut-out such as on the conventional fuselage split line, it is best to line up the two halves and secure them with a little tape. When you are satisfied that all is correct, score around the matching waste areas to be removed.
Now separate the taped halves and where the score lines reach the edge of the part, make a positive nick with the knife.
Now support the fuselage at the nick with the finger and thumb or a small pair of pliers, then start to shear the waste with the other thumb nail or a second pair of pliers. When the waste part is begining to move, change to the other side of waste bit and start off the shear there. Within seconds the tear should follow round the score line and the waste part should break cleanly out. When pressure is first applied some distortion may be apparent but you will notice it springs out.
For rectangular areas in thicker material,make two cuts with a fine razor saw, the ends of which are joined with a score line and then cracked out.

When an aperture needs to be made in in a fuselage side or a wing surface we apply a slightly different technique.
Score around the area accurately and carefully. It does not matter if the shape is rounded or square, but if the shape of the required cut-out is complex (for instance a Spitfire wheel bay) divide into separate areas,ie a circle and a rectangle. Now score diagonal lines across the waste area's with in the scored outline and at the intersection of these lines make a hole by forcing in the scalpel tip or if the plastic is too thick make a hole with a small drill. Using the scalpel tip, start to apply a cutting pressure along each diagonal in turn. It will be noticed that the little tri-angular pieces are starting to curl inwards shearing along the scored lines. Now, take a blunt instrument like a small screwdriver simply push in the tri-angles one by one. They should drop out like petals, with moderate force. A pair of needle nosed pliers may be helpful in removing the waste and it actually takes less time than reading this paragraph. For very thick plastic, use a fretsaw / piercing saw.

If you do not possess either of these useful saws, or a razor saw, you should!

Glues,
For vacuum forms use the thin liquid solvent glues. These are often Methyl Ethyl Ketone based. The correct method of use is to hold the parts together and apply the glue to the joint with a brush or Touch 'N' Flow solvent applicator. Capillary action will take the glue through the joint while light pressure is applied. I do not recommend solvent glues for laminating plastic sheet (use slow set Cyano).
Always work in a well ventilated room when using any solvent based glue and keep the glue covered when not in use.

The wide family of Cyanoacrylate or more commonly called 'super-glues' are best used when small, or dissimilar materials are to be joined, or reinforcements or instant results are required. If cyano's are used on canopies a white 'blooming' of the transparency may occur. This is caused by the 'gassing' cyanoacrylate reacting on contact with the hygroscopic plastic surfaces, and being clear you can see it. Do not remove the top of your cyano bottle and dispense glue straight from the bottle, the tingle in your eyes is the same effect as on your canopy!
Buy a small glass mirror or culture dish lid and dispense a drop of glue at a time, dip a pin or a cocktail stick into this to apply the glue. For a measured drop try breaking off the tip of the eye of a small needle so as to produce a fork (be careful of your own eyes when doing this). You will need to clean out the fork with the tip of a blade occasionally. An excellent way of dispensing along "run" of cyano is to use an old fashioned draftsmans bow pen, just load with cyano instead of ink. No it wont work with a Rotring type pen.
There are a number of accelerators (often called "kickers") on the market which speed up the setting rate of cyanoacrylate glues. These can contain 1.1.1. Trichloroethane, so treat with caution.
Ordinary Bi-carbonate of Soda has a similar effect, and can be used for building up areas quickly. I will expand on this later.


P.V.A. base glues such as Kystal Klear are the best for affixing transparencies. Apply with a small brush or cocktail stick. Any excess can be cleaned off with a damp cloth. P.V.A. can also be thinned with water.



Transparencies
These seem to give more than their fair share of problems. I seldom put a knife any where near a canopy, instead prefering a small very sharp pair of scissors. Buy high quality. Next, can you see what you are doing. I find that working against a mono coloured background a help. You will find the background required varies according to the light. If the frame lines are indistinct, then cut strips of masking tape and use them to define the no - go areas. Work carefully, trim the waste off a little at a time, Flex-i-files are good for sanding the edges, but remember to remove the dust and most importantly do test the fit of the canopy to the fuselage frequently.
When you are finally satisfied with the fit, hold the canopy into place. Now run a brush full of liquid glue around the edge, then apply slight pressure. Repeat with the glue and hold for a minute. If you allow the glue to dry you will find that the canopy is nicely bedded in. It can be easily removed for painting and may be finally affixed using Krystal Klear.
If there is no moulded rim on which to seat the canopy then glue strips of thin plastic card to form a rim around the inside of the cabin opening. Should you then find that the fuselage plastic is of thicker gauge material than the canopy, then simply build up or pad out the rim with narrower strips, until the canopy is flush with the fuselage surface .
This is fiddly but not difficult.
But remember if you have over sanded the fuselage, your canopy will not fit!


Battle damage repairs.

Or, "I've taken off too much plastic". It's not the end of the model, we can repair most mistakes. Most initial problems are caused by failing to mark or score out accurately. So if for instance an inconsistent score line has caused a piece to stay with the backing sheet when breaking out, simply retrieve it and glue into place using super-glue, then sand down as normal. If it's a large tear/spilt then you might want to reinforce with a piece of plastic card.
All repairs are best carried out using super-glue (Cyano's, Cyanacrylates), because you get instant strong joints, which sand well.

A more common mistake is, over sanding of parts. especially on fuselage halves. Usually this is caused by not obeying the ink line or by being over enthusiastic when sanding down and not checking often enough. If one fuselage side has had too much removed from the middle (banana) then the answer is to assemble the parts together with tape and assess how much is missing. Once this is ascertained, glue some suitable strips (taper if required) into the gap, glueing only to the wounded side. Gap filling cyano can be used but if this is not at hand, use super-glue and bi-carbonate of soda (baking powder) to bridge the gaps. You just apply super glue and then a pinch of bi-carb, this soaks in the glue and instantly sets hard, Repeat the process until the wound is filled. Then restore the contours using a tool such as Flex-i-file or Flex-i-pad.

The result will be a strong hard repair much quicker than using two part or tube fillers.

If the case is a trailing edge with a large piece missing, then the best approach is to cut out the area and square it up, then glue into place a piece of suitable size plastic strip, use super-glue and/or baking powder again and file to shape.

When damage occurs to a corner of a wing tip, prop blade or something like the end of a tip tank or radome, simply apply super-glue and then dip in a small pile of bi-carb, this will harden immediatly. Repeat the process until a suitable sized blob has formed and then file back to shape. If you have to use those vac-form props then this is the solution for filling the blades.

When joining fuselage halves it is usual to strengthen the joint with strips or tabs of plastic card glued into one half so as to form a rim on to which the other fuselage half fits. A better fit will be achieved on very curvaceous fuselages if these tabs are placed at intervals and stick outwards, 10 thou card is best. It is a tedious job cutting a number of these tabs, so I use an office paper punch to produce a load of little plastic discs which will contour nicely around the inside of a fuselage half, even if the half fuselage does look temporarily like a Viking ship.

Perhaps here a word of caution about choosing your subject. Vacuum form kits vary in quality. If you have never before attempted a vacuum-formed kit please don't be tempted to go out and buy that 15 year old Scruggs Four Engined Wonderplane kit. Instead try a few simple exercises, get some plastic card and make a new tailplane for that damaged Mustang, or practice making holes in a piece of plastic card. There are lots of cheap vacuum formed kits around often from Eastern Europe, and they can be picked up at model shows. Examine the kit and if it's crisp and cleanly moulded it will probably fit together well, If it looks blobby and ill defined, don't buy it.
If some items like spinners or wing roots are thin and crushed then re-inforce with Milli-put or bi-carb but never use tube type fillers (most tube type fillers are only good for shallow surface blemishes as they usually work by solvent evaporation).
Milli-put if properly mixed and placed on a storage heater or hot domestic radiator (below 70deg) will harden very quickly and not affect the kit plastic. (Here's a tip, mix and heat the Milli-put before applying it -it will harden just as fast, but use it quickly. It is advisable to wash your hands immediately the putty is mixed and again after the application is completed.

The following useful tip came via one of my customers.
To fill well fitting joints such as leading edges and fuselage centre lines scratches or panel lines, use Tippex Correction fluid, Note it must be the bottle which incorporates a Red oval 'Perfect' design in the label and not the one with a Green oval. The enviromentally friendly one may do wonders for typists but it's no good for modelling. Tippex bonds very well, dries quickly and sands beautifully.

White metal
Most recent vacuum formed kits contain detail parts cast in white metal, or suitable parts can be purchased to improve older kits. The best adesive is cyanoacrylate. White metals usually contain a proportion of lead, (Those called Pewter should not) so don't eat when working with it and do wash your hands.
Blow holes or any deficiency in the castings are best repaired with the super glue and bi-carb combination. Milli-put or Plastic Padding car body fillers also adhere well to white metal.
If a hole in a propeller or engine is too big then bush it with a piece of plastic or metal tube. Household pins make good strong prop shafts.

However the occasion often arises when there are no under carriage legs available for that old large kit. The solution is Aluminium or Brass tube. This can be bought in a variety of concentric sizes with which you can fabricate oleo legs. If you can not find it in your local plastic kit store, then make a visit to a Model Railway shop or one specialising in flying models. You will be amazed what goodies you will find. It does puzzle me still just how parochial many 'plastic kit bashers' are!
Tube can be easily cut with a fine saw or even with a heavy duty craft knife by rolling the tube back and forth with the blade as you apply pressure. Plastic card fillets or fairings can be stuck on to the metal with super glue or 5 minute Epoxy, then filed to shape. Brass has the advantage of being soldered for greater strength (exit plastic modeller-stage left).
Axles can be glued to the end of the tube, or drilled right though to accept a piece of wire (a section of sewing pin) which can be sleeved up with metal or plastic tube to scale size.
If you are boxing in a wheel bay, make the top from thick plastic card or if it is a kit vacuum formed item, strengthen it so that it can be drilled to take the under-carriage leg.
Metal tube can be utilised for wing spars, and when threaded through a fuselage it can be bent either side to set the dihedral angle.

Jigs
The assembly of any type of kits can be facilitated by making jigs. A jig can be as simple as a piece of plasticine, or an elaborate affair constructed from plastic card. With only a little imagination, a few pins, cocktail sticks,plasticine,right-angled tri-angles cut from card and a square of card with lines drawn on to it,for a base even the most complex biplane can be set up for accurate final assembly. There is now my purpose built metal Biplane Jig only available from me.

Vacuum formed models do require some hand and eye skills but remember these can only be discovered or improved upon if you are prepared to have a go, the hardest part is picking up the scalpel and making that first cut,(sorry,score). If this article fires some of you to stretch your horizons or provides a solution to a particular problem then it has achieved its aim. If on the other hand you are going to sit back and wait for the Big Injection Company to produce that Scruggs Wonder plane , I have it on good authority they never will. So you might just use your time while saving up for the resin from Blob-o-Kit (who probably nicked it from the vacuum form anyway),to have a go, and find as my youngest daughter used to say the World can be your Lobster!
Copyright . John W. Adams.