Wednesday, 30 September 2009

Daggerboard Case

This can be constructed either from Marine plywood (heavy) or end grain balsa. I was lucky to find a supplier in the UK who would sell individual sheets of balsa. Normally you have to buy a full case which is expensive and more than you actually need. The panels are supplied as 4'x 2' sheets with the balsa blocks attached to a flexible backing scrim.

Assembling the sides. A plywood insert is added in the top section  for the compression loading from the mast. 2 layers of glass are laminated either side of the balsa sides. I vacuum bagged the layers after making a small extension for the table, as this is a long piece, and would not quite fit.

After laminating and attaching the down pieces (Ash) , I coated the inside with several layers of epoxy. The down side of balsa is that it would soak up water if there are unfilled gaps or holes.

Photo shows the rope channel for pulling the board up and down. This has been laminated over and sealed, after digging out the balsa around the edge and replacing with solid putty. Before I can do anymore on this I need to find a suitable cheek block....

Beam fairings

Made using molds traced from Full size patterns and. constructed from foam strips about 25mm wide. It is hard to get them to stay in place. Beacause of the shape of the fairing, (deeper at the outer end than at the inner end) the strips need to bend backwards and forwards, up and down and twist as well.

 I ended up having to hot glue each strip to the lower strip and hold every strip in place with screws in every single mold!  After that  right angled brackets were used from the outside, to hold it all in place, and the screws on the inside removed before laminating. Just make sure there is enough room to get your screwdriver in to get the screws out. By the time the sides have been built up, there is not much space left inside.

The end result is rather "gappy" on the outside. It is virtually impossible to get the strips to align nicely along their entire lengths.  I will have to try and squeeze some resin/putty into these gaps later. The shape is not that good either with a lot of ridges to be sanded. I think that there ought  be a better way to make these. It has taken a lot of time and the results are not that impressive really. (i.e you have just created more work for yourself!)

After a bit of sanding/fairing they look a bit better. Pity I forgot to put any peel ply on the inside after laminating though..

I am going to leave the beams at this stage for the moment. There is still quite a lot more to do but I am running out of space in my current workshop. Interestingly I had an update to the F-39 plans recently form Ian Farrier, and he mentioned that several builders or potential builders had enquired about purchasing ready made beams from Farrier Marine. I can certainly see the appeal of that. It is too late for me, but if I had a choice I think it would be well worth it.

Beam Tops

After removing the laminated beams from the mold, tops need to be fitted. These are the 2 aft beams which areslightly shorter at the tip than the forward pair.

The mold for the beam tops is made from the 2 cut-off from the beam mold itself. i.e the opoosite curve
I thought I would vacuum bag these as it only needs a small alteration to the mold to give a flat surface.

The mold is just made from slats running from side to side. I added this piece of 6mm ply to give a surface to bag on.

To hold it in place a few  right-angled brackets were needed around the curve. Otherwise the slats were pulled out of the chipboard sides.

Positioning the foam. The black tape is covering another removable strip, which will be dug out from the otherside later on. (Same as in the beam bottom.) The slits for the strip should be completely sealed with putty before laminating. The gap at the front is where the top goes over the reccess mold. The smaller rectangle higher up is where the highest part of the UFSR will go.

Holding the faom in position without screwing from the otherside (will lose vacuum) was a bit tricky. I ran a bead of hot glue right down the sides whilst clamped down, and this was just about enough to hold it in place. ( I did have to use some screws from underneath on the bend, but I put some hot glue down the holes before screwing them in and it did not seem to affect the vacuum too much.)


Vacuum bagging


Oops ..Disaster! I did not seal the slits for the removable strip well enough and the mold itself was too rough.The resin stuck well.

I remained fairly calm under the circumstances else there would be no photos!. I just cut it all up and quietly put it in the bin.It put up a fair old struggle before breaking considering it was less than 24hr old, Even so it is a reminder of how brittle resin can be after it is just cured. I though afterwards that it would have been more economic to smash up the mold and save the part, but it did not occur to me at the time. (So far, I'm glad to say this is the only part I have completely wrecked. I hope it will be the last as well!)


Repaired mold this time totally covered in plastic tape!

Finished beam top.


Friday, 25 September 2009

Carbon anchors postcure

The carbon anchor strips need to be postcured at this stage. I thought about using my domestic oven for this but found that the temperature was very variable. Ampreg 22 postcure is 16 hours at 50C or 8 hours at 70C. The higher temp is no problem for the resin, but it is too much for the Core cell A foam which I am using. I spoke to SP Systems who manufacture Core cell and they were not keen for the foam to go above about 55C.

I built a simple oven from a box, some light bulbs and a dimmer switch.  A couple of old computer fans helped to distribute the heat evenly.

I gave them about 16 hours at 55C. You can certainly tell the difference with this resin as to wether it has been postcured or not. After postcure when the anchors are knocked together they sound very like ceramic/china.

Thursday, 24 September 2009

Beams -Carbon Anchors

Ian Farrier's later beam designs incoporate carbon anchors in place of the usual metal parts.

Getting ready to laminate the assembly. If you don't get the carbon UD started EXACTLY perpendicular across the assembly, each wrap will move sideways until it is falling off the assembly.. The sides  help to keep things in their right place to a certain extent.

 Anchors peel-plyed and drying. The longer one at the bottom will be made into the carbon anchors for the hull

Each anchor blank needs to be cut ino to 8 strips. The plans say to use a bench saw with a diamond blade, but I found my bench saw was not up to the job really. On top of this it was carving out about 5mm per cut. That would end up turning 35mm of precious anchor into dust! (There is about 20mm of anchor to spare which includes any edge defects). I opted to have them cut by abrasive water jet in the end. It was expensive but worth it, and they turned out very well. Even the foam did not get damaged by cavitation from the cutting jet.

Beam mold continued

The mold needs to be quite strong and sturdy. By the time it comes to take the beam out of the mold, it is heavy and awkward. I reckon it must be in excess of 20Kg, on top of which they are an awkward shape. (When you lift them up from both ends to get them out,  they immedialely try to fall over sideways) I could not get them out of the mold without assistance. Recess mold at far end, as positioned by the template mentioned  above.

To make sure I did not have any extra proplems with sticking resin, I opted to entirely line the mold with parcel tape. It could well save a lot of agro, -the last thing you want to have to do is bash the mold around to get the beam out. That would be a sure fire way to upset the alignment.

Mold is about 3m long in total. I put it in the only available space I had, but it would have been a whole lot easier if I could have walked all the way around it more easily.

Mold lined with foam. I chose to line the Recess mold  with a loose fit resin proof plastic cover. In practice, when it came to getting the beams out of the mold, it was actually easier to unscrew the Recess mold from underneath and lift it out while still attached to the beam. It could be removed later easily. The central strip  towards the outer end of the beam is where 2 cuts have been made. This strip of foam is removed later from underneath for further lamination to be done.


Beams -mold making

Basic mold is made from 2 sheets of approx 4' x 9' sheet materials 18mm thick. The critical thing with constructing this mold is getting the pivot pin alignment holes in the right place, and perpendicular to the sides of the mold and parallel to each other. The shape and curve of the mold are defined by a template made from the Full Size Patterns (FSP)

 I bolted the 2 sheets together before drilling the holes in an attempt to prevent any misalignment. Even so, it is tricky. Plans suggest using a drill press, but in reality humping 2 heavy sheets 4 x 9' around is really not possible. In the end I brought the drill press to the sheets, and then had to try and get it all level and wobble free etc. Infact unless you have a drill press with a deep throat, you cannot actually get near the second hole.
The white tubes are where the pivot pins will go in the final beam. Have to make sure the sides themselves are dead upright and parallel to each other first. otherwise you cannot get the tubes perpendicular and exactly level across the required. I  struggled for several days before I was happy that all was OK.

The template is made from the FSP and is to check the relationship between the pivot pins and the top of the recess mold, which is important for correct beam/float alignment. Also a good check that the pivot pins are in the right place, and that the reccess mold is the correct shape. (Has sloping front and sides, and was a bit  tricky to make). Sliding the template across the mold from side to side does at least check that the pins are parallel to each other

Close up shows things look OK

Sunday, 20 September 2009

Doorway/passage way

Both of the Fwd beam bulkheads have doorways in and 1 of the Aft ones has a passage way to allow access to the Aft cabin. A flange is formed around the doorway cut out ( on one side only)  - many wraps of UD fiberglass which is bonded to the bulkhead with tape on both sides of the bulkhead . Photo shows the mold for the flange. The peel ply will save me having to sand shiny epoxy later when I need to tape around to the other side..Photo shows Stbd b-head.

Lamination finished and mold removed. (Port b-head).

Finished flange on Stbd FWD beam bulkhead now trimmed to size. This bulkhead now finished and ready for bonding into the hull at a later date. Extra layers have been built up around G10 pivot pin tube.

AFT beam bulkhead with passage way. (Sorry poor photo) Also a flange has been added which runs from the outer edge of the slot across to where the cockpit sea will bond later. Another 12 layers of UD! Beam bulkheads are now quite heavy and awkward to move with all the layers of glass and resin which have been added. Other photos show close up of flange area which is now very thick with solid laminate. Also collection of bulkheads ready for fitting to the hull

Bulkhead lamination

8 layers of fiberglass are needed over the mold and flanges, each slightly smaller than the one before. Strips of  Unidirectional fiberglass (UD) also go in this area and down the outer sides of the bulkhead. Cutting the glass for these shapes is a bit tricky. I made this weird looking template to speed things up.

Laminating the layers. Perhaps I should explain the different resin colours. The resin I am using Ampreg22 comes with different coloured hardeners. Yellow is fast/ Purple is standard and Green is slow. Because of my previously mentioned problems with the distorting plastic on the mold sides, I used slow hardener for these layers. The downside of the slow hardener is that it has to be postcured, whilst standard and fast do not. I prefer to use the standard hardener when ever possible.

Photo shows the UD point reinforcement  layers sandwiched in between the other layers. 5 wide strips and 8 narrower ones.

Partially finished bulkhead slot area with the mold removed. A mock up strut seems to go up and down centrally in the slot which is a good sign!


Saturday, 19 September 2009

Beam Bulkheads continued...

Molds reattached to the bulkheads. Despite having tried to keep all the holes in the mold exactly perpendicular to the mold sides, when I came to check it, I found there was sufficient play in the alignment for errors. This little set up was to ensure that the 2 pieces of G10 tube with acetal bushes (lightly tacked to the mold sides) were correctly attached to the mold. Lining the hole with thin sellotape also helped keep the alignment rod tight while the G10 tube was glued on.

Trying to get rods and tubes perpendicular with set squares is a bit difficult as the edge keeps slipping ot the round sides. A couple of straight strips taped on helps to make it more accurate.

Aft beam bulkheads ready for laminating. Molds (which are wider than the panel ) have been blended into the panel with large HD putty fillet around the cutout area.

Beam Bulkheads

Before laminating the panels for the beam bulkheads, a high density insert is added around the area which will later be form the mold for laminating over.

 Checking the shape of the prelaminated panel against the Full size patterns. It is very important that the cutout goes back into the exact spot it came from, to which end there are two "ears" on both the cutout and the bulkhead panel..

 One off the  bulkhead cut out sections. The small hole is the where the stainless steel pivot pin will go later to attach the strut to the bulkhead. The idea here is that the cutout section has spacer plates added either side of it before being reattached to the bulkhead using the "ears" on the cutout. Then it is laminated over either side, before being removed, leaving a slot into which the Upper Folding Strut will pass.

Adding the spacers either side of the cut out section. The  white tube and set squares are an attempt to keep all the holes in all the layers correctly aligned, ie perpendicular to the mold. Spacer are MDF sheet .

Cut out has to be made resin proof, to which end I added UHMW Polyethelene sheet either side of the mold, which was held on with tape and hot glue (glue only in areas which would be accessible after lamination!.).
( "Ears" for repositioning on the bulkhead obviously not covered which plastic).

When it came to getting the mold out of the slot it would only be a matter of slitting the tape and breaking the hot glue seal, and the centre section (cutout plus MDF) would pull out leaving the plastic spacers inside the slot which could then be collapsed inward and pulled out easily.

The above worked well except for one disasterous unforseen problem. The plans say to use 8/10mm plstic spacers, but I thought why not use 6mm MDF and 2mm plastic spacers!  The problem is that when there is a temperature differential between the two sides of a thin piece of plastic it  basically starts to bulge out and distort. With 8 layers of laminate to go over the cutout area, the heat from the curing resin caused the loosely attached plastic sides of the mold to bulge out and distort, which was a serious problem, not least because the carefully position G10 tube would also move (with the plastic sides)  and lead to misalignment. All 4 molds were constructed in the same way and where all attached to the bulkheads and glued and screwed in position. They could not be removed without wrecking them. It turned out to be a real headache!

With Ian's advice I got around this problem in the end by lamintaing individual layers on in a cool room using my slow hardener which generates very little exotherm. After the first 3 layers where cured, they where sufficiently strong to stop the plastic sheet from moving.  But it was a real pain and dragged out what should have been a straightforward laminating job into several weeks of frustration and agro including some midnight laminating sessions in a chilly room! But there you are, how many times have you been told to "FOLLOW THE PLANS!" . So if the plans say use 8/10mm spacer, you had better do it!

Adding the flanges to the cutout section

Friday, 18 September 2009

Early days

I originally bought the plans from Farrier Marine in about 2006, but was not in a position to get started until Sept 2007, when I bought the first batch of materials.- fiberglass, peel-ply,release film, breather fabric and vacuum bagging film etc.

I built a 6'x8 laminating table from white furniture board panels  from the local DIY store, and a simple rack to hold the rolls.

 For a project of this size, I thought it would be worth buying a new vacuum pump, although it was pretty expensive. It is one of the models sold by West System/ Wessex resins. (Actually made by Becker , Model VT 4.8 -and I am sure you could get it cheaper from another source!)

 It pulls a vacuum of 25.5Hg/150mbar, which is not terribly strong, but it does however have a high capacity. (i.e it can shift a lot of air quickly)  This means that if there is a leak in the vacuum bag  ( which there often is), the pump still has some chance of pulling a half decent vacuum. So far even with some badly leaky bags I have never had less than about 24.5Hg, which is plenty strong enough to give a good laminate.

Many pumps with very high vacuums have low capacity and can be overwhelmed by leaks. I bought 2 hoses and 2 breach units, as there are 2 inlets on the pump. With the non return valves on the breach units you can do 2 bags simultaneously, adding the second later on than the first..

As working with fibreglass was new for me, I initially started off vacuum bagging the smaller bulkheads and panels individually.  This is rather a slow way to do it though, and as I got more proficient, I was able to cram as many parts as possible onto onto the laminating table. The secret is preparation, you really need everything cut to size and at hand -then there is no panic to get it together before the resin gells.

 One of the smaller float bulkheads being vacuum bagged.  Rack for rolls. Some finished panels in the corner. As I do not have a resin trap between breach unit and pump, I keep the pump up on a pair of old step laders. The hoses are about 6 feet long, so I should not get resin into the pump, which would be an expensive disaster!