Hello Everyone-
I have been told that my 1.5# EPS blanks look beat up on the stands.
I shrugged it off but now am realizing that I am probably pulling out more beads than others do shaping.
Hot wire and electric planers seem fine, it’s the hand work that does it.
I am currently using a HF ‘surform’, hardware store drywall screens, and other miscellaneous pads and papers. I have a 36 grit ‘torture board’ I used to use a lot but am not using it on my current build.
Would it be a game changer to get a micro raps set?
How about the foam shaping blocks or pad sets from Flexpad or Foamez?
Are some screens or papers better than others for shaping and finish sanding EPS? Brands? Grits?
I am not ruling out operator error either. I am only good for a couple boards a year so I go in soells between making things.
I have a 9’8" SUP for my daughter on the stands and am pretty much through banding, need to start thinking about getting things smooth.
Thanks, J
I used to shape 1lb. and found the flexible 150 grit abrasive at Home Depot was good to prevent gouges when finishing the details. It’s expensive, but it doesn’t really wear out. It just curls up.
1.5 is inherently softer to shape, beads are fused but loose, bigger gaps between beads. This will always be prone to rip out. I use 1.5 lb for timberflex type boards only. 1.5 is to soft and needs extra glass which makes the board more like an egg shell. I predominately use 2 lb now for regular shapes… I have been using WNC (San Diego Company) EPS since Segway Ken left the scene. WNC has real nice EPS foam, it’s fused well and even polishes out well with 150-120 grit. Joel at WNC is a nice guy too.
But with that said EPS scratches real ez. and tears a lil bit around the stringer and tail nose. So you are best getting it as nice as possible, then use the spackle to fill the voids. Hit that with 150-120 grit and be done with it.
No sanding screens…Only sand paper. I find that the dry wall screens tear to beads out by the root.
I’m not about to bash other makers of EPS foam, but there is a big difference in the foam. Some very big foam producers in the US have the crappiest EPS. What I mean by crappy is the foam is fuzzy when you sand it, it never gets a nice polished finish. WNC 2 lb finishes nice.
I use a regular Hitach Clark planer with a sharp blade, I blend the shape in with quality 40 grit with a full sheet pad, and a soft flex pad 1/2 block, move to 100 grit doing the same thing, then 120 grit to polish and finish. If the blank needs lightweight spackle then I do it after 150 grit, then polish out with 120 and lay down the art work…done
I’ve been shaping #1 and #3/4 SUP blanks. I’ve been using the blue shaping pads from FGH (https://www.youtube.com/watch?v=HUAw802MB_w) . Of course I seal the blank and finish with 120 screen on a foam pad. It seems to work for me.
The drywall screens seem to work well, I have 150 and 220 grit. 100, 150 and 220 grit sandpaper too. I do a lot of shaping including rail bands with very course home made sanding blocks, then use the drywall screens for finishing. I use a handle that is made for the screens https://www.homedepot.com/p/Wal-Board-Tools-3-1-4-in-x-9-1-4-in-Plastic-Hand-Sander-88-006/100403174 and I just hold them for the rail work. Just be careful about how you hold the sanding media to avoid scratches and gauges when you get to the finishing. If I don’t concentrate, or if I rush, I’ll get bad results. Don’t push down too hard either.
I have course grit on one side of my sanding block like 36 or 60, and 100 on the other side. I made them 24" long to be able to go across the whole board. I also made a 36" x 6" block I’ll run lengthwise to get bumps out. I use XPS foam off cuts to make curved sanding blocks. It’s hard enough to use as a sanding block, but easy to make any curve you want. I glue sanding belts to them. I just made a simple tool with wood and hinges that has a strip of sanding belt pulled tight to sand the crown on decks.
I found an unused sheet of screen made for a vibrating floor sander I rented when I bought my house 20 years ago. It’s about 9" x 12" or slightly larger and I’ve been using that with a foam pad. It’s basically a larger version of the drywall screen, about the size of a full sheet of sandpaper. I also took a soft foam pad about an inch thick that was the same size as a sheet of sandpaper and I glued a glove on one side, then I spray glue sandpaper on the other. I usually have 100 grit and use that for finish sanding on foam, but I’ve also used 220. I wear that and don’t have to hold or grip it. I’ve made a bunch of sanding pads with the foam that comes as insulation when you buy electronics.
Personally, I think 220 will get EPS or XPS foam too smooth for a good bond with the resin.
For your shop, you might want to check out these kinds of sanding blocks. They’ll keep you shop a lot cleaner. You do need to play with them to get the feel for how the vacuum pulls them against the board, and the hose hanging off the back. I use one for my indoor working space, mostly in the glassing phases. https://www.amazon.com/Mirka-MVHB35-Faced-Multi-Hole-Vacuum/dp/B01GV2X9PS/ref=sr_1_4/146-2380811-3866856?ie=UTF8&qid=1523943606&sr=8-4&keywords=mirka+sanding+pad
Ran an EPS factory back in the day and yes, the type of bead makes a difference in how it finishes out. I personally don’t like screen for EPS and use sandpaper. I have a set of grits/blocks that I only use on EPS and they have lasted so far. Much good info has been posted here, so you can try out the various techniques and use what works for you and the type of EPS you have. One thing that hasn’t been mentioned yet is heat. EPS is very sensitive. If you are sanding with sandpaper, watch your heat and don’t work any area for too long. The heat softens up the bead and creates tear-out, specially in areas that are not well fused or are thin. Just my 2c…
Thanks everyone, I appreciate the advice. I feel a little less clumsy knowing that 1.5# can have looser beads…
I think I am going to test some papers and screens on the off-cuts before I go after ‘the boat’.
-J
