Vacuum bagging

[Kez]

Trying to mold a fuel tray using 3 Oz cloth. The 3 Oz cloth did not conform to corners very well and the cloth lifted in many placed. I know 0.6 Oz cloth will work but it takes many layers to build up.

I am thinking vacuum bagging may keep the cloth on the mould. A few questions:

1. Will regular plastic bag or big freezer bag work? I know it may leave some creases but I can always sand it out.

2. Will a Shop Vac work as a vacuum source?

3. Will fiberglass mat conform better to curves than cloth? I am using polyester resin not epoxy.

Thanks,kez

 

[HendricX]

If the mold is a block .. you can wrap the cloth/resin with kitchen-foil.

If the mold is a 'tub' ...Kitchen-foil / a simple balloon , a cover , and some bricks will do the trick too.

If air in the balloon is not enough ... fill the balloon with water.

 

[gil sonsino]

Hi Kez 3oz is too much heavy for this purpose.I've been making fuel trays with 1oz cloth(4 laywers is enough) with good results hand laid will be ok no need of vacuum bagging for this work.Gill

 

[Terry Keeley]

For something as small as that why not make a male/female mold?

 

[SeanKewley]

I would just do a hand layup with 1 - 1.5oz cloth (4 plys)like Gil suggested. The 3oz cloth will lay in there fine after 4 plys of 1.5 oz cloth if you want it stiffer.

 

[Kez]

If the mold is a block .. you can wrap the cloth/resin with kitchen-foil.

If the mold is a 'tub' ...Kitchen-foil / a simple balloon , a cover , and some bricks will do the trick too.

If air in the balloon is not enough ... fill the balloon with water.

The mold is a block. I made a plug for the fuel tray so that the finished tray is smooth inside. I have never tried wrapping it with Saran wrap. Might give it a try. The balloon idea is interesting.

 

[Kez]

Hi Kez 3oz is too much heavy for this purpose.I've been making fuel trays with 1oz cloth(4 laywers is enough) with good results hand laid will be ok no need of vacuum bagging for this work.Gill

Hi Gill,

I will try some 1 Oz cloth next time. I have some 0.6 Oz and it covers nicely. I was just trying to get it done quickly and thought I could get away with 3 Oz cloth. I like the tray to be strong so I will probably do 6 layers.

kez

 

[Kez]

For something as small as that why not make a male/female mold?

Terry,

I have a male mold for the layup. Can you explain how I can make a female mold while account for the thickness of the part? The female mold has to be larger all around, correct? If I can come up with a way to do this I can have a part that is smooth on both side.

kez

 

[Terry Keeley]

For something as small as that why not make a male/female mold?

Terry,

I have a male mold for the layup. Can you explain how I can make a female mold while account for the thickness of the part? The female mold has to be larger all around, correct? If I can come up with a way to do this I can have a part that is smooth on both side.

kez

Got any pics?

 

[Bart Drieghe]

To make a female/male mold you need to fill up the place with something .

It kinda depends on how thick you want to have your piece but you can do it with wax sheets . Easily to find in dental shops but i'm sure that your epoxy/polyester supplier can supply you this too . ( i do think that a dental shop will be easier on different kinds of thickness )

How do you do it . Simple , got the female mold , heat up the sheets and push them in the mold , do this for the entire piece . Once you have done this , fill up the female mold with the wax and make a male mold on the female . (Female /male mold making is similar to male /female , i bet you know what i mean .)

Hope this helps ,

B

 

[Kez]

Sean,

I will try lighter cloth as you and Gil have suggested. I am not sure if the 3 Oz cloth will go over the 1.5 Oz too well as I think the corners of the plug has too small a radius.

Terry, I am attaching a photo of the plug and the first fuel tray I pulled from it. The fuel tray is heavier than I had hoped. I have to use a lot of resin to keep the cloth from pulling out...hence the question of vacuum bagging. I can use this fuel tray if I have to by sanding the creases out. The inside as a pretty good finish. I usually "season" the mould a few times before pulling the real part. So I will be trying lighter wt cloth etc. If there is an easy way to make a female mould, I would like to learn.

Bart, how high a temperature do I need to heat the sheet assuming I can find a source for it?

Thanks,

kez

 

[Terry Keeley]

Sean,

I will try lighter cloth as you and Gil have suggested. I am not sure if the 3 Oz cloth will go over the 1.5 Oz too well as I think the corners of the plug has too small a radius.

Terry, I am attaching a photo of the plug and the first fuel tray I pulled from it. The fuel tray is heavier than I had hoped. I have to use a lot of resin to keep the cloth from pulling out...hence the question of vacuum bagging. I can use this fuel tray if I have to by sanding the creases out. The inside as a pretty good finish. I usually "season" the mould a few times before pulling the real part. So I will be trying lighter wt cloth etc. If there is an easy way to make a female mould, I would like to learn.

Bart, how high a temperature do I need to heat the sheet assuming I can find a source for it?

Thanks,

kezView attachment 28720

Now I see what you're tryin' to do.

What about taking that part, sanding and finishing the outside of it and use that as your "spacer"?

 

[Bart Drieghe]

Hi Kez ,

those sheets heat up by putting them in water of 35°C up to 60°C . You also could go through a flame with the sheets ( shortly then ) and a few times . They will get weak but i think the water trick gives you the best "control" of how long , how soft you want them to be . Find a dental lab in your neighbourhood or a dentist , both have those sheets or can tell you where to get them .

I do have to say that Terry has a good idea too : IF you sand your part , finish it and you got the space you want to have .

Good luck

B