I need to add around 8 inches to my EPS block in order to get a longer board out of it. I have thought about a few different ways to about this by using some of my scraps from previous blocks
First thought is to simply cut out an 8" long rectangle and use white gorilla glue to adhere the extra foam onto the block. from there hotwire my blank and go about business as usual.
Or i figure i can hotwire blank off of regular sized block and then add the foam as a tailblock of some sorts.
This will need to get a stringer put in so option one sounds better to me.
Anybody have any thoughts or ever done something similar??
If you want to add only foam, I would use a scarf joint or arrow splice. But really, in my opinion, a stringer is the best for overall use and longevity. It’s up to you on the kind of ride you want.
I’ve done it both of the ways Tblank mentions, but these were for compsand boards with a balsa perimeter rail and balsa skins that covered the foam. I’ve also just added a block of foam, but that board had 2 extra thick stringers.
I’ve done lots of tests and stringer or no stringer, have NEVER had EPS break on the glue line using Gorilla Glue. I suspect that the glue line ends up being the strongest section of the overall structure.
I did a small test piece with two pieces if foam butt jointed together and those were my thoughts after i tried to break it right on the gluw line and found that it broke the foam and nowhere near glue line.
I almost always use the side templates to hold the added piece in place without glue and hot wire. The glue is sometimes hard to get the wire through. I glue after cutting the profile and outline when possible. Use a joint that has the hot wire coming through at a 90 degree angle if you need to cut after gluing. use as little Gorilla glue as possible the foam is much weaker than the glue as stated above so there is no problem with strength.
Down side of gorilla glue is that it is harder than the foam and can make a ridge or tear foam when you shape. But I haven’t found anything better. I’ve used spray glue, elmer’s white glue (don’t use this), carpenter’s wood glue, elmer’s foaming PU glue (just like gorilla glue).
Some of the spray glues can melt foam, or separate when you shape.
On the positive side, I have several boards made from rocker slices and some people think they are multi-stringered boards.
I’ve done a few additions to blue xtruded poly styrene. Adding a nose or tail block works fine. Try using Mataco’s method of doing the cuts without glue, then you have the option of applying the glue on the interior area of the addition surfaces so the glue avoids shaping/sanding. The glue will always be a different hardness, touphness than the foam which makes a smooth sanded joint very difficult to do if the glue is exposed. Gorilla glue works great, mix it with water on a platten to increase the foaming so it sands softer but the foaming, water mixed or not, will spread the joint so clamp it somehow as tight as possible. Adding a tail or nose block works fine.
Any tips on what to final sand and blend the glueline ridge with??
Thanks everyone some solid tips thrown down! As usual with most of sways vast knowledge base ill probably take a little from everyone and see what works best.
I determined by testing that resin pigments and ‘universal’ colorants work with foaming PU glue. I have also learned though experience that artists’ acrylics make the glue go off way too quick and foamy due to their water content.
