Introduction: How to Make a "Bulletproof" Polycarbonate Longboard!

Picture of How to Make a "Bulletproof" Polycarbonate Longboard!

In an incredible epiphany, our team at SPHS decided to make a longboard deck out of polycarbonate!  

Not only is the deck completely see-through, it is also bulletproof!  
*But please, don't quote on us on that.  We are not responsible for any liabilities involving injuries or death regarding the use of the deck as protection equipment.*

But anyway let's get to it!  

Onto the materials!

Step 1: Materials

Picture of Materials

-3 axis or higher milling machine
-42"x12" sheet of polycarbonate with at least a 3/8" thickness (You may use other dimensions to suit your needs but I don't recommend that you use anything less than the stated thickness.  For a stiffer board, get a greater thickness.)
-MasterCam Program (we used the X5 edition)
-1/4" flat endmill
-1/8" flat endmill
-Sandpaper or sand belt machine
-Griptape
-Common sense

Step 2: Design

Picture of Design

For our design, we first sketched it on paper.  

We chose a simple shape, almost in the shape of a bullet, with grooves in the middle of the board on both sides.  

After the sketch, we transferred the drawing to MasterCam.  

We attached the board file as a dwg so please feel free to use it as you wish.  

*We didn't want to sketch anything too difficult, otherwise we wouldn't be able to redraw it in MasterCam.  But if it is within your level, by all means go ahead and get as intricate as you want.*

Step 3: Milling

Picture of Milling

Before we milled out the board, we did some test runs to see how the polycarbonate would mill.  

At first, we cut it straight through but that was a disaster but we ended up using depth cuts for the milling.  
For the settings, we used a medium cut speed and a high spindle speed.  

*Please experiment with the settings as various thicknesses will alter how the material will cut*


Step 4: Final Product

Picture of Final Product

Take the board to sandpaper to smooth out the edges and apply griptape however needed.

The board turned out VERY flexible but can still be ridden.  We attached a video to show how flexible the board is.  The rider is about 150 pounds.  

Take note that this is more of a novelty than something for actual riding.  You can still ride the board but nothing too intense like downhill bombing can be done.  This board is more for a wow factor.

That's all and thanks for following this tutorial!  

Comments

RayJN (author)2017-11-30

I did a ballistics test on polycarbonate some time ago. 3/8" of the type sold for windows will barely stop a 22 LR, I started with one 3/32" thick piece, went though without leaving a hole, but a black spot from the lead bullet. 4 pieces stopped it in a polycarbonate bubble, protruding about the length of the bullet. On the other hand there was a shop that would bullet proof your car, had a 1 inch thick sample with a 7.62mm bullet that had gone only half way through. Not all polycarbonate is the same.

SaintsTech (author)2016-07-18

you need to make a curve mold, heat the plastic, and set it in the mold. the curve will help give it strength. im gonna make my own and will try to post it on here.

mikey.powell.501 (author)2015-03-10

would 12" x 48" - Clear Acrylic Plexiglass Sheet - 3/8'' Thick Cast work instead?

hifatpeople (author)2014-08-22

Actually a bullet would go straight through this. attatch a layer of acryllic to one or both sides (depending if you one one or two way bulletproofing). the acryllic will get hit by the bullet and get compressed between the bullet and polycarbonate. As acrylic compresses it gets harder and harder, flattening the bullet and spreading the force out for the polycarbonate to absorb without penetration.

mjohnson116 (author)2013-12-15

I designed a board in inventor 2014 and set the material to polycarb after analyzing a stress test of a flat board I bent the part upwards then re did the test the result was a board that sat about level with the trucks. I know from my work with lexan that it bends fairly well. also using three sheets of 1/8 lexan seems to make it stronger. hope these suggestions help. happy making.

deluxelespaul (author)2013-06-03

In the name of safety, I'd round that spear point off the front for when you inevitably wipe out and send the board spiraling through the air at a high rate of speed and into you or someone else...

We actually kept the pointy spear of death for laughs. The board is definitely not fit for street use and as said before, is more of a novelty.

Glad to hear that...ouch!

Kiteman (author)2013-05-31

This is cool, but could you post your video to YouTube or Vimeo, then embed it here, so that it is a lot easier to watch?

sphsengineering (author)Kiteman2013-06-04

We would, but our high school does not allow youtube or vimeo.

Kiteman (author)sphsengineering2013-06-04

You could do that bit from home...

DavidNZ (author)2013-06-04

You should give fiberglass a go on that :3 would look bloody sick with lights :D

astrofolk (author)2013-05-31

What if you made one with layers of carbon fiber, poly carbonate, then carbon fiber? Would that stiffen it up?

It would definitely stiffen it up but the reason we chose polycarb was for the transparency

M3G (author)2013-05-31

Awesome board!

sphsengineering (author)M3G2013-06-03

Thank you sir

kyle brinkerhoff (author)2013-05-31

i like the extra pointy looking tip of death on the front

We do too. The design was to imitate a dagger. Works pretty well haha

wetware9 (author)2013-05-31

Suggestions: A polycarb stiffener from truck to truck bolt patterns would make a stiffer board without adding dimension or much weight. For a lower tech entry approach, a medium duty bandsaw with a fine tooth blade will cut polycarb just fine ,so really the need would be to print the design, tape to stock and cut along line. The drill pattern for the trucks is not a blind hole so hole pattern layout isn't a CNC necessity. The watchword with polycarb is to minimize stress risers, so finish sanding is very important since the piece with be under dynamic flex load. A rattail file is your friend for those holes ;). Clear wheels or lighted bling wheels would flash this up too, a bit of cool neon wire added would also up the wow factor, perhaps added along said stiffener. Cool project, will add to builder class. Thanks for posting.

sphsengineering (author)wetware92013-06-03

We were actually thinking of adding neon lights to jazz the whole thing up but we didn't have the time or money for it. The stiffener was also in the plans, but again, just not enough time.

Thanks for looking!

Beergnome (author)wetware92013-06-02

said it better than I could..

chuckyd (author)2013-06-02

There are a couple of things that may help with the flexing. One would be thicker material. The other would be a couple of stainless steel rods connecting the trucks,

Oh, there's a third alternative: make the board shorter.

sphsengineering (author)chuckyd2013-06-03

Yeah, this board was the very first one we milled out so it didn't turn out too great. Had we had more time, we would have milled the thicker and shorter lexan we had in stock.

pterwey (author)2013-06-02

This whole situation has my mind blown.......I'm a Cnc machinist in mn and the manufacturing company i work for makes composite wood and plastic kitchen products. About 3 weeks ago i had a left over piece of clear acrylic and after thinking for a while what to make i decided on a long board. I'm just got this app and started browsing projects and it blew my mind to see my board (or what resembled it almost exactly, Down to the wheel color). Just wanted to share and ask if you feel it's coincidence or parallel thinking.?

sphsengineering (author)pterwey2013-06-03

It was actually for a high school project so I'm guessing it's entirely coincidence. Plus, there was leftover lexan from other projects too. Nice board though! Cool shape. Our wheels are actually green, they just look dirty.

stephenfitton (author)2013-06-03

I was making and selling clear lexan Skate- boards 35 years ago, a couple of hints (1) Leave the coating on till all cuts and holes made. Be careful cutting with any saws, as soon as heat builds up,jams blade and if a jig saw will bounce up and down Destroying your finish.(2) Sand-blast for grip.(3) this type of board performs the tightest turns possible (Only at slow speeds) As the wheels twist in a turn the board is actually strengthened. Keeping you upright. Have -Fun!

Thanks for the advice!

emaxon (author)2013-06-02

I wholeheartedly agree about a bandsaw & drill press being perfectly adequate for making such a board. Even a bandsaw blade made for wood is fine for cutting polycarbonate. How about pressing hot silica sand, or glass beads, (tiny ones for bead blasting or projector screens with gain,) directly into the surface instead of grip tape? Seems a shame to ruin the clear surface with grip tape. (Anybody make clear grip tape?) Re stiffening, back in the late 70's, early 80's, some guys used a brace between the center of the deck and the bolt in the center of the rear truck... it wasn't supposed to stiffen the deck, just prevent the rear truck from getting caught on the coping when coming out of a bowl/pool. In your case, a pair of 'em might stiffen the board enough. If not, resort to another old-school add-on... Instead of soft plastic strips meant to protect the bottom of your pretty deck from getting scuffed, stiff fiberglass strips screwed to the bottom of the deck lengthwise, secured with several screws, might further stiffen the floppy polycarbonate deck. Since you *do* have access to a CNC machine, you'd end up with a much stiffer deck by laminating TWO pieces together, the top being solid, the bottom with most material removed save say a 1/2in wide border and a few reinforcing ribs. You need not screw it together... You can fusion weld polycarbonate with Methylene Chloride. Just weight it down well, inject the MC along each edge with a syringe/needle, (it will be drawn in by capilary action.) Lastly, (really,) you can also heat-bend Polycarbonate if you'd like tapered ends... Not so easy with 1/2 thick material though. Eric.

rodella (author)2013-06-02

I'm definitely going to do this :)

drewscreen (author)2013-06-02

Wonderful Instructable! Although heavy, polycarbonate has just the right amount of flex to easily bump over small gravel that might stop a plywood board AND if you find yourself in the wrong place at the wrong time, a little bullet protection (theoretically).I've had a polycarbonate short, flat "commuter board" for decades. A flat board makes a handy furniture mover. I used scrap-bin 1/2 inch Lexan and used simple hand woodworking tools to shape it. One caution -- PC degrades in sunlight -- so don't store it outside unless you want to have a surprise snap-in-half resulting miles of walking.

enil01 (author)2013-06-01

Not sure what would stick to that, but for clear grip tape alternative I've always used fiberglass resin, polyurethane, ect. (whatever was clear and at hand at the time) with the chunkiest salt or sugar I could find. Lay down a coat or resin then sprinkle salt on top. The salt eventually devolves and leaves the surface nice and grippy and clear.

_soapy_ (author)2013-06-01

Nice idea. I've found 4mm polycarbonate pretty good for some stuff. Still a bit flexible for this though. I'd make a second piece that sits under the main board and connects just the two wheel mounts together. This will keep the weight down but add a lot of rigidity to the board. Perhaps bond them together for even more strength, though you might lose some transparency.

erictheaznskater (author)2013-06-01

I think it would be cool to have some pattern (like diamonds) etched into the top of the board to substitute for grip tape.

Iron Cowbell (author)2013-05-31

I thought the point of the "Bullet-proof" glass was so you could do crazy stuff.

sprout_less (author)2013-05-31

You did not use a "1/4" flat endmill drillbit". That doesn't exist. You used a 1/4" endmill, and probably a 1/4" Drill bit. Call me OCD, but that really bothers me.

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