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Vacuum Pump discussion/questions

RoadRash

Member
There is a technique used in Vacuum Casting (for lost-wax casting, for making jewelry) where they use a vacuum pump to pull a vacuum on a much larger chamber.

Right when the hot molten metal is poured into the mold, a switch is thrown, and the volume around the mold gets exposed to the bigger vacuum. It sucks the hot metal into the mold, which is slightly porous.

I wonder if you can use something similar to help with the extraction process. But it would be a pulsed process, not continuous.

I suggest Auction BDI as a possible source for surplus vacuum pumps. They are a big surplus re-seller in Silicon Valley. They sell almost everything.
http://www.auctionbdi.com/

I got my one vacuum pump from a surplus electronics place in San Diego.
 

Jnugg

Active member
Veteran
I'll look into them Road Rash,just waitin' on GW to get back to me on that kit I just posted.
 

Gray Wolf

A Posse ad Esse. From Possibility to realization.
Mentor
ICMag Donor
Veteran
There is a technique used in Vacuum Casting (for lost-wax casting, for making jewelry) where they use a vacuum pump to pull a vacuum on a much larger chamber.

Right when the hot molten metal is poured into the mold, a switch is thrown, and the volume around the mold gets exposed to the bigger vacuum. It sucks the hot metal into the mold, which is slightly porous.

I wonder if you can use something similar to help with the extraction process. But it would be a pulsed process, not continuous.

I suggest Auction BDI as a possible source for surplus vacuum pumps. They are a big surplus re-seller in Silicon Valley. They sell almost everything.
http://www.auctionbdi.com/

I got my one vacuum pump from a surplus electronics place in San Diego.

That is called reverse gravity casting and as far as I know was developed by Hitchner.
 

Jnugg

Active member
Veteran
Trying to find a better (but still economical) vacuum chamber because all the ones on ebay and amazon have only 1/2" to 3/4" lids which Greywolf advises against.They also all have rivets in the handles which either don't allow full vac due to leaks,or hold vac poorly because of leaks.I think the rivet leak issue can be solved with a little JB weld,but unsure of how long the lids will last before deflecting and breaking.He also says they come with crap gauges,but I could replace the gauge with a quality analog gauge if need be.

Anyone using one of the vac chambers I posted above?

I wanted to get a steel/aluminum one so I can just set it on my griddle/hot plate for heat vac purging.

But I suppose I could go with one of those belart food saver/dessicators...but how would I add heat?


Interested to hear from those using a ProVac or Best Value Vac vacuum chamber.

2 Gallon Aluminum Vacuum Chamber & 3 CFM 50 micron Single Stage Vacuum Pump Kit from best value vacs for $250


3 gallon ProVac vacuum chamber
 

Sirdabsalot46n2

Member
Veteran
While I realize Best Value Vac only provides the 3/4” lid (I mistakingly thought they were uniformly 1”)
.. As long as you don't drop that lid, crack it, chip..or fracture in any way....

The integrity of the lid should hold up...

@GW.. Have you had a chance to inspect these chambers first hand? I will never doubt your advice, as it is of more value than a precious metal in our context...

But I've had the chance to use one, and I must say, they are well-made...

Deflection is not visible to the naked eye..
I have two friends running the 3 gal and one running their 5 gal about once a week, and they are both pleased with the results.

Perhaps the proverbial...

” better safe than sorry ” should apply in this application.

Particularly if you plan on using the chamber a lot.

I will contact the friend with the Best Value 5 gal, he works in the industry and uses his maybe up to 3 times a week, I'll even visit him and inspect and inquire about the integrity of the lid.

I will report back on this thread after the evaluation.
 

Jnugg

Active member
Veteran
That's kind of reassuring to hear SirDabsAlot...

At most I would be making oil once every two months if I do 3oz to 1/4 pound runs (weight in material,not oil).

And please do report back.I've heard of the chambers/pots deflecting/warping.
 

Gray Wolf

A Posse ad Esse. From Possibility to realization.
Mentor
ICMag Donor
Veteran
While I realize Best Value Vac only provides the 3/4” lid (I mistakingly thought they were uniformly 1”)
.. As long as you don't drop that lid, crack it, chip..or fracture in any way....

The integrity of the lid should hold up...

@GW.. Have you had a chance to inspect these chambers first hand? I will never doubt your advice, as it is of more value than a precious metal in our context...

But I've had the chance to use one, and I must say, they are well-made...

Deflection is not visible to the naked eye..
I have two friends running the 3 gal and one running their 5 gal about once a week, and they are both pleased with the results.

Perhaps the proverbial...

” better safe than sorry ” should apply in this application.

Particularly if you plan on using the chamber a lot.

I will contact the friend with the Best Value 5 gal, he works in the industry and uses his maybe up to 3 times a week, I'll even visit him and inspect and inquire about the integrity of the lid.

I will report back on this thread after the evaluation.

No I haven't. I just calculated deflection.

Have you laid a straight edge on it and slid a gauge under it?
 

GreenBlood420

New member
Hi I just joined having some questions about purging and found all of my answers in this thread rite hear. First off I want to say I been on multiple sites researching for weeks and u guys are the best. I am new to bho but been intrigued for quite some time, I finaly got a great opportunity to run a large amount of material for a friend and hoped on the opportunity and bought a 3gal best value vac chamber(awesome lid an gasket no issues so far) and a robinair 15300(3cfm-2stage) with this setup I am pulling a complete vac past 30 and was wondering why the bubbling never stop at 110-115*f thin film, I now know thanx to use I had a feeling that couldn't still be butane bubbles. My question is what can I do to stop my chamber from going past 29.5hg? I really don't want to play with the valve for an hour bak an forth trying to keep it in range.
 

GreenBlood420

New member
Trying to find a better (but still economical) vacuum chamber because all the ones on ebay and amazon have only 1/2" to 3/4" lids which Greywolf advises against.They also all have rivets in the handles which either don't allow full vac due to leaks,or hold vac poorly because of leaks.I think the rivet leak issue can be solved with a little JB weld,but unsure of how long the lids will last before deflecting and breaking.He also says they come with crap gauges,but I could replace the gauge with a quality analog gauge if need be.

Anyone using one of the vac chambers I posted above?

I wanted to get a steel/aluminum one so I can just set it on my griddle/hot plate for heat vac purging.

But I suppose I could go with one of those belart food saver/dessicators...but how would I add heat?


Interested to hear from those using a ProVac or Best Value Vac vacuum chamber.

2 Gallon Aluminum Vacuum Chamber & 3 CFM 50 micron Single Stage Vacuum Pump Kit from best value vacs for $250


3 gallon ProVac vacuum chamber

I am using the 3 gal best value vac and so far the thing is a beast granted its only been a week but no issues so far, I also got it on top of a griddle and everything's been kosher :yay::yay:
 

Jnugg

Active member
Veteran
My question is what can I do to stop my chamber from going past 29.5hg? I really don't want to play with the valve for an hour back an forth trying to keep it in range.


The ball valve.

I don't see what's so hard about it...turn the vacuum pump on,once your chamber reaches a vacuum of -29.5" HG just shut the ball valve the pump is connected to and turn off the pump.

What is it you're trying to make (shatter,wax)?

I have read to do an initial vacuum of -15"HG and then devac,etc.

But I'll let GW and the others answer.
 

GreenBlood420

New member
The ball valve.

I don't see what's so hard about it...turn the vacuum pump on,once your chamber reaches a vacuum of -29.5" HG just shut the ball valve the pump is connected to and turn off the pump.

What is it you're trying to make (shatter,wax)?

I have read to do an initial vacuum of -15"HG and then devac,etc.

But I'll let GW and the others answer.

Well the reason i dont do that is cause i was under the impression u wana keep the pump on with the valve open to keep new air circulating threw i thought if u just shut it with the valve closed moister can build up in the product?? And also im making shatter
 

GreenBlood420

New member
I guess a better question would be how long can i leave the valve closed at my desired vacuum before i have to start worrying about moister and burp it?
 

Jnugg

Active member
Veteran
Well your cac chamber should have two ball valves on it.One is connected by tubing to the vacuum pump and the other not connected to anything (but maybe a coffee filter over it).

Close the ball valve that isn't connected to it.Open the ball valve that is connected to the pump via tubing.Pull your vac down to -29.5" HG,then close the ball valve that's connected to the pump via tubing and turn off your pump.

When you go to devac,DON'T open the ball valve that's connected to the pump,the reason being that there is a vacuum pulled in the vac chamber and if you ope that ball valve you could end up pulling the pumps oil into the chamber...so instead,open the ball valve that isn't connected to the pump to devac the chamber.

When you're ready to pull another vac,shut the unconnected ball valve,open the ball valve that's connected to the pumps tubing.
 

GreenBlood420

New member
Well your cac chamber should have two ball valves on it.One is connected by tubing to the vacuum pump and the other not connected to anything (but maybe a coffee filter over it).

Close the ball valve that isn't connected to it.Open the ball valve that is connected to the pump via tubing.Pull your vac down to -29.5" HG,then close the ball valve that's connected to the pump via tubing and turn off your pump.

When you go to devac,DON'T open the ball valve that's connected to the pump,the reason being that there is a vacuum pulled in the vac chamber and if you ope that ball valve you could end up pulling the pumps oil into the chamber...so instead,open the ball valve that isn't connected to the pump to devac the chamber.

When you're ready to pull another vac,shut the unconnected ball valve,open the ball valve that's connected to the pumps tubing.
Yes all of this u just said i allready know man, that dosnt answer the question about moister??
 
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