wonwinglo
SMF Supporter
- Joined
- Apr 18, 2004
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- First Name
- Barry
BUILDING VAC FORM MODELS.
What is a vac-form ? well to fully understand the purpose of these limited production run type of kit it is important to understand why they are made in the first place ? The larger manufacturers rely heavily on recouping the high costs of producing the master pattern or mould as it is termed,to this end they must ensure that the subject that they choose will reach high levels of sale ie the well known Spitfire's,Hurricane's,Me.109 etc are guaranteed money spinners,but what about the types of aircraft models that builders want for their collections ? well this is where the cottage industry come into force with simple vac-forming equipment capable of building adequate model kits,I use the word 'adequate' because this is what is offered,a basic set of mouldings in thin plastic sheet and sometimes you as the builder aer required to scratch build undercarriages,propellers and other detail parts.But true modellers look upon these kits as a stepping stone to building those rare elusive types of aircraft and jump at the opportunity to build something very different from the usual run of kits.
This is what you get for your money,a basic sheet of plastic parts that have been hot blown over a master mould,this kit is an Airmodel Bristol Brigand which has not yet to my knowledge been made as a conventional moulded kit.
Start by drawing around the shapes with a marker pen,the reason for this is that it gives us a guide as to where we are going to sand down to,it is much easier to see the pen mark than to judge where the blade has cut into raw plastic.
The first requirement is to tape a sheet of wet & dry paper onto a piece of plate glass,this will provide a perfectly flat surface from which you can prepare the various parts to build the model,you can either tape the paper or better still tack glue the sheet to the glass with a 'cow gum' adhesive,or even use double sided tape to do the job.
To make life easier firstly seperate the pieces leaving a reasonable gap between the parts as above,this makes the parts more manageable at the initial cutting stage.
Use an Olfa cutter to scribe ( not cut through) the various parts,simply butt the blade against the plastic and pull gently towards you,a slither of plastic will be pulled from the plastic leaving a slight 'v' cut this is exactly what we want.
Next carefully snap away the parts,the pieces should break away easily.
You will then be left with a kit of parts that look like this...
Dont throw the scrap material away,you will need some of this valuable material later.
You now need some pieces of alloy 'T' Section,you can get a set of these very reasonably from Aeroclub.
Using some new Bluetak,stick the pieces one by one to the pieces of 'T' Angle,do not press too hard,just enough pressure to grip the pieces.
With plenty of water to hand carefully draw the parts back & forth over the abrasive paper,do this until you see a slither of plastic start to appear,also and this is important observe where the black marker line just starts to vanish,then is the time to stop sanding and reach for the next part.
For places such as the wings,make up simple balsawood spars,use superglue ( cyno ) to stick these to the inners of the parts.
Likewise use inner stiffners made up from the scrap plastic,to get the inner shape press in modelling clay,slice through with a blade and draw around onto the scrap plastc,score and snap as before when we cut out the main components.
Once the main assemblies have been put together,carefully use the drawing to assemble the parts,small joins can be easily filled with Squadron model filler,allowed to dry and blended in with wet & dry paper.
Note the old donor plastic model underneath which has been used to provide the engine nacelles and any other useful parts not easily reproduced in vac formed plastic.
Here the undercarriage legs were soldered up from wire,doors and small fittings have been made from scrap material from the kit,see I told you that they would come in handy ! keep fairing in and sanding until you are happy with the results.
Now go to Part 2 for the completion photographs....
What is a vac-form ? well to fully understand the purpose of these limited production run type of kit it is important to understand why they are made in the first place ? The larger manufacturers rely heavily on recouping the high costs of producing the master pattern or mould as it is termed,to this end they must ensure that the subject that they choose will reach high levels of sale ie the well known Spitfire's,Hurricane's,Me.109 etc are guaranteed money spinners,but what about the types of aircraft models that builders want for their collections ? well this is where the cottage industry come into force with simple vac-forming equipment capable of building adequate model kits,I use the word 'adequate' because this is what is offered,a basic set of mouldings in thin plastic sheet and sometimes you as the builder aer required to scratch build undercarriages,propellers and other detail parts.But true modellers look upon these kits as a stepping stone to building those rare elusive types of aircraft and jump at the opportunity to build something very different from the usual run of kits.
This is what you get for your money,a basic sheet of plastic parts that have been hot blown over a master mould,this kit is an Airmodel Bristol Brigand which has not yet to my knowledge been made as a conventional moulded kit.
Start by drawing around the shapes with a marker pen,the reason for this is that it gives us a guide as to where we are going to sand down to,it is much easier to see the pen mark than to judge where the blade has cut into raw plastic.
The first requirement is to tape a sheet of wet & dry paper onto a piece of plate glass,this will provide a perfectly flat surface from which you can prepare the various parts to build the model,you can either tape the paper or better still tack glue the sheet to the glass with a 'cow gum' adhesive,or even use double sided tape to do the job.
To make life easier firstly seperate the pieces leaving a reasonable gap between the parts as above,this makes the parts more manageable at the initial cutting stage.
Use an Olfa cutter to scribe ( not cut through) the various parts,simply butt the blade against the plastic and pull gently towards you,a slither of plastic will be pulled from the plastic leaving a slight 'v' cut this is exactly what we want.
Next carefully snap away the parts,the pieces should break away easily.
You will then be left with a kit of parts that look like this...
Dont throw the scrap material away,you will need some of this valuable material later.
You now need some pieces of alloy 'T' Section,you can get a set of these very reasonably from Aeroclub.
Using some new Bluetak,stick the pieces one by one to the pieces of 'T' Angle,do not press too hard,just enough pressure to grip the pieces.
With plenty of water to hand carefully draw the parts back & forth over the abrasive paper,do this until you see a slither of plastic start to appear,also and this is important observe where the black marker line just starts to vanish,then is the time to stop sanding and reach for the next part.
For places such as the wings,make up simple balsawood spars,use superglue ( cyno ) to stick these to the inners of the parts.
Likewise use inner stiffners made up from the scrap plastic,to get the inner shape press in modelling clay,slice through with a blade and draw around onto the scrap plastc,score and snap as before when we cut out the main components.
Once the main assemblies have been put together,carefully use the drawing to assemble the parts,small joins can be easily filled with Squadron model filler,allowed to dry and blended in with wet & dry paper.
Note the old donor plastic model underneath which has been used to provide the engine nacelles and any other useful parts not easily reproduced in vac formed plastic.
Here the undercarriage legs were soldered up from wire,doors and small fittings have been made from scrap material from the kit,see I told you that they would come in handy ! keep fairing in and sanding until you are happy with the results.
Now go to Part 2 for the completion photographs....