Author Topic: Recommended Vacuum Pump and Chamber  (Read 428 times)

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Offline magicsmoke

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Recommended Vacuum Pump and Chamber
« on: January 24, 2021, 12:20:27 am »
I want to purchase a vacuum pump and chamber for varnishing coils and degassing epoxies for casting. Maybe some other uses later. Does anyone have recommendations for vacuum pumps and chambers?

For the chamber ideally I probably need something 3 or 4 gallons in size with a glass lid. On the chamber I am hoping to spend $150 or less.

For the pump I was looking at two stage pumps in the 3 to 4 cfm range. One of the brands I was looking at was Yellow Jacket. Are they recommended? I was planning to get an outlet oil filter otherwise are oil less pumps worth it. For the pump I am hoping to spend $275 or less.

Are any particular fitting type recommended? Other features that are recommended?
 

Online coppercone2

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Re: Recommended Vacuum Pump and Chamber
« Reply #1 on: January 24, 2021, 04:21:03 am »
keep in mind before you get excited about epoxy degas its only useful for epoxies that are like corn syrup or thinner

If you have thick epoxies you need to mix them under vacuum (or use a mix nozzle, they are pretty good). You also need to pour them under vacuum for anything but the most liquidy ones. You need to be able to control pressure finely too because it will boil the epoxy.

If you don't follow these guidelines the effects are kind of dubious. Maybe its good for varnish but I would not get too excited about epoxy.

Have you ever put it under a vacuum in like a food sealer to see what it does?

my suggestion : get a EPX glue gun and a bunch of nozzles and forget about degas as much as you can. Sometimes stuff like JB weld you can spread it out over a wide surface and degas it I guess but its not recommended by epoxy pros to do so with such viscous fluids. I have a post about it somewhere in specifics. So basically if its too thin the benefits of degas are non, if its too thick it does not work, so it only is useful with a narrow epoxy range.

For casting something really thin, with weird geometry, a degas could help if the stuff is fluid enough, but if you want to cast with thicker stuff, you need to pour or possibly even mix both under vacuum, a rupe goldberg affair to the nth degree.

Make sure its useful to you before you invest in it, I was pretty frustrated. A ghetto apparatus can be made by gluing rubber to an acrylic sheet and putting it on top of a cooking pot without seams after smearing some grease on the lip.
« Last Edit: January 24, 2021, 04:26:52 am by coppercone2 »
 

Offline james_s

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Re: Recommended Vacuum Pump and Chamber
« Reply #2 on: January 24, 2021, 04:24:34 am »
For that kind of use I'd probably just pick up a refrigeration service pump from Harbor Freight. You don't need a really deep vacuum and you'll contaminate a really good high vacuum pump with vapors. The chamber is harder, make sure whatever you do can take the pressure without risking a spectacular implosion. The difference in wall loading between a very poor vacuum and a very good vacuum is actually very small.
 

Online coppercone2

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Re: Recommended Vacuum Pump and Chamber
« Reply #3 on: January 24, 2021, 04:27:44 am »
For that kind of use I'd probably just pick up a refrigeration service pump from Harbor Freight. You don't need a really deep vacuum and you'll contaminate a really good high vacuum pump with vapors. The chamber is harder, make sure whatever you do can take the pressure without risking a spectacular implosion. The difference in wall loading between a very poor vacuum and a very good vacuum is actually very small.

this is more then true because you CANNOT use too low a pressure with epoxy because messes with it. The rules are there is a minimum allowable pressure and a specific time you can use it for. Usually only like 1 minute.

the cheapest HF pump is enough I think, no need for the 2 stage IIRC.
 

Offline jonpaul

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Re: Recommended Vacuum Pump and Chamber
« Reply #4 on: January 25, 2021, 11:35:04 am »
Hello Depending on the type of epoxy, itme dimensions,  viscosity and cure cycle, you may need a vacuum oven.

Some need the vacuum during cure.

Finally the gasses emitted may damage some pump seals and components.

What exactly are you manufacturing?

Jon
Jon Paul
 

Offline bill_c

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Re: Recommended Vacuum Pump and Chamber
« Reply #5 on: January 25, 2021, 05:50:30 pm »
Locate the pump outside or pipe the exhaust outside, you will never be able to filter all the oil vapor.  You don't want oil vapor coating every surface inside.
Do NOT use PVC pipe for vacuum (or compressed air), seen it implode and go through the side of a metal building.
 


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