'wildy', 'halcyon', 'lokbox', 'probox larry', 'tridrles', others ??? ....'core mat' fins....

[or whatever else it is called , worldwide]

 

re:

.....'core mat' [or whatever other name[s] it goes by worldwide !]

 

have [m]any of you guys you used it ?

 

  i like the look of the Futures and the FCS ones i've seen , some have a 'foam-core-like' appearance ...

106_0192.jpg picture by chippy61

 

so , of course , i'm keen to buy this stuff ......and have a go at making some !!

 

  the american , Will, at my local supplies place said it's good , because 'it can be dyed , tinted, pigmented , sprayed' ....so , there 'should' be some interesting effects available , i reckon ! [i'm thinking the one posted above was a tint job]

 

anyway, i eagerly await people's practical feedback / experiences of using this material....

 

   cheers , crew !!

 

  ben

Hi Chip, they are referred to as RTM (resin transfer molding).  In most cases it is a molding process that involves the use of an insert (coremat in the picture above) which can be many different things. Fiberglass is placed into the mold, then your insert, then more glass. There is an injection port where resin is fed into the mold, and then it is usually pressurized or vacuumed to remove all of the bubbles. Once the mold is re-opened and the fin pops out..you'll have a flashing that can be quckly sanded off  and you have your fin. The resin can be tinted or opaqued.  This process is difficult to do consistently and requires skill and knowledge of the mold and molding process. The end result is a molded fiberglass fin, that is usually lighter than a traditional hand lay-up depending on how thick your insert is (which takes the place of x amount of glass and resin that would be in it's place otherwise).  The big benefits are obviously weight, and of course you get a consistent foil shape over and over and basically eliminate the foiling process which cuts down on waste since your not foiling away layers and layers of glass and resin. The only people that I know of doing any production with this process outside of china is Greg Trotter at Soar fins in Terrigal NSW and Probox Larry at Fibreglass fin co. with the Aerocor fins. As mentioned it's a tricky process especially when it comes to getting out all of the bubbles so they are often opaqued or painted to hide them. The chinese have the process pretty dialed and do most of their production with tinted resin where you see the insert clearly. The better factories there do them with little to no visible bubbles. I am not completely knowledgeable on the process so that's the best I can explain it. Maybe Larry will chime in and correct me if I've explained anything wrong. Cheers Jim

 

Here's a couple of links for you -

 

http://www.raptorfins.com.au/RTM.html

 

Soar fins latest project -

 

http://www.surfstitch.com/index.cfm/a/catalog.brandprodshow/brandid/237/KINETIK-RACING

 

http://www.google.com/images?hl=en&gbv=2&tbs=isch:1&q=RTM+fins&sa=N&start=20&ndsp=20

 

 

Here's one of ours -

 

[IMG]http://i39.tinypic.com/j8mzwk.jpg[/IMG]

 

 

.....very nice !!

 

  thanks for the feedback , Jim ! good to hear from you mate ! [ I read your comments on fins in the Surfers Journal article with interest , too !!]

 

'Probox Larry' , and others ...do you have anything else to add , please ??

 

  I'll hand lay up mine , but hopefully , 'should' be able to cut down on at least HALF the layers of fibreglass cloth , so as you say , less wastage in terms of foiling away excess layers

 

  stay tuned ....

 

  cheers

 

   ben 

could a scrap piece of foam be used instead of the core mat?

Hey Chipfins!  Nope, sorry haven’t tried RTM (?)  I’ve read about it and figured I didn’t want to put the time/effort to learn it.

Have you tried making curved fins yet?  Lets see!

Les

 

     its called soric when you hand foil it it will rough out  and no look so good but you can do it you wont get the r t  look

if you want a bit yell out

 

   cheers huie

thanks for the offer huie!

 

  i'll take you up on that mate

 

  i'll 'p.m.' you my address

 

  cheers

 

  ben

 

  yes , knowaloha , i've tried foam core too , i'll give it a go again , i'm sure [i had a problem with the tab snapping on the one set of sideys i made ....]

well, been a while between drinks , on THIS thread , at least , anyway !  [ I'll post it here , instead , as I couldn't find my original "thanks huie !" thread ..."search" ? .... gone wrong !  :( 

 

  Here, finally , is the result of using the  coremat / 'soric' ,  that 'Huie'  sent me a while ago .

  I put two layers of [clear] 4oz down , then the 'soric' , then about ? 28 ? more [these ones were ] red tinted layers of 4oz , in the end . I was wanting to make  two side fins out of it . To match three commercial glass-on fins , that I had found on a thrown away snapped board , last winter here [august ...in west oz !] . THANKS , to whoever throws their board away , with fins still attached !   [.... yewwww ! I SCORED !!  :) ]

 

   Anyway , here are some photos .....

zresfins0.jpg

zresfins00.jpg

alongside one of the three re-tabbed glassons I found ...

zresfins.jpg

in the walden ...

zresfins2.jpg

 

 I think that I may need to seal the edges [and base ] , where the cutting and foiling exposed the 'soric' ...I'm hoping just a brush on of resin [?gloss coat ?] could suffice ?

 

   cheers !

 

  ben

 

 

 

really useful comments

i’m studing the possibilite of design a RTM mold of fins, i have some experience in RTM process and i thing that could be easy a 3cavitymold

with the hand lay up i have no enogh compaction, and microbubbles appears along the fibers.

i’m working on it , i will upload some pictures

 

I’ve been doing hand layups with coremat. There are some cool bits to working with it, an some pains in the ass. 

  1. Yes you can reduce the number of layers of fiberglass, but with the 2mm coremat I have worked with it’s no where close to half. You don’t want to jump into the 4mm stuff since it will start poking out when you’re foiling. 

  2. Air bubbles at the edge of the coremat are a pain in the ass. I just laid up a fin using roving at the edge of the coremat to help that and it worked. Although the woven roving that I pulled my roving from is pretty stiff and kind of tricky to get to stick when I wanted, although it completley solved the air bubbles. Might try the next ones with layering tiny strips of 6oz fabric at the edge. 

  3. Visually (looking at the contour of the layers) hand foiling your “top side” (the side of the fin that was not on the glass panel during layup) can be tricky. This is because how the coremat creates a “lump” in the panel, with the FB layering over it. Have yet to foil the fin with the roving at the edge and but hopin the smoother “lump” helps somewhat. 

4… The coremat creates a stiffer fin than just a pure fiberglass layup. Once I’ve mastered hand laying up it I want to try puttin selective patches of it in. 

thanks for that updated feedback  !

Please let me know how you feel they surf eh , compared to other fins you have made / ridden …CAN you feel any difference ?

 

   cheers , guys !

    ben

Can I feel the difference in the coremat versus plain fiberglass? Definitely since the coremat provides a lot less flex. What I want to try is how much flex difference you’d get in orrienting all of your cloth layers in the same direction versus alternating the angle every layer.

cheers , ‘Scientistblank’!

 

And , how thick was the coremat ?

 

Do you have any photos of the finished fins , please ? I’d be keen to see other homemade 'coremat ’ / ?“soric”? fins …

 

The stuff I bought  was like blotting paper thickness. Inlaying two layers , it was pretty THICK,  and soaked up a LOT of resin , to laminate it  fully. Whereas , the "soric’’ ,  that  ‘Huie’ sent ,  was thinner and easier to work with and , from memory , I inlaid only ONE layer in the panel.

 

  cheers !

  ben

 

 

The stuff I have is 2mm. I know they make the soric and some coremat in everything from 1mm to 10mm. I might get pictures tonight as school hasn’t given me much time to toil over foiling fins.

But here is my first experiment layed up. All of them but the bottom right corner are 10 layers deep with 10 layers bellow the coremat. The bottom right is 15 layers deep with 5 layers below it.

hey

i ve upload a pic of my last fin ,

it was made with 8 layers of fiberglass and coremat honeycomp,

i don’t like this construction because there are no enough force with the deslamination , that’s why i’m gonna try rtm to obtain a low level of deslamination between layers, and reduce the micro air bubbles arround the coremat

sientistblank, i will try tyo put a thin strip ob 6Oz in front of the coremat to reduce the bubbles this weekend, i will inform you of my progress.

i like this forum because there are a lot of knowledge about this

 

what is the advantage of having a core? 

I would imagine this is weaker and harder to make then a completely fiberglass fin?

the teory says that is more flex and less heavy

do you know which resin are used in the fcs fins?

have you got some image of the fcs process to obtain a rtm fin?

thx