Hard Top Coating

[Mopus]

Im new to the forum but Ive been peeking in on some of the things people are doing and I have a question about a problem I'm having with a helmet.

Budget Build:

I've mad a dredd 3d helmet out of a bmx helmet, plastic canvas and masking tape. I put a replacement motorcylcle helmet visor in and it's causing the helmet to bow outwards. I was going to get a metal strip and line the inside to force the shape, but I was wondering if there was anything I could coat over the helmet to make it rock solid and help reinforce the shape while being real tough.

also-Im not trying to use auto putty (but it was my first choice). My parents think I'll get cancer and it will destroy whatever it touches @_@

 

[3d-builder]

Try Aves Apoxie sculpt......it's non toxic.

 

[Propsjonnyb]

its the canvas and masking tape that's causing you the problems , strip it back and either use plasticard or cardstock, then coat the cardstock with several coats of PVA glue adding paper tissues soaked in PVA to thicken all the sides, leave each coat to dry before progressing on to the next or you'll cause yourself more problems, it will dry out nice and hard , then use either a car body fibreglass kit or car p38 filler ( Bondo ) to give it a thicker coat , then sand , sand and re sand, until you have it perfectly smooth . Then follow normal guidelines for cleaning, priming and painting.

 

[Wellss01]

Polyester Resin or maybe even polyester gelcoat


Check me out:
www.facebook.com/steamjunkprops Or Steamjunkprops.deviantart.com

 

[Mopus]

My initial thoughts are to take the visor off first. Then harden and re-attach the visor. Cus the canvas looks real nice on it. but it is fairly flimsy. so if I add a hard top coat to the entire helmet and add the visor back later, it should keep the original helmet shape right?

 

[Ray48]

You have a challenge ahead. Fiberglass and it's cousins, including carbon fiber composits have great flexibility ( examples: fiberglass bows, fishing rods, skis.787 composit wings) in short, it may not solve your problem. Car body filler has another problem...it weighs a ton when you go thick enough to avoid cracking. By the way, fiberglass is just as toxic. Your real problem is one of engineering. How much resistive force will it take to overcome or counter the flex? A solution is to increase the curvature of the visor so it more closely matches the radius of the helmet. That way it will no longer act as a spring, forcing the sides apart. Two ways to do that. 1. Buy a visor sized for women's or children's helmets. 2. Bend the one you have with heat. That's how they curve it in the factory. They are usually made of Polycarbonate plastic. You can heat it in your mom's oven. DON"T WALK AWAY WITH PLASTIC IN A HOT OVEN! EVER!. You can find temperatures for bending it online. Easier is to start at the warm setting but nothing over 200. You will need some means to clamp it in the new desired curve but nothing across the face. As the plastic softens, anything across the face will leave scars. Don't use tape; it won't hold in a hot oven and will burn or melt. Don't get the oven too hot above all as your visor will first develop bubbles and distort or collapse in a heap. In short, try 175 degrees F. for about 10 minutes. Take it out with welders gloves or hot mitts, it's hot...duh. keep the clamp on till it is cool, like on a cookie sheet. Take the clamp off and see if it keeps your new curve. If not, back to the oven and turn the temperature up another 25 degrees. By no means should you have to go over about 250 F.. At some point it will retain the new curve and won't distort your helmet. Finally, another solution is to find a different material for the visor. You didn't say if it was clear or shaded. There are all kinds of protective plastic face shields and raw plastics out there, thinner is better because it flexes more easily. If you need to tint it you can get tinted mylar to adhere to it. If you try the oven, make sure a parent is there! It really presents little risk if you watch it thru the oven window and don't exceed temperature or time limits. You can also bend your own from flat acrylic, which bends more readily...that involves a mandrel. Good luck...maybe you will solve it yourself by the time you see this.