Vacuum bagging

[Bart Drieghe]

Hi Guys ,

Got a question concerning vacuum bagging .

I'm doing some epoxyjobs with the vacuum bagging technique , quite often the result works great but i do have a "small" problem sometimes , sometimes i can't keep the bag under vacuum . So i got a leak ........ or leaks ....... But how can i find them ??

My hearing is pretty well so i can find some leaks but those tiny ones are too difficult to find .

Have you got a technique to find the leaks ?

Yes , i do realise that there are devices to find the leaks , ultrasonic leak detectors . I know that but they are most of the times sooo expensive and i can't afford lots of money .

IF someone would know a link or so to a cheap ( but still working) leak detector , please let me know

Thanks already

 

[Terry Flynn]

you could try something like this,and just look to see were it gets sucked in at.

http://inspectusa.com/matches-smoke-emitter-white-splintax-seconds-s210-pack-p-242.html

 

[TCHedOff]

Bart, couldn't you use smoke of some kind... fill up the bag and see what leaks out where?

Just thought I'd toss it out there - have no idea myself. Now you got my wondering what you're up to to kick my butt again this year!

 

[TimothyJones]

If you have a vacuum gauge meter monitoring the vacuum you can use acetone or a high flash point solvent.

Tim

 

[HendricX]

Blow-up the vacuüm-bag ... and throw it in the bathtub ... airbubbles will indicate the leak.

Blow-up the vacuüm-bag ... and sponge it with 1/2 water/1/2 dishwash-soap ...

or buy Motip-leak detector at a carparts-store.

Go to a bicycle-shop or Halfords , and buy a leak-detector > L I N K

 

[Terry Keeley]

l just go around the seal area (mastic) pressing and squeezing while watching the vacuum gauge, it'll usually be in a corner or around the fittings.

Whatcha molding?

 

[Mike Hughes]

You should hook up your pump to a 5 gallon container with a auto shut off. That way if a leak does happen at any time the container will help to mantain the vacuum. When the negative pressure gets to low than the pump will kick on. This is what I plan on doing to my setup. Just have not gotten around to it. My buddy Eric uses this same technique with no issues. I have an old propane tank(outlawed ones) for my container. You can also use those throw away helium ballon container you get from the party stores. They are about 3 gallons or so. The only thing I am lacking is the pump controller. I could try and get a hold of what he uses if you like.

Mike

 

[steve wood]

anyone tried the brush on silicone bag from smooth on ?

 

[Tony Jacuzzi]

l just go around the seal area (mastic) pressing and squeezing while watching the vacuum gauge, it'll usually be in a corner or around the fittings.

Whatcha molding?

me too always seems to be in the corner, then i try and roll out re-squeeze that area, you can usually see the gauge jump when you start poking around the sweet spot

 

[Bart Drieghe]

@Terry Flynn, I can't seem to open that page ?

Putting the bag in a bathtube is almost impossible because the mould is inside the bag . If i'd do that , water could come in the bag and i don't want that .

Blowing up the bag could be possiblem but i'm using rather large bags so it takes a while to blow it up and then to get it vacuum.

I haven't tried the extra container thing but its certainly something that stands on the list now to try .

@Terry Keeley , lol i'm doing a V boat , european style . Kinda like a mono .

Size is 1.5 feet width , 6 feet long .

@ Hendricx , explanation above

Smoke , hmmm might be an option but not sure how well this would go .

@ Mike , i have an old compressor wich is good for i think 10 gallon , i will convert that to use as a container , that should do the trick . I do need to find a pump controller , something that works on the pressure ( just like for a compressor except now for vacuum )

I've had someone on the line who works quite often with epoxies and vacuum , he told me that his firm bought the ultrasonic leak detector cause they were doing expensive jobs and really needed that . They tried it with a stethoscope in the beginning but that was really time consuming .

I'll see what i can do the next time !!!

Thanks already for thinking with me !

Bart

 

[Mike Hughes]

I look at McCaster Carr and found this vacuum controller. Part #4779K11 With this and a short extension cord you can make a good controller for around $106. Cut the cord in half and hook up the hot wires to the contacts. Plug the male end into power and your pump into the female end. Just have to get a T fitting to attach the sensor to the vacuum line. 10 gallon will work great. Hey come to think of it, that sensor might just mount where the existing presure controller is on the compressor. Even easier.

Mike

 

[Mark Anderson]

This is the switch that I used on my cycling system. http://www.veneersupplies.com/products/Vacuum-Pressure-Controller-18-NPT.html. I now have a continuous duty pump. I just work the mastic with a small roller and watch the gauge. I can usually get it sealed up completely in a couple of minutes.

Mark

 

[Terry Flynn]

@Terry Flynn, I can't seem to open that page ?

I just tryed it and it opened for me, Any one else having this problem?

 

[DaveMarles]

Bart, Its your hearing that is the problem. If ever I tell you to move over in a race you don't hear me.

Anyway, my guys use this for the hard to find leaks ultrasonic

 

[SCOTT WITHERELL]

http://www.fibreglast.com/product/Brass_Plastic_Two_Way_Shutoff_Valves_01504_A/Vacuum_Bagging_Tools

 

[Bart Drieghe]

Bart, Its your hearing that is the problem. If ever I tell you to move over in a race you don't hear me.

Anyway, my guys use this for the hard to find leaks ultrasonic

AHHHH thats what you've been yelling at me lol

Thanks for the link Dave, this comes into my budget

I did a test yesterday and this time i have found the leak , my pressure valve ( or a one way valve ? ) is faulty , i lost vacuum while it should have been the thing that kept my vacuum . But after that , the bag stayed vacuum and was still like that this morning !!!

Thanks all ,

B