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Vaccum bagging pump.

Old 06-17-2007, 11:37 AM
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Default Vaccum bagging pump.

Hi Everyone,
I am building a vaccum bagging setup & collected all items except pump. I got one but didn't sure that this pump suits well for vaccum bagging or not. Here is the link-

http://www.technicsindia.com/technical.htm

Please visit the link & suggest me which is suitable for my needs among them.
Manish.
India
Old 06-20-2007, 10:16 AM
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Default RE: Vaccum bagging pump.

For a low tech and very cheap solution look for a discarded fridge or freezer and see if the compressor is running.

Remove it and use it as a vacuum pump.

If you need a regulator visit a car scrapyard and find a vacuum unit of a distributor on a car ignition system. One of these plus a microswitch and a spring plus a bit of suck it and see will get you a regulator. Mine worked fine.

Recycling is good There is info out there on how to do this.
Old 06-20-2007, 06:34 PM
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Default RE: Vaccum bagging pump.

Just buy one of those cheap direct-drive piston air compressors and modify it to suck instead of blow.

That's what we've done and it's great.

A fridge compressor will give you the necessary vacuum but it's *slow* to evacuate a large bag. The modified compressor is fast -- and because it has a tank, it will cycle far less often (because no bag/connector/hose setup is totally leak-free).

I posted pictures here a while back but since then it appears my image posting privileges have been revoked so I can't re-post them.
Old 06-21-2007, 01:56 AM
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Default RE: Vaccum bagging pump.

Manish.

Some things to consider when selecting vacuum pump:
1. Is it intended for continuous operation?
2. Does it have a vacuum regulator mechanism? (This will switch the compressor off at a pre-set level of vacuum, and start it again when the vacuum drops due to leakage etc.)
3. What level of vacuum do you require? (For molding in a female mold, use as much vacuum as you can get, (22-28 In Hg) but for laminating or gluing balsa skins on white foam, 0,2 bar (5-6 in Hg) vacuum is sufficient, anything more may damage your foam.
4. How large vacuum bags do you use? (Larger bags will leak more, and require a larger capacity pump)
5. Is this strictly for occasional hobby use, or regular "professional" use?
6. Is it noisy? (You may have to leave it on for up to 24 hours)


I am sure there are other points to consider as well, but this is what I could think of just now.

The pumps you are listing may very well be suitable for vacuum bagging as they come from the manufacturer, but I would guess that they are strictly on/off units, with no relulators, vacuum tanks etc.
You would need to add these items if you want to use it for foam.

Regards,
Magne
Old 06-22-2007, 11:31 PM
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Default RE: Vaccum bagging pump.

try this
[link=http://www.rcgroups.com/forums/showthread.php?t=699270]Found surplus pumps for vacuum forming[/link]
Old 06-23-2007, 08:13 AM
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Default RE: Vaccum bagging pump.

That looks like a great pump for the price, thanks Kevin!
Old 06-24-2007, 07:56 AM
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Default RE: Vaccum bagging pump.

Hi Everyone,
I am some but busy last week & can't come online.
First of all thanks for giving such good suggestions.
XJET, can you please sent photos of your compressor vaccum bagging setup in detail.
Magne, If i purchase this pump what are the things/ spares i require to complete & where to get it. Is this vaccum regulator mechanism is used in compressor, or any other machines. It comes readymade or we have to built it. If we have to built it then, how?
Manish
Old 06-24-2007, 11:25 PM
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Default RE: Vaccum bagging pump.

This is my set up for now. I have this pump on order and have a 5 gallon air tank to use for a holding tank and a stand with wheels
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Old 06-25-2007, 03:49 AM
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Default RE: Vaccum bagging pump.

Manish.
Many (most?) airplane modellers make these systems up themselves. There have been several threads here on RCU with instructions, diagrams etc.
Kevin in post #8 above has one example.
I made my own using a refrigerator compressor, but any vacuum pump may do the job. I think the vacuum pumps you referred to in the first post are just the pumps, with no vacuum regulation, vacuum tanks etc. (These may be suitable for continuous work at full vacuum, but will damage foam cores because they are too powerful.)
Here is a link to one design, by Norwegian modeller Ola Fremming:
http://home.online.no/~ofremmi/HowTo.../VacuumBag.htm
This design use a membrane from a car engine distributor to regulate the vacuum, but electronic switches (vacuum switches) may also be used.
I have previously purchased some carbon and fiber glass materials etc. from Aerospace Composite Products in USA. They list vacuum pumps and components, including vacuum switches, but I have not tried these systems.
http://www.acp-composites.com/acp-vbes.htm
(Their shipping costs may also be high to India, they certainly are to Norway.)

Regards,
Magne
Old 06-25-2007, 10:13 AM
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Default RE: Vaccum bagging pump.

Hi everyone,
I have everything now except vacuum switch. Now i have to search vaccum switch in India's market or i have to make vacuum regulator mechanism. Search for swithch is going on. But can anyone plese tell me how to make vacuum regulator mechanism & from where to purchase raw material for making it.
Manish.
Old 06-25-2007, 02:46 PM
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Default RE: Vaccum bagging pump.

I prefer continuous operation pumps myself, as opposed to one that goes on and off all the time.

If your running continous, you don't need a regulator, but just a small adjustable air bleed. You just open it enough to let out air to maintain a certain vacumm pressure.
Old 06-25-2007, 11:52 PM
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Default RE: Vaccum bagging pump.

Hi Dave
I have lost a few wings from that way. I use a Vac switch all the time. If you look at the pic you can see it between the 2 tanks. And the light switch is set up to run all the time or with the vac switch. I still do glass bagging on blue foam.
I tryed the bleed off way and the bag fixed it self a few time and got more vac then I wanted. Have you ever seen a flat wing it is real ugly!!!!!!!!!!!!!!!!!!!
Old 06-26-2007, 04:28 PM
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Default RE: Vaccum bagging pump.

The air bleed screw I use is between the pump and the suction hose, and once the proper bleed is set, you tighten the second nut up to the first one freezing it in place.

Never had a problem with this.
Old 06-26-2007, 11:09 PM
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Default RE: Vaccum bagging pump.

Hi Dave
What has happen to me was , a small air leak in the bag thated fixed itself and to much Vacuum happen and a flat wing!!!!!
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Old 06-27-2007, 08:51 AM
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Default RE: Vaccum bagging pump.

We use the following McMaster Carr item (1/4" NPT) as an adjustable vacuum relief for bagging wings and running the pump continuously. It is a very simple item and works great, and will relieve the vacuum as required to maintain a set level even if the bag leaks more or less during the cure time.

*****************************************
Brass Adjustable Vacuum/Pressure Relief Valves

Adjust these brass valves to relieve vacuum pressure from 0 to 27" Hg. They can also be configured to work as pressure-relief valves for low-pressure compressed air applications. Pressure adjusts from 0 to 20 psi with the knurled adjustment screw. They are not factory set to a specific pressure. Valves have a Type 302 stainless steel spring. The 1/4" pipe size valve has a metal-to-metal seal with a Type 440C stainless steel disc; 3/8" and 3/4" pipe size valves have a Buna-N seal with a nylon disc. Temperature range is -40° to +250° F. Connections: NPT male bottom inlet and vented top outlet.
Pipe Size Ht. Each

1/4" 1 3/4" 48935K25 $7.70
**********************************************

Old 06-27-2007, 10:19 AM
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Default RE: Vaccum bagging pump.

I got mine from Aerospace Composites, here is the blurb from their site (unfortunately, no picture):

BLEEDER VALVE
An adjustible valve that allows the vacuum to be regulated to prevent crushing of light density foam. It's an inexpensive way to regulate vacuum pressure. However, the vacuum pump must run continuously until the epoxy resin cures.
Old 07-16-2007, 02:06 AM
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Default RE: Vaccum bagging pump.

hi guys.
i'm going to built a vacuum pump too. actually I tryed to use a refridge pump. it was good before it died it was providing max vacuum -0,8 bar. thats it: http://forum.rcdesign.ru/index.php?a...ntry&id=100183
http://forum.rcdesign.ru/index.php?a...entry&id=95928
here you can find some more photos: http://forum.rcdesign.ru/index.php?a...og&blogid=113&
but that pump died, or better to say i killed it. certainly i can buy a new refridge pump but for flow 37lpm it will cost more than vacuum pump like this:
http://www.made-in-china.com/image/2...acuum-Pump.jpg
is it possible to use such pumps with pressure switch?
i'd like to built a pump for noncontinious work.
Old 07-23-2007, 08:30 AM
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Default RE: Vaccum bagging pump.

Doug Walsh has a great deal on unused surplus Thomas Wob-L (oilless rocking piston) pumps at www.build-stuff.com right now. Under $100 for a pump that would retail for three or four times that.

I have two and they're great. (A bit overkill for most vacuum bagging, but for under $100, who cares?) They have high enough flow to work well for vacuum forming, and they can be used as compressors for airbrushing as well.

If you can't go $100, you might consider the really low-ball approach of using a converted bike pump. You can buy an old-fashioned bike pump and a few parts for about $18 total, and convert it easily in about 20 minutes. Check it out:

http://www.instructables.com/id/EA58LR1F35J1I9N/

Don't laugh at the idea of a manual vacuum pump for bagging. My bike pump can pull over 20-24 inches of Mercury, and can pump a gallon jug vacuum reservoir down to 20+ inches in less than a minute. (There's a popular kit from Roarockit for vacuum pressing skateboards and small woodworking stuff, using just a wine-bottle vacuum pump that's much slower.)

You can also convert a 12V electric tire inflator-type air compressor to a light-duty vacuum pump. (Light duty, but plenty high vacuum.) I made one for a few dollars using an inflator I got from a Goodwill Outlet Store.

http://www.instructables.com/id/E791HNXF23Z39P6/

A FoodSaver kitchen vacuum sealer can also make a good light duty vacuum pump. They generally pull 23+ inches of mercury. I used to use one for a small vacuum forming setup, before my wife confiscated it and started bagging food with it.

A "nebulizer" pump should also work. They don't pull as high a vacuum (about 17 inches of mercury), but that's enough for most bagging of foam wings and stuff. You can get them cheap on eBay and even cheaper at Goodwill sometimes. (I've gotten three for $2 each at the Goodwill Outlet.)

For these little electric pumps, you'll want to have a vacuum switch, and a pretty well-sealed bag. They'll likely burn out if you run them continuously for more than a few minutes.
Old 08-08-2007, 06:25 AM
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Default RE: Vaccum bagging pump.

Hey,

If you have a compressor, all you have to buy is a transducer. I dont know how much they cost or were you can get them from, but just by looking at them, shouldnt be anymore than $50AUD.
They work by using compressor air through a venturi, and the vacuum line is tapped off the middle of the venturi.
You will have a constant sound of leaking air and the constant use of compressed air. What i have done to stop using compressed is to vacuum it to ur 20"in.hg + and then have a tap and shut off the vacuum. If your vacuum bag doesnt have any leaks, your vacuum shouldnt drop, but i always monitor it with a vacuum gauge every 10min or so.

Cheers
Old 08-08-2007, 11:18 AM
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Default RE: Vaccum bagging pump.

A venturi vacuum generator will work if you have a compressor that can pump 4+ cubic feet per minute at 90 PSI. They only cost about US$15 at Harbor Freight.

Unfortunately a lot of people have little compressors that can't do the duty. (The kind that can drive a brad nailer but not more air-intensive air tools.) They may be able to pump a few CFM, but not at 90 PSI.

A venturi vacuum generator isn't an efficient way to use a compressor---you use a LOT of compression to get a much smaller volume of vacuum---but that's not much of an issue for most vacuum bagging. If you have a compressor that can pump enough air, it's a good cheap way to go.

If not, you might consider converting your small compressor to a vacuum pump, which is much more efficient than driving a venturi.
Old 08-08-2007, 11:21 PM
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Default RE: Vaccum bagging pump.


[link=http://search.ebay.com/search/search.dll?from=R40&_trksid=m37&satitle=Gast&categ ory0=]Ebay is a great place to find Gast pumps at good prices.[/link]

I used [link=http://www.acp-composites.com/acp-vbes.htm]These guys[/link] for the Vacuum switch ($40).

Barry
Old 09-24-2007, 04:42 AM
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Default RE: Vaccum bagging pump.

Hi Glueit,
I have tried all the above cheap approaches and found they all have their faults. The refrigeration motors are ok (while they last) but difficult to regulate. I killed four of these before I went down the route of a pump rated for continuous operation - price was not cheap though Aus$1000.00 although I have not looked back and I do all types of work with it.
Mine was for a small business operation but I would suggest that you look on eBay or elsewhere for a secondhand unit - you won't regret it.
rjmods
Old 09-26-2007, 06:12 PM
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Default RE: Vaccum bagging pump.

If you're looking for a "real" vacuum pump, the surplus Thomas rocking piston pumps (4.5 CFM, 115V, around 27 in. Hg) pumps Doug Walsh is selling at www.build-stuff.com are the best deal I know of. (Like Gast, Thomas is a major and respected brand of pumps.) Under $100 shipped.

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