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  1. #1
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    Carbon DH frame DIY build thread (updated with pics)

    As promised, a thread about my little DIY DH frame project.

    A few pics, showing the mold parts, the jig, and the foam core of the main frame.

    This shows the first of 3 builds. Each to be slightly different in suspension design.

    The other 2 foam cores are also ready to go.

    The fiber and the epoxy arrived a couple of days ago, so when my job allows, time will be spent on this.


    Magura
    Last edited by Mr.Magura; 07-06-2011 at 11:18 AM.

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    very cool!

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    HI!

    Can you put the BOM of this project? (is that Rohacell IG?)
    The U part (with 3 holes) is it for Shockmount?
    Are you going to use Aluminium insert for BB/Main bearing/Headset?
    Also, I don't know if you are aware, but this guys over here www-8020.net (don't mind publicity! I dont work for THEM nor I do have Comission!), but nice JIGs can be made out of it.


    GREAT WORK - in portuguese: "EXCELENTE TRABALHO!"


    PS: don't get me wrong, but it's a bit IBISish! I would like to have some time at work to do something in those lines!...

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    Quote Originally Posted by Tkul View Post
    HI!

    Can you put the BOM of this project? (is that Rohacell IG?)
    The U part (with 3 holes) is it for Shockmount?
    Are you going to use Aluminium insert for BB/Main bearing/Headset?
    Also, I don't know if you are aware, but this guys over here www-8020.net (don't mind publicity! I dont work for THEM nor I do have Comission!), but nice JIGs can be made out of it.


    GREAT WORK - in portuguese: "EXCELENTE TRABALHO!"


    PS: don't get me wrong, but it's a bit IBISish! I would like to have some time at work to do something in those lines!...
    The BOM for the front triangle would be along these lines:

    A few kg worth of PTFE for the mold parts.
    A block of PS foam (Rohacell has too many disadvantages, though it sure is stronger).
    Approx. 6m2 300g/m2 unidirectional carbon
    1m2 woven 160g/m2 carbon
    1m2 465g/m2 ballistic woven Kevlar
    Approx. 100m 3K carbon rowing
    A 7075T6 linkage mount
    Approx. 2.5kg of epoxy

    The U-part is for the linkage plate pivot.

    All the bearings will be mounted directly in the carbon.

    Yeah, the 8020 system is good for jigs, but I prefer to have a flat surface as a reference point, as this is a bit more complicated than just setting up tubes in the right positions.
    By using a plate, I have my zero in close vicinity at most points.
    I did though consider something like the 8020 system in the beginning, but couldn't think my way out of the lack of a reference plane in the setup phase.

    I just took a look at the Ibis, and sure you're right, the front half looks a bit like the Mojo.
    It will however not bear much of a resemblance once the fiber has been added.


    Magura


    EDIT:

    What are you doing for a living, since you have such possibilities?

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    Looks like a great project! I cant wait to see it progress.

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    Quote Originally Posted by j_raquet View Post
    Looks like a great project! I cant wait to see it progress.
    Well, I hope to have the first front end ready within 2 weeks. The linkage and the rear will take another couple of weeks I suppose (if work permits spending the time).



    Magura

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    Way cool, subscribed. I want to build a full suss fat bike before summer is out. This will be inspiring!

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    So, a quick rundown of the details.

    The bottom bracket is the dimensions of a Shimano external type, but all of it is internal, so the bottom bracket is pretty wide. Like 105mm as I recall.
    All bearings are to be glued directly in the frame, so no alloy bearing cups.
    I aim for around 4 to 4.5kg for the frame without rear shock.
    Adjustable head angle, BB height, suspension compression curve, chain-stay length, and so forth by a few different rear ends.


    My target for this frame, is to make a hard wearing, versatile, and stiff DH frame.
    It is also my intentions to keep the man hours down, in order to be able to make a few for experiments.
    As I wrote initially, the first batch consists of 3 frames, but I expect to make a few a year in the future.
    Having said that, I guess I better point out that they are not for sale, before I get the usual lecture about that "I" am a company or manufacturer or whatever the clown in question can wring from his imagination
    I do this for fun and education, and that's it!
    That it's posted here, is to inspire others to take on a project like this themselves (and due to a few requests).


    Magura

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    Thank you for sharing this project.

    Are you making molds out of fiberglass to layup the carbon?

    What is your layup schedule going to be?

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    Quote Originally Posted by shirk View Post
    Thank you for sharing this project.

    Are you making molds out of fiberglass to layup the carbon?

    What is your layup schedule going to be?

    I am going to make them moldless, using the foam core as positive mold. Hence the setup in the photos, as I need to keep everything in position till the fiber is applied and the vacuum is up.

    What is a layup schedule? You'll have to forgive my ignorance, but I'm not a native English speaker, and the term is not easy to make sense of from a dictionary


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    Layup schedule refers to the number of layers and the orientation as well as the type of cloth used.

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    Quote Originally Posted by Mr.Magura View Post
    I am going to make them moldless, using the foam core as positive mold.
    I take it that means the foam will be staying within the finished frame? You'll have the quietest, strongest bike on the planet! Keep us posted please

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    I'm impressed. The frame plug is very well made. Why not use it to make a cavity mold for the composite frame, and use inflated bladders to compact the resin/fiber matrix?

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    Quote Originally Posted by Fix the Spade View Post
    I take it that means the foam will be staying within the finished frame? You'll have the quietest, strongest bike on the planet! Keep us posted please
    AFAIK you can remove the foam by disolving it with acetone.


    Quote Originally Posted by forwardcomponents View Post
    I'm impressed. The frame plug is very well made. Why not use it to make a cavity mold for the composite frame, and use inflated bladders to compact the resin/fiber matrix?
    how does one do the layup using a female mold and pressure bladders?

    to the OP: great work. I would definitely like to do something similar.

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    Quote Originally Posted by sonic reducer View Post
    AFAIK you can remove the foam by disolving it with acetone.

    how does one do the layup using a female mold and pressure bladders?

    to the OP: great work. I would definitely like to do something similar.
    Bladder molding frames of this nature normally require custom bladders which are costly to make for prototype runs. They are also not perfect out of the box, often requiring changes in the bladder design to allow for layer build up in specific areas, with bagging external dimensions will change when layer buildup is changed.

    Bladder materials are either latex or nylon, and are often used in prepreg layup,although I have bladder molded hollow parts using wet layup. The viscoscity of a wet layup and bladder molding on frame would require perfect sealing on A and B mold halves or else as the bladder pressure increases it can force out resin.... that is unless the part is layed up damp, and resin is pulled through the mold. For this to happen the mold parting halves must be perfectly sealed or else when you pull vac to draw resin through the mold it will pull air through parting line.

    Moral of the story, bladder molding is best left to prepreg on parts which have multiple unique shutoffs on parting line... like seat tube, and head tube.

    His method is sound for making short run prototypes, and if going production an aluminum tool, bladder, prepreg, and a heated platen press would be used.

    Josh

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    Interesting project. I made something remotely similar when I made a carbon fiber neck over an obeche core for a headless bass guitar. Looking forward for more pics and story.
    Marko

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    Quote Originally Posted by MPU View Post
    Interesting project. I made something remotely similar when I made a carbon fiber neck over an obeche core for a headless bass guitar. Looking forward for more pics and story.
    Marko
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    Been waiting for you to start a building thead after reading about this here bike in the "DH Carbon" thread, Magura! Looks promising for sure. Nice work. Eager to see the linkage designs you adopt for testing.

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    Quote Originally Posted by shirk View Post
    Layup schedule refers to the number of layers and the orientation as well as the type of cloth used.
    Thanks for the clarification

    The number of layers differs a lot depending where on the frame you look. I have an entire A4 sheet of notes for this (handwriting), so it would be quite a task to post it.
    I am going to use mainly 300g/m2 UD carbon. 0, 20, and 45 degrees to the axis of the tubes.
    I will add carbon multi wall nanotubes to the epoxy (5% by weight), to enhance the properties.
    In areas of potential hard impact, I will use ballistic weave 463g/m2 Kevlar.


    Magura

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    Quote Originally Posted by Fix the Spade View Post
    I take it that means the foam will be staying within the finished frame? You'll have the quietest, strongest bike on the planet! Keep us posted please
    Yes, the foam core will stay in the frame, as the 120g weight penalty seems to be well worth the benefits. I did it the same way when I made a road fork of carbon 15 years ago, and have seen no ill effects of that approach.

    I am not sure there is much strength to gain from leaving the foam core in there, but it makes for a dead silent frame, instead of the terrible noise a hollow frame makes. It also keeps water and dirt from entering the frame, which in turns keeps the bearings in the bottom bracket dry on the inside.


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    Quote Originally Posted by sonic reducer View Post
    AFAIK you can remove the foam by disolving it with acetone.




    how does one do the layup using a female mold and pressure bladders?

    to the OP: great work. I would definitely like to do something similar.
    Thanks for the compliment.
    This is not rocket science, so just go ahead and get your feet wet.

    Yes that's right, acetone will dissolve the PS foam core if I one day will feel like making the experiment some day.

    To use female mold and bladders, a completely different approach is required. Then we are talking prepreg and custom bladders. That in itself is no big deal, as DIY custom bladders are relatively easy to make, but to cure the prepreg, you need to heat up the entire mold.
    Considering those issues, and the limited (if any) benefits it may offer, that approach is a bit overkill for a limited series.
    Also keep in mind, that I do not want more than one frame of each design, so making new molds for each design, makes for a very man hour intensive, and expensive toy.
    Like I do it now, I can make the entire frame for something like 400$.


    Magura

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    Quote Originally Posted by joshuagore View Post

    Moral of the story, bladder molding is best left to prepreg on parts which have multiple unique shutoffs on parting line... like seat tube, and head tube.

    His method is sound for making short run prototypes, and if going production an aluminum tool, bladder, prepreg, and a heated platen press would be used.

    Josh
    This conforms well with my experience. I have seen a few people over time, try to fight all the issues of bladder molding prototype runs. So far they have either failed, or ended up with hefty expenses, and a very limited (if any) quality increase.

    With lots of attention to design and careful processing, I can get 70% fiber content by vacuum bagging, using a closed cell foam core. That is more than good enough for something like this.
    The void count can also be kept low if done with care and attention, according to my experience.


    Magura

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    Todays progress was to test the batch of foam used for the core, and my new vacuum pump.

    It turned out rather good. The pump is offering a max. vacuum of 70 cm/Hg, which is quite good for something like this project.
    The foam is able to survive full vacuum from the pump, which simplifies the whole thing.

    Next step is to make tailor made vacuum bags for the project. This may sound easy, but rest assured that it is among the hard parts of this project.


    Magura

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    This looks awesome, something I'd like to do some day, but not quite yet, good luck!

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    Great project!

    Can't wait to see updates!

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    Quote Originally Posted by joshuagore View Post
    Bladder molding frames of this nature normally require custom bladders which are costly to make for prototype runs. They are also not perfect out of the box, often requiring changes in the bladder design to allow for layer build up in specific areas, with bagging external dimensions will change when layer buildup is changed.

    Bladder materials are either latex or nylon, and are often used in prepreg layup,although I have bladder molded hollow parts using wet layup. The viscoscity of a wet layup and bladder molding on frame would require perfect sealing on A and B mold halves or else as the bladder pressure increases it can force out resin.... that is unless the part is layed up damp, and resin is pulled through the mold. For this to happen the mold parting halves must be perfectly sealed or else when you pull vac to draw resin through the mold it will pull air through parting line.
    what on earth are you talking about???

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    Quote Originally Posted by MPU View Post
    Interesting project. I made something remotely similar when I made a carbon fiber neck over an obeche core for a headless bass guitar. Looking forward for more pics and story.
    Marko
    Weren't you that guy who posted a pictorial on how to do a carbon fiber bass neck on the Luthiers Corner on Talk Bass??
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    very interesting!
    subscribed

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    That is way cool!!!

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    Quote Originally Posted by compositepro View Post
    what on earth are you talking about???
    I may mix and match injection mold terminology, but someone with a knowledge of bladder or vac infusion should get my drift. Is there something specific about my ideas I can clarify?

    Josh

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    Quote Originally Posted by joshuagore View Post
    I may mix and match injection mold terminology, but someone with a knowledge of bladder or vac infusion should get my drift. Is there something specific about my ideas I can clarify?

    Josh

    Im just wondering why you would apply a vaccuum to a bladder mould perhaps with your experience in this field you know something the rest of us dont . Have you ever worked with composites?

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    Quote Originally Posted by dhbomber View Post
    Weren't you that guy who posted a pictorial on how to do a carbon fiber bass neck on the Luthiers Corner on Talk Bass??
    Yep, that's me.
    Marko

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    How did you make the foam core? It looks very well made. I'm about to jump into building my own frame. I'm just copying the frame of one of my other bikes but I'm a little worried about making the core. My plan was to just cut the rough shape out with a hot wire and do a lot of sanding.

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    Quote Originally Posted by jd1828 View Post
    How did you make the foam core? It looks very well made. I'm about to jump into building my own frame. I'm just copying the frame of one of my other bikes but I'm a little worried about making the core. My plan was to just cut the rough shape out with a hot wire and do a lot of sanding.
    Your plan is not too far off.

    I made a few aluminium templates to use for guiding the hot wire cutter.
    Being 3D it takes a bit of planning. The actual cutting is less than half an hour.

    After that, it's a matter of marking up the chamfers and so forth, and get the sanding block out.


    Magura

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    Quote Originally Posted by compositepro View Post
    Im just wondering why you would apply a vaccuum to a bladder mould perhaps with your experience in this field you know something the rest of us dont . Have you ever worked with composites?
    Will respond to original poster in pm if further elaboration is required.
    Josh

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    Quote Originally Posted by Mr.Magura View Post
    Your plan is not too far off.

    I made a few aluminium templates to use for guiding the hot wire cutter.
    Being 3D it takes a bit of planning. The actual cutting is less than half an hour.

    After that, it's a matter of marking up the chamfers and so forth, and get the sanding block out.


    Magura
    If you have the 3d why not cut on cnc? What does your rear triangle look like?
    Josh

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    Quote Originally Posted by joshuagore View Post
    If you have the 3d why not cut on cnc? What does your rear triangle look like?
    Josh
    I meant 3D drawing by hand in this case. Cutting foam on CNC milling machines, is going to require a PVC foam instead of the PS foam I use.

    My rear is only a couple of drawings so far. The rear will be a few different designs.
    The first is going to be along the lines of the FSR design.


    Magura

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    Quote Originally Posted by Mr.Magura View Post
    PS foam I use.
    This just occured to me, if PS means Polystyrene, what Epoxy are you using and will it melt your core into horrible black globs when you apply it?

    This happened to me, with a surfboard no less, there was swearing.

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    Quote Originally Posted by Fix the Spade View Post
    This just occured to me, if PS means Polystyrene, what Epoxy are you using and will it melt your core into horrible black globs when you apply it?

    This happened to me, with a surfboard no less, there was swearing.
    Seal the core with PVA first before using polyester resin or slow cure epoxy?

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    Quote Originally Posted by Fix the Spade View Post
    This just occured to me, if PS means Polystyrene, what Epoxy are you using and will it melt your core into horrible black globs when you apply it?

    This happened to me, with a surfboard no less, there was swearing.
    As far as I know, none of the commonly used epoxies will damage PS foam.

    Are you sure it wasn't polyester instead of epoxy you had your little mishap with?
    I have seen people end up with funny looking structures before, when using polyester and forgetting to isolate the core.

    The epoxy system I use, was used for the test of the vacuum setup yesterday, with no ill effects.

    Magura

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    If it works then fair enough

    It probably was Polyester (repairing a fibreglass board), my main memory is of adding the hardener/catalyst and then it all got very angry.

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    Quote Originally Posted by Fix the Spade View Post
    If it works then fair enough

    It probably was Polyester (repairing a fibreglass board), my main memory is of adding the hardener/catalyst and then it all got very angry.
    I bet you it was

    I did something similar when I was 10.
    I had gotten an idea to make a fiberglass model sailboat. I shaped a hull from PS foam, and covered it in fiberglass and polyester. The day after I went to the workshop to inspect the grand result, only to find some crumpled up mess on the floor

    That little setback did however seem like a disaster at that age


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    Quote Originally Posted by MPU View Post
    Yep, that's me.
    Marko
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    Hi there!
    Just some sujections:

    If you're using tisue, use only 0/45/90.
    20 (or other than 45) layup is not that effective (but still works)

    Also, use glass (it can be E-Glass) at intersections with metal. Just a thin layer will be ok! You won't want to have a fuel cell in there!

    I remeber using a kind of plastic has a "bag".
    It's easy to do - you just put the stuff on the mold, and let it cure...
    and you have the vacum bag!
    No more mastiks, and cutting... and dealing with plastic!
    I also rember that's not cheap! But... since it's small, you only need some portions!

    OH, and the thing never wrinckles! It's really a great vacum bag! (Edit: and reuseble! If you did use CFRP, you wouldn't need: brether/plastic/mastik or anything! Just layup, put the bag, seal it in the limits... and You're off! Also in small and complex parts, you can print in 3D, make the mold and you're off! No need for CNC or anything!)

    Just let me push y brain cells or find it in Google. If I don't remember, monday I'll put the name of the stuff!


    Continue the good work!
    Last edited by Tkul; 06-18-2011 at 01:21 PM.

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    this thread just more or less made my day!
    excellent work, the mold looks incredible, can't wait to see end results

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    Quote Originally Posted by Tkul View Post

    I remeber using a kind of plastic has a "bag".
    It's easy to do - you just put the stuff on the mold, and let it cure...
    and you have the vacum bag!
    No more mastiks, and cutting... and dealing with plastic!
    I also rember that's not cheap! But... since it's small, you only need some portions!

    OH, and the thing never wrinckles! It's really a great vacum bag! (Edit: and reuseble! If you did use CFRP, you wouldn't need: brether/plastic/mastik or anything! Just layup, put the bag, seal it in the limits... and You're off! Also in small and complex parts, you can print in 3D, make the mold and you're off! No need for CNC or anything!)

    Just let me push y brain cells or find it in Google. If I don't remember, monday I'll put the name of the stuff!


    Continue the good work!

    Ohh, going public are we?

    I'm all ears.

    I do wrap the aluminium parts in glass fiber. I have learned my lesson in that regard a couple of years ago, when my DIY carbon cranks after like 8 years of reliable service, all of a sudden decided to let go of the threaded inserts for the pedals. It turned out that a combo of lack of insulation and plenty of road-salt did the trick.


    Magura

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    Quote Originally Posted by Tkul View Post
    Also in small and complex parts, you can print in 3D, make the mold and you're off! No need for CNC or anything!)

    :
    look up something called windform

    just note im not suggesting making a bike from this but we use this regurlaly in brake ducts and ither parts plus rather usefull for tooling for cfrp

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    Quote Originally Posted by Mr.Magura View Post
    Ohh, going public are we?

    I'm all ears.

    I do wrap the aluminium parts in glass fiber. I have learned my lesson in that regard a couple of years ago, when my DIY carbon cranks after like 8 years of reliable service, all of a sudden decided to let go of the threaded inserts for the pedals. It turned out that a combo of lack of insulation and plenty of road-salt did the trick.


    Magura
    your adhesive should provide plenty of insulation whoever started the old wives tale of fibreglass is 20 years out of date it is not the correct way of doing it as all you have done is add an extra point of failure.

    i would put more time into researching surface preparation for bonding

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    Quote Originally Posted by compositepro View Post
    your adhesive should provide plenty of insulation whoever started the old wives tale of fibreglass is 20 years out of date it is not the correct way of doing it as all you have done is add an extra point of failure.

    i would put more time into researching surface preparation for bonding
    Back then I did not bond the aluminium inserts in the carbon, but had them in the casting process instead, so they were directly in contact with the carbon.
    I intend to do the same with the aluminium insert I have for this frame, just glass fiber insulated, is this a bad solution?
    You can see how the U-shaped aluminium insert in question looks. Would you just glue it on top of the carbon surface instead?


    Magura

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    Quote Originally Posted by compositepro View Post
    look up something called windform

    just note im not suggesting making a bike from this but we use this regurlaly in brake ducts and ither parts plus rather usefull for tooling for cfrp
    For others whom may be interested in reading up on the subject, here is a starting point:

    http://www.windform.it/


    Magura

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    Quote Originally Posted by Mr.Magura View Post
    Back then I did not bond the aluminium inserts in the carbon, but had them in the casting process instead, so they were directly in contact with the carbon.
    I intend to do the same with the aluminium insert I have for this frame, just glass fiber insulated, is this a bad solution?
    You can see how the U-shaped aluminium insert in question looks. Would you just glue it on top of the carbon surface instead?


    Magura
    tI sent you a pm on an approach you may be able to consider.If you think about it simply you bond fibreglass to the part you then bond carbon to the glassfibre....the epoxy glasfibre to aluminium will still fail if your preperation of the aluminium was not correct ....the prep of the alloy alone will take care of the galvanic issues if you use a dedicated adhesive this will add further insulation

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    Quote Originally Posted by compositepro View Post
    tI sent you a pm on an approach you may be able to consider.If you think about it simply you bond fibreglass to the part you then bond carbon to the glassfibre....the epoxy glasfibre to aluminium will still fail if your preperation of the aluminium was not correct ....the prep of the alloy alone will take care of the galvanic issues if you use a dedicated adhesive this will add further insulation
    Understood and point taken. Surface prep it is then.

    Cheers


    Magura

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    Yeah... somethings must be transmited!
    Anyway, all aluminium must have a E-glass (since it's cheaper than S-Glass) to isolate it from Carbo Fiber (CF).
    This is due to Electric Potencial difference, nothing more.
    Basically when putting the plyes, the 1st one should be glass. It would be something like:

    Aluminium part / E-Glass / CF

    Normally it is used nomex honeycomb and when using Stell/titanium/aluminium a light e-glass tissue it's use. Electrical potencial, nothing more!

    For assembly / layup or anything, and if the metal bolts(pins enter in contact with composite, it would be needed to remove material from the honeycomb (where the bolt or other thing would go), put a paste (like "putty") and then put the metal thing.
    This was done to garanty that no moister would enter inside the honeycomb:
    Moister up --> water --> cold --> Ice --> expand... you can imagine what happens next!!

    So, back to frames!!!!

    Sincerelly I would put e-glass surounding all metal parts!

    oh... I think you thought about it, but it's never more, to remember about cables!!! Look at what Santacruz did with the Tallboy!
    That is something smart

    I think in next frame, you should think about changing frame design, and replace the Al. U wiht some "U" (or other type of conection - if it could be a continuity of the frame layer it would be better!) in composite?
    Sorry for being so critic don't take me wrong!

    PS - I really need to install Catia in this computer!!!
    Just a sujection: if you have difficulty in laying somethings, heat up the layer

  55. #55
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    Quote Originally Posted by Tkul View Post

    oh... I think you thought about it, but it's never more, to remember about cables!!! Look at what Santacruz did with the Tallboy!
    That is something smart

    I think in next frame, you should think about changing frame design, and replace the Al. U wiht some "U" (or other type of conection - if it could be a continuity of the frame layer it would be better!) in composite?
    Sorry for being so critic don't take me wrong!

    A version without the aluminium U-bracket is sure in the pipeline. Remember this frame is the first of 3. I just wanted to take the known route for the first frame, to avoid too many unknowns. The next frames are going to be more technically interesting.

    Looking at the Tallboy, I fail to see what you mean by smart cable routing?

    http://www.santacruzbikes.co.uk/tallboy

    It looks pretty much standard to me, so what little smart detail am I missing here?
    It's as far as I can tell, the same as on my old '99 Intense M1.


    Magura

    EDIT:

    I see what you're saying now, they cast in the cable mounts. I am intending to do the same, as I don't really feel like drilling holes in the composite.
    Last edited by Mr.Magura; 06-18-2011 at 03:49 PM.

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    I meant cable "security" - basically it's a big fat boundle without any rivet or anything.
    I also have to upload some pictures I took at the Cannondale cutout frame (Flash... i think)

    EDIT (also ) - kids put me as slow poster! yeah that's it

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    Quote Originally Posted by Tkul View Post
    I meant cable "security" - basically it's a big fat boundle without any rivet or anything.
    I also have to upload some pictures I took at the Cannondale cutout frame (Flash... i think)

    EDIT (also ) - kids put me as slow poster! yeah that's it
    In that case I agree I am in the process of making a mold for casting such cable eyelets.


    I'd sure like to see what a Cannondale looks like on the inside.



    Magura

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    Quote Originally Posted by compositepro View Post
    tI sent you a pm on an approach you may be able to consider.If you think about it simply you bond fibreglass to the part you then bond carbon to the glassfibre....the epoxy glasfibre to aluminium will still fail if your preperation of the aluminium was not correct ....the prep of the alloy alone will take care of the galvanic issues if you use a dedicated adhesive this will add further insulation
    After having read up on the subject, my conclusion is that chromic acid anodizing is the solution in this case. I have chosen chromic acid anodizing, due to availability (I can DIY this solution) and that it is relatively versatile regarding adhesive choice.

    Thanks CP for the heads up, and spoon feeding of scientific papers.



    Magura

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    Todays progress was anodizing of the aluminium linkage pivot plate mount.



    Magura

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    I intend to use the good old Hysol 9430 glue for gluing in bearings.

    Anybody got a better suggestion?


    Magura

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    No better advice for glue, is the Hysol 9430 really still the best solution?
    .....Or just a slow day?

    I kinda need that advice soon, as I will need it sometime next week.
    I expect the main triangle to be ready for mounting bearings by then.


    Magura

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    I can recommend this but my experience has been between stainless and carbon. I also don't like the fact that its re-branded by fiberglast.
    http://www.fibreglast.com/product/Ep...1/Epoxy_Resins

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    Quote Originally Posted by Mr.Magura View Post
    No better advice for glue, is the Hysol 9430 really still the best solution?
    .....Or just a slow day?

    I kinda need that advice soon, as I will need it sometime next week.
    I expect the main triangle to be ready for mounting bearings by then.


    Magura
    How do you plan to attach the bottom bracket and shock linkage? Or do you have a source that I can read on how it's done.

    Part of the frame I plan to make has a bolt that attaches the shock link to the seat tube. I'm assuming I can't just tap a thread right into the carbon and I'd need to glue in a metal piece.

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    Quote Originally Posted by jd1828 View Post
    How do you plan to attach the bottom bracket and shock linkage? Or do you have a source that I can read on how it's done.

    Part of the frame I plan to make has a bolt that attaches the shock link to the seat tube. I'm assuming I can't just tap a thread right into the carbon and I'd need to glue in a metal piece.
    In your case I would just make a mold insert to form the hole needed for the axle for the link plate pivot in the carbon mold. If you take a look at the photos of my core, you can see Teflon mold inserts. Those are to make precision holes fit for gluing the parts in question straight to the carbon frame.

    I have chosen to glue the bottom bracket cups directly in (external type). This allows me to support the bottom bracket all the way.


    Magura

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    Quote Originally Posted by Mr.Magura View Post
    In your case I would just make a mold insert to form the hole needed for the axle for the link plate pivot in the carbon mold. If you take a look at the photos of my core, you can see Teflon mold inserts. Those are to make precision holes fit for gluing the parts in question straight to the carbon frame.

    I have chosen to glue the bottom bracket cups directly in (external type). This allows me to support the bottom bracket all the way.


    Magura

    Are you machining the bottom bracket custom and sourcing a bearing or just modifying a readily available unit?

    Josh

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    Quote Originally Posted by joshuagore View Post
    Are you machining the bottom bracket custom and sourcing a bearing or just modifying a readily available unit?

    Josh
    I am just using a standard Shimano style bottom bracket, as they sport aluminium cups and a sealed center tube. That is too easy to pass up.


    You just need to machine the Teflon mold inserts to fit your bottom bracket of choice.


    Magura

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    I gotta see this good job Magura, subscribed. Inspired by Ibis eh?

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    Quote Originally Posted by mimi1885 View Post
    I gotta see this good job Magura, subscribed. Inspired by Ibis eh?
    Thanks Mimi.

    You would be the second to think "Ibis", but if you look closer, you'll see that the part that resembles the Mojo, is the front half of the front triangle. That part actually does look like the Mojo, and the V10, and some of the Intense offerings.......and about a zillion other carbon frames

    What I did have one eye on when designing the front triangle, was actually the M9 from Intense. Add a bit of M1 to the pot, plus some V10, and you pretty much got the basic idea.
    I only noticed the Mojo after having the resemblance pointed out to me earlier in this thread. The mechanics behind my design, couldn't possibly be more different from the Mojo than they are. The key here is the seat tube, as I don't have it connecting the bottom bracket. That makes for a completely different piece of engineering.
    That I have chosen to avoid the VPP rear design as well, takes my design pretty far from just about any current carbon design I know of in this segment.

    My aim with this, is to make a bike with all the benefits from the big shot manufacturers, to avoid the VPP system, make it possible to tune it in a versatile manner, and avoid the issues of a fragile frame.


    Magura

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    Quote Originally Posted by Mr.Magura View Post
    I intend to use the good old Hysol 9430 glue for gluing in bearings.

    Anybody got a better suggestion?


    Magura
    Hysol 9394

    or maybe 3M 8115

    Maybe not better but some other options.

    you can pick up 8115 at autobody supply shops.

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    Quote Originally Posted by flynfrog View Post
    Hysol 9394

    or maybe 3M 8115

    Maybe not better but some other options.

    you can pick up 8115 at autobody supply shops.
    Thanks.


    Magura

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    subscribing...

    can't wait to see this! great work so far.

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    Quote Originally Posted by summud View Post
    can't wait to see this! Great work so far.
    +1^

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    Subscribed...

    .... and more pictures would be great, too.

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    Here you can see the core, that has been stiffened up by a layer of carbon.
    This is done to be able to just throw the whole frame in a bag for the vacuum process later.

    Now I am waiting for the glue for mounting the aluminium bracket for the link pivot point.
    If things goes as planned, I will get the glue tomorrow.


    Magura

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    Why are you gluing the bb and bearings into the frame?

    Spin up a mandrel then do your own carbon tube for a Shimano press fit BB92 bb.

    Design your pivots to use the same cups.



    This is going into a bamboo hardtail I am building.

  77. #77
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    Quote Originally Posted by shirk View Post
    Why are you gluing the bb and bearings into the frame?

    Spin up a mandrel then do your own carbon tube for a Shimano press fit BB92 bb.

    Design your pivots to use the same cups.

    This is going into a bamboo hardtail I am building.
    If you look at the first pics in this thread, you will see that I have made mandrels, but made them to fit a standard BB, as they cost like 20$, and work quite well.

    The bearings are made for press fit in the main triangle.


    Having said that, I guess these frames are going to be "disposable", meaning that I will just make a new frame before changing bearings becomes an issue. I don't think I'm going to ride the same frame for even an entire season.
    These frames are meant as a development platform.
    Once I settle for a more long term design, I will sure make a frame with carbon press fit bearing seats for the BB as well.


    Magura

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    Mr.M,
    Concidering the money that your trowing at the project, I would design thinking in "serviceable frame".
    sure, it may cost a fraction of nothing to you... but it has some value and would be a shame to send the frame to "recycling" because of bearing faileur
    Press-fit is something that appear and is really compatible with composite.
    Threads in composite is something to avoid... it's a "metal assembly design"
    Don't forget the e-glass on interface.
    Also, for the quick look, I thought about the plies you place:
    Can you cut a ply to cover has much surface has it's possible?
    If you can cover as much as you can with a ply, the frame will be stronger.
    Also overlap is necessary and can be between 25 to 45 (mm).
    Yellow lines correspond to 1st layer or ply. red is the "second" ply.
    Has you put more plies, you should also overlap the thing in order to not put on the same place the "end of the ply"

    and finally, if this was facebook, i would put "LIKE"




    Shirk - did you make that thing to final dimension?
    Personally I would put "needed dimensio" + something and cut to "needed dimension".
    Attached Thumbnails Attached Thumbnails Carbon DH frame DIY build thread-mr.magura.jpg  


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    Quote Originally Posted by Tkul View Post
    Shirk - did you make that thing to final dimension?
    Personally I would put "needed dimensio" + something and cut to "needed dimension".
    I have not cut it to final dimension yet, I still need to do that.

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    Great project! Thanks for sharing the process.

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    Quote Originally Posted by Tkul View Post
    Mr.M,
    Concidering the money that your trowing at the project, I would design thinking in "serviceable frame".
    sure, it may cost a fraction of nothing to you... but it has some value and would be a shame to send the frame to "recycling" because of bearing faileur
    Press-fit is something that appear and is really compatible with composite.
    Threads in composite is something to avoid... it's a "metal assembly design"
    Don't forget the e-glass on interface.
    Also, for the quick look, I thought about the plies you place:
    Can you cut a ply to cover has much surface has it's possible?
    If you can cover as much as you can with a ply, the frame will be stronger.
    Also overlap is necessary and can be between 25 to 45 (mm).
    Yellow lines correspond to 1st layer or ply. red is the "second" ply.
    Has you put more plies, you should also overlap the thing in order to not put on the same place the "end of the ply"

    and finally, if this was facebook, i would put "LIKE"



    The bearings can be replaced, I just fail to see a need for it, so I don't pay much attention to serviceability for those frames.
    Those frames will be short lived. Once I have gotten the info and experience from the frame I need, it will be replaced by a new model.
    Considering the legal circus around selling such a frame (or even giving it away for free), those frames are simply going to be retired on the wall of fame (ok, the wall in the shed ).
    The linkage bearings are going to be press fit, I will just glue the bottom bracket in.

    The plies you see on the core now, are not a structural part of the frame, but just to stiffen up the core adequately to have it vacuumed out of the jig.
    For the structural plies, all layers are going to see overlap and are cut to shape.
    95% of the fabric for the structural part, is going to be UD, so it's simply a matter of a lot of footwork, to have the exact layup schedule on the wall prior to starting up, and the corresponding carbon cut and ready. I currently am working on transferring my written layup schedule, into something a lot more descriptive (almost cartoon style), in order to keep confusion to a minimum during the layup. From what I can tell at this point, I will be pressed for time if I have to go back to make a correction, so the layup process will have to run in "no stupidity" mode

    Regarding the E-glass interface, here you got a little goodnight read, the link is curtesy of Compositepro:

    http://www.ismithers.net/downloads/c...ngineering.pdf

    That should put the issue to rest


    Magura

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    While waiting for the glue to cure, I did a quick and dirty test of the viability of making carbon springs for rear shocks.

    Carbon spring for rear shocks?


    Magura

  83. #83
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    I have not been following this. Sorry but I don't have a Hysol Catalog here at home, and lightning is on it's way so no time to look before shutdown of the computer.

    Did you do the entire lay up in one process? Knowing Hysol products, how were you able to get the resin content acceptable. Hysol is pretty thick stuff, good, but viscous.

    You might consider something like Huntsman 5052 or Epocast 50a with 9816, Epon 828 is a good general purpose product with decent wet out.

    Really the way to do this is with pre preg. All the time you need, within reason. No mess, good resin content. You mentioned building the spring in a clave, so pressure and heat should be a non issue.

    In regards to type 1 chromic acid annodize as a prep, it is good, but you may find it easier to ac 130, with BR127 primer. For bonding the aluminum you could set it with film and / or foam adhesesive around any gaps. This will also act as a densifier in the local area.

    Awesome project, too bad you aren't in the US, I'd offer some expired "stuff" to test.

    PK

  84. #84
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    Quote Originally Posted by PMK View Post
    I have not been following this. Sorry but I don't have a Hysol Catalog here at home, and lightning is on it's way so no time to look before shutdown of the computer.

    Did you do the entire lay up in one process? Knowing Hysol products, how were you able to get the resin content acceptable. Hysol is pretty thick stuff, good, but viscous.

    You might consider something like Huntsman 5052 or Epocast 50a with 9816, Epon 828 is a good general purpose product with decent wet out.

    Really the way to do this is with pre preg. All the time you need, within reason. No mess, good resin content. You mentioned building the spring in a clave, so pressure and heat should be a non issue.

    In regards to type 1 chromic acid annodize as a prep, it is good, but you may find it easier to ac 130, with BR127 primer. For bonding the aluminum you could set it with film and / or foam adhesesive around any gaps. This will also act as a densifier in the local area.

    Awesome project, too bad you aren't in the US, I'd offer some expired "stuff" to test.

    PK

    I ended up using the Hysol 9466 glue as it was the recommendation of the local Locktite rep. So far it seems like a good solution.
    I only used the 9466 for gluing in the aluminium part, I use an epoxy resin from Fibermax called 2930 for the layup.

    I am going to do the entire layup in one process, as I have bad experience with de-lamination when done in more processes. I do however also think it's easier to do it in one go. I have bough a roll of 3K rowing for fixation of the layers, so it's gonna be like laying up a layer, fixation, next layer, and so forth. This way it seems to be relatively easy to make everything stay in place.

    My clave is just a small cube DIY version, inner dimensions are like 300 x 300 x 300mm, so much too small for a frame. It is mainly intended to make sterilization tests for medical purposes, as that is needed for my work. Had the clave been bigger, I would have gone the pre preg route for sure. I don't find liquid epoxy all that charming

    I'd love to have been able to get a few samples of some real high tech fabrics, as that is about as hard to find here, as a good looking 25 year old virgin.

    So far I have been relatively well off regarding materials. http://www.fibermaxcomposites.com/shop/ has more or less the basics, and in a fine quality. They also sell by the m2, so I don't have to buy an entire roll to see if it works for the application. (got no affiliation with them) On top of that, they seem to be fine with DIY customers whom needs some advice to make it.

    Could you extrapolate on the bonding process you recommend? Or drop a link for me to read up on it.


    Magura

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    Ac130 is a nice environmentally friendly form of surface prep no anno needed but essentially it serves the same purpose .Aerospace people like it br127 is an epoxy primer which stops corrosion it's common in the aero industry Uk wise at least can't remember who makes which but cytech rings a bell


    Just been reading a post on brake pad heatsinks that I found quite interesting I may need to
    A. Borrow an idea
    B. Find out how to do anodising at home ....any tips DIY could save me some money

  86. #86
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    Quote Originally Posted by compositepro View Post
    Ac130 is a nice environmentally friendly form of surface prep no anno needed but essentially it serves the same purpose .Aerospace people like it br127 is an epoxy primer which stops corrosion it's common in the aero industry Uk wise at least can't remember who makes which but cytech rings a bell


    Just been reading a post on brake pad heatsinks that I found quite interesting I may need to
    A. Borrow an idea
    B. Find out how to do anodising at home ....any tips DIY could save me some money
    Thanks for the explanation.

    A. drop me a PM, I can't go entirely public regarding the material.

    B. DIY anodizing is a walk in the park. Drop me a PM with your requirements, and I'll sort you out.


    Magura

  87. #87
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    Yes Cytec. BR127 Adhesion Primer.

    The downside of Chromic Acid Annodizing is the prep. It must be etched, hopefully in a tank process, then rinsed very well, a desmutt process is a good step, then rinsed, then annodized.

    AC130 is very straightforward, and as mentioned much more environmentally friendly.

    In regards to the clave being small. Go prepreg and build a small oven. A tight vacuum bag with a good pull of 29" can debulk the material tight to the core. Careful placement and working out wrinkles will minimize it bunching up. Once under vacuum, you can use a smooth hard roller to help compact it more.

    Let it debulk for a few hours, then cure it.

    With some ingenuity you can build an insulated wooden box, use some heat guns and buy or build a temp controller. You should have no problem using 250f prepreg and curing it.

    Just be certain all your materials can handle the heat, bag, sealant tape, core, vacuum hoses, peel ply, etc.

    Also, ensure the bag is tight, you don't want to draw hot air through the pump and trash it.

    PK

  88. #88
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    BTW, I doubt there are many 25 YO Virgins here either. At least none you would want to be with.

    PK

  89. #89
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    Quote Originally Posted by Mr.Magura View Post

    I'd love to have been able to get a few samples of some real high tech fabrics, as that is about as hard to find here, as a good looking 25 year old virgin.
    what would you like to get hold of?

    do you order all your stuff from greece?Why not the Uk (cost or qty)? I would have thought it was closer.

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    Quote Originally Posted by compositepro View Post
    what would you like to get hold of?

    do you order all your stuff from greece?Why not the Uk (cost or qty)? I would have thought it was closer.
    I order all my stuff from Greece. The shipping is more or less the same as from the UK.
    The cost from Fibermax is among the cheapest I know of for small quantities, and a major plus is actually the way they pack things, as they deliver it in a way that makes it easy to keep things clean (wrapped in film, and packed in a tube bag).

    If I could get my hands on Vectran, I would forget about aramid for impact protection. Unfortunately I have only seen relatively light Vectran available in small quantities, but none of the 300g/m2 and up. I could sure use more layers of the lighter fabric, but the end cost would be high then.

    I had a bit of Vectran some time ago, and it was just so much easier to work with, plus it wets out much easier as well.


    Magura

  91. #91
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    subscribed! very glad to see this frame coming to form
    <(*-*<) Go Ride (>*-*)>

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    Quote Originally Posted by SamL3227 View Post
    subscribed! very glad to see this frame coming to form
    The weather forecast claims that I will have sub 20C here around Thursday this week, so the main frame is getting cast then if possible.


    Magura

  93. #93
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    So sweet, gotta follow this!

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    Good to see your build thread Mr Magura!

    lol I'm finding your thread more interesting than all the typical "check out my awesome huck" video/youtube stuff!

    What they say? "the journey is more interesting than the destination" .. or something like that

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    Ooo, I'm following this thread.

    I can't believe the tools and workshop you have at your disposal. I probably wouldn't be able to make any of this stuff even though I had that at my disposal but I would still love to have it

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    Quote Originally Posted by gladegp View Post
    Ooo, I'm following this thread.

    I can't believe the tools and workshop you have at your disposal. I probably wouldn't be able to make any of this stuff even though I had that at my disposal but I would still love to have it
    The only speciality machinery I have at my disposal, which is needed for this, is a small lathe, a small milling machine, a vacuum pump, and a modified oven for the post cure.

    The rest is mostly constructed from elbow grease.

    The only equipment that is essential, is the vacuum pump, the rest could be worked around, and even a vacuum pump could be worked around if needed.

    So go ahead, give it a shot.
    The biggest thing there is to this, is knowing how to. To actually make the thing, is just a mere detail.


    Magura

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    Quote Originally Posted by Mr.Magura View Post
    So go ahead, give it a shot.
    The biggest thing there is to this, is knowing how to. To actually make the thing, is just a mere detail.

    Magura
    Hmm you're planting seeds...planting seeds I say...

    The vacuum pump is already at my disposal from vacuumbagging when I build skis. And I know that is a lot of work, I suspect this is a couple of steps up the complexity ladder. But maybe one day

  98. #98
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    Quote Originally Posted by Mr.Magura View Post
    The only speciality machinery I have at my disposal, which is needed for this, is a small lathe, a small milling machine, a vacuum pump, and a modified oven for the post cure.

    The rest is mostly constructed from elbow grease.

    The only equipment that is essential, is the vacuum pump, the rest could be worked around, and even a vacuum pump could be worked around if needed.

    So go ahead, give it a shot.
    The biggest thing there is to this, is knowing how to. To actually make the thing, is just a mere detail.


    Magura
    Are you inferring that this was cut out by hand? I just assumed this was profiled with CNC but looking at it closer, it seems perfectly reasonable that it was done by hot wire and hand. Care to elaborate on how you made the blank?

  99. #99
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    Quote Originally Posted by jay_ntwr View Post
    Are you inferring that this was cut out by hand? I just assumed this was profiled with CNC but looking at it closer, it seems perfectly reasonable that it was done by hot wire and hand. Care to elaborate on how you made the blank?
    Yes, it was made by hand.

    The hot wire cutter setup, was a 0.5mm constantan wire, pre-tensioned to approx. 100N.
    The power supply was an adjustable current limiting SMPS based PSU.

    I made guides for the hot wire cutting, of aluminium sheet, cutting one plane at the time.
    All was aligned for each cut, according to a zero plane.

    The surface was then sanded, to get rid of the "fur" from the hot wire cut.

    That's all.

    It is actually relatively simple to do, if the planning of the cuts and guides is done right.

    The biggest challenge was to find foam of relatively high homogeneity, as that is mandatory to keeping the final core from casting.


    Magura

  100. #100
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    Quote Originally Posted by Mr.Magura View Post
    Yes, it was made by hand.

    The hot wire cutter setup, was a 0.5mm constantan wire, pre-tensioned to approx. 100N.
    The power supply was an adjustable current limiting SMPS based PSU.

    I made guides for the hot wire cutting, of aluminium sheet, cutting one plane at the time.
    All was aligned for each cut, according to a zero plane.

    The surface was then sanded, to get rid of the "fur" from the hot wire cut.

    That's all.

    It is actually relatively simple to do, if the planning of the cuts and guides is done right.

    The biggest challenge was to find foam of relatively high homogeneity, as that is mandatory to keeping the final core from casting.


    Magura
    Not to say this wasn't already a cool project--'cause it was--but now it's REALLY COOL IMHO.

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