After 3 fails its time to ask where i go wrong..


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jeffrey bres
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As mentioned..   3x not a charm here.

I have this isseu every time.
Clearcoating without gelcoat would be an option. But allso that isnt easy with small holes like this.

Now i used gelcoat. Hoping it would help.

Gel had cured at 25 degrees for 5 hours was dry to touch.

I used 3m high tack clear spray adheasive to hold the fibers in place. (AS LITTLE AS POSSIBLE)


on the vacuum catch pot the dail says my vacuum is 100%
I leace the pump running over night.  In the morning when the resin is hardned the vacuum line form the ez composite starter kit to the pot is flat from the vac. 

(I dont have an official cacuum pump.  I use a 35l/m fridge pump. Whitch seems to work fine.   I can add an extra pump if i need more cfm...)
If my vac is to strong.. i can make a bleedvalve to reduce vacuum.   

But idialy i would love to have a perfect finish.

I use easy lease release agent..  denoulding is a breeze..




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Hanaldo
Hanaldo
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Yeh its a lot of air, so you definitely have a leak. Gelcoat can't fix that, and in fact makes it worse because the air gets trapped behind the gelcoat so you can't even salvage the part by clear coating.

You can't trust the analogue gauges, they are extremely inaccurate and their reading will even change with the weather. All they are good for is indicating a leak over time, so after pulling a vacuum clamp the part off and leave it clamped off for 5-6 hours or ideally overnight. When you come back and unclamp it, watch the gauge closely - it should not even flicker when you unclamp. If it moves at all, even a touch, you have a leak. 

Normally I actually say forget the gauge, they are misleading. You can often tell instantly if you have a leak just by listening to your pump, their tone is much more sensitive than the gauge. When you clamp off your part, the pump should not change tone at all (and you have to listen closely, minute leaks make minute changes to the tone). Keep looking for leaks until your pump doesn't change tone at all, then do one final drop test by clamping the bag off and leaving it for 30 minutes to an hour. The longer you can leave it, the easier it will be to detect a small leak. When you come back and unclamp, listen to the tone of your pump again. Again it should not sound any different at all the moment you unclamp the bag, and there should be no vapour coming from the exhaust. This is genuinely one of the most reliable ways to check your vacuum integrity, these days I have fancy digital vacuum gauges and obscenely expensive ultrasonic leak detectors - the tone of the pump is 99% of the time the first indication I still have a leak.

You dont need a fancy vacuum pump either, the only critical thing is that it can pull 99.995% vacuum. The CFM does not matter at all, you can connect 20 individual 15CFM vacuum pumps together, but if none of them are capable of pulling 99.995% vacuum then they arent good enough. CFM determines how fast the pump can pull the air out of the bag, it doesn't determine the ultimate vacuum level you can achieve. So just check the specs on your vac pump and make sure it can pull very high ultimate vacuum levels.
jeffrey bres
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Hanaldo - 4/11/2021 1:10:57 AM
Yeh its a lot of air, so you definitely have a leak. Gelcoat can't fix that, and in fact makes it worse because the air gets trapped behind the gelcoat so you can't even salvage the part by clear coating.

You can't trust the analogue gauges, they are extremely inaccurate and their reading will even change with the weather. All they are good for is indicating a leak over time, so after pulling a vacuum clamp the part off and leave it clamped off for 5-6 hours or ideally overnight. When you come back and unclamp it, watch the gauge closely - it should not even flicker when you unclamp. If it moves at all, even a touch, you have a leak. 

Normally I actually say forget the gauge, they are misleading. You can often tell instantly if you have a leak just by listening to your pump, their tone is much more sensitive than the gauge. When you clamp off your part, the pump should not change tone at all (and you have to listen closely, minute leaks make minute changes to the tone). Keep looking for leaks until your pump doesn't change tone at all, then do one final drop test by clamping the bag off and leaving it for 30 minutes to an hour. The longer you can leave it, the easier it will be to detect a small leak. When you come back and unclamp, listen to the tone of your pump again. Again it should not sound any different at all the moment you unclamp the bag, and there should be no vapour coming from the exhaust. This is genuinely one of the most reliable ways to check your vacuum integrity, these days I have fancy digital vacuum gauges and obscenely expensive ultrasonic leak detectors - the tone of the pump is 99% of the time the first indication I still have a leak.

You dont need a fancy vacuum pump either, the only critical thing is that it can pull 99.995% vacuum. The CFM does not matter at all, you can connect 20 individual 15CFM vacuum pumps together, but if none of them are capable of pulling 99.995% vacuum then they arent good enough. CFM determines how fast the pump can pull the air out of the bag, it doesn't determine the ultimate vacuum level you can achieve. So just check the specs on your vac pump and make sure it can pull very high ultimate vacuum levels.

I did a test.. and no hissing sounds on the part. I did a drop test.   Nothing.  After about 2 hours. I had it leak free i thought. Clamping and unclaping without the gouch moving.. at all.     The pro of these motors is that they are super quiet. So listening for leaks is more easy.

While infusing it all starts perfect. Its all nice and uniform collor. The problem starts after a while.. then the mesh starts to show air inside... and you see the bubbles move through the mesh towards the pump.

It starts at random.    Halfway inside the part allso without a trace of leakage.

Could it be gassing of the resin?   Or do i need to let more resin in?       (This part will get painted. So it doesnt matter its not perfectly infused. But that is offcourse my goal here.)     Allso.   I enveloped a part allso..   same result.
My gauch says full vac. (Needle goes over the furthest point on the clock.) (Funny. That reminds me of a car i had. Lol going faster thenbthe speedometer could)
Anyway. .  I have made 4 parts now.  All 4 show the same isseu.   With el2 and in2 resins. With and without gelcoat

Reason i used gel now is i have a smooth surface anyway. And bridging is easy to fix by injecting resin.

Il try t make a flat carbon pannel and see if i have the same isseu.   

Does it matter i leave the pump running the whole time?

Edited 4 Years Ago by jeffrey bres
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