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Tool time.

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  • Davidh
    replied
    Thankyou David,

    Can you elaborate?

    Dave h

    Leave a comment:


  • He Who Shall Not Be Named
    replied
    Latex bad. Silicon good.

    M

    Leave a comment:


  • Davidh
    replied
    Hello all.

    I was hoping to have some feedback on the questions that I posed about latex. Maybe I've scared HWSNBN off my threads. I haven't been berated about using Timber for my mike project yet either so Either David is too busy or ill or I don't know what else...

    As can be seen from the previous pictures I'm pretty chuffed about the way in which these clear mould pieces for my Gotland class came out of the moulds. This silicon stuff is the bomb. The sprue and vent system has worked well for me and these are only initial pieces. I have taken to filling up the cavity and then using a paper clip inserted down into the sprue and stirred a little just to stir up any bubbles.

    Moving along and intrigued by the glove and hardback set up for flexible moulds of larger pieces that require layup I have decided that I will utilise the big tub of latex I bought a couple of months ago when what I really wanted was silicon but was rather annoyed at the cost. I bought the latex anyway and eventually coughed up for the silicon. Silicon is great but I may as well give the latex a go..

    David mentioned the TC -5040 silicon. I have been looking up Australian suppliers to try and find it or something like it , There is little on offer here. Most suppliers have maybe one or two silicons and I'll simply have to look around further for a wall clinging one.

    So I pulled out the sail master of the Resolution class that I have just completed earlier this year. I would like to make and sell a couple of hulls of this boat. (don't laugh). A complete set of tooling for just one boat is a huge task. I've completed most of the tooling already in the form of the silicon moulds for appendages and surfaces. However the sail being a layup I didn't want to use a huge amount of silicon if I could avoid it hence latex.

    I have cleaned up the sail of the Resolution. Re-etched the plates and cleaned up some of the detail. Scribing and etching has never been a strong point for me. The first photos show an adequate effort.
    With latex you can only put down thin layers at a time one after the other after the previous has dried. You need about 20 layers. The next picture looks like I coughed up half a lung. but this is the dried latex. Comes out white and looks like phlegm when hard!
    I was concerned because half way through the lay up at around layer 10 I noticed that around the edges where the master meets the moulding board the latex was separating. Pressing down around the edge of the mould the latex would pop back up, surely not good
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ID:	108977 . Is this common? I was wondering if my use of a heat gun may have caused the drying layers to contract or pull and thus separate the latex from around the edges of the master and board. Any illumination on this? Is this a common problem. I could just see this playing havoc with the overall accuracy of the finished glove.

    The next photo shows my response to how to fix this. Once 20 layers are on I then laid up a GRP hardback. Polyester resin and cloth. I then clamped down 3 small strips of wood around the edges of the master to clamp down the latex. It also helped pull down the GRP cloth , two birds..... Once the hardback had dried I pulled the whole assembly off and was pleased to see that the fidelity in the latex was fantastic. Every little detail was there. However I am concerned that when I lay up my first GRP piece that the flexibility in the latex is going to cause problems. Even with the hardback in place does it really support accurately the shape of the glove mould?

    I would really appreciate some answers / suggestions to these questions.

    David H

    Leave a comment:


  • Davidh
    replied
    Thankyou Trout for the advice.

    Every time I have made another mould I have tries to do something differently. After the first half baked attempt I then increased the number of vent holes around near the top of the mould. Doing them either side of the metal shaft insert. I found that pouring the resin into the mould requires a fair amount of steadiness that I'm guessing could be assisted by moulding a funnel shaped entrance to the sprue. I have moulded a funnel shaped section into my latest mould design to see if this would help.

    As you can see the mould set up features aluminium tubes. These create the mould for the sprue. The black lines are the intended vents that will be cut into one side once both moulds have been made, just making sure they are not going to go through a register bump. To create funnel I simply placed some modelling clay around the end of the tube where it meets the wall. after the first attempt made with grey pigmented polyester resin I decided to use a clear resin. I wanted to be able to see the air bubbles and where they form but also I have a theory that may or may not be bedded in truth, that pigment slows down curing. As you can see form the third photo of the clear pieces still in the mould, this is the best attempt so far. There were virtually no air bubbles. There was a fair amount of resin loss along the joint of the two moulds in the form of flashing but so what. You loose some in the sprue. you can see the funnel shape at the top of the sprue. The funnel idea does make it easier to pour and the attribute the zero bubble to increased air ventage.

    More later.

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  • trout
    replied
    David,
    Your write up is like gold. With this new system, can we post in the style like you did with the rubber glove over the mold?
    Davidh, Yes practice helps. Yes you are on the right track on cutting a vent. I like having vents, but look closely at David's pictures he also uses a short sprue that leads nowhere and its sole purpose is to give the trapped air a place to go. I think you are doing great!
    Last edited by trout; 07-05-2015, 01:42 PM.

    Leave a comment:


  • Davidh
    replied
    So I have made a couple of silicon moulds as I wish to produce some planes and components for HMS Resolution that I have just built. This thread has been very interesting and useful.
    I have been a little fastidious with the tooling production. I like to make a box out of MDF and have the moulds created with a flat surface, using minimal clay around edges.
    As you can see from these pics it has been a learning curve. The initial mould is for the vertical rudders top and bottom of the Resolution. These are the largest silicon moulds I have made to date and the layer of silicon is possibly a bit thin? I have not poured resin into these yet. Since then I have made silicon mould parts, thicker. I don't know what the optimum thickness is yet. Maybe David or others can guide on this. But as mentioned earlier at $65 a litre these mould are a little pricey, but I can see the tremendous advantages in them.

    Most of my moulds so far have been of parts where the top edge of the part is exposed at the top of the mould. This allows a large area to pour the resin and allow air to escape. However the last series of photos show my first attempt at producing a sprue and air vent type mould design. I made the two parts of the mould using an aluminium tube as the sprue and simply cut a small air channel after the two parts were made.

    Being my first attempt at producing parts using this method went a little pear shaped however I can really see the potential. The last photo shows the messy result of the sprue and air vent set up. The mould tried really hard. There is an air pocket at the top of one of the pieces, I'm guessing I should cut another air channel at the top? I know that with practice the art will get better and pieces will start looking the business. It's just a time thing however any advice would be appreciated.

    Dave h

    Leave a comment:


  • Davidh
    replied
    Thankyou David,

    fantastic write up, when you get the chance I would love to see photos of the surface of the inner glass layup over the silicon. Do you get air bubbles forming underneath the glass resin if there's lots of dried silicon dribble of does a thick gel coat deal with that?

    I am very interested in the rubber glove/hard mother mould arrangement. Chasing down the precise silicon that would be ideal for not running down the side of a hull is a bit tricky here, not a lot of choice at the supplier. However I do have a big bottle of latex. I assume this would work just as well ,just lots of layers?

    thanks,

    dave h

    Leave a comment:


  • He Who Shall Not Be Named
    replied
    Originally posted by bwi 971 View Post
    I found the time to sit back and enjoy reading this topic......again many lessons learned and plenty stuff to put in practice.

    grtz,
    Bart
    Thanks, Bart. Just passing on what others taught me. You all have an obligation to do the same.

    Keep the ball rolling, guys. This Craft ain't dead .... yet!

    M

    Leave a comment:


  • bwi 971
    replied
    I found the time to sit back and enjoy reading this topic......again many lessons learned and plenty stuff to put in practice.

    grtz,
    Bart

    Leave a comment:


  • He Who Shall Not Be Named
    replied
    My pleasure, sir.

    M

    Leave a comment:


  • Davidh
    replied
    Hi David

    Thankyou for this incredibly detailed write up. I am currently in Canberra showing my kids the war memorial. It is a very extensive museum and took some good photos of the japanese midget submarine that attacked Sydney harbour. I also have some nice pics of a beautiful little model of AE1 Australia's first submarine. So I haven't had to time to read the write up but should in the next couple of days when i get back to the coast.

    David h

    Leave a comment:


  • He Who Shall Not Be Named
    replied
    MOTHER MOLD-GLOVE MOLD AND HULL LAY-UP

    Hard shell tools suffer from an inability to flex significantly. Therefore the hard shell tool looses utility when the job is to produce GRP parts possessing high relief surface detail (rivets, raised and engraved panel lines, high relief clinker strips and plate, weld beads, and other such surface depressions or projections) and/or significant draft. Unless provision is made to break down the hard shell tool into many sections, to reduce relative draft between tool and GRP part, the hard shell type tool is only suitable for producing hull and other parts that are as simple and smooth as a babies bottom. Attempting to capture high detail and deep draft forms with a hard shell tool usually results in tool damage after only a few lay-up cycles as the parts break away the high-draft, narrow tool projections.

    The cure to the problem presented by richly detailed hull and sail masters -- to capture them in the tool and have the tool survive production -- is to employ a rubber tool element to give form to the GRP part, and to contain the rubber tool within a strongback or GRP tool element to give rigidity to the assembly the rubber alone cannot provide. This hybrid is said to be made up of the mother-mold (the strongback) and glove-mold (rubber). The mother mold-glove mold tool not only captures the smallest detail of the master, but can even handle negative draft relief -- there is nearly no limit to the complexity of geometry a mother-glove mold can handle and to do so without damage to tool or deformation of GRP part.

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    After securing permission from the British guy (sorry, I can't find your name) who produced a small resin kit of the STINGRAY I went on to produce tooling from which I could render thin walled GRP parts for an r/c version of the model. I made this mother-glove tool for the models hull to accomplish the task. Pictured here is one-half of the two piece tool. The brown mother-mold is a GRP construct and holds the semi-clear glove-mold element. During part layup the assembled combination presents a rigid cavity that is prepared and used like a hard-shell GRP tool.

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    But, unlike the hard-shell GRP tool, the flexible glove of the assembly pops out of the mother-mold when the completed GRP hull piece is yanked out. It is then a simple task to 'peel' the glove-mold away from the model part as you see here.

    Since the mother-mold was laid up over the glove-mold the two register perfectly. So, after peeling the glove off the model part, it's an easy matter to re-insert the glove-mold back into the mother-mold with perfect registration between the two, and everything ready for another GRP hull fabrication cycle.

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    Caswell-Merriman produces a 1/96 Type-212 GRP hull kit. The masters of which were roughed out by Steve Neill, super-detailed by Brian Starks, and that master used by me to make production tooling. Here are pictures of a completed kit.

    The exceptionally well done engraving Brian did on the master literally screamed out for use of the hybrid mother-glove type tooling. The keel, bilge-keels (actually sonar array projections), and very deep engraved lines would never work in a simple, two-piece hard-shell tool. In rubber? No sweat.

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    If your hull master is not split; if it's the entire unit, you need to 'hide' half of the hull within a mold-board constructed for the task, like what I've done here with the Type-212 master. Rose is holding one of the securing screws that runs up through holes in the mold board base and up into the hull to hold the model down on the mold board assembly.

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    The rubber glove-mold tool that will be poured over the half-model (capturing in negative the shape of the model) and mold board (that produces the flange running equatorially around the cavity) must not leak through any gaps between the two. You want as tight an interface between the two as possible; a no-leak transition between mold board and master. This is done by filling any gaps between mold board and master with modeling clay.

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    In this condition the master and mold board can either be used to give form to a hard-shell GRP tool, or a rubber tool. Which type tool you fabricate depends on the detailing and draft of the master. The Type-212 master demanded creation of the mother-glove type tool.

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    Building up the RTV silicon rubber tool that forms the glove-mold over the master is done with a special 'brushable' material. BJB's TC-5040 is what I use. You first pour it on and work it with a spatula (or old credit-card) to cover the entire model. What's magic about this form of silicon rubber is that it tends to stick to vertical surfaces without running down. It takes 3-5 layers of rubber to get the required nominal wall thickness.

    (sorry, didn't have a shot of this process as I worked up the 1/96 Type-212 tooling)

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    The glove-mold built up, its flange (those portions where the rubber adhered to the face of the mold-board) is cut back to be just a bit wider than the wall thickness of the rubber covering the master.

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    The rubber and mold board are waxed and the hard-shell tooling material is build up over both. This can be GRP or a specialty hard-shell material like the Freeman Repro two-part polyurethane resin. Note that I left plenty of 'runs' in the glove-mold rubber -- these key with the mother-mold, insuring that re-assembly of the two will occur with perfect registration.

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    Since I'm going to make hundreds of GRP parts off this tooling, I want it to sit in the shed season-after-season and not warp on me. So, I egg-crate the mother-mold to keep things in shape. Note that I use the same mother-mold forming material (which is glass shard re-enforced) to hold the wooden elements of the egg-crate brace together.

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    Once the egg-crate brace is permanently bonded to the back-side of the mother-mold the entire unit is inverted and the three screws securing the master to the mold board are removed and the mold board carefully pulled away from the hull master, glove-mold, and mother-mold with bonded egg-crate -- what you see in this photo. It's then an easy matter to pull the master and rubber glove-mold away from the mother-mold, and to strip off the glove-mold and put that master, and it's purpose build mold board, into safe storage. The glove is made up to the mother mold, part-release applied and GRP part production begins.

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    And GRP hull production begins -- the hull part glass lay-up process the same as that done for hard-shell GRP tools.

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    The virtue of the mother-glove tool becomes apparent when it comes time to separate the GRP part from the tooling: All the undercuts and deep draft items (those flank bilge keel looking things, for example) would have locked the GRP part forever within a hard-shell type tool. However, with the hybrid, you pop out the part still attached to the rubber glove-mold. Then, without the stiff backing of the mother-mold supporting and giving rigidity to the rubber glove-mold, it's an easy task to strip off, like a glove, the rubber mold from the GRP part.
    The rubber element is put back into the stiff element and another GRP hull production cycle can begin.

    M

    Leave a comment:


  • He Who Shall Not Be Named
    replied
    OK, Dave, it took a few days of part-time work, but here's the second part of the information you asked for, this one dealing with GRP hull fabrication tooling. Enjoy.

    TOOLS FOR GRP LAY-UP (HULL MAKING)

    Fiberglass hulls are laid-up within large multi-part tools (called molds in some circles). Typically a set of tools comprises an upper-lower or left-right set for the hull and a left-right set for the sail. Regardless of tool type, the end game is the same: production of thin walled, strong fiberglass structures.

    Glass reinforced plastic (GRP) hulls and sails are preferred over other substrates for three main reasons:

    1. GRP's very thin wall thickness -- the less water the above waterline structures displace, the less ballast tank you need to get the model up to the designed waterline (only a consideration for wet-hull type r/c submarines)

    2. strength

    3. the ability of the initial gel-coat laminate to capture the most complicated of detail within the tools cavity without the need to resort to exotic pressure differential equipment (pressure/vacuum vessel)

    The hull-sail tooling can be GRP hard-shell, cement, a hybrid of rubber and GRP (mother-glove mold), clay, cuttlefish bone, heavily filled resin, or any number of other materials that can capture, in negative, the form of a master (pattern, or model if you will).

    However, this discussion will be limited to the cement, GRP hard-shell, and hybrid mother-glove mold type tools.

    GRP HARD-SHELL TOOL AND SPACE STATION TORUS GRP PART LAY-UP

    The traditional (most often used) type is the GRP hard-shell tool. It's both cheap and easy to make.

    (Surprisingly, I can't find any pictures in my massive collection of pictures of a hard-shell GRP tool applicable to submarines. But, as a stand-in I present these shots showing the fabrication of the master, tool, and model parts of a 'wheel' type space station model, based on an effects miniature used in the old George Pal movie, The Conquest of Space).

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    The first picture is of the finished space-station model fabricated principally from GRP -- those parts fabricated in a hard-shell GRP tool of unique form. The second shot is a frame enlargement from the actual film, The Conquest of Space. A magnificent movie that does not get the credit it deserves.

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    Though a bit outside the preview of this discussion, I thought you would like to see how I gave form to the master of the torus. If you will, the 'hull' of the space station. The process is called screeding -- giving form to a pliable mass, in this case warm modeling clay initially, followed by an over-coat of uncured automotive two-part filler.

    A circular screeding blade swings around a fixed pivot over the mold board. The blade gives form (half a torus) to the clay as it's pushed in a circle about the mold board -- this is described as circular screeding.

    Note the larger semi-circular blade at the top. This one is used to give form to automotive filler, which goes over the clay. The clay is there to reduce the amount of filler needed to make the torus half-master. The filler formed spoke elements were linearly screeded on another board and transferred to the torus to make up the space-station half-master. The central hemisphere was turned from solid Renshape.

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    The space-station master and mold board was first given several coats of wax, buffing between coats. Finally, the entire master and mold board was spray coated with polyvinyl alcohol (PVA), a water soluble film that serves as a barrier between the soon to be applied epoxy laminating resin and the waxed surface of the master and mold board. This type barrier is referred to as a mold-release.

    This mold-release step, and the products used, are the same as used between the submarine master and its mold board and the hard-shell tool (mold) that will be laid up over them. And, conveniently, the same wax and PVA are used as part-release agents forming a barrier between tool and GRP model parts.

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    In this shot you see the GRP space station hard-shell tool under a space-station GRP part. The broken popsicle sticks and hammer were used to pry the GRP part off the GRP tool. An ugly affair but no damage resulted during the 'liberation' effort. Once a second GRP part is made, they are trimmed to the flange face of the tool and bonded together forming the complete torus and spoke assembly that represents the space stations hull.

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    With the exception of the dumb-bell central parts and white-metal mirror support pieces, the entire model was constructed of very thin walled GRP.

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    How thick (wall thickness) should the r/c submarine GRP hull be? We want it thick enough to have the strength to survive normal handling, and moderate collision forces. But we don't want it so thick that the structure above the models waterline displaces an unreasonable amount of water. Balancing these two requirement, strength and displacement takes some though and experiment.

    My considerable experience in the field has taught me to keep the nominal wall thickness of a GRP hull at about 1/16" - 1/8" thick. 1/16"thick for small models up to 50" in length. And 3/32" - 1/8" thick for the longer model hulls.

    The thickness of the gel-coat and number and weights of fiberglass cloth/mat laminates is driven by the geometric complexity of the tool cavity. The more complicated the geometry, the thicker the gel-coat(s), the more laminates of light-weight weaved glass. A simple hull like the DELPHIN only required one gel-coat, and two laminates of 15-ounce glass mat.

    Above is a test I did for a simple of geometry 70" long submarine hull. The nominal wall thickness was to be 1/8", built up from the minimum number of laminates I could without having the saturated glass bunch up and produce the dreaded air voids. Several test samples were laid up from scrap material into the most complicated section of the tool -- the objective to work in the gel-coat and glass laminates, finding the heaviest glass weave and mat that would wet out completely without producing air voids. On this particular model I found that a gel-coat, followed by one laminate of 4-ounce cloth, a laminate of 10-ounce cloth, and a laminate of 15-ounce mat produced a GRP structure able to produce void free parts and achieve the 1/8" wall thickness goal. This established, the required number, weight, and type fiber glass sheets were cut out, and work laying up the GRP hull halves began.

    CEMENT TOOL AND HULL LAY-UP

    Darrin Hataway -- an excellent professional model builder, and responsible for several of the excellent OTW hull kits -- gave me an old cement tool he made for a large scale model of the WW-2 era German DELPHIN one-man submarine. This tool was made from a fine grained type cement, sometimes sold as 'hydro-stone' or dental cement. This type mold making material is good for producing tools whose surface is not festooned with high relief engraved lines or plating, as the cement is relatively weak in shear and such details would break off with usage. However, as a quick-and-dirty, cheaply made tool for un-detailed GRP hull fabrication, it's perfect. Owing to the rigid nature of the material there can be no negative draft to the cavities, and zero draft is to be avoided or you'll never be able to de-mold the laid up GRP part after lay-up.

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    I laid up the upper and lower GRP hull pieces in the tools. The two hull parts were then cut (lower hull bow and upper hull stern) and re-assembled and glassed back together to achieve the Z-cut so favored by those assembling GRP type r/c submarines of the wet-hull type.

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    Darrin's tools arrived already saturated with part-release wax. It was a simple matter to lay down a fresh coat of wax, buff it out, and spray in three coats of PVA barrier film -- this readied the tools for gel-coat and GRP lay-up.

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    Gel-coat is simply a thickened laminating resin, laid down without glass re-enforcement. It's the first layer of material to go into the tools cavities that forms the eventual model part. Therefore the gel-coat becomes the surface of the GRP model part. You want this layer (the gel-coat) to be strong, and able to wet out every portion of the tools cavities -- the primary job of the gel-coat is to capture all the details present in the tools cavity and to produce a softened, curved (fillet) transition between sharply angles projections within the cavity, over which the laminations of fiberglass cloth and mat will go. Sometimes multiple coats of gel-coat are applied to areas of sharp relief to further fillet the area so subsequent laminations of glass won't be stressed to the point of de-laminating and producing voids.

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    A simple hull form, like the DELPHIN, results in hull tools that permits laying in relatively heavy material over the minimal thickness of gel-coat. Glass mat or weaved cloth is measured by weight of the square-yard. In this case I went right in there with 10-ounce weaved cloth, three layers (laminates).

    For economies sake -- particularly if you have many laminates to build up and/or you are going to make multiple copies of GRP parts -- it's a good practice to trim one piece of the glass cloth to make a tight conformal fit within the tool, mark off where the cloth meets the tools flange face, remove it, set it over a big piece of poster-board, and trace its outline with one-inch more boarder for safeties sake. You can see the DELPHIN's orange poster board glass marking template in foreground -- used to cut to mark out all subsequent glass cloth pieces for cutting. This saves material and time doing it this way.

    GRP HARD-SHELL TOOL AND HULL AND SAIL LAY-UP

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    My boss, Mr. Caswell, purchased tooling for a 1/72 M-1 submarine kit and asked me to evaluate it by laying up a hull for him and me. This tooling is of the classic GRP hard-shell type. However, a bit unusual in that there is no egg-crate support structure backing to prevent these long items from warping over time. But, I found to my surprise that the GRP model parts I pulled from these tools fit near perfectly. So, no egg-crating, no problem.

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ID:	98996 Click image for larger version

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    Once the initial fit of glass cloth bits to fit the tool is made and that cloth laid out over some pink poster board (pink???) and the templates made, the templates are used to cut out all the pieces of cloth and mat needed to achieve a full laminate.

    The perfect cutting tool for glass fiber sheet is a pizza-knife over a plywood cutting board. You lay the cloth over the cutting board, use the template to mark out the outline of the cloth/mat, and then cut the laminate out with the circular-knife/pizza-knife. The knife is very easy to steer and won't pull and snag the tough glass material as an X-Acto blade or scissors would.

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    Here's the M-1 tooling. Whoever did this work is damn good at it: thick, wide flanges; good tool design (optional superstructure stand-alone tool or superstructure incorporated in the hull tools); and the sail tools were indexed to clamp together permitting me to bond the two halves together in-tool. A joy to work with!

    Here you see all tooling after receiving their third spray coating of PVA. I use the heat gun between layers of PVA to speed up the work.

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    These tools came to us already built up with wax, so all I had to do was lay down and buff up my own wax layer, spray on three coats of PVA and get to the gel-coat. Now, there are various fillers you can add to laminating resin (by the way, I like the West System laminating epoxy laminating resins -- I use the 'fast' one) to thicken it up so it will build fillet between harsh angled items in the tool cavity. On the M-1 there are near zero draft angles between the hull and superstructure, and the hull and deep keel -- these areas required more than one coat of gel-coat to soften their edges. If you fail to do this, even the lightest fiberglass cloth will bunch up and leave awful air voids.

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    The most difficult glass work is the sail. Lots of gel-coat, and many layers of 4-ounce cloth, cut into small bits so the class could negotiate the tight fillets without bunching.

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    Once the GRP sail part had cured hard, it was popped out of its tool and the excess GRP that extended past the flange line (obvious on the parts, so no need to mark it while still in the tool) ground off. The flange and cavities of the two tool haves were then waxed up in preparation of the next step.

    The GRP sail halves were re-inserted into their tools, and the two indexed tools assembled, putting the edges of the GRP parts up tight against one another and in perfect registration. It was then a simple matter of wetting the seam area from the inside of the part and sticking a strip of glass in there to back up the seam, turning the assembly into a one-piece sail. Pretty slick took design!

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    The open sail tool with the three securing bolts used to hold the assembled tool halves together as the GRP sail halves are bonded into one unit.

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    Between laminates of gel-coat, glass cloth and/or mat I sand the surface of the hardened laminate while it's in the tool to knock down bumps and give plenty of tooth for the next layer of resin saturated glass to grab onto. There is no cohesion at work between a cured hard surface bonded with epoxy or polyester resin to the next laminate, so the agent of 'stick' is strictly mechanical and adhesive in nature.

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    A completed M-1 GRP hull half part next to the tool that gave it form.
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  • Albion
    replied
    Nice game. Glad you tube wasn't around then.

    Question Mike, I assume airlines wouldn't like me putting casting resin or RTv type products in my luggage?

    Leave a comment:


  • Albion
    replied
    Nice game. Glad you tube wasn't around then.

    Question Mike, I assume airlines wouldn't like me putting casting resin or RTv type products in my luggage?

    Leave a comment:

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