Hi I'm Paul from Easy Composites and in this video we are going to be showing you how you can machine from epoxy tooling board,
accurate patterns and then apply a very high quality surface finish using the S120 Board Sealer.
Now the main focus of this video will be working on a pattern that subsequently in a later video we will be making this prepreg tool from.
However it is perfectly possible to use all the same machining and finishing methods to make low volume or prototype tooling straight from the board.
Here we are using a simple desktop CNC router loaded with a 6mm flat end mill cutter to machine the epoxy modelboard.
In most instances a 3 axis machine is all that is required for machining patterns for mould making
as patterns generally have a positive draft angle,
therefore the cutter can normally access the entire tool surface.
After this initially roughing cuts.
The machine will then move on to the finishing passes.
We are using a 0.25mm step over and we are going to do a perpendicular pass.
So, 1 at 0° and 1 at 90°.
The machining has left some very slight marks on the surface these can be easily removed using some 800 grit paper.
Complex geometries and compound curves are normally directly sanded by hand.
For flatter areas a block will make lighter work of the flatting process.
as the epoxy board is specifically designed to be machined and finished like this you
will find that you will very quickly get the final finish you require.
After sanding all of the dust should be carefully removed using a dry cloth.
The 800 grit paper has left us with the bare minimum of machining marks and a really smooth and consistent finish.
This is now ready for a gloss and a seal using the S120 Board Sealer.
There are 3 main methods of applying the S120 Board Sealer.
The first and probably most common is to apply it using a lint free wipe.
This requires lots and lots of coats but it does give you a very even, consistent and glossy finish.
The other methods suitable for larger patterns is to use a HVLP spray gun the same as you
would use for painting a car and that covers large areas very quickly.
We are going to be using a spritzer nozzle which takes the advantages of the spray process
so it builds up thick coats but has the convenience of being able to work on smaller patterns
without excessive over spraying equipment.
Because the S120 is highly moisture sensitive we recommend that you only buy enough for your immediate project.
Which is why we have it is a range or sizes right down to a very small 50ml.
The sealer should be sprayed in a methodical manner.
Essentially you are looking for the thinnest possible coat that achieves a consistent gloss coverage.
In common with spray painting care must be taken not to overload the surface as this can lead to pooling and runs.
After applica tion the sealer should be left for approximately 20 minutes to dry and cure onto the surface.
You will notice that the first coat has been largely absorbed by the board and we are starting
to get some of the satin finish coming through where it has been absorbed in.
Some areas are already starting to look quite glossy.
That is where is hasn't fully absorbed in but you will notice is has gone completely
touch dry so we are ready for the next coat.
All subsequent coats should be applied in exactly the same manner as the first coat.
Allowing a minimum of 20 minutes between applications.
When using the spray application methods, generally to achieve a full seal and gloss lik e this will take between 3 and 5 coats.
Having applied 4 spray applications it has now been left for several hours to fully cure on the surface.
We are left with a few small nibs on the surface here that we are going to just knock out with 1200 grit paper.
This flatting an de-nibbing operation is only required when surface finish and flatness is of paramount importance.
However you will find the operation to be very quick and easy as all of the imperfections
are in the positive to it takes a bare minimum of effort to remove them.
With the surface now fully de-nibbed and flatted out to a standard that we are happy with we are ready to apply the final coats of board sealer.
These will be done using a lint free wipe as this gives us a very flat thin and even
coating that should maintain the accuracy of the pattern.
A small piece of cloth should be liberally soaked and then the material evenly wiped over the surface of the pattern.
Once an area has been coated it should not be revisited as there is a likelihood that
the materials will be partially cured and it can easily lead to wipe marks and smearing.
it takes around about 20 minutes depending on conditions and how thickly it has been
applied before you apply the next layer.
As you are doing this you will see with each subsequent layer the level of gloss will build until you get to your final finish.
To avoid exposure to the air tightly reseal the container between every application.
This pattern took 4 wipe applications to bring it to a full finish and gloss.
Although the board sealer feels completely touch dry after around 20 minutes and essentially the sealing is now completed.
We have got an amazing gloss finish, really flat surface perfect for taking a mould from.
But before we go on to applying a release agent we need to let this fully cure.
Now this can be left overnight to fully harden.
Alternatively like we are going to do you can accelerate this by putting it into an oven at 60°C for around 20 minutes.
This pattern is now finished and ready to take a mould from.
Epoxy tooling board is compatible with virtually all composite tooling methods.
In the next video we will be using it to produce this prepreg carbon fibre mould.
Alternatively for prototype parts or short production runs, remember it is totally possible
to machine moulds directly from the tooling board.
This is a mould that has been machined to produce a 90° tube section and this could have the prepreg carbon fibre laid straight into it.
To see us complete the process by using this pattern to produce a prepreg mould and then part check out our later videos.