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oekmont
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Hanaldo surely has way more experience in moulding than you, maybe than me, too. Mat and Warren (and myself) think that vacuum bagging isn't needed for mould making, too. So I find your behaviour quite strange. All those guys know what they are talking about.
You could perfectly vacuum bag your mould, but
A: why would you, if you can do it without (weight isn't an issue usually)
B: vacuum bagging complex hollow objects can lead to difficulties.
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Eddie Walsh
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+x+xWhen you rub or break by hand a powder pound CSM, then usually you will get a white powder falling off as you rub or break it. Vacuum bagging is generally not necessary. For example, the putty if correctly applied, will fill the sharp corners and recesseses - thus no voids. The laying up of the cloth is then much easier and just requires good quality laminating by hand to achieve a void free finish. So there is little to gain from vacuum bagging that hasn't already been achieved through proper and good quality laminating. In theory it may well help for very high temperature applications but this is rare and i have not heard of anyone vacuum bagging the moulds even in this situation. I would expand on what Warren said - The important part is getting the gel coat into all the corners and crevices. As this is like a very thick paint when warm, you can't vacuum bag it as it will simply squish all over the place!. You then add the paste whilst the gel coat is still tacky (but firm enough that pushing on the paste doesn't disturb it- correct me if I am wrong Warren or Paul, but I use the fingerprint test, if my finger leaves a print but the gel doesn't come off on my finger it is ready for the next stage) and then add the fibreglass over the whole lot. For smallish parts I use an old domestic oven bought from eBay. There are plenty on there, here is an example. Simply drill a hole through the side for the vacuum tube :-) https://www.ebay.co.uk/itm/neff-Electric-oven-You-Arrange-Courier-Or-Collect/323346305953?hash=item4b48f113a1%3Ag%3AKUAAAOSwpz5bR6-N&_sacat=0&_nkw=domestic+oven+electric&_from=R40&LH_ItemCondition=4&rt=nc&_trksid=m570.l1313 Hi Steve, Don't get me wrong, but I know the basics as I have been doing Fiberglas for over 30 years, so I have lots of Moulds and am forever repairing then, mainly because they were not made well to start with, none have been Vacuum Bagged, so now I want to start learning the correct way and Materials to do CF, so want to start with Hand Layup and Air dry, and if I get on with then I will buy a large oven to accommodate large panels such as Bonnets, doors, Undertrays, the Ferrari Undertrays are very large approx 6ft X 4.5 ft, so I do not want to run before I can walk, Like I said to Warren the Mould is the most important tool as it is going to be used lots of times, and especially if you have a perfect item to Mould the last thing you want to be doing is repairs to a new Mould, so when I found this Forum I was hoping for some great advice, but when someone says no need to VB your Mould I find it very hard to believe that that is best practice, so anyway I will persevere and try VBing my Moulds, so thanks for all you advice and help, I will let you know how I get on, Regards DM
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Steve Broad
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Group: Forum Members
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+xWhen you rub or break by hand a powder pound CSM, then usually you will get a white powder falling off as you rub or break it. Vacuum bagging is generally not necessary. For example, the putty if correctly applied, will fill the sharp corners and recesseses - thus no voids. The laying up of the cloth is then much easier and just requires good quality laminating by hand to achieve a void free finish. So there is little to gain from vacuum bagging that hasn't already been achieved through proper and good quality laminating. In theory it may well help for very high temperature applications but this is rare and i have not heard of anyone vacuum bagging the moulds even in this situation. I would expand on what Warren said - The important part is getting the gel coat into all the corners and crevices. As this is like a very thick paint when warm, you can't vacuum bag it as it will simply squish all over the place!. You then add the paste whilst the gel coat is still tacky (but firm enough that pushing on the paste doesn't disturb it- correct me if I am wrong Warren or Paul, but I use the fingerprint test, if my finger leaves a print but the gel doesn't come off on my finger it is ready for the next stage) and then add the fibreglass over the whole lot. For smallish parts I use an old domestic oven bought from eBay. There are plenty on there, here is an example. Simply drill a hole through the side for the vacuum tube :-) https://www.ebay.co.uk/itm/neff-Electric-oven-You-Arrange-Courier-Or-Collect/323346305953?hash=item4b48f113a1%3Ag%3AKUAAAOSwpz5bR6-N&_sacat=0&_nkw=domestic+oven+electric&_from=R40&LH_ItemCondition=4&rt=nc&_trksid=m570.l1313
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Warren (Staff)
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Group: Administrators
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When you rub or break by hand a powder pound CSM, then usually you will get a white powder falling off as you rub or break it.
Vacuum bagging is generally not necessary. For example, the putty if correctly applied, will fill the sharp corners and recesseses - thus no voids. The laying up of the cloth is then much easier and just requires good quality laminating by hand to achieve a void free finish. So there is little to gain from vacuum bagging that hasn't already been achieved through proper and good quality laminating.
In theory it may well help for very high temperature applications but this is rare and i have not heard of anyone vacuum bagging the moulds even in this situation.
Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant
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Eddie Walsh
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Group: Forum Members
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+x+xHi Matt, Thanks again,as you can imagine I have quite a bit of Chopped mat Strand which I have used for my Fibreglassin so can I still use this with your HT Gel and Resin, also my MEKcat is that compatible, as I do not want to mix the wrong one and ruin my Mould etc, what is the polypropylene sheet for ( or is that the corrugated sign board ?) so again Thanks for all the help, Regards DM Hi Matt, another observation ??? looking at your Video Making the Bonnet Mould for the 27th time I suddenly realised you did not Vacuum Bag it and especially on the first layer over the Gel Coat which is the most important coat to make sure there was no air bubbles or voids under the gel, as I could understand no reason to VB any further layers, as the Mould is the most important piece to get spot on as hopefully you will be using for lots and lots of Mouldings ?? Regards DM Which kind of chopped strand matting do you have? Typically there is emulsion bound and powder bound. Epoxy lacks the solvents required to break down the emulsion binder, so we recommend the use of powder bound CSM as any resin will break the binder much easier. You will NOT need MEKP for our EL160 and EG160 as both are epoxy based and have their own specialist hardeners that need to be used. The polypropylene sheet is for use as a baseboard and to create flanges. Fluted signboard can be used to do the same thing albeit the surface finish is slightly ribbed compared to the perfectly smooth finish of pure polypropylene sheet.. Generally speaking, vacuum bagging is not needed for mould making. Wet lay mould making like suggested for your project is done without any vacuum bagging. As long as you pay careful attention to applying the gelcoat properly and the first layer of putty and glass, then you should not have any voids to worry about. You may be thinking of tooling pre-pregs, where depending on the system used and mould size, thickness etc, vacuum debulking may be necessary. Hi Warren, I do not know what type of CFM I have it is what I used for Fiberglassing ?? so how can I tell, it does not say on the label. I am just amazed that you do not recommend Vbing your Mould, as with my Airbox and the intricate Flange there is no way I could lay up and be sure I got all the air out and the Paste and Glass forced right into the very tight corners, as the last thing I want to be doing is trying to repair the Flange in my mould once released, a major nightmare, Regards DM
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Eddie Walsh
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Group: Forum Members
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+x+x+x+x+x+x+x+x+x+xHi I have been looking at this Air Box and trying to figure out how I can Vaccum Bag ??? to me looks impossible, so any help appreciated, Regards DM Hi There, Actually, I think you might be overthinking it. Unless there's something I'm missing - I'm assuming that the bottom face which we can't see it completely open - The the bag would actually be very simple, it would just need to also be very large (like more than twice the size of the part). I can't see the mould so I don't know if you're planning to envelope bag or tape to the mould flange but the principle would be the same either way. If the bag was large enough you could just feed two 'socks' of bag into the inlet tubes and then would blank off at the mouth of the tubes (again, I can't see the mould but I assume the mould too blanks off at the mouth of these inlet tubes). As Steve has posted we also don't know what the rectangle is but I'm assuming it's just a cuboid shaped recess which is fully closed off, in which case you could just bag around this using the huge excesses of bag I'm suggesting again too. If you were envelope bagging then just imagine an absolutely massive bag with the part and mould inside and the bag sealed all around. When you do this you can picture yourself just stuffing bag into those two inlets (as though you'd fashioned some tube shapes from the big bag and fed them into these inlets) and then and the rest into the main area. I hope this helps but if I've missed something then let me know! Hi Matt, Thanks, as yet I have not made the Mould ( The Pic I got Online) so just trying to figure out how to go about it, this is just to top part of the air box as the bottom rectangular portion is completely open as the Air Filter sits between the top and bottom portion, also the 2 round tube sections are completely open, and also the ends of the tubes have quite a hefty Flange which is used to bolt to the MAF's ?/ so how would I go about these flanges as well, again I will enclose 2 more pics, and thanks for all your help, I will get to make some CF parts very very soon with your help,Regards DM Well, the inlet tubes would have been blanked off in the mould and then cut open when the part is trimmed. Knowing that will probably change how you think about the bagging. As for the flanges, they are quite likely to be separate components that are bonded on afterwards but they don't have to be. I can't really see from the images but you could either make them as separate parts or set up removable barriers on the mould to form these flanges. Hi Matt, Looking at Steve's pic of his mould with both ends open, so looks like he just stuffed one end of his bag through one end of his mould and out the other end, and then pulled the other end of his bag over his mould and back to same end and sealed it there,?? is that correct, as my Airbox is very similar only difference is I have 3 openings, so is there any need for me to Blanks off the round open ends of mine, again thanks, Regards DM The blanking off was not really to make the bagging easier or possible (it's both of these things with or without the blanking), I was only pointing out that blanking off these opening on the moulding would be quite a normal way to make the mould (which you've not done yet). There's a lot of posts and input on this now so I'll try not to confuse matters any more for you. There is no problem bagging the shape you want to bag, with or without blanking off some of the inlets and as Hanaldo has pointed out I think we've covered well the basic principle of bagging a tubular shape in our airbox video where you can see that the principle would be the same whether you have one, two or more openings. Make your mould with confidence, when you get to the bagging stage, it will be do-able! Hi Matt/ Steve, and everyone else who advised, Yes I know you are all right, it is only me having to understand the process, as being an older Fiberglasser and over the years have had a few Major blunders where what could go wrong went wrong like trapped Moldings etc, so again Thanks for all the advise and help, I will bite the bullet very soon, Regards DM Trapped moulds, been there and got the relevant T-Shirt :-) Hi Steve and matt, I am almost ready to start, rather than Moulding the Air Box from my 458 I have just bought one from Ebay so I can still use my car, so first question how would you go about moulding it ?? as far as I can judge it will have to be a two part mould so split down the middle ?, so what material do I need to make my Mould, I will do all hand wet layup air dry/cure, and good enough to use with prepreg and an oven later on if all works out, I am thinking same materials as you used in your EC Video of the Car Bonnet, and if and when I get a good Mould made then the most difficult bit will be getting the two round Flanges laid up should I use the same Paste/Putty your EC Video of the Louvre mould used, and should I also use it on the Mould Flanges, so again any help very much appreciated, Regards DM Make sure you use high temp resin (eg easycomposites' EL160) and gel coat (EG160). Also use a fibreglass woven matt that has no chemical binders. The split, IMO, will have to be through the long axis so the tubes form half pipes.  What do the flanges attach to? One option would be to remove the flanges and bond them to the new carbon box. Just a thought, without actually having the item in my hand it is difficult to be definite on how I would do it. If you can manage to make the mould incorporating the flanges (both circular and flat) then this is by far the best option as it keeps your OE box in one piece :-) To make sure that you get an accurate mould of the flanges I would use EMP160 moulding paste in these areas as this can be pushed on to the gel coat, making sure it is tight into the corners. The fibgreglass mat has a tendency to creep away from tight internal corners (unless you vacuum bag it). Hi Steve, how can I tell if my fibreglass woven matt that has chemical binders ??, Regards DM
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Warren (Staff)
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Group: Administrators
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+xHi Matt, Thanks again,as you can imagine I have quite a bit of Chopped mat Strand which I have used for my Fibreglassin so can I still use this with your HT Gel and Resin, also my MEKcat is that compatible, as I do not want to mix the wrong one and ruin my Mould etc, what is the polypropylene sheet for ( or is that the corrugated sign board ?) so again Thanks for all the help, Regards DM Hi Matt, another observation ??? looking at your Video Making the Bonnet Mould for the 27th time I suddenly realised you did not Vacuum Bag it and especially on the first layer over the Gel Coat which is the most important coat to make sure there was no air bubbles or voids under the gel, as I could understand no reason to VB any further layers, as the Mould is the most important piece to get spot on as hopefully you will be using for lots and lots of Mouldings ?? Regards DM Which kind of chopped strand matting do you have? Typically there is emulsion bound and powder bound. Epoxy lacks the solvents required to break down the emulsion binder, so we recommend the use of powder bound CSM as any resin will break the binder much easier. You will NOT need MEKP for our EL160 and EG160 as both are epoxy based and have their own specialist hardeners that need to be used. The polypropylene sheet is for use as a baseboard and to create flanges. Fluted signboard can be used to do the same thing albeit the surface finish is slightly ribbed compared to the perfectly smooth finish of pure polypropylene sheet.. Generally speaking, vacuum bagging is not needed for mould making. Wet lay mould making like suggested for your project is done without any vacuum bagging. As long as you pay careful attention to applying the gelcoat properly and the first layer of putty and glass, then you should not have any voids to worry about. You may be thinking of tooling pre-pregs, where depending on the system used and mould size, thickness etc, vacuum debulking may be necessary.
Warren PenalverEasy Composites / Carbon Mods - Technical Support Assistant
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Eddie Walsh
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Group: Forum Members
Posts: 52,
Visits: 294
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+xHi Matt, Thanks again,as you can imagine I have quite a bit of Chopped mat Strand which I have used for my Fibreglassin so can I still use this with your HT Gel and Resin, also my MEKcat is that compatible, as I do not want to mix the wrong one and ruin my Mould etc, what is the polypropylene sheet for ( or is that the corrugated sign board ?) so again Thanks for all the help, Regards DM Hi Matt, another observation ??? looking at your Video Making the Bonnet Mould for the 27th time I suddenly realised you did not Vacuum Bag it and especially on the first layer over the Gel Coat which is the most important coat to make sure there was no air bubbles or voids under the gel, as I could understand no reason to VB any further layers, as the Mould is the most important piece to get spot on as hopefully you will be using for lots and lots of Mouldings ?? Regards DM
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Eddie Walsh
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Group: Forum Members
Posts: 52,
Visits: 294
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Hi Matt, Thanks again,as you can imagine I have quite a bit of Chopped mat Strand which I have used for my Fibreglassin so can I still use this with your HT Gel and Resin, also my MEKcat is that compatible, as I do not want to mix the wrong one and ruin my Mould etc, what is the polypropylene sheet for ( or is that the corrugated sign board ?) so again Thanks for all the help, Regards DM
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Eddie Walsh
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Group: Forum Members
Posts: 52,
Visits: 294
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+x+x+x+x+x+x+x+x+x+xHi I have been looking at this Air Box and trying to figure out how I can Vaccum Bag ??? to me looks impossible, so any help appreciated, Regards DM Hi There, Actually, I think you might be overthinking it. Unless there's something I'm missing - I'm assuming that the bottom face which we can't see it completely open - The the bag would actually be very simple, it would just need to also be very large (like more than twice the size of the part). I can't see the mould so I don't know if you're planning to envelope bag or tape to the mould flange but the principle would be the same either way. If the bag was large enough you could just feed two 'socks' of bag into the inlet tubes and then would blank off at the mouth of the tubes (again, I can't see the mould but I assume the mould too blanks off at the mouth of these inlet tubes). As Steve has posted we also don't know what the rectangle is but I'm assuming it's just a cuboid shaped recess which is fully closed off, in which case you could just bag around this using the huge excesses of bag I'm suggesting again too. If you were envelope bagging then just imagine an absolutely massive bag with the part and mould inside and the bag sealed all around. When you do this you can picture yourself just stuffing bag into those two inlets (as though you'd fashioned some tube shapes from the big bag and fed them into these inlets) and then and the rest into the main area. I hope this helps but if I've missed something then let me know! Hi Matt, Thanks, as yet I have not made the Mould ( The Pic I got Online) so just trying to figure out how to go about it, this is just to top part of the air box as the bottom rectangular portion is completely open as the Air Filter sits between the top and bottom portion, also the 2 round tube sections are completely open, and also the ends of the tubes have quite a hefty Flange which is used to bolt to the MAF's ?/ so how would I go about these flanges as well, again I will enclose 2 more pics, and thanks for all your help, I will get to make some CF parts very very soon with your help,Regards DM Well, the inlet tubes would have been blanked off in the mould and then cut open when the part is trimmed. Knowing that will probably change how you think about the bagging. As for the flanges, they are quite likely to be separate components that are bonded on afterwards but they don't have to be. I can't really see from the images but you could either make them as separate parts or set up removable barriers on the mould to form these flanges. Hi Matt, Looking at Steve's pic of his mould with both ends open, so looks like he just stuffed one end of his bag through one end of his mould and out the other end, and then pulled the other end of his bag over his mould and back to same end and sealed it there,?? is that correct, as my Airbox is very similar only difference is I have 3 openings, so is there any need for me to Blanks off the round open ends of mine, again thanks, Regards DM The blanking off was not really to make the bagging easier or possible (it's both of these things with or without the blanking), I was only pointing out that blanking off these opening on the moulding would be quite a normal way to make the mould (which you've not done yet). There's a lot of posts and input on this now so I'll try not to confuse matters any more for you. There is no problem bagging the shape you want to bag, with or without blanking off some of the inlets and as Hanaldo has pointed out I think we've covered well the basic principle of bagging a tubular shape in our airbox video where you can see that the principle would be the same whether you have one, two or more openings. Make your mould with confidence, when you get to the bagging stage, it will be do-able! Hi Matt/ Steve, and everyone else who advised, Yes I know you are all right, it is only me having to understand the process, as being an older Fiberglasser and over the years have had a few Major blunders where what could go wrong went wrong like trapped Moldings etc, so again Thanks for all the advise and help, I will bite the bullet very soon, Regards DM Trapped moulds, been there and got the relevant T-Shirt :-) Hi Steve and matt, I am almost ready to start, rather than Moulding the Air Box from my 458 I have just bought one from Ebay so I can still use my car, so first question how would you go about moulding it ?? as far as I can judge it will have to be a two part mould so split down the middle ?, so what material do I need to make my Mould, I will do all hand wet layup air dry/cure, and good enough to use with prepreg and an oven later on if all works out, I am thinking same materials as you used in your EC Video of the Car Bonnet, and if and when I get a good Mould made then the most difficult bit will be getting the two round Flanges laid up should I use the same Paste/Putty your EC Video of the Louvre mould used, and should I also use it on the Mould Flanges, so again any help very much appreciated, Regards DM Make sure you use high temp resin (eg easycomposites' EL160) and gel coat (EG160). Also use a fibreglass woven matt that has no chemical binders. The split, IMO, will have to be through the long axis so the tubes form half pipes. What do the flanges attach to? One option would be to remove the flanges and bond them to the new carbon box. Just a thought, without actually having the item in my hand it is difficult to be definite on how I would do it. If you can manage to make the mould incorporating the flanges (both circular and flat) then this is by far the best option as it keeps your OE box in one piece :-) To make sure that you get an accurate mould of the flanges I would use EMP160 moulding paste in these areas as this can be pushed on to the gel coat, making sure it is tight into the corners. The fibgreglass mat has a tendency to creep away from tight internal corners (unless you vacuum bag it). Hi Steve, Thanks again, as they say a Pic says it all that was what I was thinking but not sure so thanks, when you say HT gel and resin does this need to be oven cured as I do not have an oven yet, so for now I will stick with air drying, all I want is my Mould will be able to be used if and when I get an oven ?. The Flanges are part of the Airbox so as you say to remove would ruin the Airbox, so best leave alone and Mould the complete Airbox and also looks a lot better if it is all done in CF, the Flanges are bolted to the MAF sensors so just 2 through holes on each one for bolts and nuts, also the MAF's have a 50mm section that slides inside my Airbox Flanges with an O ring to seal, the EMP160 moulding paste sounds great for the Mould but can this also be used in my Molding as I will first have to get CF into the flanges and to keep it there will be difficult so if it was backed up with the Paste as well would that be correct, also I will for the first time be Vacuum Bagging ?? so that should help avoid and Bridging and voids etc,
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