How much vacuum do I need?

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#1

I rigged a very inexpensive setup tonight and can only get about 18" How much does vacuum infusion require? …and yes I’ve searched but as you can imagine about a 1000 posts pop up with “Vacuum” in it.
I’ve also attached a pic of my mold if that’s any help.
Thanks

#2

Nice work on the mold. Flanges are a little on the small side, so infusion may be a bit tricky.

27"+ is what you want to infuse properly. It also needs to hold at max vac for at least a couple of minutes with the vacuum shut off. A leak will be worse than low Hg.

#3

Thanks for the compliment. This is the second mold I’ve ever made and the first was very small in comparison. I figured that I’d need more vacuum. What is the best vacuum pump for the money that will work for me. Can I also run it continuously as I’m on a budget and don’t want to spend the extra $$$ for all the vacuum controls.
Thanks for you help.

#4

bought a 7 CFM pump from http://www.ctd4ac.com/vacpumps.html and am very happy with it. My vacuum gauge goes from 0" to 30" yes 30"

#5

Someone had earlier asked how to regulate the vacuum pressure. What i did/do is always run full open vacuum at the pump and valve. Then I leave a part of the vacuum bag open to atmosphere pressure ( don’t tape the bag down fully ). Once I have my laminate stack massaged down to the mold surface and it looks and feels right, I then finish taping down the vacuum bag. If the laminate stack doesn’t feel right or look right… DO NOT CONTINUE onto the next step. Lift your bag up and fix the problem before moving foward.

If you are infusing the part make sure to keep your resin line clamped off during that time. Also when infusing let your bag achieve full vacuum for at least 5 minutes prior to starting the infusion. This gives you plenty of time to wait for leaks to occur and find any leaks. I just use a small piece of bag tape to seal any leaks. If you have just one tiny leak on an infused part it will show in the quality of the part - sad to say.

#6

Found the makings for a vacuum pump right under my nose and it cost me nothing. This setup pulls 28" no problem.