Here is another good way to attach the darts with screws or bolts, without having to bondo or glue a screw/bolt into the darts, then bolt it to the plastic.
First you will need:
A 3/16" Drill Bit
A 3/16" Tap Bit, which looks like THIS:
A Drill or Drill press
A crescent wrench OR small channel locks (crescent preferred)
A 3/16" bolt with a matching nut, and a washer
and your Knee Armor.
OKAY! so first thing you need to do...is to take your 3/16" drill bit and your knee darts. You will then drill a hole into your Knee Dart that is about the lenght of your bolt. I would suggest nothing larger then a one inch bolt, unless you feel confident in your drilling abilities.
For this (since I dont have any knee darts handy at the moment) I used a cylindrical shaped piece of styrafoam.
**If you have a drill press, make sure you are holding onto the knee dart, and just a normal drill, hold on to the darts...i needed one hand to take the picture**
So now that you have drilled the hole go ahead and get your Tap Bit. Place the Tap Bit into the crescent wrench, like this:
Make sure you keep constant pressure on the crescent scroll so you keep the bit in there. Now take the knee dart and place the Tap Bit into the drilled hole. Don't force it. You will slowly **SLOWLY** turn the bit Clockwise into the hole. This creates the treads for the bolt.
Now when you get to the length of hole you drilled back the bit out in the OPPOSITE DIRECTION (Counter-Clockwise) SLOWLY!
Now you have a threaded knee dart!
So now go get your knee armor. For this I am using a small piece of styrene (because I have no knee armor handy).
Take the 3/16" drill bit, and drill a corresponding hole in the armor for where the bolt will come through and the dart will sit.
So now you have a nice hole in your Knee Armor!!
Then you take your bolt and place it through from the inside of the armor, so that the bolt is facing outward where the darts go:
BUT PUT THE WASHER ON FIRST!!!
now just take your knee dart, and screw it onto the bolt, as to end up like this:
Fairly simple. This gives you more strength dexterity for the dart and if it gets snagged, it wont snap the bolt and bondo out of the dart.