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Thread: Anyone here made carbon fiber gudgeons?

  1. #1
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    Default Anyone here made carbon fiber gudgeons?

    My original bronze ones failed. I am contemplating making my own using this technique. I will detail my own build over the week if the a quote to remake bronze ones i find to be quite too high. This technique once done will be sleeved in teflon. could be a great application and use carbon fiber rods to hold into place. Total cost for the build should be under $50.

    7EF9A1FB-D06E-440B-A809-76BDF7F1C317.jpg

    D689BCE0-A2E1-4DE5-BE11-EF9D63CF5C02.jpg


    Last edited by Ted Hoppe; 07-01-2019 at 10:01 AM.

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    Default Re: Anyone here made carbon fiber gudgeons?

    I have made many such objects.

    Peace,
    Robert

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    Default Re: Anyone here made carbon fiber gudgeons?

    I like your idea. However I wonder if the entire assembly will be tough enough.

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    Default Re: Anyone here made carbon fiber gudgeons?

    Quote Originally Posted by amish rob View Post
    I have made many such objects.

    Peace,
    Robert
    I was wondering since the difference between s-glass and carbon fiber for load bearing is about 15 percent, I was thinking of building a combo. The s-glass factor would be slightly more flexible if an impact occurred to rudder. The skeg aspect allows the protections. I am planning on using a g10 fiber tube for center sandwiching the Teflon and the bronze rudder post.

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    Default Re: Anyone here made carbon fiber gudgeons?

    Quote Originally Posted by Ted Hoppe View Post
    I was wondering since the difference between s-glass and carbon fiber for load bearing is about 15 percent, I was thinking of building a combo. The s-glass factor would be slightly more flexible if an impact occurred to rudder. The skeg aspect allows the protections. I am planning on using a g10 fiber tube for center sandwiching the Teflon and the bronze rudder post.
    Iíve made some one off pieces from cloth/resin matrices in a couple different ways. The ideal way to make somesuch like that would be in a mold, to get optimal compaction/saturation, I think. Simple enough to make, really.

    Different fibers have different qualities, to be sure. A matrix of cloths and oriented strands is probably the best bet, but i sure donít have all the answers for THAT particular piece.

    Peace,
    Robert

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    Default Re: Anyone here made carbon fiber gudgeons?

    Teflon is relatively soft and will crush and distort if the rudder comes under lateral forces exceeding the capacity of the material.

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    Default Re: Anyone here made carbon fiber gudgeons?

    Quote Originally Posted by navydog View Post
    I like your idea. However I wonder if the entire assembly will be tough enough.
    i think I could try this way -

    the entire piece after fabricated would be cut in half, fitted, epoxied in place with carbon rods holding the rudder in place. Carbon epoxy tape held with painters tape would bind the “O”. Temporary screws hold the gudgeons in place. Remove the screws and replace with carbon fiber rods.

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    Default Re: Anyone here made carbon fiber gudgeons?

    The Custom Fabrication picture shows a number of features that are critical to making the carbon fiber bearings work. If you copy all of those features, your gudgeons should work. Make sure that the carbon fiber is coated with a non-conductive layer anywhere that it can touch metal, fastener holes included.

    There is an inner bearing liner. It is supported on both sides by continuous layers of fabric.
    There are no sharp bends in the fabric.
    There is some filleting between the inner bearing and the fabric reinforcement layers that eliminates any sharp bends.
    There is a fillet on the inside between the rudder and the bearing that eliminates any hard spots bearing on the carbon fiber.
    Carbon fiber is electrically conductive and at the far end of the galvanic series so the bearing liner is almost certainly non-conductive to prevent galvanic corrosion of the pin.

    EDIT:
    Different fibers have different qualities, to be sure. A matrix of cloths and oriented strands is probably the best bet, but i sure don’t have all the answers for THAT particular piece.

    Peace,
    Robert
    Carbon is stiffer than any other fiber. The less stiff fibers should go on the outer surfaces where they will see more strain, insulate electrically, and they are generally tougher.

    The fiberglass liner in its expensive, off the shelf form: https://www.astbearings.com/filament...bricating.html
    Last edited by MN Dave; 07-01-2019 at 10:46 AM.
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    Default Re: Anyone here made carbon fiber gudgeons?

    Quote Originally Posted by navydog View Post
    Teflon is relatively soft and will crush and distort if the rudder comes under lateral forces exceeding the capacity of the material.
    it would be a very thin sleeve. Marine grease would work as well.

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    Default Re: Anyone here made carbon fiber gudgeons?

    Quote Originally Posted by Ted Hoppe View Post
    i think I could try this way -

    the entire piece after fabricated would be cut in half, fitted, epoxied in place with carbon rods holding the rudder in place. Carbon epoxy tape held with painters tape would bind the “O”. Temporary screws hold the gudgeons in place. Remove the screws and replace with carbon fiber rods.
    I would use metal rods because the shear strength is higher. Shear is normally 60% of uts for most metals, Carbon rods have much lower shear. In the example below it is 2.5% of uts.
    Pultruded products perform incredibly well in bending and tension (pulling) applications since all the fibers are oriented along the length of the tube (or rod). They do not however perform well in other loading scenarios such as torque and crushing. These parts are made by pulled fibers through a shaped die while simultaneously injected with resin to create the required profile. *Note - We do not recommend pultruded tubing or rod in applications such as drone or UAV motor (boom) arms.
    https://www.rockwestcomposites.com/r...uded-solid-rod
    https://www.rockwestcomposites.com/r...-rod/47314-l96
    Minimum Properties Solid Strip (Rectangle):


    • Tensile Strength: 250 ksi / 1.72 GPa
    • Ultimate Shear Strength: 6.0 ksi / 41.3 Mpa
    • Flexural Strength: 265 ksi / 1.83GPa
    • Coefficient of Thermal Expansion: -0.1 ppm/cm≥ / -0.2ppm/ ļC
    • Density: 0.54lbs/in≥ / 1.5g/cm≥
    • Fiber Volume: 62%
    • Matrix Material: Bisphenol Epoxy Vinyl Ester


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    Default Re: Anyone here made carbon fiber gudgeons?

    Quote Originally Posted by MN Dave View Post
    The Custom Fabrication picture shows a number of features that are critical to making the carbon fiber bearings work. If you copy all of those features, your gudgeons should work. Make sure that the carbon fiber is coated with a non-conductive layer anywhere that it can touch metal, fastener holes included.

    There is an inner bearing liner. It is supported on both sides by continuous layers of fabric.
    There are no sharp bends in the fabric.
    There is some filleting between the inner bearing and the fabric reinforcement layers that eliminates any sharp bends.
    There is a fillet on the inside between the rudder and the bearing that eliminates any hard spots bearing on the carbon fiber.
    Carbon fiber is electrically conductive and at the far end of the galvanic series so the bearing liner is almost certainly non-conductive to prevent galvanic corrosion of the pin.

    EDIT: Carbon is stiffer than any other fiber. The less stiff fibers should go on the outer surfaces where they will see more strain, insulate electrically, and they are generally tougher.

    The fiberglass liner in its expensive, off the shelf form: https://www.astbearings.com/filament...bricating.html

    I meant the exact engineering of the piece in question. As I said, I have a lot of experience doing this.

    Peace,
    Robert

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    Default Re: Anyone here made carbon fiber gudgeons?

    Quote Originally Posted by amish rob View Post
    I meant the exact engineering of the piece in question. As I said, I have a lot of experience doing this.

    Peace,
    Robert
    I never doubted that. We are not only talking to experienced people such as yourself. There are a lot of people who will read these posts who don't have your knowledge and experience. Without considerable experience, none of this is obvious. They need the important details spelled out. You also have to look at the time of the post. I started my first answer just after your first, and there were 5 more posts before I hit save.
    I don’t know squat and I know it
    Peace,
    Robert
    With all due respect, that is a crock.
    Last edited by MN Dave; 07-01-2019 at 11:35 AM.
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    Default Re: Anyone here made carbon fiber gudgeons?

    Quote Originally Posted by MN Dave View Post
    I never doubted that. We are not only talking to experienced people such as yourself. There are a lot of people who will read these posts who don't have your knowledge and experience. Without considerable experience, none of this is obvious. They need the important details spelled out. You also have to look at the time of the post. I started my first answer just after your first, and there were 5 more posts before I hit save.
    Oh, I hope you didnít take that as argumentative. Just trying to clarify what I meant.

    And, I try to NEVER dispense advice. If I may accidentally do so, I always qualify it. I will surely talk with Ted, who I know, about these candidly, but I wouldnít feel as free with a stranger. Not my place, I donít feel.

    I donít know squat and I know it, so I try to not broadcast.

    Peace,
    Robert

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    Default Re: Anyone here made carbon fiber gudgeons?

    It looks entirely feasible Ted.If it was my project I wouldn't include the foam that is in your first post.I would try to get hold of what is known here as 10G40 Tufnol and you would call it G10.It won't crush and is very stable.It is also the worst thing I have ever found for blunting tools.Do you have any underwater hardware that might cause electrolytic activity with carbon?

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    Default Re: Anyone here made carbon fiber gudgeons?

    Quote Originally Posted by John Meachen View Post
    It looks entirely feasible Ted.If it was my project I wouldn't include the foam that is in your first post.I would try to get hold of what is known here as 10G40 Tufnol and you would call it G10.It won't crush and is very stable.It is also the worst thing I have ever found for blunting tools.Do you have any underwater hardware that might cause electrolytic activity with carbon?
    There is none from me but the dock does get "hot" with dropping power cords. I will layer a sheet of s-glass and epoxy over the carbon to slow electrolytic action.


    for everyones info:
    The quote for a custom bronze gudgeon that holds a 1 1/4" rudder post was $1100 and three weeks time minimum. my lay days start on Friday at 60 per day.

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    No technical advice from me Ted, but plenty of sympathy. That's a crap position to find yourself in. I hope it works out.

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    Default Re: Anyone here made carbon fiber gudgeons?

    Iíve done similar gooseneck bracket for carbon mast. Used G10 tube (McMaster) and microspheres bog for filler. Seems to be doing the job.

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    Default Re: Anyone here made carbon fiber gudgeons?

    Composite gudgeons can be a challenge because the material is not the same strength in all directions like metal is. Many parts (such as carbon chainplates) can be easily made because the fibers can be aligned with the loads. The simplest way for me to describe the way a laminate such as a gudgeon would fail is with the phone book analogy. If you bend a phone book 90 degrees and pinch it tightly, it will resist bending further because the pages all tighten against each other, but if you bend the opposite way the pages separate from each other and it bends easily. It's the same with fibers and resin. A right-angle laminate will be very strong when bending the angle closed but break easily if opening the angle because the laminates separate from each other at the bend.
    The gudgeon section posted is beautifully built, but I think it's likely that it will be combined with a horizontal flange (as seen on cassette rudders) to take the shear loads. Making a part like that takes an incredible number of layers and many separate baggings (because bagging lots of layers at once causes wrinkling fibers).
    Making laminated hardware is really fun and satisfying. It's good to make stuff that your life doesn't depend on. That rudder gudgeon looks to me like a good thing to make from metal.
    Usually when I post here I seem to kill the thread and I hope it doesn't happen this time. Composite hardware and wood boats go together well I think.

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    Default Re: Anyone here made carbon fiber gudgeons?

    Quote Originally Posted by Russell Brown View Post
    Usually when I post here I seem to kill the thread and I hope it doesn't happen this time. Composite hardware and wood boats go together well I think.

    Russell, no matter how many times you think this happens... please keep posting. I enjoy everything you write.

    Jeff

    PS. If the thread dies now, you didn't kill it. I did.

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    Default Re: Anyone here made carbon fiber gudgeons?

    Quote Originally Posted by Russell Brown View Post
    Composite gudgeons can be a challenge because the material is not the same strength in all directions like metal is. Many parts (such as carbon chainplates) can be easily made because the fibers can be aligned with the loads. The simplest way for me to describe the way a laminate such as a gudgeon would fail is with the phone book analogy. If you bend a phone book 90 degrees and pinch it tightly, it will resist bending further because the pages all tighten against each other, but if you bend the opposite way the pages separate from each other and it bends easily. It's the same with fibers and resin. A right-angle laminate will be very strong when bending the angle closed but break easily if opening the angle because the laminates separate from each other at the bend.
    The gudgeon section posted is beautifully built, but I think it's likely that it will be combined with a horizontal flange (as seen on cassette rudders) to take the shear loads. Making a part like that takes an incredible number of layers and many separate baggings (because bagging lots of layers at once causes wrinkling fibers).
    Making laminated hardware is really fun and satisfying. It's good to make stuff that your life doesn't depend on. That rudder gudgeon looks to me like a good thing to make from metal.
    Usually when I post here I seem to kill the thread and I hope it doesn't happen this time. Composite hardware and wood boats go together well I think.
    As one thread murder to another, I have to agree that perfect alignment of the fibers makes for a stronger part. I would also point out that the properties that I listed below, 250 ksi tensile for a pultruded bar, which is inherently well aligned and of a high fiber to matrix volume ratio is about 8 times as strong as bronze, so a good bit of slop in the layup is tolerable. It looks like Ted laid up some trial pieces that do have the G-10/FR4 or filament wound fiberglass liners. When I fussed about shear strength, I was thinking of carbon fiber pintles, but now I think he meant to use the rods for something else. Whatever, the stuff is great for tension and mediocre for torque and shear. I think that the loads will be mostly tensile, so it's all good here. As for making it from metal, well yeah, it would be more durable, but not as much fun to make and discuss. A casting http://www.porttownsendfoundry.com/rudder-fittings or brazed assembly are options subject to budgetary constraints and personal preference. (Ted seems to like the carbon fiber idea and apparently has the materials on hand.)

    As for galvanic corrosion, as long as it isn't electrically connected to any other metal, there is no problem. I was only warning against direct contact with pintles and fasteners. The glass liner isolates the pintle and the screw holes will need some sealant. I would consider drilling slightlyoversize and lining the holes with a hard epoxy like Loctite Marine epoxy, which is far better than its hardware store bubble pack might lead you to believe.

    The 'foam' in the https://www.blacklinemarine.com/home...m-fabrication/ gudgeon looks like an epoxy syntactic foam, possibly even a hard urethane. I will distribute the loads. I would not skip that part.
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    Default Re: Anyone here made carbon fiber gudgeons?

    Quote Originally Posted by Ted Hoppe View Post
    I was wondering since the difference between s-glass and carbon fiber for load bearing is about 15 percent, I was thinking of building a combo. The s-glass factor would be slightly more flexible if an impact occurred to rudder.
    No, the stiffer fibre, carbon in this case will attract more load leaving the s-glass relatively unloaded. So there will be little benefit especially under high impact loading..
    Back in the early days of carbon fibre a (slightly sloppy) engineer thought that he could save some expensive carbon fibre by using the aluminium pipe mandrel as a strength member. However aluminium is far more elastic than carbon, and so took up hardly any of the load and the carbon failed resulting in the loss of the rudder.
    It really is quite difficult to build an ugly wooden boat.

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    Default Re: Anyone here made carbon fiber gudgeons?

    Quote Originally Posted by Peerie Maa View Post
    No, the stiffer fibre, carbon in this case will attract more load leaving the s-glass relatively unloaded. So there will be little benefit especially under high impact loading..
    Back in the early days of carbon fibre a (slightly sloppy) engineer thought that he could save some expensive carbon fibre by using the aluminium pipe mandrel as a strength member. However aluminium is far more elastic than carbon, and so took up hardly any of the load and the carbon failed resulting in the loss of the rudder.
    Happened with bicycles, too. DAMHIKT.

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    Default Re: Anyone here made carbon fiber gudgeons?

    Here is my game plan after consulting with a well respected maritime fabricator whom thought this would be stronger & safer than the bronze original (or even what he could make with stainless or bronze) or the original carbon plan.

    He suggested using a mold of the original side. I will fill the molds with marine epoxy with fine chop fiber strand and 4 thin carbon fiber rods. The tinsel strength at will be 7500 psi and shear strength will be over 5000. 9A wack more than that to a skeg racing rudder would be devastating either way.) I plan on adding 2 sheets sheets of s-glass over 2 sheets of bi directional carbon fiber will encapsulate the outside giving even more shear strength with a slightly more flexible skin. The G10 tube sleeve fit over over the bronze rudder post and glued in place on the Gudgeon.

    i made the silicone molds last night. I’ll cast the epoxy, chop strand and carbon fiber rods today and let cure 24 hours. I’ll hand polish the pieces and lay the 4 layers of pre preg cloth. The new gudgeons can slightly more beefy than the original bronze but still run nearly flush against skeg.

    28BB5226-829F-4E63-9DF5-3BBF72FCE4E8.jpg

    4DFF8FBA-54F8-4029-B643-538CFFC871A0.jpg

    B6A37CE6-5D0C-4228-9734-D4DE093038AA.jpg

    Carbon fiber breaking under overload while fiberglass remains remains in tact isn’t all that bad as it serves the purpose to be able to bring you home when a fully carbon piece would not.
    Last edited by Ted Hoppe; 07-02-2019 at 02:11 PM.

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    Default Re: Anyone here made carbon fiber gudgeons?

    The composite parts seem to require more space, so it is kind of difficult to change without changing the geometry.
    You end up with a lighter stiffer assembly, but it is less compact than its metal equivalent.
    I was taught to wrap fiber around the finished laminate to prevent what Russell said above.
    I have often found that the clearance around the pintle isn't enough to make me feel confident that I have enough fiber there.
    In these cases I have cheated and put a stainless U bolt in the the perimeter of the stack.
    I figure that the carbon will get wonky and loose as things go wrong. The stainless will give me some time to do something before the rudder falls all the way off.
    Carbon parts are binary, they are either there or they are not. Having something that elongates, hates it but sticks around is the idea.
    I haven't ever really put this to the test because I haven't broken one of those parts.
    SHC

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    Sounds like you've got this Ted. I'd probably have had something welded up in stainless just because I'm completely unfamiliar with carbon.

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    Default Re: Anyone here made carbon fiber gudgeons?

    Quote Originally Posted by Ted Hoppe View Post

    Carbon fiber breaking under overload while fiberglass remains remains in tact isn’t all that bad as it serves the purpose to be able to bring you home when a fully carbon piece would not.
    No, you miss the point. If the carbon breaks, the glass will also break as it is of lower ultimate strength. It just breaks nanoseconds after the carbon has given up. If the glass is strong enough to not fail, you do not need the carbon.

    I suggest that the carbon fibre should wrap right around the gudgeon from end to end.
    Make it like this:Scan_20190702.jpgLike the example in the OP. Do not try to reinvent the wheel, or in Americlese, "If it ain't broke, don't fix it"
    Last edited by Peerie Maa; 07-02-2019 at 04:31 PM.
    It really is quite difficult to build an ugly wooden boat.

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    Default Re: Anyone here made carbon fiber gudgeons?

    Pre-preg carbon?Its a bit too critical to dabble with pre-preg unless you have a bit of previous experience.The whole topic of composite engineering is vast and not quite as easily understood as pouring molten metal into a mould.Having typed that,I prefer almost anything to castings,other than for ballast.Keep in mind that there are many varieties of carbon itself and lots of different weaves,choose wisely or consult a composite engineer unless you have the freedom to overbuild.

    Cross posted with Nick.Fibre continuity is a very important concept and his sketch is a good one.
    Last edited by John Meachen; 07-02-2019 at 04:28 PM. Reason: almost simultaneous post

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    Default Re: Anyone here made carbon fiber gudgeons?

    Quote Originally Posted by Peerie Maa View Post
    If the glass is strong enough to not fail, you do not need the carbon.
    I was thinking along these lines, and found myself wondering if the carbon is really necessary. Its outstanding virtues of lightness and stiffness seemed somewhat redundant in this context.
    Money may not buy happiness, but it can buy a boat that will pull right up next to it!

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    Default Re: Anyone here made carbon fiber gudgeons?

    Quote Originally Posted by John Meachen View Post
    Pre-preg carbon?Its a bit too critical to dabble with pre-preg unless you have a bit of previous experience.The whole topic of composite engineering is vast and not quite as easily understood as pouring molten metal into a mould.Having typed that,I prefer almost anything to castings,other than for ballast.Keep in mind that there are many varieties of carbon itself and lots of different weaves,choose wisely or consult a composite engineer unless you have the freedom to overbuild.

    Cross posted with Nick.Fibre continuity is a very important concept and his sketch is a good one.
    I truly understand your valid concerns. I worry myself on my engineering and hair-braining.

    I am not the novice as I seem. I have been making carbon fiber parts for motorcycles and camera systems for several years, I built a 15’ double sleeved carbon fiber boom for the boat which i was told multiple times by professional fabricators as excellent. (Where I sail - everything needs to be oversized and the boom might be the strongest piece on the boat). I have a small portable DYI epoxy vacuum system which facilitates small projects like this one. I did make some good boom rings which now lets the sail be loose footed. I also am making a carbon sprit for the 1D35 which actually may become mine if my buddy buys on from the class maker instead of using mine.

    I am a great observer of things. I have been lucky enough to have seen how they made stuff for the AC boat building and spent a bunch of time with the fabricators when they were here in San Francisco (Alameda).

    Not all prepreg has to be retail bought. I do a ziplock with an west epoxy impregnating into the fiber. I press out the epoxy via a steel roller on a flat hard epoxied board work table. The working time for the cloth when in the ziplock bag is slowed down as it sits in a cold cooler until I am ready to use. It keeps me from rushing and lets me take my time in the layup. It works as well as the expensive pre-made but with costs closer to s-glass thanks to my discount at tap plastics. It has been my practice to split the bag and lay it up the uniformed impregnated strips with the s-glass sheets layered on top. Once done I will bag it and vacuum. You and I are on the same page as you suggest will at the end when I mount the gudgeons place a mult layer layup chopped epoxy and s-glass and chopped the split once on the rudder post bronze bushings and g10 fiber sleeve.

    I am also making the other style carbon fiber gudgeons too as practice. I’ll need a backup if I fail with one.

    Time for me is also of the essence. I am still working 50 hours a week and have to squeeze it in when I can. Thank goodness this is the 4th of July week which cuts me some paid work slack. This Gudgeon replacement is the last big project for me on this boat. If I have to haul out in a month to replace them with bronze, it will still be cheaper than paying $1500 or more in lay days waiting for the fabbed parts.
    Last edited by Ted Hoppe; 07-02-2019 at 06:59 PM.

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    Default Re: Anyone here made carbon fiber gudgeons?

    Quote Originally Posted by Peerie Maa View Post
    No, the stiffer fibre, carbon in this case will attract more load leaving the s-glass relatively unloaded. So there will be little benefit especially under high impact loading..
    Back in the early days of carbon fibre a (slightly sloppy) engineer thought that he could save some expensive carbon fibre by using the aluminium pipe mandrel as a strength member. However aluminium is far more elastic than carbon, and so took up hardly any of the load and the carbon failed resulting in the loss of the rudder.
    You are mixing pure tension with bending. In tension, the carbon fiber has a 1-2% strain to failure, and S2 glass has a 5.6% strain to failure. So yes, the carbon with its higher modulus will take the bulk of the load and dump it on the glass when it lets go. In tension, the glass is used as an insulator to prevent galvanic issues and structurally is just along for the ride.

    When you bend a beam made of a uniform material, the outer fibers are loaded more than the inner fibers. That is because they are subjected to more strain. Stress is the product of modulus times strain. If you laminate a bar with a lower modulus material on the outside, there will be less stress in the lower modulus layer for the same strain. With more engineering than we can do here, glass on the outside of a tube can be used to advantage. The low modulus aluminum mandrel would not contribute anything on the inside unless the failure mode was buckling.

    I would only recommend a fiberglass outer layer for electrical insulation. If you want toughness, start mixing Kevlar with carbon.
    High_Strength_Glass_Fibers-Technical.pdf properties-of-carbon-fiber/ carbonfibre/mechanicalproperties_2.asp
    Quote Originally Posted by Ted Hoppe View Post
    Carbon fiber breaking under overload while fiberglass remains remains in tact isn’t all that bad as it serves the purpose to be able to bring you home when a fully carbon piece would not.
    Quote Originally Posted by Peerie Maa View Post
    No, you miss the point. If the carbon breaks, the glass will also break as it is of lower ultimate strength. It just breaks nanoseconds after the carbon has given up. If the glass is strong enough to not fail, you do not need the carbon.

    I suggest that the carbon fibre should wrap right around the gudgeon from end to end.
    Make it like this:Scan_20190702.jpgLike the example in the OP. Do not try to reinvent the wheel, or in Americlese, "If it ain't broke, don't fix it"
    OK, Now I have to stop arguing with Nick and start wholeheartedly agreeing. Chopped fiber, regardless of the fiber can only do so much. Chopped carbon can only provide roughly the same strength as chopped glass fiber. Chopped carbon will provide a lower density, but this is a bronze substitute in a strength and toughness driven application. The Blackline Marine gudgeon is a good illustration of the way you need to build this part.
    Last edited by MN Dave; 07-02-2019 at 07:27 PM.
    Management is the art of counting beans. Leadership is the art of making every being count. --Joe Finch

  31. #31
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    Default Re: Anyone here made carbon fiber gudgeons?

    Ted,

    Are you planning on testing one of these to find the strength?
    There are so many intricate details that affect strength.

    I sincerely hope you are going to wrap continuous fibers around the inside and outside of this gudgeon - like your original picture. Post #23 doesn't show how the two halves of the gudgeon will be joined. My apologies if I am being too simplistic.
    4 little rods vertically are not going to do much, due to the small area.
    If you are going to use chopped strand in epoxy for fillers, it needs to be very dry to provide much support.

    If you are not going to do a failure test, I'd agree with Russell Brown.

  32. #32
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    Default Re: Anyone here made carbon fiber gudgeons?

    Are you suggesting my 4 carbon fiber rods (8 total) inside the chopped fiber and epoxy piece is insignificant in your strength analysis?

    In a little theoretical question - if an interstructure part breaks but does not part the outer structure - doesn’t that mean some integrity may be enough to get home despite the shear impact. If that is the case the whole thing is Kaput and all the fibers broken maybe the carbon fiber is the wasted material and I should make it out of s-glass which has only 15% less strength but flexible enough for recovery
    Last edited by Ted Hoppe; 07-02-2019 at 07:57 PM.

  33. #33
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    Default Re: Anyone here made carbon fiber gudgeons?

    How did the original parts fail? The half gudgeon in the picture looks almost like it was a two part assembly that clamped around the pintle. The break, if it is a break, looks very flat and corroded, not at all like a fresh break. It doesn't look like it fits the gap(?) in the rudder pictured.
    Management is the art of counting beans. Leadership is the art of making every being count. --Joe Finch

  34. #34
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    Default Re: Anyone here made carbon fiber gudgeons?

    Quote Originally Posted by MN Dave View Post
    How did the original parts fail? The half gudgeon in the picture looks almost like it was a two part assembly that clamped around the pintle. The break, if it is a break, looks very flat and corroded, not at all like a fresh break. It doesn't look like it fits the gap(?) in the rudder pictured.
    Above is the port side of a two part system, clamped on via 4 screws. There was an open gap between the grudgeon arm which collared the rudder post sleeve. The other piece broke off a while back but I was unaware until we hauled/ The rudder felt loose but still functioned enough to sail a proper course.

    the rudder was last “repaired” in 1968 after losing the final SORC race which broke its winning run as boat of the year.
    Last edited by Ted Hoppe; 07-02-2019 at 08:44 PM.

  35. #35
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    Default Re: Anyone here made carbon fiber gudgeons?

    Devils advocate-ish discussion points.

    i) The original brass design was totally up to the job, and failed due to electrolytic issues, de-zincification or suchlike, due to inadequate sacrificial anodes or bonding. Therefore replace with same in possibly a slightly more modern brass with tuned zinc retention properties, do more to prevent electrolytic issues, or get used to replacing it every decade or two.

    ii) A carbon fiber gudgeon can be designed and be perfectly engineered for the job... as long as you don't try to recreate a brass one in carbon fibre. It should be a clean sheet design and not be handicapped by fitting footprint of a brass part. To use an extreme analogy, you can make a boat out of ferrocement, but you can't make a cedar strip method canoe out of ferrocement strips.
    2019: returning from being sidelined with medical probs, crossing fingers worst is over, still in "armchair enthusiast" mode for time being.

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