DIY

Replica of a military helmet made of composite material

A copy of a military helmet made of composite material  A copy of a military helmet made of composite material The master craftsman is fond of aircraft modeling and participates in aerial combat competitions with radio-controlled scale models of aircraft from the First World War 1: 8 and the Second World War 1:12.
Helmets are a must in these events, as fast RC planes can get out of control in mid-air collisions. Since this sport includes aircraft from the two world wars, many of the participants prefer to use helmets from the same historical period. In particular, the master has been using the original M59/M85 Yugoslav Combat helmet for many years.
The problem with the originals is that they are made of metal and therefore difficult to wear throughout the day, and in addition they get pretty hot in the summer sun.
In this article, the master will share with us his experience in making copies of old military helmets from modern materials. Composites of various fibers (carbon, glass, aramid, basalt) and epoxy resin are strong and lightweight. Many modern military helmets are also primarily made from Kevlar/Aramid composites.
Tools and materials:
– Mold;
– Lubricant for molds;
-Epoxy resin;
-Various materials: fiberglass
Carbon
kevlar
fabric from basalt fiber;
-Filling;
-Seme paper;
– Paint or varnish;
-Nylon belts;
-Holders for a belt;
-Belt clips;
-Sewing machine;
-Engraver; -Diamond disc for an engraver;
< a href = "https://usamodelkina.ru/uploads/posts/2021-02/1613549525_1-3.jpg" rel = "prettyPhoto">A copy of a military helmet made of composite material A copy of a military helmet made of composite material A copy of a military helmet made of composite material Step one : mold
This article will not include instructions for making a mold. The DIYer's friends already had ready-made molds and he simply borrowed them.
If you have no one to borrow the mold, there are 2 ways to make it yourself. The most common is the manufacture of a casting mold for an original helmet from a composite. The second option is to print it on a 3D printer. There is still some surface work to be done in printing, but since 3D printers are getting better every day, this is not a big deal anymore.
Photos show the white mold that was used in this job. It is made of composite materials over the original helmet. The gray-red uniform is a 3D printed version.
A copy of a military helmet made of composite material A copy of a military helmet made of composite material A copy of a military helmet made of composite material A copy of a military helmet made of composite material A copy of a military helmet made of composite material A copy of a military helmet made of composite material A copy of a military helmet made of composite material Copy of a military helmet made of composite material Step two: helmet number 1 – carbon
The article will consider the manufacture of three helmets from various materials. Regardless of the materials, the mold must be well lubricated before work. This will simplify the process of removing the blank from the mold in the future.
The master used 2 layers of wax for the molds + 1 layer of PVA between them. The PVA should be completely dry.
Pulling the workpiece out of the mold can sometimes be difficult, but blowing in compressed air (8 bar) between the mold and the product works best.
A copy of a military helmet made of composite material A copy of a military helmet made of composite material The outer layer of the first helmet is made of fiberglass and then carbon. Mixed materials inside. Carbon is known to be strong and lightweight, but can become sharp when cracked. First you need to cut off pieces of fabric. Then place in the form. Each layer must be completely impregnated with epoxy resin.
Helmet # 1 consists of the following layers:
-80 g fiberglass
-160 g carbon
-220 g basalt
-220 g Kevlar (only inside, it should not reach the edge, as it is difficult to cut and grind)
-220 g basalt
-220 g basalt
-160 g carbon
It took about 250 g of epoxy to completely saturate all of the above layers.
A copy of a military helmet made of composite material A copy of a military helmet made of composite material A copy of a military helmet made of composite material A copy of a military helmet made of composite material A copy of a military helmet made of composite material Before taking out the workpiece, he heats it together with the mold to about 50 ° C for 3 -5:00. This will speed up the curing process of the epoxy to reach its final strength.
A copy of a military helmet made of composite material  A copy of a military helmet made of composite material Step Three: Helmet # 2 – Kevlar
Kevlar/Aramid is known to be “bulletproof”. This is the most durable of the three helmets. The only problem is that Kevlar is very difficult to cut. There is a little trick not to buy expensive scissors.
You need to take good quality scissors and grind their edges with an angle grinder, as if we wanted to damage them. The blade will have small indentations that will hold the fiber while the blade cuts it.
The technology for making a helmet from Kevlar is the same as in the previous step, the material you need is the following amount:
-80 g fiberglass
-300 g Kevlar
-300 g Kevlar
-240 g fiberglass
-240 g fiberglass
This helmet also needed about 250 g of epoxy.
A copy of a military helmet made of composite material A copy of a military helmet made of composite material  A copy of a military helmet made of composite material Step Four: Helmet # 3 – Basalt
Basalt fiber is somewhere between fiberglass and carbon fiber. The material is cheap, but it doesn't look as pretty as carbon.
The layers are as follows:
-80 g fiberglass
-220 g basalt
-160 g carbon
-220 g kevlar
– 220 g basalt
-220 g basalt
It took about 220 g of epoxy resin to fill.
A copy of a military helmet made of composite material Copy of a military helmet made of composite material Step five: trimming, grinding, painting
Edge trimming should be done with a diamond wheel. It is easy to cut carbon, basalt and glass with such a circle. Kevlar/aramid is more difficult, but it is also possible.
After trimming, you need to sand down
Sanding should be done with another sandpaper. Start at about 150 and finish above 1000. This is best done with water.
 A copy of a military helmet made of composite material With the exception of carbon, which is covered only with a transparent polyurethane car lacquer (in several layers), the rest are first covered with putty and sanded again.
Then it does painting – sanding – painting – and sanding/painting again until the finish is perfect. The helmets were covered with 3-5 coats of paint/varnish.
The carbon helmet is covered only with a transparent varnish, the kevlar one is covered with green color RAL 6025, and the basalt – matt RAL 7016. Also, all 3 of them are covered with transparent varnish from the inside to give them a glossy look.
 A copy of a military helmet made of composite material A copy of a military helmet made of composite material Copy of a military helmet made of composite material A copy of a military helmet made of composite material Copy of a military helmet made of composite material These are the helmets after painting.
A copy of a military helmet made of composite material Copy of a military helmet made of composite material A copy of a military helmet made of composite material Copy of a military helmet made of composite material Step six: fixing
Now you need to somehow install the mount and secure the liner. The comforter itself will be made of nylon straps and the fasteners are made of 1.5mm aluminum and then painted. The master has attached the files with templates for making the mount.
helmet holder1.dxfhelmet holder 2.dxfhelmet holder 3.dxf
 A copy of a military helmet made of composite material A copy of a military helmet made of composite material A copy of a military helmet made of composite material A copy of a military helmet made of composite material Master holders decided to glue it to the inside of the helmet with epoxy. For correct orientation and even distribution of the fastener around the circumference, he cut out a plastic strip and first installed the holders on it.
Places where they will be placed must first be cleaned.
A copy of a military helmet made of composite material  A copy of a military helmet made of composite material A copy of a military helmet made of composite material  A copy of a military helmet made of composite material A copy of a military helmet made of composite material  A copy of a military helmet made of composite material For strength, the master mixes some cotton fibers into the epoxy resin. For black helmets, he also used black pigment to make it black.
A copy of a military helmet made of composite material A copy of a military helmet made of composite material A copy of a military helmet made of composite material A copy of a military helmet made of composite material A copy of a military helmet made of composite material Step seven: straps
For the comforter, the master uses nylon straps 25 and 15 mm. He cuts and sews the belts.
A copy of a military helmet made of composite material  A copy of a military helmet made of composite material A copy of a military helmet made of composite material  A copy of a military helmet made of composite material A copy of a military helmet made of composite material  A copy of a military helmet made of composite material A copy of a military helmet made of composite material On the side that is not sewn, the edges need to be burned, so they will not bloom.
A copy of a military helmet made of composite material Copy of a military helmet made of composite material A copy of a military helmet made of composite material Step eight : Fitting the straps
The location of the straps is best seen from the photos. The 2 straps around the perimeter should be tightened according to the size of the head.
< img class = "aligncenter" alt = "A copy of a military helmet made of composite material" src = "https://usamodelkina.ru/uploads/posts/2021-02/1613549614_1-64.jpg"/> A copy of a military helmet made of composite material  A copy of a military helmet made of composite material A copy of a military helmet made of composite material  A copy of a military helmet made of composite material A copy of a military helmet made of composite material  A copy of a military helmet made of composite material After installing the belts, the master weighs the helmets.
A copy of a military helmet made of composite material A copy of a military helmet made of composite material Copy of a military helmet made of composite material A copy of a military helmet made of composite material Original metal the helmet he is using now weighs 1200g.
The carbon helmet weighs 487g, the Kevlar helmet weighs 545g and the basalt weighs 526g.
They are all close in weight, but much lighter than the original metal one.
Done .
A copy of a military helmet made of composite material Copy of a military helmet made of composite material  A copy of a military helmet made of composite material A copy of a military helmet made of composite material The video below provides an overview of helmets and some techniques work with materials.

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