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Shaping Tips
 

Shaping Expanded Polystyrene foam is a little different than shaping urethane blanks. It requires learning a few new techniques and tooling procedures. Experiment with the outlying scraps first, and you will soon find you can create the same level of finish as in any other system.

Your initial deep cuts will remove "beads." Rasping and then sanding, will slice the "beads" to a progressively smoother surface.

sFoam™ blanks can be shaped with standard shaping tools with some exceptions. Roughing out can be done with same power planers you use on urethane blanks, but you must note that if you use the same "stroke speed" you might pull out some beads in the process. This will leave pukas about 1/16 to 3/32" deep, so keep this in mind in relation to final shaping.

If you can slow down your "stroke speed" and still keep your shaping "rhythm" - then try experimenting with the following method of rough shaping: Make sure your cutting blades are sharp - slow your stroke to about 1/3 speed. With practice this method will cut the blank smoothly.

We do not recommend using a Surform or Surform type blades. These will pull beads and chunks of beads. 24 grit tungsten carbide rasps designed for EPS foam are available now and do an excellent job. Also, rasping papers in 24 and 36 grit are available where drywall supplies and tools are sold.

We do recommend planers equipped with the new tungsten carbide drum abraders. These can be had from shaping equipment dealers, and will retrofit common planer models. Use rasps, grit pads and sandpaper to do final and finishing shaping. Please check our ' Useful Links ' in the FAQs section of this web site for tunsten carbide rasps and drum abraders.

Please note that EPS foam has a consistent density throughout, unlike urethane blanks that have dense "skins" and lighter cores. With urethane blanks, shapers opt to thin the blank mostly on the bottom. This leaves the dense skin on top where it will protect the deck from pressure dings. This is not necessary with sFoam™ blanks. We recommend thinning our blanks by removing as much as possible from the top. This protects the natural bottom rockers we have designed (or you have customized.)

Wrap a 1" layer of upholstery foam around your shaping racks. This will keep the blank from sliding as you work. Small lead shot bags are handy also, to add weight where you need it.

Until they are laminated, EPS blanks are more flexible than urethane blanks. Once glassed, an EPS board will flex the same as a urethane-cored board, given that both have the same dimensions, stringers and laminations.


 
Copyright by sFoam 2004