Composite Fittings

Those shiney bits
Taniwha

Composite Fittings

Post by Taniwha »

Ok guys, if you're inviting some interaction... here's a question for you.



Composite fittings. Very interested, but I am confused about glassing over stainless steel. I thought the stainless only remained stainless as long as the surface was in contact with oxygen. I thought the oxide surface was what kept rust at bay and the oxidation process is a continual process. So if you are denying the stainless contact with the air by glassing it, won't it rust ( like accidental steel screws buried under a fibreglass skin)?



Answers on a post card please.



Stupidly



Paul
admin
Site Admin
Posts: 42
Joined: Thu May 04, 2006 6:10 pm

Composite Fittings

Post by admin »

Paul
Stupidly
Not stupid to me, given it its own 'Topic'
mySerenity
Posts: 755
Joined: Thu May 04, 2006 7:36 pm
Location: Brisbane Australia
Contact:

Composite Fittings

Post by mySerenity »

Paul

There are a few here who have made their own composite fittings, all out of glass then moulded them onto their yachts. I think 44C or even Paul from Manhamanha are the gurus here. However, you may find that their components do not use stainless parts or inserts.



While I personally question the gravity of the 'oxidation' challenge (on small components), it is true about the oxidation process when covering stainless. I have had a length of stainless rod in the seabed now for just over three years and coral worm seems to cover it before the oxidation can take hold. In the mud, the rod is tarnished in colour, but still defined in its original shape – the deeper the embedded part of the rod, the less the tarnish. The bottom end (1m below mud surface) is as good as new still holding its stainless colour.



Pure Majek has some stainless deck fittings that have been powder coated and are yet to show any signs of oxidation, including one where the paint was badly chipped when I dropped it on the concrete floor.
James
______________________________________________
https://www.diycatamaran.com

https://www.youtube.com/user/puremajek
_____________________________________________
RW
Posts: 92
Joined: Sat Apr 21, 2007 7:00 pm
Location: Melbourne

Composite Fittings

Post by RW »

Hi Paul, it is possible to glass over s/steel. The main thing is not to let the s/steel come in contact with any carbon fibre. So when laminating make sure that there is a glass layer next to the s/steel then apply your carbon fibre laminates.

Also noted that Tom from Scrumble has built some composite pad eye straps. Here is the link: http://scrumbleproject.wordpress.com/20 ... -pad-eyes/

I am building a foam sandwich boat & am not keen about stressing the deck with through bolts. I am making composite anchor cleats. Also making composite hinges & various other little bits & pieces. Others on here have made composite staunchions etc.

Here is a carbon fibre deck bollard that i have just made. I shaped the foam to the shape of the hull & glued a piece of flat c/fibre to it. Then laid up 4 layers of carbon fibre uni. This will then be glassed to the hull side.



This is sitting high but will be glassed in lower.









Also have made composite hinges for the anchor well & also the internal cupboard doors.





Cheers



Rod

Farrier F82 R

http://rwf82raus.blogspot.com/
mahnamahna
Posts: 580
Joined: Wed Aug 02, 2006 4:48 pm
Location: Gosford NSW

Composite Fittings

Post by mahnamahna »

Hi Guys,

I have a method for making composite cleats that do not need anything inside them. You make a glass "rope" by wetting out a piece of glass (uni, bi, tri, I dont think it matters much). Once it is rolled into a rope you fold it in half and pull that folded rope through a length of appropriate inside diameter (appropriate to what you are making, ie what size cleat you want) plastic hose, preferably clear, so you can see the resin and glass inside it, and of course it needs to be a tight fit. You will get a lot of resin force squeezed out of the hose. Then whilst it is still wet you wrap that plastic hose which is now filled with glass and resin, around a mold you have made to make the shape you want to end up with. For example the mold could be a sheet of mdf or ply with a half round trench routered into the edge and an appropriate radius cut into the shape you want. Be careful not to make the radius too tight or as you wrap the hose around it, it will cause a compression on the inside of the hose and this will result in you losing your roundness. You can make a straight section either side of the curve to the length you want your cleats to be on one side and the depth down your bulkhead you want to go on the other straight section.



When set, you cut away the clear pipe to reveal smooth round section glass rods with a bend in them. You cut the straight sections to length and with a pair of them, glue and glass them to each other back to back (you wrap glass around the 2 ends to join them into 1 unit) or you can glass one each side of a bulkhead (through the deck) leaving the thickness of the bulkhead gap between them although if using this method I would glass a ply gusset between them for added strength. Of course you will also need to cove and glass them to the deck. You may also just need to key them a little to have paint stick to them.



If this does not make sense I can post diagrams. Or wait until I get to that stage and you will see me do it on my build.
Taniwha

Composite Fittings

Post by Taniwha »

Everyones clearly champing at the bit for something new to read judging by the speed of the responses!



Puremajek - I think I read in Nigel Calders book that the molybdenum (?) added to the steel forms an oxide at the surface and prevents rusting of the steel (an oxidative barrier like with aluminium). It also said that stainless immersed in oxygen deficient water could rust as the stainless was deprived of the means to maintain the oxide. Sounds like you've experienced the opposite with that stainless bar you describe, as I would expect that mud is pretty oxygen depleted, yet that very part of the bar is in the best condition. Confusing! I can see why you question the whether the whole issue is a big deal.



RW - very neat job mate.



Mahnamahna - And I thought hose was only useful for making water levels - it would never have occurred to me to do that. Thats a great tip - thanks. When you say you make a rope, do you roll it lengthways or just twist it up? I particularly like this method as it contains no stainless. I'm sold.



Another question that is bugging me is what do you coat these composite fittings with? One advantage of stainless is that it will cope with all the abrasion thrown at it. What do you put on a composite cleat if you don't want to be touching it up all the time, which frankly sounds a bit pervy. Carborundum epoxy, or would that still need a protective coat?
Romeo
Posts: 49
Joined: Sun Nov 09, 2008 10:32 pm
Location: Western Australia

Composite Fittings

Post by Romeo »

I never thought that a composite fitting had any stainless steel in it other wise it would be called a stainless steel fitting.

Romeo
Post Reply