Flat Blade Construction

How to make flat bladed weapons.

Start by cutting three strips of flat foam Part number 8865K211 for a 2’x2′ sheet, or 8865K311 for a 4’x4′ sheet), at least two inches wide, and the full length of the blade of your weapon.  Cut all three strips to be the exact shape you want for the blade, they need to be identical (or as close as possible).  Cut a half-inch strip out of what will be the center layer, but leave the last 3 inches or so in place on one end.  This will be the two-inch thrusting time, plus one inch of closed cell past the core plug.

Now get the core ready. Cores, Look at the O.D. column to determine which size you are ordering.  We recommend .505 OD for one-handed weapons, and .602 OD for hand-and-a-half or two-handed weapons)  Cut the core to be the total length of your weapon, minus 6 inches.  You must plug both ends of the core, so the foam ends aren’t forced down into the core.  You can use the strip you cut from the flat foam for this.  Cut a three-inch section and shove about half of it into the end of the core, then spiral wrap electrical tape up and back down it (onto the core too!) to hold it in place.  Don’t use so much that it isn’t flexible, and then cut it off to extend about an inch past the end of the core.  This gives the core a flexible tip, which makes it less likely to tear through the foam blade.  It should be roughly the same diameter as the core, so it will fit nicely into the groove you cut out of the flat foam.

Next you assemble it all without glue to make sure it fits together correctly.  Lay down one solid strip of foam and put the one with the groove cutout on top of it.  Lay the core into the groove, and then put the third piece of foam on top.  This gives you the basic sword (unglued!).  Make sure all the edges line up with each other, or you’re going to have trouble gluing it into proper alignment.  If the edges don’t line up closely, you’re going to want to trim them down so they do.  It’s easier to do it now rather than later.

Once you have the alignment looking good, it’s time to glue it.  3M – Super77 spray adhesive is recommended, and it works well.  It’s a little tricky to get the timing right, though.  If you don’t wait long enough after spraying the glue on to attach the pieces, it won’t stick well.  If you wait to long, it won’t stick.  Generally, you’ll need to wait around ten minutes, but that time varies with the temperature and humidity.  Test the glue by touching it with your finger.  If it feels sticky, but doesn’t come off the foam onto your finger, it should be about right.  You’ll want to glue it together in two steps.  The first step will be an outer layer of foam and the inner layer with the core groove.  Then put the core in place in the groove and glue the second outer layer in place, sandwiching the core in the middle.  It’s a good idea to clamp the weapon between to long and flat surfaces for a few hours to let the glue dry…  Overnight is best.  You can also use adhesive-backed foam instead of using spray adhesive.  Part numbers for adhesive-backed foam are below.

Now it’s time to bevel the edges to make it look like a blade instead of a block of foam.  Take a sharpie and draw a smooth line on the flat of the blade.  Keep the line parallel to the end of the foam, but roughly 3/4 to an inch away from the edge.  Pick a distance and make it consistent the entire way.  If your blade is 2 inches wide, ¾ inch is the maximum width you can use for the bevel.  Any more than that and your core will be too close to the edge of the foam.  If you have a blade that’s wider than two inches, you have a bit more freedom here and can make adjustments for aesthetics.  You’ll use this line as one of your cutting guides.  The other will be the line of glue one the edge of the blade where this outer layer of foam meets the inner layer.  Now take a brand new razor blade (it needs to have that perfect sharpness of a new blade, or it’ll be a pain in the rear!), and use those two lines as guides for your bevel.  Make the cut as smooth as you can.  There’s a knack to it that just takes practice…  Your first one is going to look rough, they all do.  Make this cut on all four corners of the foam block, and you’ll have a nice looking blade shape to your weapon.

You may notice that the imperfections in your cuts are really going to be noticeable when you tape it together.  You should use sandpaper on all the edges before you tape it.  This will make the weapon look better, and soften the foam a bit, too.  Use a medium to fine grade of sandpaper, or you’ll dig into the foam and ruin it.  This foam gouges pretty easily, so go light and slow.  You’ll probably have the most luck by using a sanding block or taping the sandpaper down on a smooth surface and drawing the beveled edges back and forth across it.  Like you’re sharpening a blade…  Cause you are.  This will produce a lot of fine foam dust, so you should wear a breathing mask if you don’t want to inhale it.  

Once the imperfections are sanded out of the blade, you should cut 2 to 3 inches off the tip of the blade.  The tip you just cut off is coincidentally the exact shape you’ll need to cut out of open cell foam for the thrusting tip!  So take another new razor blade and get to carving.  When you have the tip carved to your satisfaction, use double-sided carpet or duct tape to affix the tip to the end of the blade.

Now it’s time to tape it.  Use as little tape as possible, and apply it in long strips along the length of the blade…  The more tape you use, the heavier and harder your weapon will come out.  The “Mainstays” brand from Wal-Mart is recommended.  It’s light and sticky, and that’s what you’re looking for in tape to use for boffer weapons.  The thicker, heavier tapes don’t stick as well to the foam, and don’t give as much, which results in harder weapons that the tape peels off of.

The nice thing about this style of weapon making is that you have the freedom to make your blade truly unique.  You can make a leaf blade, a Chinese war sword, a machete, or anything you can imagine.  It’s all down to what you can cut and tape well.  Just make sure you always have at least a half-inch of foam surrounding the entire core.  That’s the only restriction unique to this design.  You still have to meet the safety requirements of standard boffer weapons (a two inch open-cell thrusting tip and a foamed pommel), of course.

 

Adhesive foam:

12″ Length —  12″ Width

Gray 8865K512 $7.80
White 8865K511 7.80

24″ Length —  24″ Width

Gray 8865K612 $26.83
White 8865K611 26.83

48″ Length —  48″ Width

Gray 8865K712 $72.69
White 8865K711 72.69