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Author Topic: Vacuum Pump  (Read 4855 times)

Offline BlueBee

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Vacuum Pump
« on: January 10, 2012, 10:33:36 pm »
Any of you out there own a vacuum pump?  I’m slowly getting around to making a few more foam based hives for Summer 2012.  This time I’m thinking of using a vacuum pump for my foam lamination process.  I hear some wood workers use vacuum pumps when gluing veneer to plywood and auto guys use them for AC work.  Does anybody have some useful tips to consider before buying a vacuum pump? 

Online Michael Bush

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Re: Vacuum Pump
« Reply #1 on: January 11, 2012, 04:12:46 am »
The other upside is you can use the vacuum chamber to fill comb with syrup.  Dunk the comb and suck out the air.  As the pressure falls the air will come out of the combs.  As you let the air back it the syrup will go into the combs...
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Offline BlueBee

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Re: Vacuum Pump
« Reply #2 on: January 11, 2012, 06:24:48 am »
Sounds interesting Michael, but I think I’ll just let the bees put the syrup in the comb.  I make a big enough mess in the kitchen just mixing up the syrup  :)

Online Michael Bush

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Re: Vacuum Pump
« Reply #3 on: January 11, 2012, 06:54:46 am »
Someone has been discussing using a vacuum to get it into the comb rather than spraying or sprinkling when trying to get emergency feed on bees.   I might try it if I already had one.  :)
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Offline derekm

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Re: Vacuum Pump
« Reply #4 on: January 11, 2012, 11:47:30 am »
I will fessup to a vacuum pump collection about 8 of them ...
depends on how low in pressure and how much volume you want to go and how clean
water vapour pressure at 20C is 2 Kpa = 2E-2 Bar = 17mm hg = 17 torr =2% of atmospheric
any old single stage rotary pump should get there.
diaphram pumps  wont get there they stop around 10% atmospheric 10Kpa 76mm hg 76 torr
single stage rotarys stop around 3 E-5 bar =2.2 E-2 Torr
double stage rotaries stop around  1.5E-6 Bar = 1E-3 torr
diffusion pumps, turbomolecular pumps scroll pumps ....
If they increased energy bill for your home by a factor of 4.5 would you consider that cruel? If so why are you doing that to your bees?

Offline BlueBee

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Re: Vacuum Pump
« Reply #5 on: January 11, 2012, 02:42:48 pm »
I’m looking at a modest cost vacuum pump probably from Amazon.  A Rotary vane pump + fractional hp induction motor (1/3hp?) rated at about 3 cfm.  Sounds like most modest cost units are single stage, but many still claim to pull a vacuum down to 0.01kPa.  Anything rated with those specs I hope can pull down to 1kPa in real applications.  If so that should be 14.5 psi of pressure on my foam laminations.  That’s equal to a 66,000 pound weight on a 4x8 foot sheet of lamination.  

I think the foam is only rated at 15psi, so I don’t want to go too high  :) 

There sure are a bewildering number of units for measuring pressure isn’t there!  I like to work in kPa myself.

Offline derekm

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Re: Vacuum Pump
« Reply #6 on: January 11, 2012, 03:14:18 pm »
Quote
I think the foam is only rated at 15psi, so I don’t want to go too high [\quote] Lol

15 psi =1 baR = 760mm hg =760torr= 100Kpa = 1 atmosphere =10m water gauge
If they increased energy bill for your home by a factor of 4.5 would you consider that cruel? If so why are you doing that to your bees?

Offline windfall

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Re: Vacuum Pump
« Reply #7 on: January 11, 2012, 05:40:20 pm »
The last shop I subbed in had a basic vacuum pump rig and it was great. You could layout and glue all sorts of complex assemblies that would be near impossible otherwise.

For most applications you need very little pressure.....although really this is dependent on your adhesive of choice.

You want a way to dial in the pressure, most basic pumps just try to draw their max, a simple bleeder tube and ball valve let you dial it in by intentionally allowing a small controllable leak.

You will want breather cloth for any large panels. Its really just polypropylene "fluff" that allows the pump to pull air evenly. Sometimes the plastic sheeting will seal itself off against a smooth surface without this, leaving areas beyond without vacuum.

You may also want "peel ply" It is a permeable membrane that allows some adhesives to migrate through but won't bond down itself...helps keep the surface nice and the breather fabric from becoming part of the lamination.

You definetily want a "trap" between your work and the pump to capture excess adhesive before it is sucked into said pump.

Butyl rubber tape (which is basically sticky goo on a roll) is super handy for making and sealing your vacuum bags. You can seal to many surfaces and irregularities, also an easy way to make a seal around you tubing penetrations in the sheet/bag. Duct tape works too but not as well or in as many different ways.

for gluing large flat panels without a vacuum table, you can use a big flat section of concrete slab and tape a "bag" over it...pull the vacuum against the slab....worked great.

hope this helps some. I can't give much input on motor types and recommendations.

Separately, I have a hard time believing empty comb wouldn't collapse into a chunk....but maybe if you crept up on it?

Offline BlueBee

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Re: Vacuum Pump
« Reply #8 on: January 11, 2012, 09:22:25 pm »
Some good tips.  I have been doing some reading, but it always takes some experience to get proficient at something.  I hope my first foam hives for 2012 don’t get crushed like a bug under all that vacuum!  A bleeder valve sounds like a good idea in this application.

What I’m hoping to improve with a vacuum pump is the uncontrolled foaming/expansion/outgassing of polyurethane glue (ie Gorilla glue) between my foam and my luaun.  For the last nucs I built, I used 25 gallon Rubbermaid containers filled with water as a weight over my foam + luaun lamination.  However even with all that weight, the glue still foamed up enough that each panel had a difference thickness.  When all the parts aren’t dimensional, you have to start custom fitting each box; that is a pain.

What I don’t what to repeat!


Offline Shanevrr

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Re: Vacuum Pump
« Reply #9 on: January 12, 2012, 08:29:05 pm »
Check your local HVAC supply house.  They sometimes have repaired ones that got left behind for sale.  Or can just a new one.  Get something high volume
www.Valleybeesupply.com
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Offline derekm

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Re: Vacuum Pump
« Reply #10 on: January 13, 2012, 05:26:11 am »
...What I’m hoping to improve with a vacuum pump is the uncontrolled foaming/expansion/outgassing of polyurethane glue (ie Gorilla glue) between my foam and my luaun.

I dont want to be the bearer of bad tidings but there is a real chance that isnt going to work with a fast setting foaming glue...
Reducing the pressure will make the voids bigger and the expansion greater and it may set before the voids burst.
Vacuum bagging is normally used to de-aerate and compress non foaming glues and resins (e.g. epoxy) with longish work times.(e.g. 1/2 hr)

A regards the comb fill with syrup, you would use a rigid vacuum chamber with the comb face down in a tray of syrup. the maxim pressure differential is then a few mm of syrup.
If they increased energy bill for your home by a factor of 4.5 would you consider that cruel? If so why are you doing that to your bees?

Offline BlueBee

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Re: Vacuum Pump
« Reply #11 on: January 13, 2012, 03:02:24 pm »
I have that concern too Dekerm.  Kind of why I started this thread!  I guess if a vacuum pump doesn’t work for laminating foam + luaun + PU glue, I could still use it for my occasional fiberglass project or veneer project.  I wonder what else a person can do with a vacuum pump?  (No, I don’t repair my own AC equip). 

I would guess that my PU glue stays pliable for about 15 to 20 minutes.  However getting the gasses to migrate out from between the foam and luaun in that amount of time may still be my undoing.

Offline windfall

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Re: Vacuum Pump
« Reply #12 on: January 13, 2012, 04:46:40 pm »
I was starting to think about poly and vacuum as well...I don't think I have ever seen it used under vacuum.
Most SIPs(structural Insulating Panels) use poly glue. Now they set them up in stacks and put a pneumatic press to the bundle. I know guys who used to make them homespun with steel sheets and a car...what you need is a water bed matress and a spare sheet of 3/4" ply as version 2 of your gluing rig!

Gorilla Glue has a very fast reaction time. You can put it in the freezer ahead of use to buy more open working time, but it gets very viscous and hard to spread.

 

anything