I have some CNC cut blanks to sand and glass. The bottom is completely smooth, the rails have real fine lines, only the deck is coarser.
These might be bad ideas for finishing and glassing the boards - I’m just curious if anyone has tried either of them.
Method 1. Pretreat with cabosil (or some kind of putty), let it dry, sand, and glass.
Method 2. Simply paint on some cabosil, then glass right away over the cabosil.
I’m trying to make the shape smoother, and reduce the amount of rough sanding. The adhesion should still be good on the bottom, since the bottom is already perfectly smooth, and the bottom is what needs to be strongest. Next comes the rails. Mine have fairly fine lines from the CNC machine.
Anyway, I might try this with one of my blanks. I would guess the board will be at least surfable. Repairs ARE done this way sometimes.
I guess Method 2. might have too many valleys and be a disaster? The bottom would go fine, then I pull up over the rails, and it sinks too much? Perhaps I would need something thick for the rails - real thick cabosil. The lines are fairly fine.
Thanks, I’ll look at those links. I’m hoping someone has done it with CNC grooves in their board, but I’m no cheapskate, if I have to try it myself, I’m not worried about $100.00 or so for the sake of the knowledge.
I like the idea of experimenting with a “spackle” but for my first CNC blank, I’ve decided I will sand it. It’s not really all that difficult. I’ve always been good at sanding stuff. I may have a foam sanding block or two, if not, I’ll improvise. I don’t need to sand the bottom, so I can make do with a medium foam block (I think I have one). I can even curve it with my hands if need be.
I should mention that I like cabosil more than spackle, only because of the drying, shrinking, and subsequent delamination to the foam itself. So I would probably try the cabosil as the “spackle”. However, there might be a spackle (soft or hard) that might work. I don’t know enough.
I don’t think it will take me more than 15 minutes to do the job.
Well, I’ve shaped and sanded thousands of surfboards, and I’m not sure I could scrub one down (properly) in 15 minutes. All depends on the quality you are willing to settle for, I suppose.
It’s all in the details. Just scrubbing the blank will be quick, but dialing in the details such as bottom contours and rail profiles will take time. It’s just a cnc cut blank, not a finished shape.
Well, I have not had room in my basement or garage for several years, while I’m busy with other things, and cleaning it out. I just made room in my basement, opened up my cabinet with shaping tools and there isn’t much in there - no foam sanding blocks. But I DO have some screens (various 100, 120 etc…). And I DO have some sandpaper out in the garage. I realize sandpaper is NOT ideal since it’s randomly? coated with grit, not in horizontal lines. So as I’m collecting my tools, I need to think about this one, I am working up an order (it’s up to $150.00 now). The screens/gauze-style paper would cut through the beads better than sandpaper I think.
Nevertheless, I will probably start screening/sanding before the blocks arrive. I am itching too much. I have my caliper, rail gauges, my original designs (I can make these 1:1 onscreen to set my rail gauge if need be, by tweaking which aspect ratio of display setting). I might be ok if I go slow.
I have until Thursday to ponder this one. At least I remember that some of my tools are in a milk crate on the other side of my car in the garage. I can’t pull my car out in front now due to some gardening construction I’m doing. It’s hilarious how much stuff is piled up at my house right now. The piles get bigger and bigger since the house is now being used as a bed and breakfast, so the rooms are getting emptied of stuff.
Thank GOD for the basement. The spiders all just walked away - they know I’m getting ready! Before long, I’ll have the middle of my garage back again, so I just need some patience.
Heck, if I get desperate, I could take an old pair of flip flops or packing foam or whatever to use as the block for my sanding. I’ve seen some decent Youtube videos of this job - those will help.
…hello man; if this is not a joke…well, first: you never ever fill ridges on that 99% shaped blank with resin.
Regarding rasping those ridges: better to start with an electric tool; if you do not have it; grab a block and a 36 grit sandpaper; be careful because depends on the brand and density the care you need to go with this grit; it s easy, do not hurry. Then use 60 grit to get rid of the scratches, then 100, 120 and 220.
The main difference between the screens and the sandpaper is that if you have problems with pesky hard glue detached from the stringer or hard density mini pieces that in some brands really like to complicate things at the end, the screens solve all these, the paper does not.
Man, the board is just shaped by the machine, you only are getting rid of those ridges; you will fuck up the flexibility, weight and aesthetic using resin to fill.
It’s no joke. Looks like the screens will come in handy then. I don’t have 36 grit, I’ll have to use ordinary sandpaper - 40 grit should do fine. I would think 60 or 80 would work in a pinch, just take longer. I’ll find out when I start working. Gorilla glue might work as a filler. It has nice properties I believe, sort of urethany, and expands like polyurethane foam. It might take some practice and some surforming.
I know it’s a weird idea, but sooner or later, I will try some gorilla glue. Perhaps I could even soften the gorilla glue, as it’s kind of hard. Then the questions, is can I embed stuff in it? That’s always hard to do. But I could just take an old piece of foam and try the gorilla glue. I’ve used gorilla glue to bond redwood to polyurethane foam to fix planing mistakes.
Yeah, the cabosil might not be springy and not as aesthetic. It might work better to perfect some matrix of polyurethane dust or some other wood, like cedar, pauwlonia, redwood, or one of my favorites, brazilian walnut. The Brazilian walnut lines might look cool. Just have to find a suitable binder. Perhaps not easy, but something to experiment with some time, a good challenge.
From a machining POV the “correct” shape is at the bottom of the cut. The peaks between are where the curve of the bit meet on subsequent passes. By filling you would be “adding back” to the shape. Those peaks are unlikely to be even because foam breaks away at different rates in different places.
I use a soft pad with sandpaper to smooth out the peaks on the decks of boards I cut on my machine. I count passes so that I don’t oversand one half.
I use gauze on the rails and the room (side) lights to keep things smooth. It won’t take much to get the peaks down.
Are you sure you like sanded cabosil ? If you try to seal foam with resin cabosil past for first time and think you will sand it flat before lam take time to do your seal perfect… You will understand way…
According to red_boards, it might not be a good idea to fill in the grooves. I must admit, when I see a video, the board becomes almost perfectly smooth after only a few swipes with the sandpaper. I found a cool piece of rubber-coated carpeting (used for stairs), and some carpet padding, and last night, I made the part that I will hold. Today, I just have to find my spray can and stick the sandpaper on.
I strained a muscle and have trouble walking. This might have to wait for a full attempt until tomorrow, but today, I can get the sandpaper ready. Shouldn’t be too bad. I can also fire up my computer and get some rail gauges ready. I had the rail gauges three days ago - I just don’t remember where I put them.
So now I realize that the groove is the board man!
And I found my rail gauge - I had carried it smartly from my attic to my basement when I found it the other day preparing the room for the B&B.
And I just changed my display adapter to 16:9 ratio (1280 x 720), from 5:3 (1280 x 768). My monitor is 1600 x 900 which is 16:9. So I can just “zoom with a ruler” to get the right rail shape or whatever. Or perhaps lay a transparent grid over it, or mark the sides.
