Vacvuum infusion F U # 2

[Fanie]

Thanks again Andrew.

I have pulled the beam from the jig. Everything looks ok.

The 8 layers of 450g WR is 2.5mm thick right through, and very consistent by the looks of it. This means a layer of 450g WR gives me a 0.313mm thickness.

The beam weigh 4.6kg. Not too bad.

[Fanie]

Second beam done. Had to go to town first and had a bit of a late start.

One inlet bottom left, one outlet top right. 3 minutes it was all over, and I'm waiting for it to gel.

In winter this resin is going to give you hours to work with.

[AndrewK]

Fanie,

8 x 450gWR=2.5mm is very good, this should be just under 30%wt resin.
Is the laminate translucent, ie you can see the foam through the laminate?

Last night I forgot to question the choice of WR for the laminate.
In a beam you want the bulk of your reinforcement fibers to run along the length of the bem to give you high flexural and compressive properties and a smaller amount in the +/-45 direction to take care of torsional loads.
Better choice would have been 5x 450g UD + 3x 450g DB.

Cheers
Andrew

[Fanie]

I used a jig that has a more elegant form, but yes you can see through the laminate. Not very clear though. The foam gets pressed in in this case.

I don't have uni glass and the woven was draped around the jig so half the strands are in the lenth. I tested for strength with my ninety something kg's on it and only supported on the ends of 2 meters.

Mmmm... bends very slightly and still feels very firm. The beams will get glassed into 300mm of the ama's and is supported in the hull for 350mm... which leaves 1350mm where the trampoline gets fitted.

The beams are 80mm high and 160mm wide. I will be very surprized if they ever do break, and they are as stiff as anything.

[Fanie]

The fact that the resin takes longer to gell seems every ounce of excess resin is extracted before it gells. Interesting is it looks like the resin is boiling in the spiral. The resin almost looks dry on the outside.

[Wynand N]

Fanie, can I please have the name of the resin and hardener you are using now and a contact name/number?

[Fanie]

I did beam no 3 after our fishing club's Christmas tree this afternoon. Just stripped, it looks wet, then a day later it goes white and looks dried out.

By tomorrow the wet looking beam is going to look as dry as the first two, it already started colouring a while ago.

Is this right ? It looks really dry as if there's a bit of resin short.

[Fanie]

Hi Wynand, let me first make sure this stuff is ok, ok

[waikikin]

Fanie, looks a bit dodgy to me, what kinda resin are you using? All the best in your endeavours from Jeff.

[Fanie]

I've spoken with a clever technical guy at NCS regarding the whitening of the surface. He says they have seen it, it is because I vacuum all the resin off the surface.

If I want a less dry surface I can place some core mat before the vacuum line, so the resin will flow freely to the core mat but then gets restricted some and not all the resin will be vacuumed out.

To get rid of the surface white I can, with a brush or roller, apply a thin layer of resin.

[Fanie]

All four beams done. The last is in the sun to help it get through the last few moments of exothermocs and to turn white

The beams seems simple, but is actually a complicated form to vac. Wherever there is a pinch or fold in the glass, flow is restricted greatly.

I think this vac infusion is a good and very fast process once one gets the hang of it. Despite the consumables pushing the price up, I must say I'm pleased the way the beams turned out. They are lightweight but strong.

You can do a boat a day with this process.

[AndrewK]

Fanie
A good quality laminate should look translucent, this is what you should be getting with infusion.
You mentioned that you thought the resin was boiling in the spiral, thats most likely what it is. Is it boiling in both the feed spiral and the vacuum spiral?
Since you have a clear lid on the catch pot put some unreacted resin into a clear glass jar and place this into the pot. Slowly increase the vacuum until it starts to boil, first you may get a bit of a surge this should be just dissolved gases then it should stop. If it does stop then continue to increase vacuum until it starts to boil again or until you reach the max vacuum your pump con produce. Also do this at the maximum temperature you are likely to experience.
If it continues to boil then your white looking fiber is due to the resin gassing up and effecting the resin to glass coupling. This is not good and you need to make sure it is not just the surface. Brushing more resin on top should not improve it by much as the glass fibers should no longer soak up resin as they are already coated to some extent with the gelled resin.
If you do not have the resin boiling then the problem is likely due to air leaks flushing resin out of the laminate while it is gelling. Alternatively you may be having the resin gel in the vacuum line before the laminate has gelled. If this is the case you may be loosing vacuum in the bag and decompressing the laminate stack to a degree where there is insufficient resin in the laminate for a proper wet out.
How much resin is in the shade cloth when you strip it off?

Regards
Andrew

[AndrewK]

Fanie, if you are placing the beams out it in the sun while the resin is exotherming and under vacuum then your problem should be resin boiling.
Do not do this, wait util the laminate has fully gelled before you put it out in the sun.

[Wynand N]

Originally Posted by Fanie

If I want a less dry surface I can place some core mat before the vacuum line, so the resin will flow freely to the core mat but then gets restricted some and not all the resin will be vacuumed out.

I do not think the Coremat will restrict the flow of resin, moreso with that thin stuff you are using.
In all my experiments I used a 2mm Coremat between layers and today I went for broke.

I laid up another test piece consisting of;

3 x 450g CSM
2 x 610g WR
2 x 2mm Cormat (with wr in between and csm on the outer sides)

This is a serious dry stack and the two Coremats did not restricted the infusion at all and in fact, had a 600mm run of the whole test piece without gelled out (1% hardener - 12 minutes to gel). And this is with normal Polyester resin which is thicker than the magic stuff you now uses.