bead rolling ..how much skrinkge??

wanting to cut out some tin for the firewall and flooring...but i don't know how much bigger to make the panels so i can take them and have some beads rolled into them for strength..material is going to be 18 gauge for the floors, and am thinking probably the same for the firewall....flooring panels are only about 13" wide by 24".....1 on each side of the trans hump.....and are braced with 14 ga square tube on all edges and a center bar at the 12" mark on the length...would be easy enough to make them (pattern wise) a tad larger....but i hate to have to trim them a ton afterwards.....

any way to calculate how much shrinkage there is??i assume it varies from width and depth of bead and how many????????

tired of my feet hangin

 

You basically answered your own question, if you are running the bead through the whole panel.

If you are going to run the bead partially through the panel, pre-stretch in the area of the bead, then the finish size panel will be the starting size panel.

 

do a test piece, then measure and for every bead subtract, if you make the beads the same you should be able to get it on the first try... good luck

 

Yeah, use an english wheel to pre-stretch the area that you're gonna be beading. You don't have to use alot of pressure, and a flat bottom or lightly crowned one on the wheel will give enough relief for the beading. I have had to, in thicker metal i was beading, 14ga i think, use a torch to heat up the metal to soften it a bit before beading it.

 

That worked for me.
With a little trimming after.
Err on a slightly larger size.

 

Prestretch! That is the only way to go if the beads don't go all the way from side to side of the sheet. Otherwise it is hard to get a flat panel.

Mario

 

thanks for the advice guys.....looks like i'm going to be leaving this to who ever i get to do the rolling....don't own one and am too budget choked to buy one right now...

my main concern is the firewall....there is such a small area of flooring, i am wondering if it even needs to have any beads in it?????? or is there something else to stamp into a floor panel to help keep it from flexing????

 

I've never noticed any.

 

Same here, since the bead roller actually stretches the metal in the process, I always have to do a bit of shrinking on the ends of the beads to get the panel flat again. I have made closing tools to finish the end of the bead to aid in this.

 

wow these are some great looking firewalls!!!!!wish ya was closer...

right now i only know of 1 guy around here who does it, and that's a friend of a friend.....think the car needs to be looked at to decide what would fuction and look best.......