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 HOT Post Details
Group: Forum Members Posts: 17, Visits: 163	No problem let go on pm
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Djekouk	Djekouk posted 11 Years Ago HOT Post Details
Group: Forum Members Posts: 30, Visits: 987	roger sbk composites (22/02/2014) the black thing is a second heater as that 1500 watt max temp was 60c constant running so i added the second one and now they both come on on and of.... morepower i actualy purchased this one wich has two and wireless also.. check you pm http://www.ebay.com/itm/131102947836?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649 and i also purcahsed 6 of these to mount in a box and be able to know the temp of all the molds in there http://www.ebay.com/itm/331132715664?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649 I see u used mdf boards, are u using any insulation to keep temp? Or just closed mdf box? Im in the process of moving to prepreg as i have found awesomely cheap ooa prepreg here in turkey which they claim the results are pinholefree in oven only prepregs. May be i can getaway without getting an autoclave. (Altho i have quote for autoclave £500 yes 5 hundred quid without the heating elements, its a 500 litre and will be made from 8mm thick steel) so how big is ur oven? How long does it takes to get the relevant temp? Sorry for loads of question :-) Regards
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roger sbk composites	roger sbk composites posted 11 Years Ago HOT Post Details
Group: Forum Members Posts: 17, Visits: 163	the black thing is a second heater as that 1500 watt max temp was 60c constant running so i added the second one and now they both come on on and of.... morepower i actualy purchased this one wich has two and wireless also.. check you pm http://www.ebay.com/itm/131102947836?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649 and i also purcahsed 6 of these to mount in a box and be able to know the temp of all the molds in there http://www.ebay.com/itm/331132715664?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649
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Djekouk	Djekouk posted 11 Years Ago HOT Post Details
Group: Forum Members Posts: 30, Visits: 987	Whats the black thing on the white heater? In ur last pic. Do u use only 1 external heater blower?
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morepower	morepower posted 11 Years Ago HOT Post Details
Group: Forum Members Posts: 242, Visits: 1.2K	Get one of these too... It can be used on the parts you cook as a check of the actual temp of the mould/part as it cures. You can also use it now as you set up the oven.. I checked mine in at least 6 different locations front to back and top to bottom.. http://www.ebay.com/itm/ET72-Maverick-RediChek-Remote-Wireless-Meat-Probe-Thermometer-6-Taste-Settings-/300934234856?pt=LH_DefaultDomain_0&hash=item46111402e8 It is very basic for an oven but you will see once set up works very well...
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Djekouk	Djekouk posted 11 Years Ago HOT Post Details
Group: Forum Members Posts: 30, Visits: 987	Cool design :-)
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roger sbk composites	roger sbk composites posted 11 Years Ago HOT Post Details
Group: Forum Members Posts: 17, Visits: 163	yeah sure... after two hours of tunning the oven... and drilling venting holes i finaly got it stable and i had to add a second air heater and also brake little tabs on the termostat that the original airheaters bring to be able to adjust it behond the limits... thats untill the controler gets here... also you have to bypass the fan ... fan needs to stay on and only the heating elements be controled untill the controler gets here i wont be doing any overnight stuff i also plan on putting a braker switch board for all this just in case... and well this is only 50% of the way stable oven ... "EMPTY" now i need to see what it does full of molds because it can easy take an entire motorcycle fairing set
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Djekouk	Djekouk posted 11 Years Ago HOT Post Details
Group: Forum Members Posts: 30, Visits: 987	Nice to see progress mate, got any more pics of ur oven? Inside oven? Regards
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roger sbk composites	roger sbk composites posted 11 Years Ago HOT Post Details
Group: Forum Members Posts: 17, Visits: 163	hey guys i have some updates... i found that bridging was the problem and also my layup as in plain weave i tried to do all at once and was imposible unlike twill... here are some other i have managed to pull out and clear coat here is a test someother tests here is my radiator shroud of my bike i did with the same autoclave fabric with debulking ect. and very slow cooking for 14 hours and was almost perfect and i finaly got around to making the oven and the key is in the slow cooking and slowing everything down and full vacuum i now debulk all my parts for about 3 hours in between layer and debulk another 3 hours BEFORE i actualy cook them i will start testing parts of this oven shortly and i've also started using VARI-PREG system from easycomposites.. as a surface layer so lets see how the tests come out on the new oven stay tuned Edited 11 Years Ago by roger sbk composites
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combustioncraig	combustioncraig posted 11 Years Ago HOT Post Details
Group: Forum Members Posts: 26, Visits: 46	Hey I am new here but I am mechanical engineer and here are my thoughts. You have bridging for sure like everyone else has pointed out. I would try using a heat gun to get the prepreg pliable (but sticky trade offs) and a tool like the lil'chizlers (or any Vinyl wrap applying tools) to push the Prepreg down into the voids. It is also recommended to debulk after the first layer and then every 4-5 later after that. Doing so gets expensive quick unless you are using some sort of RVB (reusable vacuum bag). You also might be able to order just sheets of epoxy resin (at least you can here in the USA). This is a less ideal option as you will have very resin rich areas that are weaker but if you are just going for surface finish it might be a option (make sure the resins have the same cure rate as your prepreg). Hope this plus slower the ramp rate/ longer dwell time at low temp cures the problems. Also lacquer and clear coat may become your new best friends if you continue to have problems. On a side note I am going to be doing a test with some low temp epoxy prepreg for a autoclave and add a thin sheet of epoxy resin (same resin and same supplier) and see how it affects the surface finish. I am doing this because after using easy composites surface layer prepreg(resin rich stuff) I thought I might try it. If it does work this will save a ton of money but I am not too hopeful. I will do some ultrasonic testing and cut a few layers apart to see if the interior layers are full of pin holes as well just to prove the concept.
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