Tuesday, November 30, 2010

Rudder case

More filler added.  Still some shaping and another round of filler to do:

All laminations finished.  This part consists of one piece of UHMWPE, one G10 tube and 48 pieces of carbon fibre, cut from various specification fabric and with fibres oriented as specified in the very detailed and easy to follow plans.  I'm really looking forward to make use of it!

More hi build primer added and new areas sanded on the floats. Port float ready for hi build on deck, to the left stb float ready for another round of sanding and the (hopefully) final layer of hi build.

I plan to get the main hull back in the workshop tomorrow evening, and start filling low spots with my home mixed fairing compound.  I'll meet with the mast engineer Wednesday night.  I may or may not have to order some other weight carbon for the mast depending on his calculations.

Monday, November 29, 2010

Visitors this week end; some sailing, some building

I was lucky to have three of my friends coming up north this week end, to help me with the build.  That was the official excuse, anyway.  And since we all share a common interest in boats and sailing, it was no surprise that we all enjoyed the week end. The weather was nice on Saturday, with clear sky, a light northeasterly but a bit chilly with -15ºC. Anyway, Oyvind kept telling he wanted to go sailing, so that was what we did.  The only boat available at the time was the Minitonner.  A bit of snow and very slippery on deck, and a few very stiff ropes, but it was indeed an enjoyable small expedition.  N 63º 44' sailing in winter pictures below, coutesy of Erik, I hope

 Winter sailing clothing
 Preparing the boat
 Heading out
 Lots of very stiff ropes to sort out
 The sun never gets real high this time of year. This is around 1pm. The (relatively) hot water makes a nice smoke effect.
 Enjoying the day in the sun
 A few cold noses, and lots of cold feet after a while though
 Back at the dock.  We never even tried to get the old Suzuki running
After the fresh trip on the fjord, we went to the workshop to warm up and find some things to do on the F-22.  I decided to keep the mast moulds in the workshop, as it was indicated the engineers might take a trip during the week end.  Thus no fairing of the main hull.  But we took the floats back in to complete the updated deck specifications (early build #, lots of updates along the way) and prepare for painting.

 Beam attachment reinforcements.

 Nice to finally see the hull in one colour

I got my mast tang out of the mould.  A couple of pictures to show what I tried to explain in the last post.

 Solid fibreglass centre piece to be lashing hole lining

 Shaped to exactly fit inside the mast.  Behind the glass insert for the combined jib/forestay anchor

I also managed to get a fair progress on the rudder case.  Filling and taping the hinge tube to the case.

Ready for further filling and laminations

Friday, November 26, 2010

Rudder case and mast details

I laminated the first 19 carbon fibre pieces of the rudder case tonight.  Somehow, not being able to bag it, I got scared of lift off and other problems during cure, so I tried to clamp it all to the mould.  Well. We'll see tomorrow.

I was grateful for making up some solid glass and carbon fibre panels earlier, I used both types today.  Carbon spacer for the rudder hingeing glued to the G10 tube

Started the spinnaker halyard block lashing eye.  I've spent a lot of time trying to figure out a clever way of making bullet proof lashing eyes on the mast.  Tonight I decided to give it a try.  A three piece mould, fitting the curvature of the mast at the attachment point, was made from light foam. A 6mm thick massive glass/epoxy D-shape was cut to serve as the lining of the 3/4" hole to be made later. The glass piece was placed in the vertical slot in the photo, and the curved perimeter of this piece was wrapped with ten layers of 400gsm uni cut in 6mm wide strips, the ends of the uni distributed as a fan in the mast shaped piece of the mould, then covered with a couple layers of 45/45.  Next step is laminating the out-/top sides making up a total of 10 mm in the vertical tab.  It will be mounted from the inside trough a slot and covered from the inside with further layers of reinforcements.  Then a hole will be made in the tab sticking out of the leading edge of the mast.  We'll see.

Thursday, November 25, 2010

Other events have taken my attention lately.  A small update follows nevertheless.

Mast building have been put on hold, I don't know for how long yet, in order to get external help to try and optimize the design.  I was surprised by both the weight and the ruggedness of the failed piece.  I can actually jump on the section without noticeable flex, and this was a failed infusion. I will be surprised if it does not turn out I can reduce fibre weight in several areas.

That said, there have been lots of discussions on the f-boat group lately due to a few mast failures.  It seems however the problem is loads under reefed main, a situation where I expect this mast construction will have a significant advantage.

With the mast on hold, I have continued on the rudder.  The leading edge reinforced with a carbon/aramid hybrid in the pre made recess:

And the same around the head of the board:

While curing under "poor man's vacuum bag", the fit of a piece for the rudder case mould is being checked.

As the recommended wax sheets for making a spacer is only available in bulk, I chose to use a piece of vinyl (or something similar) flooring.  When heated with an electrical heat gun it folded nicely over the leading edge.  With a tight fit of the flange moulds it was kept steady. Using modelling clay for filling the corners works like a charm.

I added release wax to the whole surface.  Modelling clay in different colours cheers up and makes me want to run back to start the lamination.

Saturday, November 13, 2010

Curing disaster

It looked really promising when I left the workshop yesterday, so it was a huge disappointment to find that something had gone terribly wrong after I left.  However, it was not until the mast piece was out of the mould that I realized something was really wrong, although the vacuum meter reading one atmosphere gave suspicions.  A few dl of epoxy in the trap, and the bag seemingly in place.  However, the feeding tube was empty, leading the suspicion towards the patch mentioned in the last post:

I removed the bag and tubes, and lifted out the T-bars.  Easy release.  You can see the recess in the mast side here, and the glueing flange for the shear web.  Excess carbon extending inwards in the mast.

 The mast was released by sticking a sharp plastic spatula between the carbon and the mould, and then a thin piece of plywood.  Easy release.  As soon as the piece was lifted out of the mould, the disaster was clearly visible.  For some reason, the vacuum has disappeared after more resin was sucked out, but before reasonable curing.  The foam had straightened back to it's original shape and the outer carbon was lifted out from the mould, creating a major delamination all along the side of the mast.  The really big surprise was the considerable stiffness, taken the sandwich is obviously not functional, and the epoxy is far from a full cure.  Maybe I am seriously overbuilding?

So, this carbon monster will be brought to the dump.  Too bad.  On the bright side, the mould is still good, the release system seems to work fine, and it will definitely not be a soft stick.  Also, the trailing edge containing the boltrope track seems to be fine, and I will have this to experiment on how to cut a nice and straight slot.  You can see the saturated carbon and the "pre" bend here.

Also, the recess and flange seems to be just fine, making the joining process later more easy.  Making carbon wing masts is probably not a usual thing to do at home, and considering what they charge for these things, it is probably a reason for that.  However, I will not let this minor unfortunate incidence stop my plans for making an excellent mast.  I just have to order some more materials and pull my sleeves back up .....

Carbon wing mast epoxy infusion

First, I should emphasis that this mast is not a part of the Ian Farrier supplied design for this boat, and I must personally take full responsibility for its suitability and durability.  And as I am a surgeon rather than an engineer, I have little basis for calculating the optimal way of building it for this vessel, or any other.  It is based on "reversed engineering", trying to get it as sturdy as possible while not exceeding a maximum acceptable weight.  Time will tell if I succeed.
It has been a while now since I made any serious infusion setups.  Even though it is a lot of work, the thought struck me this evening when I was fitting the bag, listening to "sløyt og drøyt" (a music show that translates to something like far out and funky) on the radio that this is indeed a very 'cozy' way to make composite parts, as opposed to the vacuum bagging of wet lay ups that I have done mostly for a while now.  Not every job is suitable for infusion of course, but when it is, it not only provides you a supreme quality part, it also relieves the stress and makes the anxiety of not getting the bag on in time or epoxy spilling on the tape and so on redundant.  It was somewhere were this picture was taken that these thoughts struck me.

Even though all the building materials were fitted earlier today, it was still a whole lot to cut and get in the right place. Peel ply, then the perforated release film.  Then I added a double layer resin distribution media (RDM), shown as the blue net in the pictures.  In close conjunction to that I put the epoxy feeder line, led in at the lowest part of the mould.  I'm using a cable collector from "Biltema" as in-bag distributor.  Due to the shape of this part there are two high sides and hence two suctions are needed, shown in the above photo where exiting the bag at the highest point.  After I got all these things in, I had to complete the mould by adding the two T-bars, the pictures showing the starboard one in place, the port about to be fitted. The below picture at the same stage, showing the opposite side of the bag.  You can see the feeding tube entering the bag at the lowest point.

Finally, the vacuum bag can be fitted.  Astonishingly, it had no leaks when I started the pump. However, it was not long until I heard a snap and a hole was created close to the feeding tube entry.  A patch was added as shown.

Then I mixed up 4,5 kg of SP system Prime 20 LV infusion system epoxy.  I'm not used to this kind of quite heavy lay ups, the laminate here being about 2,5 times heavier than the beam bulkhead lay up of the boat.  So I spent some time making up additional batches until at last 8,4 kg in total was infused.  This means undoubtedly that I have to order more of the infusion epoxy.  What is not yet so clear is whether the mast is going to be much heavier than calculated.  A lot of this epoxy is spilled, for instance three 4,5m feeding/suction tubes (around 1000 ccm) and all that is still kept in the RDM.  I expect to find some in the resin trap tomorrow as well.  It is approximately  5,8 kg of carbon in this piece, so the optimal amount of epoxy would be about half of that plus what is needed to saturate the foam surface and fill the perforations.

Just opened for the epoxy.  It started bubblibg just inside the bag, indicating something was terrible wrong.  The vacuum fell less than 0,05 Bar, but the vacuum is not that interesting when air is introduced along with the epoxy.  i was not able to hear a leak, just the bubbling from the feeding tube.  The epoxy flowed in at a usual rate, but it was distributed unusually as shown below.  It was obviously distributed quite normal along the mould and back trough the perforations, but mostly air was distributed in the RDM.  You can also see the feeding line full of air (2% air that is, from the colour of it). This would make a dry laminate and the leak had to be defeated!

Finally I succeeded (don't know how as I never found the leak, it just stopped bubbling) and the piece was fully saturated.

On this last picture you can see the excess carbon without RDM along it extending from the glueing flanges and still saturated.  The suction lines starting to fill with resin after the inlet had been closed.  It will undoubtedly be another high quality composite piece.

I stopped the pump and the bag kept a steady vacuum, excess resin slowly filling up the suction lines.  I turned the temp up to 26ºC and left trough the winter night to have a beer and write this story.

Friday, November 12, 2010

Laying up first mast part

After the successful release of the rudder from its mould, I had no more excuses to postpone the mast lamination.  So today I finished the 5 layers of release wax and started cutting the carbon.  The first layer in the mould is a triaxial stitched of around 630 g/m^2 followed by a 420 g/m^2 unidirectional.  The fabric is really compact and will make a very nice laminate.  In between every layer I put a narrow strip of 0/90 to reinforce the mast track, I would hate to have the main sail pull out of the track when pulling in the sheet.

 Cutting triaxial and unidirectional carbon.  A special thank to Thomas for giving me the excellent Chinese tailor's scissors.

 The extra reinforcing layer outside the boltrope track tube

I placed the inside layers as well before sticking the foam core in.  The inside laminate is the same as the outside but in reversed order. Boltrope track reinforcement between each layer.  Then the tube was placed, and the foam put in between the two layers of unidirectional. I used a lot of clamps and 3M spray glue to keep the different fabrics organized.

 Most of the lay up in place.  Need to cover the inside of the boltrope tube. There will be fitted aluminum T-bars on top to create a recess outside the mast and a glue flange to glue the shear web to.

Just another view of the same

I will continue with peel ply, release film, resin distribution media and spiral tubing for delivery and suction, and then wrap it all in a bag.  The boltrope tube lumen has to be open to atmospheric pressure to avoid collapse and resin filling.  We'll see how far I get this evening.

Popping out the rudder

Yesterday I was able, with the help from gravity and a friend, to pop the rudder out of the moulds (by bending the mould as the rudder itself is inbendable).  It was indeed a pleasant feeling to hold this 1650 g extremely stiff carbon foil in my hands.

Rudder just left the mould

As opposed to the last rudder, there was very little damage to the mould this time, almost negligible as the area affected is not a part of the rudder surface.

 Small damage near the tip of the blade

Also, this was a couple hundred grams lighter than the last one.  The reason for this is no doubt that it was manufactured with one laminating step less, ie the foam was attached to the skin in one operation, hence less epoxy needed.  The finish was the same almost perfect, and a clear coat would definitely be no problem.  I will paint the rudder.

Trailing edge trimmed to give roughly the correct size

Wednesday, November 10, 2010

Joining rudder halves. More mast preps

This is what one rudder half looks like right out of the bag.  This time I did both the skin with structural reinforcements and foam core in one go, leaving the centre core area untouched.  The core was pre shaped to fit the skin, but left high.  The HD inserts was left even higher as can be seen here.

Then, using a router in a home made jig, I cut everything back flush with the centreline.  Then I digged out the foam to give room for the centre core.  This also gave me an extra quality control opportunity, as the core to skin bond was inspected and tested all along the recess.  It was of excellent quality.

Here, the two halves seen in the background as the core is being laminated with the last piece of carbon sleeve visible on the vacuum table.  After this I applied thickened epoxy (cotton chop/micro fibres) to the recesses and wetted the foam surface of both halves before I placed the core in the recess and joined the two halves.
Holes are CNC'ed in each corner of the mould for alignment, and the halves were bolted together and then placed on the table in order to cure under vacuum.

You can see here the rudder moulds under vacuum.  Bolts extending under the breather.  Object is to compress the two halves together, and make sure the whole mould is as straight as my vacuum table.  Please note the pencil added inside the bag, hopefully it will take notes from the process.  On top mast plans and jib halyard block, the builder obviously already in another mood.  The observant reader may have taken note of the wall now seemingly very close to the table; this is not the fact as it is the opposite: The table has been moved closer to the wall in order to accomodate carbon cutting in front of it.

The mast building is coming up.  I decided it was enough of filling and sanding.  The original finish of the moulds was obviously not perfect, and still it has proven to be a very effective piece of engineering, so I decided to move on.  Grey is my added fairing compound, black is old gel coat, now wet sanded till my shoulders hurt.  My fingers tell me it is ok.

This is a close up of an area earlier published on this blog, now feeling quite fair.

I cut the foam for the lower aft half, which will be the first part to be infused.  I'm using 8mm pre perforated Divinycell H100 foam core for better panel stiffness (buckling resistance) on the less curved parts of the mast. I will use this as a core for the central shear web as well.

The sail track insert is from electrician's PVC tube that come in maximum 4m length and has to be extended.  I don't need  much strength in the join, as that will come as a part of the lay up, but air tightness is absolutely necessary for the infusion process to work out.

Trial fitting the foam panels for the lower aft half. At this stage the foam was also cut to fit the molded in pre bend of the track.  After this photo was taken, the foam was removed, and the mould is worked over with the mould sealer.  Aluminum T-profiles that will be used for making glueing flanges and -recesses was also cleaned. 

Five layer of wax is next.  I'll have an idea how well this release system works tomorrow, when I remove the moulds from the rudder.  That will hopefully be a bit of fun. I have to do the rudder finish and get on with the rudder case in order to be ready for last shaping of hull before filling and fairing starts early December, hopefully.