Infusion Plan

I never infused anything, but it seems that wherever the tubes are, they would press down into the laminate more than elsewhere and the laminate would end up with a pattern of thinner/weaker 'lines' corresponding to where the tubing was. What stops that?

I would also imagine that alongside the tubes there are narrow spaces where the bag does not actually touch the glass and so it is not actually compressing the laminate, even though the glass is in a vacuum.

I would think there would be three thicknesses to the laminate. The general laminate would be X amount of thickness. Directly under the tubes would be thinner than X and in a narrow line alongside both sides of each tube it would be thicker than X.

If that's the case, wouldn't that create a pattern of 'stress points' or 'weaknesses' or whatever the term would be? Something that changes the evenness of how loads are distributed through the laminate?

 

I placed extra infusion media under the tubes, it's supposed to spread the pressure enough to prevent imprint.

I have no scientific data or experience for that matter but just from looking at how tightly this bag surrounds the hose, I don't think, especially with extra infusion media, that this can be a problem.

 

theres more than first meets the eye !!

You hit the nail on the head , people see the resin flowing anf going nto a lay up and think hell thats easy . but it all the small mountain of things just to get to that point the small tricks the small tiny details Thats what is never mentioned that what no one see's Thats what they forget !! thats what i am interested in . Have only done small things and thats all . i am still a believer that a good peelplyed lay up is better than a infused layup that is borderline with the resin content to glass . I still think for a given lay up there is a optimum resin to glass ratio and infusion goes past that point . Peely ply gets you as close as you can get to that point i feel and thats where i always work in .In 30 years have never had a failure with anything ive made or repaired guess i been lucky or its because i do a lot of preparation and have a plan worked out before i start no mater what i am involved in making big or small .
Good luck !!

 

Thanks,

I will need all the luck I can get. I can see a lot of benefits to infusion but I think the methods I am using could be much better. The vacuum hose should have it's own system for not pulling in resin (better than the MTI system), the batching should be turned into a process system (mixes as you need it) and too much waste of plastic! Anyway, I don't know how deep I will get into it but it does fascinate me, first I have to complete this boat!!

 

Yes i understand about the mixing and there are pumps like the old venus that just pump continuosly into a container and the suction draws from there on the set up i was looking at . The demo i went to the guy was mixing and pouring into a common draw off point so there was continually fresh brews going through the lines . it had all been calculated but not all mixed in one large container . as the first hoses were clamped off and others began to feed so newer resin was mixed and so on and so on .
But its all the things to get to that point that i am interested in .

 

as to how much resin to mix, you need to calculate how much resin the layup consumes, then multiply by the area of the part. I have a spreadsheet that has everything in it, right down to the last drop. Simply mix the batch in one big bucket, then clamp it off when the resin runs out. At this point, the part is not fully infused, the edges are still dry. The resin rich areas closest the inlets continue to level out and infuses the remaining areas. If you calculate very accurately, no resin gets into the vac lines, it stops just short with the part fully infused.

 

The part that scares me the most is the epoxy kicking before you get it out of the bucket. This already happened to me once, so this time I am going to use a 10' aluminum roof gutter as my bucket.

I am also going to break it up into various batches. I need about 1000 ounces so I will probably make my first batch 300 oz and then batches of 200 oz thereafter depending on how fast its getting sucked up.

I also thought about placing a ziplock bag of ice in the bucket, kind of like the bars do when they stick the bags of ice in a pitcher of beer.

 

Make a form fitting scraper from cardboard or plastic to push the resin down the gutter or you will leave a bunch sticking in there. I don't know about epoxy, but residue in a bucket from an earlier batch of polyester will set the next batch off quicker. I reused buckets after the residue hardened and cooled down, but I never used the same bucket for successive batches. Have a bunch of buckets set up with the proper amounts of resin in one and the hardener in another with a separate mixing stick for each. Any extra unmixed can be poured back into it's container.

If you chill the resin, you will change the viscosity.

You just have to plan as well as you can and accept that you can lose all the time and money you have into it. It's not a terminal disease or bankruptcy if it fails. Life goes on, you'll get over it.

I'm curious about your workshop with the ceramic tile floor. It's unusual to have a floor like that in a workshop, especially a fiberglass one.

 

I think I am going to settle for some ice bags in the bucket. It won't be able to actually chill the epoxy in that short a time but I think it might maintain the temperature and give me some extra time.

My shop is not a shop actually, it's just some extra space the company I work at let me use on the condition I did not make a mess. I told them that infusion was pretty clean so they agreed to it.

 

ok jorge, some more info for you.

The resin front speed is inversely proportional to distance squared. So lets say your front travels at 12inches in 10mins. the front will move 6inches in the next 10mins, and 3 inches in the next 10mins and so on... So the resin gets used very quickly at first, then progressively slows down as time goes on.

So, when you first open the lines, you will suck up that resin so quickly its not funny. You will probably use 500 ounces in the first 10 mins. Now your bucket doesnt have the mass of resin it started with, so it doesnt get as hot etc. Think about this flow rate if you do choose to do it in batches, but i would definitely say you wont need anymore than 2 batches, say around 650ounces for the first, then 350ounces for the second and final batch. when i infuse anything upto 700ounces, i mix it all up at once - no batching. I chose this amount because the bucket i have to mix in is only this big. if i had a bigger bucket, i would probably mix a bit more straight up. With the strategy you have chosen, with your resin lines layout, will infuse quite quickly - i don think you need to worry so much about the resin kicking provided you use the slow hardener and no more than 2 batches.

Another thing i do, is to weigh all the resin i need into the mixing bucket, then let it sit for at least 30-45mins. Just pouring the resin introduces heaps of tiny air bubbles into it and you can see them in suspension. This resting time lets all the bubbles rise up and you can physically see in the bucket (black color bucket makes it easier) when the bubbles are basically gone. Only then do i carefully pour the hardener in and mix with a drill paint mixer, making sure not to go so fast as to pull air bubbles into it again. When the resin is mixed carefully this way, it looks as clear as water and all those bubbles wont expand to 50times their size once they enter the vacuum. When you mix in batches, you cant avoid pouring, therefore you introduce more air bubbles each time etc...

 

be careful with ice... most infusion epoxies double in viscosity with every 8 degrees celcius lower temperature. The resin flow speed is proportional to viscosity, so if you double the viscosity, you half the speed.

Personally, i would forget the ice... ive often done the opposite, and warmed my resin up to get things to flow faster when gel times are not an issue as it does dramatically shorten the gel time.

 

Ok, that is some really good information ...

I am by myself so it would be hard to be mixing up batches and checking for leaks in the bag at the same time.

Tomorrow I am going to start the pump about 4 hours prior to infusing and let it boil off any humidity.

In the meantime I will weigh out the epoxy as you say to let the air bubbles dissipate. I have bought a bucket pump with a long hose in the hopes that I would not introduce that much air.

Not going to get much sleep tonight thinking about it LOL, but Thanks for everyones help. I feel pretty confident that it's going to infuse quickly myself.

 

WHAT ABOUT USING A SLIGHTLY LARGER DIA PIPE AND WARMING THE RESIN UP IN THE PIPE CLOSER TO THE MOULD AND HAVING THE MOULD WARM AS WELL ?? POSSIBLE OR NOT ?? INLINE WARMER SO TO SPEAK .

Used inline warmers in cold places iv worked with chopper guns and Gelcoaters ,they sure make a differance to the amount of flow rate and if the mould is warm to theres a better gel time!!

 

sure, that would be great if youve got one...

Jorge, one more thing, if you give me your laminate schedule and surface area of the layup, i can calculate accurately the exact amount of resin you will need.... your using M80 corecell yes?

 

ok, well if it pulls the resin that quickly, it should not need ice. My resin only has to flow 10--11 inches. I have seen videos where they pull that resin a good 2 feet or more, can't figure out how they can do that.

I probably won't need it but I will keep it handy if I think it's starting to heat up I will put in the frozen Ice pack. At best it will dissipate some heat, I doubt it will actually cool it.