Home Built Infusion Foil.

[TomW]

Thanks for sharing, for sure this is the ultimate way to do it. You'll be able to pop out product pretty easily once you get process working.

Also, be good to see your infusion setup, where you put the feed, are you using spiral feed tubes, etc. Professionals are very secretive about infusion setups, probably because of the investment needed to work it out.

I'm starting to think about doing infusion projects, and was thinking of doing some fins first.
My dream is to get a large format cnc machine from Shopbot and start making soft tooling and insert parts.

[Blackrat]

I'd be interested to know how you came up with the 70/30 theory ?

Neat looking foil !

[GrantL]

Thanks for sharing, for sure this is the ultimate way to do it. You'll be able to pop out product pretty easily once you get process working.

Also, be good to see your infusion setup, where you put the feed, are you using spiral feed tubes, etc. Professionals are very secretive about infusion setups, probably because of the investment needed to work it out.

I'm starting to think about doing infusion projects, and was thinking of doing some fins first.
My dream is to get a large format cnc machine from Shopbot and start making soft tooling and insert parts.

I have a couple of pics of infusion for mast which shows all the bits required. Will be adding some more tonight.
If you are thinking of making some "soft tooling" you will need to get to know the infusion process. The best way to do it is use a man made high density wood sheet or similar , route 1mm bigger than the finished form then infuse with resin. This locks up the surface which makes it easier to finish route and maintain hard square corners.

[GrantL]

I'd be interested to know how you came up with the 70/30 theory ?

Neat looking foil !

This combo is pretty much an industry standard in carbon fiber . Obviously you can adjust the ratio of uni's or the bias angle depending on what you are making. But I have used this 70/30 for my mast , fuselage and wings..
Obviously the more fiber you lay on an angle the more influence it will have with the twisting action of the mast. +/- 45deg is the most effective as its force components are the same in the 2 planes.
And how ever you look at it , if you want to make a slender mast <14mm the only way to minimise the bending and twisting is to use more layers.

[GrantL]

So continuing on with my mast.

From the pic of my test piece I ended up with a dry pocket around 2mm. This is what I did to try and overcome this.
OK I didn't use any heat , was a cold day around 16deg , resin was at room temperature and so was the mould.

Changed to.
Vacuum Laminate for 4hours at 35degC
Preheat the resin to 30-35degC , preheat the mould same temperature. If you infuse warm resin into cold laminate NO GOOD.
Degas resin before infusion.
Infuse slower that test piece. Test piece I infused in 6minutes , Actual final part I infused in probably 10minutes.

The Infusion Setup.
When you build a mould you need to make flanges at least 75mm . This is necessary to get all the plumbing in , and makes it easier to work with.
There are different ways to infuse ,the most common is from the center and out in all directions. In my case I only had 1 feed line which travels the complete length of the mast. I offset the feed position so it is sitting around 25mm in from the front leading edge.
Around the outside of the flange I run a vacuum line . We want the resin to travel from the feed in to the vacuum line in a balanced manner. The resin will take the least resistant path , so the design of your piping is important.
Under the vacuum feed in which is made from 8 or 10mm spiral tubing we need to position a special infusion cloth which allows the resin to run through with little resistance. This you can see in the pic as white. Under this you have standard peel ply cloth which stops the vacuum bag from sticking to the laminate . The picture shows almost everything. Peel Ply is laid all the way to the vacuum line around flange. Also rap around vacuum line.
Resin is feed directly into the feed line at a controlled rate. If you infuse to fast with thick laminate , the resin will not penetrate very deep towards the bottom of the mould as this is at right angles to the direction of flow.
To overcome this you can reduce the depth of laminate to say 4mm and infuse twice. Or as I do I add glass woven fiber which helps the resin penetrate deeper.
When the resin reaches the vacuum line you need to keep feeding more resin through the laminate.
A resin trap is required to catch the resin , and stop it reaching the vacuum pump.
As the resin gels and starts to go off , you need to keep applying heat and vac for maybe 1 hour. After that everything is set in stone. Leave for 24hours before removing all the vac bag and plumbing.
Don't remove from the mould as the laminate will still move around or shrink.
Have added 2 pics of finished halfs , board end with tuttle flangle and smaller flange for fuselage connection.

[Kamikuza]

Fabulous!

This a hobby, or you do it as a job too?

[GrantL]

No job. Just meticulous and well researched.
Amazing what you can achieve

[max]

No job. Just meticulous and well researched.
Amazing what you can achieve

So there is another stage yet to come . . .

How do you put the two halves together?

I always thought that these masts were made up by the two halves of the mold being clamped together after each half had been laid up . . . but both sides still wet. Obviously not the case when infusion is involved.

Have I missed something here . . . ?

[TomW]

Fabulous, thanks for the details. Spiral feeder down the middle, spiral vacation all around perimeter. I thought you would do cross feed, which I've seen in instructions.

Ditto Max's question, looks hollow to me!

[GrantL]

No job. Just meticulous and well researched.
Amazing what you can achieve

So there is another stage yet to come . . .

How do you put the two halves together?

I always thought that these masts were made up by the two halves of the mold being clamped together after each half had been laid up . . . but both sides still wet. Obviously not the case when infusion is involved.

Have I missed something here . . . ?

Yeap.

Once the infusion is complete and cured for 24 hours , remove all the bagging , peel ply etc. When I lay up the carbon I always over lay the laminate , but what tends to happen is you end up with a slightly thickened edge. It is almost impossible to cut the laminate exactly the correct length and width. With multiple layers you get this thickening affect. What is important is that you make sure the laminate is slightly proud in the center of the mould.
What I do now is not sand the laminate as I don't want to damage my mould flanges. I use a Carbide scraper to carefully shave the excess down to the flanges. Using a 50mm carbide scraper it is easy to monitor how much you are shaving and how flat the laminate is. Use a straight edge to keep the carbon face FLAT. If you tape around the flanges you can get right down to the flange tape without damaging the flange.
I can get down to the thickness of the tape (0.2mm) Now carefully pop the carbon part out of the mould and block sand with 60 grit to remove that last 0.2mm. Keep putting the carbon part back into the mould to check the height with a straight edge. Spot sand finally to remove any high spots. Repeat this process for the other half of your mast. If you assemble the carbon halves in their moulds and assemble together all should fit nicely. Double check with a light for any gap on the flanges. This method will give you a perfect fit together with no clearance.

As my mast is solid and extremely stiff. I will give you the bend/torsion test results later I know that the shear between the 2 halves is not to great. This being the case I choose to glue the 2 halves together. But I could of laminated the 2 halves together with 1 layer of 150gsm carbon Twill laminate just as well. Both will work as well. But if you DON'T have a solid mast layup I would recommend laminating the two halves together only.
I use a special high bond glue specifically for this type of application. It is important to prepare the faces of the part halves for the glue. There must be a glue gap (0.1 -0.2mm max) To achieve this I now carefully hand scrape the center out of the carbon faces around 0.1mm per side. I finally hand scrap and sand the perimeter of the part down to the -0.1mm. This is the ideal situation , which sound difficult but is not using a scraper.
Rewax the mould (carbon halves removed) BEFORE applying glue to carbon halves. Place 1 half in mould and spread the glue with a straight edge just filling. repeat the same for the other half out of the mould. Assemble on 1st haft and press down by hand and remove excess glue. Your cavity should be full of glue. Position other mould on top and clamp down in multiple places. The mould should clamp together tightly and aligned. Leave to cure and remove from mould.
Mast will be dimensionally as you intended , but more importantly you know that the fiber you laid is all intact , no sanding of fiber weakening the mast.