Composite

This week I will create 3D model from which I will cut the mold in foam. And I will create a composite material based on it.

software / sites used during this week

Antimony
3D modeling software that I will use to produce a 3D mold. My mold is simple so antimony is a great tool for quick 3D modeling
VCarve
Software to transform my stl file to CNC machine codes (g-code).

hardware

CNC machine
Woma big CNC machine to machine the foam and produce my mold.
End mills
4 / 12 mm end mils for rough and fine milling

All files that I have demonstrated below are also available in this zip file

Day 1: Prepare my 3D model for molding

I decided to make a hand protection for the archer. In this sport when the posture or movement done with error - the cord of the bow can hit the hand and it is highly not comfortable. This thing can be decorated by piece of leather with some laser cut on it...

So Antimony for such kind simple models is good tool. I created in antimony simple model and crated 2 sided mold. Initially I though to compress the composite between two side of mold, but later I used them as 2 different molds (inner and outer) to see a difference in production.

Antimony result

The next step is to export .stl files and pass directly to VCarve. In VCarve I generated gcode files for CNC machine. I generated 4 files: 2 for top and 2 for bottom molds (rough 12mm end-mill and fine 3.5mm end-mill pass). When files are ready - go to CNC machine.

Cutting the foam is very fast. As this material is very light in consistency - milling has no any resistance so I did processing on 120% of the speed for both stages.

Here is some video of cutting first mold

Speed view of cutting first mold

Cutting the second mold rough pass

Cutting rough second

Here are the result molds.

Result molds

And they fits.

They fits

Day 1: Prepare molds for the composite

To make molds fine and shine and to avoid that resin attach to the mold I will put some wood glue on it. It will make surface more fine.

This is the wood glue I have used (I added some water in it just to make it more liquid)

And what it is looks like at the end of preparation

Now let it dry for few hours. Will continue tomorrow

Day 2: Make composite

I need that this protection is stay thin, and I do not need that this material becomes very strong, so probably 3 layers of cotton mixed by epoxy resin should be fine.

Let make a pattern to cut cotton in good sizes. I used the old-style handy method as my shape is very simple.

Draw it on mold, cut from carton.

Then apply it and draw over.

And cut them

Now we prepare the mold by adding Wax on it. It will take about 30 mins to dry.

When it dry we can start to make our composite by making a layers of cutted cottons and epoxy resin. Epoxy resin is a bi-components resin with hardener. The proportion is 45 to 100 parts in wight. So I took 40 grams of resin and added 18 grams of hardener into it. I used plastic cups for it. Then well mixed and I have 1 hour apply resin before it start react and become harder. I started by level 0 - applying resin to the molds and then I add one cotton layer and cover it by resin (that it enter inside the cotton). Then I repeat for each layer (using the brush to remove all bubbles)

Starting by inner mold (bottom) and fulfill by layers

Then passing to outer mold (top) and starting also put the cotton and fill it by resin

Result of outer mold looks like this

Now let it dry for next 24 hours. One of mold I putted on 45 degrees to avoid that resin comes to the lower part of it and make a kind of lake inside. Better that it goes out.

Starting by inner mold (bottom) and fulfill by layers

Day 3: Take it out and test

I did not have chance to go today at Woma and take out my composite from molds. But looks like it attached to mold... Will see tomorrow. So waiting for results for the momemt.

Few days later - take it out!

Looks like that wax did not did perfectly its job and my composite rest attached to foam. But as the foam is not something realy stong - finally take it out was not a big deal. Just that form is not useful anymore and need to be done again to repeat production. Below are some results.


So result is looks ok. Even because the not fully detouched foam - it can be used as it was preview. Let see anotehr day and make it more cool.

Day 4: Finishing

Today I will remove a little attached foam, will make a holes for attachment cords and will place cords.s

First of all I use the scissors and cut-out the sides to become to initial form. Then I use crayon to place position for the holes and by using the dremels drill clean up my composite.

We can see how I cut out sides

And let make holes for attachment cords.


When holes are done - I use a simple needle and thread to fix a attachment rubber band.

So now it is looks like ready and can be tested for real. I will add some decoration on it one day, by using the vynil cutter :-). Now how it is looks like! (the rest of woam giving the kind of vintage style ;-) )