Okay thank you, 

The bubbles have to be coming from somewhere.  Have you done the leak drop test properly? perhaps for several hours even?

As suggested degas the resin. ( You can do it in the catch pot with the mould under vacuum sealed by a clamp.  Just increase vac slowly over a couple minutes so it doesnt froth).

Also try throttling the resin feed with a line clamp to slow the infusion down a bit, maybe its just too quick at the moment.

As has been said, it should be possible for you to achieve a pinhole free finish with infusion when done correctly and there is no technical reason i can see that a mostly flat tray should be any different.

With soric you will still have a smooth side like normal.

Go see:

https://www.easycomposites.co.uk/resin-infusion-starter-kit#video

04:45. Step 8. Add an additional 2 EXTRA layers of infusion mesh on top of the original infusion mesh...

11:25. Step 20. Degas for 10 min...

12:50. Step 23. Clamp feed line once resin reaches the catch pot... (let it drip into the cup for 2 or 3 seconds)

13:00. Step 24. Wait 10 seconds and then clamp the vac line...

These are the steps that I think will help you a bit more.

Take note of the size of the mold/part in the video, I would say about 800mm x 800mm, Matt only "bleeds" the resin for about 10 seconds... I would say your tray was about 550mm x 400mm and if you "bleed" it for 30 seconds it could come out a bit dry. I have also noticed that different weaves/twill/materials/cores/part sizes all have different infusion and bleed times and it can be tricky...

Does the top of your tray face the peel ply and infusion mesh?

the tray is something that could go with my dinner plates once i do another batch!!

Hi Arsouille,


I think the advice you've received from our forum members in this thread is exactly right. Firstly perform your infusion at full vacuum. If you have a vacuum regulator (nice and useful product) you should be using it for applications like vacuum bagging or vacuum bonding, not infusion, which you need to be doing at full vacuum.

Secondly, make sure you're running slightly resin rich by clamping off the vacuum line soon after you clamp off the resin feed line. This will significantly reduce the chances of any air bubbles.

Regardin the stiffness of the part, a core material is certainly the way to go on this one. What you need in your tray is deflection strength and the best way to acheive that is to create thickness - the best way to do that, without adding lots of weight and cost (of solid carbon or kevlar laminate) is to include a core material. If you use Soric you'll have a slightly denser core than you could have using something like a PVC foam core but you will find it very easy to work with. If you use a closed cell foam then you'll need to drill it all over (2mm holes and 15mm centres) so that the resin can get from the top surface (where the mesh and peel ply are) down onto the surface.

The other thing you might want to consider is the orientation of your reinforcement. In your photograph you are demonstrating how easily you can 'twist' the tray. This is 'torsional stiffness' and will be considerably less then the stiffness across the width and the length of the tray if you have oriented all of your fibre at 0,90 (i.e. with the weft and warp in line with, and perpendicular to, the tray). If you rotate some of the inner layers by 45 degrees then you will improve the torsional stiffness of the tray, at the expense of some of the 0,90 stiffness that you have now.

I hope this helps.

--Matt

Matt Statham
Easy Composites / Carbon Mods - Technical Sales

as said you need FULL vacuum on the guage.

rather than clamping the feed as the resin gets to vacuum line, make sure you mix some excess and allow some resin to bubble up the vacuum line into the catch pot. That way you are ensuring resin has reached all of the part.

Also once happy, clamp the resin feed then about a minute or two clamp the vac feed after.  vary the time depending on when the bag goes tight around the resin feed area. that way you ensure there are no tiny bubbles trapped in the fabric or from the resin as youve sucked through a good slug of resin through the part.

Also ensure you leave your fresh mixed resin to degas or degas it in the catch pot.   What may seem a 2mm bubble in the resin goes into the part and "explodes" under vacuum into a much bigger volume.

You can fill the pin holes using multiple layers of lacquer. You generally need a thicker layer to fill the holes which is not ideal.

a better solution if there are not too many pin holes is to use a bit of fresh mixed resin and fill them with a pin and a drop of resin.  Then gently sand it smooth before you lacquer the part.


if you use a foam core, the cores can be bent around slight curves with a heat gun but probably not on your tray as its too sharp.  You could try the soric core material as its more flexible.

I think with a foam core on the bottom you should be ok.

Hi,

The full carbon one looks nice too... Thats great.

And thx Kevin for additional informations and pics.

 



 


    A $1000 electronic device will always protect a 10 cents fuse

If your only getting -0.8 bar you are not at full vac, follow the EC instructions/video!

ABSOLUTE vac is needed for the infusion, you are technically going to "degas" the resin in the bagging stack and this can be observed by the bubbles in the bag moving faster than the resin. If you pay close attention to the feed and vac pipe/connector blocks you will see almost no bubbles collecting around these areas or in the pipes within the clamps if done correctly! Also pay attention to the areas that have 3 layers of mesh, usually at the feed and/or vac connections, almost no bubbles should be in these areas too, this will be a good indicator as to the final product.

I have just done an infusion with tinted blue resin and white diolen to show the process/bubbles clearly... I will post some pics soon...

Small pinholes can be fixed with the correct colour wax crayon, for carbon/diolen/carbon kevlar use black, it will not be a perfect solution but will stop dust and moisture from filling the voids and making the problem worse. Obviously you wouldn't do this on a performance part, but for a quick fix on a small household part this should be better than throwing it away!

Cheers,

Kev.

Update:

See pics. Notice the diolen is photographed in the negative and any imperfections/pinholes/voids would show as black spaces or dots... But its clean!
Also note that the area around the vac connector block is free of bubbles, as was the feed connection area , this was made easy to observe with the blue resin...