Probox roving wrap

General Discussion
1

So I found something that might be helpful to those of you doing these fin box installs. The probox install has the roving wrapped around the box before it is dropped into place. I have tried wrapping the roving prior to install, however the roving always seems to catch on the edges of the hole, or come loose when dropping into place. It also never seems to want to conform to the box, especially toward the middle where the box tapers in like an hourglass.

 

While it is something small I found this on accident after having to take the box out and start over. If you get the sides on the box wet with resin prior to wrapping, the roving easily conforms to the contours. At that point you can easily drop into place without having to worry about everything unraveling. This seems a bit basic but if someone else finds it helpful then it was worth posting.

2

I dont do the roving thing

but that does make good sense to wet it first

I just do the two liner patches with 6oz, never had a problem

3

spray adhesive is also a good choice…less mess going in.

I pinch it at the center of the box when dropping it in the hole to keep the loose strands from catching and then break a wooden stir stick in half to push down anything that got snagged or otherwise didn’t go down properly.

 

4

Hey foamball.

That a great tip…

I do something similar except I don’t use rovings but twist a scrap piece of   4 oz. woven S glass about  18 -20" long  x  about 2" wide  into a rope type of thingy, ,and  tack that to the box at one end using a small dab of 5min. epoxy…

After the dab has dried,  I finish wrapping the rolled up glass rope thingy fairly tight (but not overly tight) around the box until  the other end can be secured with another small dolup of 5min, to hold it and make it easy to handle…     This allows you to repeatedly handle the roving wrapped boxes with out worry of it unravelling…

I do this on nights when I want to work on board building ,  but not enough to get overly involved… So I sit at the table and pre-wrap and stick these on boxes so they’re ready for future use…

I also line the hole with 6oz. s-glass scraps like  Ken does above…

All of this is over kill for you guys…No question about it…

But   kite  boarding  inflicts a more prolonged and heaviy load on a  fin set … This construction method probably adds very little extra weight for lots of added security…        If anything,  the more glass filled the cavity is the stronger the joint should be,   so really you’re replacing excess resin with excess glass…

I make sure  I pre-wet out the wrapped home made rovings with a finger load of epoxy just prior to inserting into the board… And this sticks the glass down to the contours like you mention in your post…

With this much glass in the hole, you don’t want any of it to be left dry…

I also cap my finish- installed  pro-boxes with a pretty butterfly patch…   But hell,  I’m insane so who cares…lol…")

Hey…And if you’re really nuts,   you can twist up really long scrap pieces of glass cloth with a corless drill and a clamp, then cut them to length… But that’s strictly left for the seriously deranged…")

5

The other methods you have mentioned sound good and less messy. I'm going to have to try the twisted s glass at some point. My tip was found trying to avoid a disaster. Initially I had dabbed two spots on the roving while wetting out the cloth that lines the box. I had put about half the epoxy needed in the box but it was showing all full along the dam. Not to mention I caught some of the roving on the side when putting everything in and coudn't get it back in without seeing lots of air bubbles. I knew that something wasn't right so I had to take the boxes out. Lots of air underneath so I ended up pouring about 1/2 oz into the hole before re installing. In addition the roving was removed to start over. I thought I could get away with adding gradually from the sides in a couple pours to avoid everything getting too hot but it obviously wasnt working.

With the tip I described above one hand that stays dry just holding the prongs on the sides of the box. The other had needs a glove to smear a little bit of resin around the sides and lays the roving along the box wall. Pinching at the hourglass part once completely wrapped and wet it just all conforms perfectly. Once you let go you don't have to worry about it all coming unwrapped.

6

     Howzit foamball, When they first came out we used milled fibers in the resin mix and I see no reason why you can't still use them, I do. I don't even wrap Bahne fin boxes but I do put a layer of 6 oz in the bottom of the hole to help keep the box from punching through the deck. Aloha,Kokua

7

I use west system 404 mixed into the resin or epoxy. 404 is the adhesive additive for bonding hardware on boats.  It mixes smooth, and sands well.

 

Just put you layer or two of 6 oz in the bottom of the hole, pour some goop in, slam the box in the hole, then pour a little around the crack.................no brainer....and you keep all your hands clean.  Don't make it more difficult than it has to be.

8

what is the purpose of the roving wrap?

9

 

I forgot to quote, but this is directed at Greg’s question:

 

If you look at the side profile, the pro box itself is tapered down to the bottom  and hour glassed slightly as well…

The routered hole is straight  cut and and as wide as the widest part of this side profile…   The roving’s fill in this void area… If you just want to use thckened epoxy to fill this void that’s fine…   But, I was taught that glass was stronger than plain resin that is just poured in thick layers…And probably not much different in weight overall…

The woven glass I use, or even the rovings used by some have higher fracture and shear resistance than plain resin and powders…    Zfennel, help me here !!

Would you make a glass roving, glued on style of leg rope attachment, and leave out the rope, and just go with resin ???

 

Probably less exotherm to boot…

Do whatever makes you happy…I gotta’ learn to keep my opinions to myself…lol

10

I line the hole with 2 x 6oz, and never had a problem. THough a little overhead is as big as i surf, and not that often, so they're not under that much stress!.

11

when i last did probox this was mentioned in a thread somewhere as a discussion point, i suggested they could put a notch in the box (similar to the one on a reel of fishing line that you could snag it in) but someone else suggested the 5 min epoxy and its way easy, dab on either side of the box in the middle, wrap your rovings round then just apply a spring clamp just to hold it till it sets then  hey presto, rovings dont have chance to move as you slip her in the box...

12

I mentioned exotherm as kind of an after thought in my posr above, but it is probably as good, or better a reason to add more glass as any, if you’re potting boxes into lower densities  EPS …

 I pot boxes into core-cell inserts, heat is not that much of a concern…

The larger the quantity of  relatively pure resin left in any  confining container heats up rapidly and sometimes violently…

The glass lined hole, and rovings  act as “heat sinks” and channel away some of the excess heat compared to a hole full of goop…

 it’s just common sense… 

Try this sometime you’ve got some excess resin left in a container…

Pour out the resin equally into into 2 separate small containers, such as  yogurt cups… Leave one partially full of pure resin… With the other cup,  dip a scrap piece of glass cloth into  it, fully saturating it, roll it into a ball, then push it into it’s cup… Watch both, and see/feel which heats up the most…

I know I do things 'overkill style, but I can live with that… Most surfboards are still built like they were in the 60’s and 70’s, except for those willing to make them stronger and technically more up to date…

To each their own…

13

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I line the hole with 2 x 6oz, and never had a problem. THough a little overhead is as big as i surf, and not that often, so they're not under that much stress!.

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that's how do it too... no problems yet

14

I have been doing both rovings and lining the box with 6 oz. Just an extra step but more peace of mind.