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Old Nov 05, 2012, 08:10 PM
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In need of help in the Georgia area

I am need of help to produce a quality carbon fiber mold the mold is pretty simple. The mold is a merely of half 110mm tube. I need someone who could help me produce the prepeg of 54% Carbon Fiber 46% Epoxy Resin by weigh, and cure it using a vacuum/oven process. If you or anyone in the Georgia are is capable of helping post, pm, or email at david.m.grado@gmail.com
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Old Nov 06, 2012, 07:28 PM
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wyowindworks

Contact Adam and clue him in on what you are trying to do. I am sure he will be able to come up with a solution to help you out.

I think your making this harder than it needs to be.

I have a couple rolls of 250 Deg. F Unidirectional 90 and 150 Gram in the freezer.

Vacuum bags and a toster oven also.
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Last edited by Air Head; Nov 06, 2012 at 07:35 PM.
Old Nov 06, 2012, 10:57 PM
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I cant compromise on the fact that the composite part is made from both the samurai 1k spread tow fabric and the specified prepeg ratio other than that I only need someone to help me with making the prepeg and supplying the vacuum I can then post cure in my home appliance oven. Of course this person will be compensated accordingly
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Old Nov 07, 2012, 06:26 AM
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Magnasanti... Are you making ports for a vented speaker enclosure? (apologies if you're not) If you are then forget prepreg. It's not neccessary.

Ive been into speaker building for many years and I can tell you this. The material a port is made from will make little to no difference to the sound! You're better off buying off the self ports such as the PSP ports. The 100mm dimpled flared port is nice.

There's no need to go prepreg! save yourself the hassel. If you really want to Id love to hear your reasons behind doing so. I cannot think of a means to justify the cause but if you can please share?

Ben
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Old Nov 07, 2012, 10:46 PM
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no actually this is for the speaker diaphragm its self its made to pulsate like a balloon to give a 3d sound wave
http://imgur.com/edit
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Old Nov 08, 2012, 12:12 AM
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Why dont you contact

whom it is that makes this part your trying to copy? That way you would get what your looking for. Trying to get some prepeg made to your exacting specifications is going to be a bit of an exotic challenge for the toy airplane builders in this forum your posting on. There are composite forums that may be more in line for this, but your most likely looking a minimum order production run. What sort of quantity are you looking for? Getting specific and exacting as you want from someone that can certify the material is going to cost id bet a small fortune. Out of date surplus or uncertified material that could be utilized you can purchase in minimal amounts.

I may be wrong but I am guessing your not wanting a 100 yard production run.

It has already been pointed out that this is going to be a difficult target to hit - even if you find someone to help make it.

Can you give us a clue what it is your trying to end up with so we can grasp the concept?

I keep reading about autoclaves and prepegs with specific resin content - and you don't know what type of resin you need which could change the performance of the component even if you get your 54% 46% right. You need the 46% of the resin that the part your copying is made from if your trying to get an exact duplication. Epoxies have differing characteristic's just the same as the fibers do. The term composite is just this a composition of materials.

46% resin content is not going to duplicate your component unless you duplicate the exact resin and process it the same as who your copying does it.

There are more variables than just 54/46
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Last edited by Air Head; Nov 08, 2012 at 12:34 AM.
Old Nov 08, 2012, 02:49 AM
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Anymore info on this speaker? Sounds interesting.
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Old Nov 11, 2012, 02:51 PM
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The speaker company MBL. The company is ran in Germany and only has about 50 employees they are very secretive about their world renowned technology. there cheapest "budget" speakers cost 16,000. It would be very hard to find out the resin they use, although possible with lots of work. Since this is a commercial establishment they must use prepeg for the convenience as well as the R/C ratio.
From what I know they cure the composite in an autoclave at a high heat and pressure, and can be stored for months. I have MGS resin since it is supposedly the best I have enough carbon fiber to spare to experiment with this resin system and test the sound produced with a high end calibrated microphone. I want a production run for maybe 12 cures. This isn't for commercial purposes only diy.
I want to use MGS, Samurai carbon fiber and prepped at 54/46. I would also like to vacuum bag/oven cure. or vacuum bag let cure and then post cure in my oven.

Edit I have all of the components listed: MGS, Samurai carbon, and all the vacuum materials and prepeg liner needed only need assistance and someone to provide the vacuum pump

http://www.mbl-northamerica.com/main/
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Old Nov 11, 2012, 08:48 PM
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Just because they use a 54:46 (by weight) prepreg doesn't mean that the final part has that ratio. The ratio of the final part is what matters and will be critical to specify for a producer.

A producer will be reluctant to help you because you are trying to specify the process rather the properties of the final product. There are many ways to process a composite to yield similar properties. Specify the properties and let the producer worry about the process.

Also, MGS is one of the best room temp. curable epoxy resin. Autoclave high temp resin are a different animal that exhibit much higher HDT-Tg properties. MGS 285 and 385 will never have the Tg and HDT of an autoclave cured pre-preg resin.

Also, a vacuum pump can be acquired for the cost of 2 yards of Samurai fabric.
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Old Nov 12, 2012, 01:11 AM
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Firstly I dont know about your experience with composites or speaker building. I hope you have atleast a few years experience with both before attempting something like this..

Seams to me that for these speakers to work the ballon must flex under the driving force of the magnet motor. This then propogates soundwaves, very accurately according the pricetag.

My honest advice is to experiment without the pregreg and vaccum bags first till you find out that what you're trying to do has potential.

Have you had hands on experience with these speakers before? Having a close look at one would help alot!

There are alot of different resins out there that will majorly effect how the speaker produces sound. Composites are difficult enough without bringing resonances and harmonics into the equation. It could very well turn out MGS resin could be the worst resin for what you're trying to do.

I apologise if im coming across over critical but. You are talking about high end processing, pre preg, vac bagging and possible autoclave use so im assuming you are wanting a very high end result. A high end result isnt going to ever happen if you dont put in the hard work yourself.

Im not that concerned about the composite side of things as compared to designing a speaker like this composites are easy.
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Old Nov 12, 2012, 05:07 AM
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Quote:
Originally Posted by wyowindworks View Post
Just because they use a 54:46 (by weight) prepreg doesn't mean that the final part has that ratio. The ratio of the final part is what matters and will be critical to specify for a producer.

A producer will be reluctant to help you because you are trying to specify the process rather the properties of the final product. There are many ways to process a composite to yield similar properties. Specify the properties and let the producer worry about the process.

Also, MGS is one of the best room temp. curable epoxy resin. Autoclave high temp resin are a different animal that exhibit much higher HDT-Tg properties. MGS 285 and 385 will never have the Tg and HDT of an autoclave cured pre-preg resin.

Also, a vacuum pump can be acquired for the cost of 2 yards of Samurai fabric.
I am not sure if HDT, and tg really matter in my application
the properties would be impossible to acquire through any method
the overall properties MBL went for are: dampening, stiffness "a perfect balance"
light weight and ability to flex and deflection to original shape quickness
Since I have MGS it is worth a try at least to do a wet layup and test to see if the properties are adequate. I have spoken to a person who has tried this same project still working on it 3 years later and he says he tried many different resins
and he suggested this. he also said pressuring the composite while curing and posy curing is important.

http://www.ebay.it/itm/RESINA-EPOSSI...-/260664550506
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