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Lightweight carbon fibre dual 8" 18/36V BUILD

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Keivn.Pawlus View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Keivn.Pawlus Quote  Post ReplyReply Direct Link To This Post Posted: 29 October 2017 at 8:16pm
Originally posted by Hemisphere Hemisphere wrote:

I notice you mention 10mm foam and 3/4 layers of carbon - you might want to reconsider this for future builds.

The science of layered glass/carbon and foam composite structures is that the rigidity is mostly determined by the thickness of the foam. I saw a chart which illustrated this once and it's a steep exponential curve. 20mm is several times stronger than 10mm despite costing and weighing almost the same. You could save a layer or two of carbon or comfortably substitute cheaper and easier to work with glass by using more substantial foam.

Also you probably want it to have as many layers inside as out or the panel flex will be uneven. 3 in 3 out would certainly be preferable to 2 in 4 out.

Thanks for the tip. When you say it, I think I have read it somewear also. 


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Post Options Post Options   Thanks (0) Thanks(0)   Quote Keivn.Pawlus Quote  Post ReplyReply Direct Link To This Post Posted: 29 October 2017 at 8:27pm
Some problems did occur when i tried to release the mould. It was completely impossible to release.
I think the main reason for this was the shape of the mould, I ended up scrapping the whole project and started from the beginning again.

https://postimg.org/image/15myuztusr/ -

https://postimg.org/image/6klhdfaah7/ -

This time I will try with a 4-piece split mould instead of a 2-piece split. Also a different release agent this time. 

Thank you for all the comments so farSmile
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Hemisphere Quote  Post ReplyReply Direct Link To This Post Posted: 29 October 2017 at 9:57pm
Have you considered revising the design to a more simple hand layup with flat panels? There are some very well documented foam core builds on the TalkBass forums - the ZacLite builds especially, although many of the images are now dead links

People on diyaudio talk about foam core builds quite a bit as well but I didn't see any comprehensive documenting of the builds and theory behind it as on TalkBass.

I used 25mm foam and 2 layers of 185gsm glass on each side (plus a bit extra here and there and some bracing inside). Feels solid as a decent wooden cab to me and does the job on the sound, haven't measured it or a/b with a wooden equivalent though. That's woven roving of course not CSM. Ideally you can get an even tighter knit weave of glass cloth, e-glass it may be called. The tighter the weave the better and it'll always be way cheaper than carbon.

The process was messy and laborious and the finish tricky, but the guys on TalkBass did a much better job with similar results.

Edited by Hemisphere - 29 October 2017 at 10:00pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Hemisphere Quote  Post ReplyReply Direct Link To This Post Posted: 29 October 2017 at 10:16pm
Did you use mould release wax on the mould or something else to aid release? I'm not sure if this is a silly question or not as I know nothing about glass moulding
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Post Options Post Options   Thanks (0) Thanks(0)   Quote SouthwestCNC Quote  Post ReplyReply Direct Link To This Post Posted: 29 October 2017 at 10:24pm
Originally posted by Keivn.Pawlus Keivn.Pawlus wrote:

Some problems did occur when i tried to release the mould. It was completely impossible to release.
I think the main reason for this was the shape of the mould, I ended up scrapping the whole project and started from the beginning again.

https://postimg.org/image/15myuztusr/ - </a>

https://postimg.org/image/6klhdfaah7/ - </a>

This time I will try with a 4-piece split mould instead of a 2-piece split. Also a different release agent this time. 

Thank you for all the comments so farSmile



What product are you using to finish your mould in? A strene based product requires a week minimum to stop leaching before you try taking a pull from it. 10 coats of semi permanent release works a charm on new moulds. And compressed air and blower is your friend when it comes to release it.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Keivn.Pawlus Quote  Post ReplyReply Direct Link To This Post Posted: 20 November 2017 at 7:56pm
Originally posted by Hemisphere Hemisphere wrote:

Did you use mould release wax on the mould or something else to aid release? I'm not sure if this is a silly question or not as I know nothing about glass moulding

Yes, the first time I used one coat PVA release agent. And I had to scrap it, it was impossible to remove.
I think the problem was caused by the shape of the mould and also the surface finish. So i'm not saying its a bad release but it didn't work for me.

Second time i used 6 coats of easycomposites Easy-Lease. It came of very easy Tongue The second time I also build an 4-piece split mould
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Keivn.Pawlus Quote  Post ReplyReply Direct Link To This Post Posted: 20 November 2017 at 7:58pm
Originally posted by SouthwestCNC SouthwestCNC wrote:

Originally posted by Keivn.Pawlus Keivn.Pawlus wrote:

Some problems did occur when i tried to release the mould. It was completely impossible to release.
I think the main reason for this was the shape of the mould, I ended up scrapping the whole project and started from the beginning again.

https://postimg.org/image/15myuztusr/ - </a>

https://postimg.org/image/6klhdfaah7/ - </a>

This time I will try with a 4-piece split mould instead of a 2-piece split. Also a different release agent this time. 

Thank you for all the comments so farSmile



What product are you using to finish your mould in? A strene based product requires a week minimum to stop leaching before you try taking a pull from it. 10 coats of semi permanent release works a charm on new moulds. And compressed air and blower is your friend when it comes to release it.

I used the complete"Uni-Mould Making System" from Easycomposites. Everything worked very well
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Keivn.Pawlus Quote  Post ReplyReply Direct Link To This Post Posted: 20 November 2017 at 8:01pm
This is the second attempt, everything has worked so far. Now I have some polishing to do before I can start with the carbon fibre.







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Post Options Post Options   Thanks (0) Thanks(0)   Quote Keivn.Pawlus Quote  Post ReplyReply Direct Link To This Post Posted: 01 August 2019 at 7:28pm
After two years I¨m almost finished. This project had taken far more time than I first though.
I also learned that carbon fibre is very hard work with. Right now ïm waiting on two coils that I have ordered and hopefully I will have them tomorrow. Then i can build the crossover






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Post Options Post Options   Thanks (0) Thanks(0)   Quote Keivn.Pawlus Quote  Post ReplyReply Direct Link To This Post Posted: 12 August 2019 at 8:06pm

The only thing left now is the grill.



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