Mandalorian Mercs Costume Club

Mandalorian Armor => Armor Construction => Topic started by: Cy'Mur on Feb 22, 2016, 03:04 PM

Title: Problems with sintra?
Post by: Cy'Mur on Feb 22, 2016, 03:04 PM
Why is it that when I have 2 equal pieces of the same template, one gets bigger or smaller than the other? They are the exact same size before hearing but after being heated and shaped they seem to change sizes.
Title: Re: Problems with sintra?
Post by: Kris Jasra on Feb 22, 2016, 03:19 PM
This may sound Like a strange question, but when cutting your sintra, are you flipping the template or are you cutting two using the same 1 template and flipping one when its in sintra.

As there are a few variations out there that have slightly hardened surfaces on the top. Not enough to truly make a difference most of the time, but noticeable if you have two plates which you are heating and bending when one is bent on the underside and one is bent on the topside.

I always flip my template over - that way I know that variations in the sintra density will effect the plates equally.
Title: Re: Problems with sintra?
Post by: Cy'Mur on Feb 22, 2016, 03:23 PM
That very well could be. On like parts such as shins thighs and shoulders. I'm having trouble with one of the shins. It seems to be growing taller and thinner. I used one template to cutout both of them.
Title: Re: Problems with sintra?
Post by: Kris Jasra on Feb 22, 2016, 03:39 PM
Might be. Won't know till you flip the template over and see if it happens when you've cut both parts so the top is the outside surface
Title: Re: Problems with sintra?
Post by: Cy'Mur on Feb 22, 2016, 03:44 PM
Thanks for the input. I just cut another shin piece out and it seems to be fine now. It must have wanted to fight me for some reason. I wondered if I over heated it and that caused it to warp.
Title: Re: Problems with sintra?
Post by: Vhekadla Yustapir on Feb 22, 2016, 09:03 PM
I know you are pretty far along in shaping from the sounds of things, but here is some advice based on how I went about it if the heat gun continues to give you shaping trouble.

In my opinion a heat gun is great for some pieces of armor. Particularly when you are trying to bend a localized area or one side of the plate. To get uniform shaping for most of the pieces I recommend a different method. If you have a large pan...I used a 32 gallon stock pot...then fill it with water and set it till boiling. Grab a cooler of some sort, pot, or even the sink and fill it with ice cold water and a lot of ice. With this, solid gloves on both hands, and a pair of tongs you can easily shape material with little hassle.

(http://imagizer.imageshack.us/v2/800x600q90/922/GqqvGd.jpg)

After sticking the piece into the boiling water you can tell it's ready to be shaped because the plate starts to wave a little in the current caused by the boiling water. If I recall correctly it took about ~30-45 seconds for 6mm sintra and ~15 seconds for 3mm. The reason this works is the heat causes the molecules in the sintra to loosen up but not enough that the pieces are at risk for becoming waterlogged.

Once you have the desired shape on your body stick it in the ice bath and the molecules that make up the material will rapidly solidify so you don't have to hold it in shape for it to cool or risk warping because your hand slipped or got tired.

It's not too different a process from forging honestly! The only downside to this process is it doesn't work for smaller pieces and detail work. For this and minor shaping changes to improve fit...you rely on the heat gun.
Title: Re: Problems with sintra?
Post by: Cy'Mur on Feb 22, 2016, 09:12 PM
Most of the pieces aren't too terribly big so the method I used was the oven at 175. The back plate is proving to be kinda tricky. I have the shoulders and the bottom sides molded but the middle is still out of wack. It just needs a slight bend in the middle to fit the contour of my back. Hopefully knock that out tomorrow and start to get that painted up.
Title: Re: Problems with sintra?
Post by: Modan Kordo on Feb 23, 2016, 09:12 AM
Just a quick observation about parts seeming to shrink when shaping: Don't forget about the thickness of the material.

2 pieces the exact same size will not fit over one another exactly when you shape them. The piece that's on top will need to be slightly bigger than the bottom one in order to cover the same area. I usually add extra space equivalent to the material thickness all the way around, then sand off what's not needed.

The other it I learned through wrecking many a part is that you should cut out details after shaping to get clean lines....

Oh, and the backplate is always the toughest bit to get shaped... Good luck!!!