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pre-preg pinholes.. driving me crazy
pre-preg pinholes.. driving me crazy
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pre-preg pinholes.. driving me crazy
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roger sbk composites
roger sbk composites
posted 11 Years Ago
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this is the third part that comes out exactly the same and i've done 3 diff things so far.... my kitchen oven minum is 76c so i leave that 2 hours and then take it to 110c this time i added peelply on the edges but nothing... the stack is as fallowed 2 layers of pre-preg aviation no face side... ... eassycomposite unperforated release film and breather all over the mold put inside a bag and full vac... any ideas guys... this is dirving me crazy already
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morepower
morepower
posted 11 Years Ago
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Ok... Cool.. I know Nick from 666 and I know who made some of his moulds... long story and quite dull or not depending on who's side you hear....lol.. I had use of his hugger mould (made by the guy who made some of the 666 moulds) and it was full of stress cracks... I dont think they looked after the moulds too well at times..lol.
The pre-preg my be one of the problems as it sounds like it is an autoclave only pre-preg. The only off the shelf out of autoclave pre-preg that works is either VTF261 from Cytec in Derbyshire (50 meter minimum order now apparently) or Easypreg from Easy Composites (it is the same stuff.....). I know it works but I also have to say people have had some issues with pin holes with it too as it is not a guaranteed pinhole free finish even though you can get those results.
I use a material from another supplier which works very well but is not one they sell as a comparable material to VTF261, I just happen to have found a way to make it work.. It is part breather stack and part curing shedule and it took me 6 months of testing to find a way that would work each time I laid up a part.
The oven is not a secret and not hard to make up to be honest but it has to be well controlled and very little temperature difference between the top and bottom and I have at worst 1 degree difference top to bottom... it takes anything from 30 minutes to a day to set up how it works though.... If you imagine a open box with one side open. You need to make it so air is blown down one side (a narrow channel is enough) to the deepest point of the box then flow back out of the box again. Then you need to have a sliding door to close and stop all of the hot air just spilling out again. It has to let some air out but keep most of the heat in... The door slides to let me control how much air comes out.. Too much and the oven loses temperature... Not enough it also loses temperature but will over heat the fan heater... You need to keep air flowing at all times....
One of these will do..
http://www.ebay.co.uk/itm/3KW-10200BTU-Industrial-Workshop-Square-Fan-Space-Heater-Electric-Fire-2580-Kcal-/201006642821?pt=UK_Home_Garden_Hearing_Cooling_Air&hash=item2eccedf685
You will need a controller and relay plus a box to fit it all into.. eBay is your friend......lol. The hard part is sorting out the wiring to keep the motor going when the heating element is turned off by the controller.. You will need to remove the over heat protection from the box or find one which will let you get up to at least 90 degrees.. That heater has two one for the lowest power setting and 20 degrees I think and the second one is up to 65 degrees on medium and high power... Get an electrician to sort it out..... it is not hard but does take some thinking about... Then you have the oven....
You will need to work out how to get your material to cure yourself though... each pre-preg is different...
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Matthieu Libeert
Matthieu Libeert
posted 11 Years Ago
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I've made this video a few months ago, using the prepreg for Easycomposites.
Just like morepower says it's a matter of some trial and error in the beginning and you working with good materials is probably the start.
You can not use autoclave designed prepreg for Out of autoclave prepreg making... Easycomposites sells a finishing prepreg, it is a bit more resin rich giving a pinhole finish!
It's also very easy to put down because it has a tackfree backing. It is very important to lay your prepreg down against the mould. A perfect vacuum without leaks is a must! you may not have any bridging into your releaselayer at the bag and the bag must be tightly against the materials/moulds....
by saying all of this, a lot can go wrong...but after a while you kind of get that feeling when you know everything will go well...
Matthieu Libeert
Founder MAT2 Composites X Sports
website:
www.mat2composites.com
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pre-preg pinholes.. driving me crazy
roger sbk composites
-
11 Years Ago
left one is the previous one.. wich i started sanding to try and recover the part......
roger sbk composites
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11 Years Ago
Looks like bridging from the pictures. You haven't got the cloth into the recesses in the mould....
wozza
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11 Years Ago
Yep looks like bridging on the corners and the pin holes are going to be a problem until you can...
morepower
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11 Years Ago
i put breather EVERYWHERE.......
roger sbk composites
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11 Years Ago
more power.... want to sell me those plans for the cardboard box oven please :-)
roger sbk composites
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11 Years Ago
Ok... Cool.. I know Nick from 666 and I know who made some of his moulds... long story and quite...
morepower
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11 Years Ago
I've made this video a few months ago, using the prepreg for Easycomposites....
matthieutje65
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11 Years Ago
thanks guy.. ive seen that video im subscribed to you... i know about the eassy preg... the problem...
roger sbk composites
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11 Years Ago
Yes I cut the sides and matched them in.... Plain weave is harder to find I use a plain weave but it...
morepower
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11 Years Ago
The thing you could do is use easypreg finishing layer behind that plain weave to add some resin...
matthieutje65
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11 Years Ago
[quote][b]matthieutje65 (20/01/2014)[/b][hr]The thing you could do is use easypreg finishing layer...
morepower
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11 Years Ago
i have a crazy idea let me know if this would work.. well i live in tropical country of costa rica...
roger sbk composites
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11 Years Ago
Haha..... the sun might just do it..... I will sort something a little more specific and try and...
morepower
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11 Years Ago
well for the ones watching and wondering i will be making another test today... this time with...
roger sbk composites
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11 Years Ago
ok im running a second test on a second vac pump in my kitchen oven... this time i put the mold...
roger sbk composites
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11 Years Ago
Ramping up is not just increasing the temp by 20 degrees, it is linear increase of temperature,...
baja_patient
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11 Years Ago
ok after cooking for 8 hours at 60C then 1 hour at 110 here is the results i can count about 5-6 pin...
roger sbk composites
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11 Years Ago
looking better... Once you get a part that works you need to do it about 3 times to make sure you...
morepower
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11 Years Ago
def cooking low temp is the trick compared to the other horrible fast cooked parts i say its not so...
roger sbk composites
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11 Years Ago
found a picture of the first part fast cooked...
roger sbk composites
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11 Years Ago
thanks to the endless help from more poweri decided to try out the VARI-PREG fabric from eassy...
roger sbk composites
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11 Years Ago
That is not bad.... As you say, you need to get your layup techniques down a little more.. You need...
morepower
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11 Years Ago
You have bridging for sure. You can see how some of the resin has tried to fill the voids and...
fgayford
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11 Years Ago
Hey I am new here but I am mechanical engineer and here are my thoughts. You have bridging for sure...
combustioncraig
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11 Years Ago
hey guys i have some updates... i found that bridging was the problem and also my layup as in plain...
roger sbk composites
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11 Years Ago
Nice to see progress mate, got any more pics of ur oven? Inside oven? Regards
Djekouk
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11 Years Ago
yeah sure... after two hours of tunning the oven... and drilling venting holes i finaly got it...
roger sbk composites
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11 Years Ago
Whats the black thing on the white heater? In ur last pic. Do u use only 1 external heater blower?
Djekouk
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11 Years Ago
Cool design :-)
Djekouk
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11 Years Ago
Get one of these too... It can be used on the parts you cook as a check of the actual temp of the...
morepower
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11 Years Ago
the black thing is a second heater as that 1500 watt max temp was 60c constant running so i added...
roger sbk composites
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11 Years Ago
[quote][b]roger sbk composites (22/02/2014)[/b][hr]the black thing is a second heater as that 1500...
Djekouk
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11 Years Ago
No problem let go on pm
roger sbk composites
-
11 Years Ago
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