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Where to get epoxy?
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swchandler



Joined: 08 Nov 1993
Posts: 5746

PostPosted: Sat Dec 08, 2012 1:45 pm    Post subject: Reply with quote

U2U2U2,

I have to admit that I also use Dingstick for smaller repairs that often occur from handling or accidents on shore. Given the fact that it hardens in 20-30 minutes, it can often save a session, so I always keep it in the van. Later you can clean it up by sanding it flush, and then complete things with a more finished repair effort.

As far as using the measuring pumps, I don't doubt that on very big jobs they do an excellent job, but for most repair efforts on windsurfing boards they're not very sensible. Again, marked plastic measuring cups are the way to go.

Lastly, to take all the mystery and difficulty out of the equation, I'll again recommend the free West System User manual that I identified in my earlier post. As long as you're using 5 to 1 ratio epoxy, regardless of brand, it will tell you everything you need to know in a very simple and straight forward way.
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mark



Joined: 10 Apr 2000
Posts: 112

PostPosted: Sat Dec 08, 2012 3:42 pm    Post subject: Reply with quote

As I said in an earlier post I have long been a user of the West system products which can be found at www.westsystem.com. The dilemma that I now face when using their standard 105 resin system is that I no longer use very much. At my rate the quart kit I just bought will last quite a few years. This probably applies to most users.

While I have successfully used 3 year old resin for small ding repairs I would hesitate to use it in a critical structural application.

The small packages of 105 resin they sell are fine but they are too small for anything more than a tiny job. I currently have two small projects, re-glassing over a mast box and re-gluing a new front end on one of my 20 year old homemade carbon fiber booms. I am going to return the 105 quart kit that I just bought and try their g-flex resin epoxy system.
http://www.westsystem.com/ss/g-flex-epoxy/ For $20 you get two 4 oz bottles with a 1 to 1 mixing ratio. The product literature says that it can be used with their filler systems and for wetting out cloth. That size should be sufficient for the mast box repair project with some spare for future ding repairs. For the bonding of the front end I will still use the 105 resin system but several of the small packets should be a sufficient quantity.

I think the g-flex system would most probably be suited for the small user both because of the quantity and the 1:1 mixing ratio. It also comes in small plastic bottles which should both be easy to use and store.


Last edited by mark on Mon Dec 10, 2012 2:39 pm; edited 1 time in total
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swchandler



Joined: 08 Nov 1993
Posts: 5746

PostPosted: Sat Dec 08, 2012 5:16 pm    Post subject: Reply with quote

mark,

I'm curious why you're not considering the use of the g-flex epoxy for the boom repair. Is it because of the flex aspect of the hardened material? I wonder whether it is readily sandable. I'd be interested how the material works out for you.

Aside from your repairs, seems to me that this product would be great for a lot bolding jobs that might take some time to accomplish, especially combining odder materials. Also, it seems perfect for bonding jobs that might not necessarily incorporate structural materials like fiberglass or carbon cloth.
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Joined: 10 Apr 2000
Posts: 112

PostPosted: Sat Dec 08, 2012 7:59 pm    Post subject: Reply with quote

swchandler,

I did consider using the G-flex resin to glue the new boom head to the carbon tubes. After studying the literature I decided against it because the tensile and flexural strengths are about 50% of the 105 resin system. They did not give the shear strengths but I would expect those to be lower also. The forces on the connection are difficult to calculate and also the actual bonding strength is very dependent on how the two surfaces are prepared.

In the end I decided to stick with the 105 resin for boom connection because that is what I used on all of booms I built and it never has failed. This failure was due to the older aluminum Hawaiian Pro Line front end that I used at the time. I only have one front end left and I am not sure what I will do if I have another failure in the future. I have 5 sets of these booms and they were all made from West epoxy and have held up for 20 years. I considered replacing the front end with the Fiberspar carbon replacement end but they are no longer available.

I think the G-flex resin will work fine for the mast box repair and any ding repairs in the future. In fact I just got back from West Marine where I returned the 105 quart kit and purchased the 8 oz G flex package along with a 6 pack of 105 resin hardener packages. For sure it is less resin for the money but I won't have half of it left in 3 years.
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swchandler



Joined: 08 Nov 1993
Posts: 5746

PostPosted: Sat Dec 08, 2012 9:14 pm    Post subject: Reply with quote

mark,

I have a lot of old Gulftech arms, extensions, and rear end components from the Corpus Cristi days that have fallen victim to the weakness of the aluminum front ends common at the time. Same as those used by Neil Pryde booms in those days.

What I'm thinking about is making the custom front end connection between the two boom arms, and then I only need in incorporate the Maui Sails brand boom head. It's all about sophisticating the design, set-up, schedules and holding fixtures. The boom arms and carbon components are totally solid, so it's only about finessing the front end tubing design and its manufacture.
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joethewindsufa



Joined: 10 Oct 2010
Posts: 178
Location: Montréal

PostPosted: Sun Dec 09, 2012 8:12 am    Post subject: Reply with quote

since there is plenty of good advise here, perhaps i might ask a question?

i have used marine tex on fins and boards with success
for some quick fixes i have used solar ez
i purchased a fanatic ultra cat that needed repairs
nothing seemed to take well
too much plastic on the board, or ??
have heard epoxy does not work on "plastic" BIC boards as well ...
ie epoxy is the right material for the right board ...

thanx in advance
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U2U2U2



Joined: 06 Jul 2001
Posts: 3056
Location: Shipsterns Bluff, Tasmania. Colorado

PostPosted: Sun Dec 09, 2012 9:40 am    Post subject: Reply with quote

joethewindsufa wrote:
since there is plenty of good advise here, perhaps i might ask a question?

i have used marine tex on fins and boards with success
for some quick fixes i have used solar ez
i purchased a fanatic ultra cat that needed repairs
nothing seemed to take well
too much plastic on the board, or ??
have heard epoxy does not work on "plastic" BIC boards as well ...
ie epoxy is the right material for the right board ...

thanx in advance


I tried the G flex epoxy mentioned with link above on "plastic" boards

its made more for that type material. For fins I am not so particular Gorilla epoxy works , its not holding anything together, will flex some

but should be fine, if it cracks fix it again

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swchandler



Joined: 08 Nov 1993
Posts: 5746

PostPosted: Sun Dec 09, 2012 2:03 pm    Post subject: Reply with quote

joethewindsurfa,

It's my understanding that the Fanatic Ultra Cat was molded with an ABS coating over an epoxy/fiberglass matrix. If you sand away the ABS down to the epoxy/fiberglass matrix, you will get a proper bond. Now, if one's got a real plastic board that was roto-molded, like the original Windsurfer, I have no clue how one might repair it. However, maybe P-Tex materials like those used on the bottoms of skiis or snowboards would do the job.
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mark



Joined: 10 Apr 2000
Posts: 112

PostPosted: Mon Dec 10, 2012 11:50 am    Post subject: Reply with quote

joethewindsurfa,

I don't know the exact construction of the Ultra Cat but they were fairly high end boards so as swchandler said they most probably were an epoxy /glass construction with a skin. I would doubt that they were a thermoplastic like the original Windsurfers where P-tex was the material of choice for repairs. After watching the West System video of them cutting a kayak in half and rebonding it with thickened G/flex epoxy I am sure that it would work on a thermoplastic board. http://www.westsystem.com/ss/g-flex-torture-demo/

I have not yet used the G/flex epoxy so I don't know what its sanding and finishing properties are. I bought some yesterday to try on a mast box reinforcement project.

Getting back to your question I would suspect that the outer skin is the source of your problems. Either it is too smooth or there is wax or some other agent present that is preventing good adhesion. Make sure the surface is thoroughly roughed up with 80 grit sandpaper. You can also wipe the surface down with acetone to remove any wax. Just be careful when using acetone because it can melt the EPS core of the board. If you only put a little on a rag and lightly wipe it you should be fine.

I have successfully used both Marine Tex and West Epoxy to repair several small spots on my kids Bic Nova boards which have a thermoplastic outer skin construction. There was never any adhesion problems but I did make sure that the surface was properly prepared.

Marine Tex works pretty well for surface repairs and being white it has the benefit of being the approximate color if you have a white board. My only complaint with the product is that the packaging makes it difficult to maintain the 5:1 resin to hardener ratio. I usually mix up the whole 2 ounce container which is the smallest one they make. It may be possible that the Marine Tex that you used was either old or the mixed ratio were wrong.

As I get older I am looking for products that make the job easier. One West System product I have found that works very well is the Six10 Thickened Epoxy. http://www.westsystem.com/ss/six10-thickened-epoxy-adhesive/

It comes in a calking gun cartridge and is basically a thickened 105 resin. The resin and hardener mixing is done in the nozzle and you can use a partial tube and purchase additional mixing nozzles. I did a repair last summer on one of the Bic Novas. It was a dent about the size of a quarter with an L shaped crack through the skin. I cut off the loose piece and dug a bit of the foam around the edge of the crack so a bit of the epoxy would flow underneath the edge of the crack. I put the nozzle into the crack and pumped in the epoxy until the hole and the recess were filled flush. I then taped a small piece of mylar over the hole to obtain a smooth finish. The best part about using the product was the ease of doing the repair. In the past I would have mixed up some 105 epoxy added some thicker and then loaded up a 50 mm syringe. The calking tube made the whole operation very simple. The product even wets out glass cloth. If the hole was any larger I would have embedded several patches of cloth into the recess.

If the repair that you are doing is larger then the standard 105 resin system and cloth would be your best bet. If you haven't done so you may want to go to Eva Hollmann's web site http://www.boardlady.com. Also as mentioned before the West System web site also have some very good information regarding repair techniques.


Last edited by mark on Mon Dec 10, 2012 2:47 pm; edited 4 times in total
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Joined: 10 Apr 2000
Posts: 112

PostPosted: Mon Dec 10, 2012 12:27 pm    Post subject: Reply with quote

swchandler,

Regarding building a boom front end I think it would much easier now because you can buy a nice clamp on front end. The project is then reduced to building a tube to connect the boom arms together. For a small quantity like you are suggesting I think hand building would be more practical than building a mold unless you have a access to a machine shop and a lot of time.

If you like send me a PM with your phone number and the best time to call I would be happy to give you a call. It would help to know what your experience level is and what type of tools you have access to.

Mark
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