Bought a block of EPS (14’ x 36" x 48") and looking for advice to make 10’-14’ long templates.
Seems like masonite only comes in sheets up to 8’ that I have found.
Got my hotwire built and understand how to make templates. Currently planning to just join 2 pieces in the center with a circle type puzzle cut out.
I just did a 1/4" thick 9 foot rocker template with 1/8" masonite panels. Laminated 2 layers, 8’ + 1’ and 1’ + 8’ (keep the butt joins at opposite ends). Used contact cement to glue them up, it worked great. You can see it tacked to wall behind the blank.
Make a paper templet the size that you need, then make a spin templet from the paper one. This method could take you to almost 16’. FYI, some plywood suppliers carry sheet to 10’.
I have been using various joints (butt, jigsaw puzzle, dovetail) and they all seem to work good enough for templates. Most of the time I glass over both sides of the joint with scraps of 4 or 6oz cloth and epoxy.
Make sure to mind the joints while using the hot wire for rocker templates, the wire likes to find and stick in the small cracks. Putting masking tape over the joint often helps.
So I am assuming you are making rocker templates to attach to your block of foam to run your hot wire along?? If this is the case a joint isn’t necessary. Just overlap the Masonite six to ten inches at the center or near the end of the template. Plane or sand the over lap so that there is nothing for the wire to snag on. Glue with Construction Adhesive/Liquid Nails or Contact Cement. I do this on my shop floor and lay a piece of Ply on the overlap, placing a cinder block or bag of sand on the Ply to weight it down. Overnight dry time. No fancy joint needed. Lowel