want to make plastic vambraces, but how do I mold it?

bschwartzberg · Post by **bschwartzberg** » Fri Apr 30, 2010 5:59 pm

I recently decided to upgrade my kit to look more authentic, and that means hidden armour. I want to make some molded vambraces out of HDPE, but I don't know how to start. I have access to the plastic, but I don't know how to mold it, or on what. I know it takes a lot of heat, so molding it to my forearm seems that it would hurt a lot.

Any thoughts on the process?

Seved Ribbing · Post by **Seved Ribbing** » Fri Apr 30, 2010 6:44 pm

There was a discussion here on how to bend/form plastic armour about a month ago (using an oven). I can't find it right now, but I would do a little search.

Edit: Found it! http://forums.armourarchive.org/phpBB2/ ... ng+plastic

Cold Forge Armoury · Post by **Cold Forge Armoury** » Fri Apr 30, 2010 7:23 pm

Pretty easy. Put your piece in the oven, I *think* at about 200*F for a bit (check on that). Once it softens up, wrap your arm in a slopping wet towel, then have someone wear welding gloves to press the plastic around your arm until it cools enough to hold its shape.

Halberds · Post by **Halberds** » Fri Apr 30, 2010 11:29 pm

I am not sure about the arm insulation being wet.
When my welding glove is wet the heat shoots right through.

Ewen MacSuibhne · Post by **Ewen MacSuibhne** » Sat May 01, 2010 8:11 am

Cold Forge Armoury wrote:Pretty easy. Put your piece in the oven, I *think* at about 200*F for a bit (check on that). Once it softens up, wrap your arm in a slopping wet towel, then have someone wear welding gloves to press the plastic around your arm until it cools enough to hold its shape.

NO NO NO NO, not unless you want horrific burns. I haven't worked with HDPE, but when I did ABS I heated the oven up to around 300 degrees, and then was wearing three pairs of sweatpants to form it around my leg. It was uncomfortably warm, but not painful.

I suggest using a test piece to gauge the temperature of your oven (I also use a thermometer as my oven temp wanders over 25 degrees at times) and use the small test piece as a way to find out just how much insulation you will need for it.

Maeryk · Post by **Maeryk** » Sat May 01, 2010 8:15 am

Ewen MacSuibhne wrote:
Cold Forge Armoury wrote:Pretty easy. Put your piece in the oven, I *think* at about 200*F for a bit (check on that). Once it softens up, wrap your arm in a slopping wet towel, then have someone wear welding gloves to press the plastic around your arm until it cools enough to hold its shape.

NO NO NO NO, not unless you want horrific burns. I haven't worked with HDPE, but when I did ABS I heated the oven up to around 300 degrees, and then was wearing three pairs of sweatpants to form it around my leg. It was uncomfortably warm, but not painful.

I suggest using a test piece to gauge the temperature of your oven (I also use a thermometer as my oven temp wanders over 25 degrees at times) and use the small test piece as a way to find out just how much insulation you will need for it.

Hmmm.. we always did our shaping with a heat gun or blowtorch.. and we'd just "Form" it on well, us.. wearing a sweatshirt or sweatpants.. you can also kinda go for "a by eye" curl.. and you'll find, if you go the right direction on the barrel, it will want to curve anyway when you heat it.

The black barrels we had access too used to curve just about perfectly just by heating the backside till they started to flex, then dropping them in a tub full of water.

Remember, you want _warm_ not _melty_ when you are working this stuff. Even heat. The way we always knew it was 'ready" was the surface would have an even sheen to it and the piece would suddenly feel like thick cheese.

Malachiuri · Post by **Malachiuri** » Sat May 01, 2010 9:29 am

Cold Forge Armoury wrote:Pretty easy. Put your piece in the oven, I *think* at about 200*F for a bit (check on that). Once it softens up, wrap your arm in a slopping wet towel, then have someone wear welding gloves to press the plastic around your arm until it cools enough to hold its shape.

ACK! Wet bad! WET BAD!!!

I know from working in a kitchen that a dry side towel is perfect for pulling hot sizzle plates in and out of a salamander or oven. A wet towel leads to instant burns and me spending 10 mins with my paw in an ice bucket.

Water cooling is the rage for computers because water is really really efficient at conducting heat.

My body armour is heat bent HDPE. I set my oven to 200, put on the body armour carrier/vest thingie and put the plates one at a time in the oven with a chopstick under the middle. When i could just see it starting to sag over the chopstick, I pulled it and slipped it into the carrier/vest to form it.

Worked well and never got burned.

caladin · Post by **caladin** » Sat May 01, 2010 12:25 pm

Agreed, wet bad!

Do you want 1 piece vambraces or two piece?

I found that with one piece (think just like leather ones)
I had a hard time getting them to mold so they both looked nice and stayed shut.

Since i used 1/8" abs, i was able to cheat.

I took the cut out plastic, bent it by hand before heating, till the opening in the arm overlapped about 1/2"

I took two pieces of metal and clamped it over the overlap, to hold it in place.

then I put this whole assembly in the oven at 175-200, taking it out as soon as the plastic started to deform at all from the weight.

then I took the whole assembly out and let it cool.

When I was done they were the exact same size and shape as my old leather ones that were "sweat hardened".

two piece ones should form using your body as a mold just fine, have sweats and old towels around to insulate you.

bschwartzberg · Post by **bschwartzberg** » Sat May 01, 2010 4:38 pm

Up in the air right now, but leaning towards 2 piece.

Amanda M · Post by **Amanda M** » Sun May 02, 2010 9:33 am

Also, you can use a heat gun like the ones you can find at any hardware store or Wal Mart for stripping paint to heat and mold plastic.

Do not use wet towels or mitts to grab hot objects. I use dry towels taped in place on the part you're molding to and normal oven mitts to grab the plastic and smooth it into place.

Cold Forge Armoury · Post by **Cold Forge Armoury** » Sun May 09, 2010 12:55 am

Well, I can see your concern, folks, but I did it myself and it really was no big deal. It may have just been the plastic we were using, but that was our processand I didn't even come close to getting burned. A thin sheet of plastic like that is going to be drained of heat extremely fast by a wet towel, which in turn causes it to harden to its molded shape fast. The volume of heat in a piece like a plastic vambrace is pretty minimal and is quickly siphoned off (as opposed to a dense glass pan with a hot cake in it), especially if the baking temperature was pretty low to begin with. It works for us, but if you do it, use caution, because these gusy are rightfully concerned. But as I said, having used this process on myself, it works fine in certain cases.