First infusion = schoolboy error!

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#1

Well I managed to get round to doing my first infusion yesterday. All was going well, got everything layed out, sealed down the bag which held 28hg for around 10 mins. Mixed some epoxy and degassed, then started off the infusion.

There’s me merrily looking at the resin flow thinking ‘This is going to work nicely’, anyway it gets to about 95% infused then…shhhhhhhllllllluuuuuuurrrrrrppppp…whats that funny noise?

Oh bugger! I’d only gone and let the resin pot run dry!!! The funny thing was after all the reading I’ve done on here I was going to shut off the feed line at 75% infused anyway. Why I didn’t I just don’t know!

I’ve got enough material for another go this weekend so I’ll be a bit more careful this time.

Oh, I’ve made a nice mod to my robinair vacuum pump too. I’ve fitted a vacuum switch that shuts the pump off at around 28hg and if the vacuum drops below 25hg it brings the pump back on until 28hg etc. etc. This saves having the pump running all the time. I’ll post a how to if anyone is interested?.

Anyway here are the results of my failure to adhere to one of the most basic rules.

Pump setup

Too late to fix this!

#2

#3

I think you have issues on the radius’s because of bridging. Might want to pull a partial vacuum, and start rubbing the material into the corners a bit more, and slowly pull the rest of the vacuum, while working on the fabric.

Yeah, air sucks.

#4

R1 undertail?

Don’t sweat it, there are a lot of mistakes that can only be made when you are just starting out, and you will learn form all of them.

#5

I would love to know how you made that vacuum switch! I had the same issues on my first run of vacuum pieces, don’t sweat it, it gets better pretty quick

#6

Me too! sounds like a good idea cause im afraid my pump wont last being on for a long period…its a $130 refrigeration testing pump. Pulls full vacuum nicely though.

#7

Thanks for the encouragement guys, I was expecting a good few failures at first so its no drama.

The bridging I expected too, I did quite a bit of poking with my fingers but it seems to be more about getting the material moved right into the tight corners using the slack on the flanges instead of pulling from within the mold (hopefully that makes sense). I think this part will need a couple of relief cuts in a couple of places too.

R1 undertail indeed, 02 model to be exact. I’m planning on making a complete set carbon body panels for this bike over the next year, the tail unit will be next.

Ok, there seems to have been some interest in the vacuum switch so I’ll do my best to explain it, forgive my drawings here as I’m no visio expert.

Here’s the switch I bought;
http://uk.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=2596632
Its quite expensive but I’m sure there must be an equivalent for you guys in the US in Harbour Freight or Circuit City.

I then wired it into my Robinair pump, WARNING!!! this pump contains a fairly large capacitor, to save yourself getting an electric shock leave the pump unplugged from the mains for a good few hours before taking it to bits.

This pump has a bit of a strange switch where both the live and neutral feeds are controlled by the same switch (it has 4 terminals) The live and neutral feed from the mains plug into the top 2 and the corresponding live and neutral to the pump motor plug into the bottom 2. I removed both neutral terminals from the switch and then wired them to the terminals on the vacuum switch. Wiring it this way allows you to join the 2 terminals on the vacuum switch together and use the pump as normal. Also note that the switch on the pump still needs to be on for the pump to operate as its still controlling the live feed.

The vacuum switch has 3 terminals, from memory you need NOT use the one in the middle (that one makes a circuit when a certain vacuum is reached instead of shutting it off).

Wiring diagram, layout is slightly different to how I’ve explained above but easier to understand and works just the same.

Pipe connections

Hope people find this of use. If anymore explanation is needed then please let me know.

Thanks
Andy

#8

I was having the same dry spots around the edges. It is a combination of bridging and air pockets/bubbles.

Once you use the partial vacuum and work the cloth and fabrics down into all the tight corners - then pull full vacuum once you spend about 15-20 minutes working the cloth into those corners. Also use multiple cut up small pieces of peel ply instead of one piece. This helps eliminate bridging from the peel ply somewhat.

Clamp off your resin inlet line as close to the resin cup/bucket as you can. This keeps more air from entering the infusion. Also pull full vacuum for at least 10 minutes. During this ten minutes check for ALL leaks big and tiny. tiny leaks can screw up your part pretty bad. Always pour 2 ounces of resin more than what the lay up requires. This will prevent accidental air leakage from the resin cup end. Also I let the resin get 95% infused before I clamp off the resin line. Some people get away with 3/4ths infused then clamp, but that doesn’t work as good for me personally. I’d rather have some resin go into the vacuum line and resin catch pot than have a dry part.

Oh yeah, don’t run Airtech infusion medium around tight edges and corners. That will cause a bridging problem.

I hope that info and other peoples helps you out :slight_smile:

#9

A few tips.

  1. Infuse the part 100%. Use extra material to absorb any excess, or let it go into a catch pot.

  2. You don’t need spiral wrap on the vacuum side for that part. A little piece of fiberglass over the end of the vac tube will be enough to keep the bag from blocking the inlet. Vacuum will still be pulling across the entire piece.

  3. Put flow media anywhere you want resin to get to. DO NOT count on the resin flowing through the fabric.

  4. I highly recommend not shutting the pump off. It’s very important to maintain a full vacuum throughout the cure process. This can cause dry spots. The resin saturates fully during the infusion, but then once the feed line is clamped off and vacuum drops the material pulls away from the mold surface and creates a void with no more resin available to fill it in.
    If the pump is left running, even areas where the fabric didn’t touch the mold will still get filled in with resin and make a smooth and accurate surface.

#10

i love those spammers. its like a passing by drunkard popping in the conversation and talking wise gibberish…and then wobbling away :rolleyes:

#11

Yes, i agree. Like anyone cares what the heck they are talking about anyhow.

#12

TET,

so my parts still come out like this part this fellow made, dry and bubbly edges. Is the only reason those areas do not fill with resin is because of a lack of sufficient vacuum? Also i am thinking on some of the larger parts i make that I should use two resin inlet lines, so there is no worry about the resin geling in the cup before the part is fully infused.

Will one or two tiny bag leaks cause this problem? I usually pull around 27hg and seem to always have a couple tiny bag leaks i never seem to be able to find.

#13

could you possibly be sucking too much resin out into the catch can? I usually clamp off the hose to the catch can as well before I get any in there and then turn off the pump.

#14

well nevermind. I guess if you are having leaks then you clamp off the vacuum. You should make a video of your infusion you are doing and let us try and a solution for you. I dont claim to be an expert on any of this but I do have several thousand infusions under my belt over the years and I bet I could at least throw some suggestions. I personally do about 5 or 6 a day right now 6 days a week

#15

If I get a video camera i will film some stuff.

#16

you kill the vacuum to the part before it’s gelled/cured?
normally one clamps off the resin inlet, and leaves he vacuum running till it’s all done!

#17

well right now I am running one pump so i cant tie it up with just one part. well I do two infusions at a time with one pump. If i dont have any leakes then the bag will hold the vacuum if I clamp it off. I usually never get any resin in my resin traps unless I have a leak. I still clamp off the resin tube as well. I have been doing this for awhile no with no problems. It just makes things go by faster for me