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Vacuum Bagging
Dangerstevie - 9/1/14 at 12:38 PM

I would like to pick the brains of those experienced with vacuum bagging carbon fibre and fibreglass please.....I am going to be making a fibreglass seat based on an old on i have sat in the workshop, I could wet lay it no problem but i fancy making it a bit lighter and a bit stronger by vac bagging it. I have been looking at Vac pumps and it seems there are a few types, the proper composites vac pumps are approx £160 however on evilbay there are some refrigeration vacuum pumps for approx £55. My question is.... is there any reason why the refergeration vac pumps would not work as a vac bagging pump? I have seen people use the actual fridge compressor to pull a vacuum before but that seems a bit ghetto and hill billy.

Any advice is well appreciated.
thanks


britishtrident - 9/1/14 at 12:45 PM

Hand pump vacuum oil extractors raise a pretty good vacuum ---- Pela is the best make by far. If you buy a Pela 6000 you can use for engine/gearbox oil, coolant and and other fluid changes --- they are also very useful for other jobs such as if the washing machine breaks down full of water.


fesycresy - 9/1/14 at 02:23 PM

The same vac pumps are used in the fridge game, I'd even go so far to say they were originally designed for fridge. I'd been using them for many years on a/c before I knew about carbon.

Have a look on the 'Easy Composities' website and they have a good tutorial by Matt on resin infusion.

I'm about to make a few resin infused panels next week.


twybrow - 9/1/14 at 03:00 PM

The pump they sell at EasyComposites is available for much less on ebay. You need a pump that can achieve high vacuum (less than 5mbar residual ideally), but it does not need to pump much volume (hence why vacuum cleaners are not suitable for composites work!).

eBay Item

Something like this will do you nicely for small jobs. Just don't suck resin into the pump - this is avoided by using a catch pot to ensure nothing gets as far as the pot.


plentywahalla - 9/1/14 at 10:58 PM

The ultimate specification of the pump is not as important as getting a good seal and using an efficiently set up breather to ensure the pressure distribution is as effective and as evenly distributed as possible.

I have done a lot of vacuum bagging, not only epoxy/carbon layup but also with laminating veneers. I have learn't the hard way that a poor set up and lack of preparation is more likely to produce a poor result than using a cheap pump.


twybrow - 10/1/14 at 05:04 AM

quote:
Originally posted by plentywahalla
The ultimate specification of the pump is not as important as getting a good seal and using an efficiently set up breather to ensure the pressure distribution is as effective and as evenly distributed as possible.

I have done a lot of vacuum bagging, not only epoxy/carbon layup but also with laminating veneers. I have learn't the hard way that a poor set up and lack of preparation is more likely to produce a poor result than using a cheap pump.


Very true. The use of breather (and peel ply/release film) is important to ensure you do not get lock off when vac bagging.


coyoteboy - 12/1/14 at 11:42 AM

My vac pump came from a "side of the road dumped fridge". The owner had damaged the rad on the rear so I just chopped out the motor with some reasonable tails and went from there. Free and very good.


BenB - 12/1/14 at 01:38 PM

Most of the fridges I've seen dumped recently had the compressor taken out. Either there's lots of people doing vacuum bagging or that's where all the Ebay ones come from!