009-SPA said:
Nobody has answered my second question yet. Where can I find cheap but good quality Kevlar?
Go to
Fibre Glast online. They sell Kevlar and Kevlar/Carbon Fiber hybrid weaves at reasonable prices ($30 to $60 USD/ 36"x50" pre-cut fabric). I get my stock from here. You will need at least 6 layers to make a usable, abrasion resistant part.
Be advised that Armed Forces helmets are comprised of at least 29 layers of Kevlar molded under high compression to minimize the thickness of the helmet each layer must be completely saturated with a ballistics compatible resin and free of air bubbles between the layers which means that you will need vacuum bagging and more than likely a large oven or an autoclave to bake the resin in because a resin with a set work time will not do the trick.
Even after this expensive process you will only have a rating of Threat Level II which will only protect against 9mm and .357 magnum small arms fire for a single hit (after your armor is hit once its integrity is compromised because it is a solid shell). Also the helmet shell itself will be a moot point if you cannot get a thick enough layer of polycarbonate (possibly 3/4" or greater) for the visor,
AND figure out a way that it can be fixed in place and will not detach when struck.
Your layers should look like this with all parts from the outside to the inside:
GEL COAT
----------------------
29-35 LAYERS OF KEVLAR
----------------------
GEL COAT
Afterwords, you will need an undersuit of some type to make sure that this is not the weak point of your armor. The layers will probably look like this:
BALLISTICS NYLON
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14 GAUGE (SWG) 3/16" ID WELDED TITANIUM CHAINMAILLE
---------------------------------------------
1" SILK LAYER
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BALLISTIC CERAMIC PLATING (Only in some areas i.e.: the groin & neck)
---------------------------------------------
20 LAYERS UNSATURATED KEVLAR
---------------------------------------------
BALLISTICS NYLON
The Titanium in this is for stab resistance, not ballistics proofing. This undersuit would be like a snowsuit underneath your armor, you'd need some significantly larger hard parts to go over this.
All in all I would estimate something in the way of $500,000+ USD for this project to actually work.
But everyone on this thread seems to have a misconception on what Kevlar is actually used for in an industrial setting. It doesn't just provide bullet proofing in several layers, it also provides resistance to heat at extreme temperatures (I used Kevlar sleeves during my glassblowing class last year), and is a highly abrasion resistant material. I made a pendant out of it once, I had to use a bench grinder with a rough grit stone to shape it and it still took me about 20-30 minutes to do.
So, if you're not looking for ballistics protection and are just looking for standard impact protection/high heat (1000°F-1800°F) protection, you'd only need something say 6-10 layers thick and a heat resistant resin that can take that kind of punishment to provide more than adequate protection. Also the undersuit would likely be much less bulky and could be wrought from 2 layers of kevlar.
If you're going strictly for abrasion resistance, you'll probably only need 2 layers of Kevlar with a layer of Kevlar pulp in between on your rigid parts, and the undersuit would also probably only need to be 2 layers of Kevlar.
Good luck to you and give us some pics when you get a WIP going
