Plastic vambrace

madlarks · Post by **madlarks** » Tue Jul 28, 2009 6:55 am

So I have been slowly trying to replace my loaner armor with my own and am working mainly with plastic. I have found that the stuff does not retain its shape very well and was wondering if there is a secret to it.

In particular my vambrace. I am a smaller guy so I need a good curve to the armor and so far just heating in the oven and dunking in water after molding it doesn't seem to help it hold its form for very long. Is there a better way to get it done?

Another option I have is to cut up the plastic vambrace I have now and make it almost into splints. I could then attach those vertical splints to some suede. From there cover it with canvas and even add some horizontal pieces of 16-18g steel plates (1.5 inches wide and three long with rounded ends) for added durability if needed.

Would this be:
1. Legal protection
2. Durable enough, if not suggestions to make it.
2. would the extra plates be needed?

Thank you

P.S. I fight in the Barony of Twin Moons SCA

Sean Powell · Post by **Sean Powell** » Tue Jul 28, 2009 7:09 am

In part it depends on the type of plastic you are using and in part it depends on the temperature you get it to. I prefer to use kydex and I warm it to 200F until it will take a shape under it's own weight, not be my forcing it. I have had poor luck with quick-cooling in water. I have ancedotal experience with this causing greater risk of cracking (kydex) and the process induces surface stresses that if they don't encourage cracking will relax over time and cause loss of shape.

There are a good number of people who use plastic splits riveted to leather for forarm and even leg protection. They are light, do not rust, do not dent, rarely crack, do not mold and take SOME of the sting out of being hit. Your plan for cutting into splints seems viable depending on thickness and type of plastic.

YMMV,

Sean

madlarks · Post by **madlarks** » Tue Jul 28, 2009 7:11 am

55 gallon white barrel plastic.

Jestyr · Post by **Jestyr** » Tue Jul 28, 2009 7:54 am

ABS is MUCH cheaper than kydex and will retain its shape from the oven or a hot gun.

Pitbull Armory · Post by **Pitbull Armory** » Tue Jul 28, 2009 9:04 am

Hi there, Sean is right about the temp you get the plastic to before cooling. Its true most plastic relaxes but Barely warmed plastic will return to its original shape alot faster then a properly heated piece. I always recomend plastic pieces be stored in the shape they are supposed to be in. Store vambraces with the straps strapped to hold the shape. Yes the splints and leather should be legal if you go that way.

Take care

Pitbull

Cisco · Post by **Cisco** » Tue Jul 28, 2009 11:16 am

So if you take the oven and get it to 200F, how long does 'room temperature' plastic have to sit in it before it is ready to mold?

I've worked it with a heat gun but I was curious about trying it in an oven. Also, any suggested tips (a good open window with a running box fan being one of them)?

Konstantin the Red · Post by **Konstantin the Red** » Tue Jul 28, 2009 11:41 am

You're getting close when the plastic slumps over a form... even if you have to resort to tacking it to a wooden form in advance.

Isn't barrel plastic almost invariably HDPE?

Cisco · Post by **Cisco** » Tue Jul 28, 2009 11:45 am

So is there no generic time frame (2-3 minutes, 10 minutes, 30 minutes, 2 hrs, etc.)?

With the heat gun it seemed pretty maleable (didn't droop, however) at about 90 seconds of direct exposure. But that was only one side and a small chunk as I could only heat one small section (maybe 3" diameter circle) uniformly.

Sean Powell · Post by **Sean Powell** » Tue Jul 28, 2009 12:05 pm

Cisco wrote:So if you take the oven and get it to 200F, how long does 'room temperature' plastic have to sit in it before it is ready to mold?

I've worked it with a heat gun but I was curious about trying it in an oven. Also, any suggested tips (a good open window with a running box fan being one of them)?

How long will depend on the actual temperature of the oven and the thickness of the plastic. I shape 1/8 kydex by balancing on a fist sized chunk of aluminum foil. It is shapeable in 5-8 minutes. I go to the high side for complex shapes like corazinas but it wouldn't hurt to go just as long for other locations.

I don't generally worry about toxic fumes from heating plastic. I once set a hot pot (thought it was cold) on a plastic cutting board. It stank and I opened the windows. That was more fumes then I expect to get keeping plastic only at 200F. There is no resigual smell in the oven or contamination that I can detect. My wife dosn't complain about me abusing her stove for armoring. An open window should be sufficient.

Note: oven-mits are useful for handling hot plastic but good winter gloves with thinsulate are better. Only wear them when actually handling the plastic as they will get sweaty inside rather quickly.

Note: It takes about half as long for the plastic to cool as it did to heat up. You want to be certain that it conforms to the mold shape the entire time. If you use very thick plastic you may want someting else to help hold the plastic in shape or at least a some extra towels between your fingers and the plastic.

Good luck!
Sean

Amanda M · Post by **Amanda M** » Tue Jul 28, 2009 12:20 pm

I think the fumes problem depends on the plastic too. ABS doesn't seem to give off much. The hubby complains more about the fumes from banner making than armoring in the oven. ^_^

Cisco · Post by **Cisco** » Tue Jul 28, 2009 12:37 pm

Cool, thanks guys.

Owyn · Post by **Owyn** » Tue Jul 28, 2009 1:19 pm

One thing for sure... I would NOT chop up existing good, working armor to make new armor, not unless I was dead sure the new stuff would work.

Get more plastic, make the new armor from the new plastic. Don't chop up what you have until you have replacement gear. It's always nice to have a backup.

Also, I'd use leather heavier than suede for the base. I'd shoot for 8-10oz veg tan leather or greater. The 8-10oz will hold the armor together well enough, but adds only moderate protection itself. If you boost to a 14-16oz leather (armor grade, thick stuff) and harden it (punch your holes for riveting the splints first), THEN splint it, you might actually be up into overkill mode.

Ideally, put the splints on the inside, too (hides the plastic); but you probably already were thinking that.

Lorccan · Post by **Lorccan** » Tue Jul 28, 2009 3:09 pm

Type of plastic makes a HUGE difference - rigid plastics like ABS & Kydex will take rigid shape when properly heated & molded.

HDPE barrel plastic, on the other hand, is more springy and flexible (although it can make excellent protection). This means that it will be springy and flexible when molded, and want to spring back to it's former shape. You will likely need to heat it longer to really relax it and then keep it in the proper shape until it has fully cooled. Heat guns are not as good for this as an oven, but the gun can be handy for touch-up work.

Dunking in water will not help; you want to mold the plastic to just the right shape and let it cool gradually.