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Author: Subject: Poor man's vacumn bagging.
designer

posted on 19/3/09 at 11:29 AM Reply With Quote
Poor man's vacumn bagging.

Intending to do composites

http://www.krsuper2.com/vacuumbag.html

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RK

posted on 19/3/09 at 12:08 PM Reply With Quote
Why won't a regular vacuum cleaner work? It draws air out as well as anything if you arrange the hose correctly so it doesn't get stuck in one spot.

It strikes me that once you buy all this crap to go DIY professionally, you are beyond the purchase price of everything you'd want!


ps says the guy building his own car...

[Edited on 19/3/09 by RK]

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dinosaurjuice

posted on 19/3/09 at 12:16 PM Reply With Quote
regular vacumn cleaners require air flow to keep them cool. without this they burn out fairly quickly.






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MikeR

posted on 19/3/09 at 12:20 PM Reply With Quote
so put a fan next to the motor.
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balidey

posted on 19/3/09 at 12:27 PM Reply With Quote
Or use a venturi vac generator run from a compressor. Costs a couple of quid

EDIT: ok maybe not a couple of quid, but about £10 from RS will get you one.

[Edited on 19/3/09 by balidey]

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PAULD

posted on 19/3/09 at 12:34 PM Reply With Quote
vacuum bagging

I believe a motor/pump unit from a fridge is the thing to use.
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twybrow

posted on 19/3/09 at 01:33 PM Reply With Quote
Read the article!!! It explains why the fridge pump is no good - the CFM rate is just too low to overcome any leaks you get (which you will have).

A vacuum cleaner can only pull around 600mbar residual, whereas you need something to pull down to ~3mbar. you can pick them up on ebay from £50 upwards....

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balidey

posted on 19/3/09 at 02:00 PM Reply With Quote
depends on the size of panel and how good the seal is, but I have used a cheap venturi type vac generator with no probs.
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spewing

posted on 19/3/09 at 02:28 PM Reply With Quote
All vacuum pumps work best pulling against something.
What you need is a reasonable size canister in the line to the vacuum pump. This gives the pump a volume to pull against which in turn pulls a vacuum against the material being vac bagged.
By the time you've evacuated the bag you are just have atmosphere pushing against the resign and material and the pump can only pull against the pipe.

If the canister you put in the line is large enough you can use a fridge pump to evacuate it over some time and then open an isolator between the canister and the vac bag to evacuate the air in the bag giving the fridge pump a better opportunity to recover the vacuum.

The same applies to all vacuum pumps and if you have a canister in the line you can get good results with the venturi type vacuum pumps. (the type that use water rather than compressed air pull a better vacuum but you wouldn't want to use one if you were on a water meter)

Kev

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