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View Full Version : ?'s re installing inserts in 12-6 SUP ....


flipper
15th November 2007, 03:59 AM
I need to have a shoulder strap on my 12-6 *board sup and my plan is to install a few inserts to attach the strap to. a friend with lots of old windsurf stuff gave me a few of the inserts you see in the pix below.
my plan is to drill a hole, fill it 1/2 up with hardware-store-type 2 part 20-minute epoxy mixed with bits of fiberglass, and shove the insert in. oops-- the first thing i hope i do is tape off the hole so when the epoxy oozes out, it oozes onto the tape and not the board.
anyone see any flaws in my plan? hardware-store epoxy good enuf, do you think? and, what about the inserts themselves, think they'll stay stuck in the board okay? anything else i need to know?
thanks!

http://www.linter.org/screws.jpg

http://www.linter.org/screws2.jpg

Phill104
15th November 2007, 01:51 PM
What is wrong with just looping some straps round the board and fixing your shoulder strap to that?

flipper
15th November 2007, 06:20 PM
it's a good idea but in my situation it doesn't work that well. to get to the water i am going down a very tricky, steep, rock-and-boulder strewn hill. more like a cliff. so i need to get the board as high on my shoulder as i can, to work my way around the rocks. with a sling it'd hang too low. and under my arm is too low too.

steveC
16th November 2007, 12:54 AM
Hi flipper,

Any time you cut in a board, it's prudent to laminate over affected area with fiberglass or carbon cloth. Epoxy, even when it includes some chopped up fiberglass cloth, just doesn't offer sufficient strength. The lamination step integrates everything into the structure of the board, and it serves to provide the necessary reinforcement outside the boundary of the inserts, especially if the area will see stress of any kind. Given the fact that the weight of the board will balance and leverage off any inserts you install, quite a bit of concentrated stress will be present.

Also, if I were you, I would go for larger, more robust inserts. I would recommend checking out the molded inserts that Chinook makes for footstraps (view at Fiberglass Supply's website). It's important to establish a larger bearing surface that will better integrate with the surface structure of the board (through the use of the fiberglass/carbon cloth), as the internal foam core doesn't offer much support to speak of.

flipper
16th November 2007, 08:36 AM
thanks, steve. guess i'll have to use a standard inserts, though the ones in the pix would have been easier ...

PG
16th November 2007, 12:15 PM
... And you have to use a slower epoxy to prevent the core from melting...

flipper
16th November 2007, 06:04 PM
thanks, guys. and, pg, how slow is slow?

steveC
17th November 2007, 12:10 AM
In answer to your question about cure rates, check out the data shown for West Systems epoxy at the following location. You have quite a few options.

http://www.fiberglasssupply.com/Product_Catalog/Epoxy/epoxy.html

Another thing worthy of mention working with catalytic materials is the temperature you will be working at. It's super important to accurately measure portions of resin and hardener within the working temperature constraints.

flipper
17th November 2007, 06:21 PM
thanks again. i don't own a router so i'm not going to go with the rectangular chinook insert but with the 1" round one instead and drill 2 holes in it. and put 2 maybe 3 layers of glass over it. that ought to do the trick, right?
as far as cure rates go, given all the options, could you suggest an optimum rate in order to avoid melting the foam?
i'd read elsewhere that one way to go about it is to use a 20 minute epoxy but let it go off for a while before drooling it into the hole, thereby reducing some of the heat. i also read that it's extremely important to keep the hole as snug as possible so that the resin doesn't pool and overheat anywhere.

steveC
18th November 2007, 08:40 AM
One of the most important things to understand working with epoxy is that it really doesn't have very much structural strength in itself, unless it's combined with a good design and materials that introduce the needed structural properties (like fiberglass, carbon or kevlar).

Based on my experience, I would recommend trying to keep the tolerances between the cavity and the insert component relatively tight. However, to ensure a super robustness, I would recommend an assembly of hard foam and the insert, and than installing the completed assembly into the board. Also, in going this way, you increase the size of the integrated bearing surface, both internally in the foam and across the area of the lamination. If you have a Dremel tool, you can easily custom a cavity to suit. A router is truly unnecessary, as the cavity area will be filled and buried under the lamination structure, so any minor tolerance variations become a moot point visually.

As far as cure rates, the best choice lies in the way that you go. If a larger volume of epoxy is used, particularly if casting a larger area with just epoxy, go with the slowest cure. If things are done within specification (the mixture and temperature), you will achieve the desired result over time. Catalytic materials are very predictable, keeping in mind the contraints in the use process.

I didn't mention it earlier, but it important not to work the material beyond the recommended working time. This is quite important, as things can quickly go off the map on your project if you exceed the viable timeframe recommended. Only do as much work as reasonable in a single session. A cavalier approach on things can be a bummer, so using the 20 minute stuff and trying to proper time things can be quite risky.

However, based on my recommendations above (going with tight interference tolerances) you can use a quicker, or more regular, hardener that might also be used for laminations too. Really, if things are reasonably tight, you can lose the chopped up fiberglass and easily use microballons instead, or even use only epoxy if your fit is reasonable good. A significant volume of material creates heat, so plan accordingly.

Again, if you find quicker/hotter cure rates a problem, just go with the slower cure rate. Why have to rush things? Time can be on your side.

Two to three layers of fiberglass is sufficient. To gain a bit more dimension of the overall process, I would recommend checking out the Board Lady's website. Eva is a consummate expert, and fortunately, she has offered an incredible amount of sound information on her website. Really, a "must" review for the correct map to the job.

Randy
18th November 2007, 06:31 PM
Check out Boardlady.com for the definitive guide to installing inserts - even one about installing inserts for handles IIRC. It's not the easiest way, (first put divincyl around the insert, shape it, cut out the area, install it, glass over it.) But I don't think there is any way that is stronger.

flipper
18th November 2007, 07:22 PM
once again, thanks. these have been some quality responses and another indication of why the starboard community is so great. and now off to look at the boardlady's site i go ....

Floyd
18th November 2007, 11:23 PM
Dont want to contradict Steve BUT the inserts ypu show work fantastic. I`ve fitted loads(innner/forward straps on F2 Styles and Kombats)
Be carefull drilling hole; it wants to be around 1mm smaller than max insert size. (they pop into place)
When fitted (with plenty of resin) turn board over so resin accumulates around top (inside) of inseert.(rather than its base)
Its almost impossible to fit a deep rooted insert and laminating surface
I dont use any strands/ glass but dont over doo drilling out foam but do drill to a depth so all insert is immersed.Dont fit 2 inserts along side one another (for straps a single fixing is fine and would easily carry board))
I have a 7 year old F2 and the srtap fixings (christmass tree type like yopurs) are still absolutely fine.
See Gun site for info. (they still supply them)

Good luck

steveC
19th November 2007, 05:28 AM
Floyd, you nailed me. My approach was classically conservative, and admittedly, very "old school" in design and execution. It's interesting to get more feedback on use of these particular "designed inserts". I always wear earplugs (my ears have been a problem back since 1968, and I've had to work with the situation since then), but they incorporate a similar flared design to trap and keep the water out. A different way of working the problem, but very insightful nonetheless. I'm glad that you offered a great counterpoint.

Floyd
19th November 2007, 04:45 PM
Hi Steve
No dont think I nailed you.There`s always more than one way to do a job.To my mind when working on board simplest and smallest is nearly always best route.(It also tends to be lightest)
The inserts almost fit themselves if hole is correct diameter(didnt want to quote a measurement because they do come in slightly diff diameters)
The insert collapses on insertion and springs back.(I use a rubber malet to tap them in) The epoxy seals and strengthens.They really are are strong and simple job.I reckon they are stronger than many OE fitted inserts.(You must use epoxy resin though)Over years I must have fitted 30 or so.Never had any come out;leak or crack board.(Even ones I put in with oversized holes;which ended up flush with top of board;they normally stand a few mm proud)
Take care.

flipper
19th November 2007, 07:28 PM
when i went back to the guy who had the inserts and told him why i was returning them -- ie maybe they wouldn't hold -- he scoffed, i tell you, he scoffed. that said, floyd, if i do decide to humiliate myself and go retrieve them, do you really think one xmas tree insert per attachment point is enuf given that this board weighs maybe 25-30 lbs (i'm not sure what it is, but it sure feels that heavy ...) and there could be a lot of wind-driven torque on them? i'd feel more comfortable with 2 per, set apart by a little bit, unless that might cause structural issues of some sort. what'd'ya think?

Floyd
21st November 2007, 01:18 AM
Hi Flipper
I would never fit the inserts with less than a 5 cm gap between them.
I honestly think you would rip out a big chunk of the board out before the inserts pulled out.
I cant see how you could ever exert more force on them than with a footsrtap. which I have only ever held in with 2 per strap. (one either end)
If inserts are put in with a modicum of care you will be amazed at their strength.I dont think there is a stronger way of having a fixing.(I`ve pulled out brass inserts;glassed in straps;nylon blocks but never a christmas tree insert.
From an engineeering perspective fixing has got to be better with 2 inserts(ie to remove twisting/rotational force on a single )
Have a dummy run drilling and popping one onto a piece of sheet of some sort.It will give you a good idea how they work.(ie taper and gap for laminate).
Ask your supplier what diameter hole should be drilled .Make sure you drill (or end up with) a hole exactly that diameter.(too small and you could crack laminate ; too big and they wont sael on to laminate)

They are very good.

flipper
21st November 2007, 06:23 AM
thanks, floyd, i'm going to give a single a go.

Mike T
23rd November 2007, 08:23 AM
This Might be a silly Idea but why dont you use the two screws that hold the center fin in the board as an attachment point for a harness/shoulder strap arangement that would also loop around the nose and tail of the board. Then you don't have to worry about adding inserts. Use what is already there. All you would have to do is have some quick snap buckles that would disconnect the carry strap from the screws. If I remember correctly their is a deep tuttle box in the center of the board with two screws and a filler block in the bottom of the board. Just an idea. Good Luck! Mike T

Mike T
23rd November 2007, 08:40 AM
Hi Flipper Check this out on Surfingsports web site. Something else to think about without drilling any holes in the board. http://surfingsports.com/labels/standup%20paddleboard%20carry.asp Good Luck! Mike T