Dear friends of Easy Composites,

 

First of all, I would like to congratulate youfor your complete web site (also carbonmods) and your very well explainedvideos.

I write you because I plan to start a projectwith carbon fiber very soon and even though I have been reading a lot about howcomposites function and also watching all your videos in youtube, still I havesome unanswered questions related to my project. Hope you can help me a littlebit with that.

My project consists in making a transport casefor my musical instrument. But I have several problems mostly in how to makethe first steps and also in which way I can get the best possible results.

1. I am planning to make a mould, but I wouldn’tlike to put any wax or release agent, gel coat etc. over my expensiveinstrument. So I thought about making a copy of the structure with metal plateor with foam. Which material do you think works better for making round edgesin several directions?

Then I am thinking about two possibilities: oneis to use the structure made with the new material as a mould and apply thecarbon fiber layers over that structure following a kind of skinning process inorder to make the case around of it. Is it possible? How should I proceed foravoiding the metal or foam to get stuck to the carbon fiber? The best qualityresult should be in that case the outer layer, is it possible to get nice resultsin the last applied layer with this system? Should I sand paper it and polishit later for getting the good results?

The second possibility is to do the opposite:create a mould from the copied structure of the instrument and then work likewith a normal mould, applying the carbon layers inside the mould.

 

2. Then, my instrument is very sensitive totemperature changes, and is very common that it’s damaged going from -20ºC instreet to +22ºC in a room. I was thinking in putting a layer of carbon fibre,layer of Kevlar and layer of carbon fiber, because I don’t want to be too thickcase. What do you think? Is Kevlar good thermic isolator? Do you recommend someother material for this purpose compatible with epoxy resin?

 

3. I was thinking about placing a special foamhigh resistance to impacts and also thermic isolator. Do you know some foam suitablefor this purpose? Which is the best way of attaching the foam to the compositecase? Do I need special glue for that or what do you recommend?

 

4. And the last question, I would need also toseal the two parts of the case when they close. Would be perfect to find amaterial which could seal air-tightly and isolates temperature. I have readthat PVC is quite good on that. Do you recommend some material for this? Is PVCcompatible with epoxy resin? How can I attach it to the composite?

I am sorry about asking so many questions, but I amtrying to figure out by myself taking out a lot of sleeping hours and I can’tfind the answers.

Thank you very much in advance for your patienceand attention, and hope to read soon from you.

Best Regards!

 

Hi,

Thanks for your detailed post and sorry for the delay in getting back to you. Warren has given some good advice.

I'll try to answer all your points:

1. I agree entirely with Warren. If you can 'copy' an existing case (and you're happy with its size/shape/design) then do that - use the case as a 'pattern' and make a mould using that pattern. This will leave you with a female mould that's the right shape for your instrument and with a good finish on the inside (which will become the outside of your part).

If you can't find a case like this then you should certainly look at making a 'pattern' for the case. I would imagine this pattern would be a simpler, smoother shape than the exact shape of the instrument and also be larger (maybe considerably larger) in order to accomodate the foam lining that you will use inside the case. For this reason, applying anything to your instrument itself is not neccessary and would not really help, far better to start from scratch making a foam or MDF pattern and then make moulds from this pattern (like you would if you were copying an existing case).

2. Again, Warren is spot-on. Kevlar is a reasonable insulator and because of its VERY high tempertaure tollerance it does get used in some insulation applications but this is always for protection from very hgih heat, not because Kevlar has a particuarly high U-Value. At the thickness you would be using the Kevlar its thermal insulation performance would be pretty insignificant. For thermal insulation (and shock protection) foam would be a very good idea.

Don't worry about the compatibility of the foam with epoxy because you'll be making the case first and then bonding the foam into the case, which you can use any contact adhesive to do.

3. As above, I think foam is a good idea. Profiled polyether foam ('eggbox foam') is great for lining cases and suchlike. You could also consider 'memory' foams. We don't supply these materials and they're quite bulky so I would suggest just checking with some local suppliers.

4. This one's more of a question of what system you can find. If you've got two surfaces that come together pefectly then you should be able to find an off-the-shelf sealing system somewhere (although I can't recommend anything myself). Try checking with seals suppliers or silicone extruders to see if they have a section that would suit. My guess would be a silicone or rubber section that's bonded to one side fo the case and then accepts and seals with the other side of the case shell.

I hope this helps and look forward to working with you.

Best regards, Matt

Matt Statham
Easy Composites / Carbon Mods - Technical Sales