www.TK560.com

[crashmann]

I've been seriously considering upgrading my table to use a real vacuum pump and tank. I've considerd using beer kegs, but they only hold 15 gallons each. According to the Prop Builder's Molding and Casting Handbook, I would need a 40 gallon vacuum chamber for a 24" x 32" table. This would require daisy chaining 3 beer kegs together (it would be a great time emptying three beer kegs )

So, I was passing through the Sears hardware department, and noticed they sell air compressors with gigantic tanks... Hmm, all I need is the tank (since I already got a great deal on a Gast 1065 pump) but I'm not ready to shell out $600 for a complete air compressor unit.

The Casting book recommended using a hot water tank, but to buy one new is cost prohibitive. Plus they're enormous!

I've gone digging online for large size air tanks, but I can't find the tank by itself (greater than 11 gallons).

The sales clerk at Sears told me to call (800) 4MY - HOME to see about ordering parts for their tools, since they couldn't sell me just the tank.

Does anyone know where to find a 40 gallon (or 60 gallon ) air tank?

Thanks!

Charlie

[jegner]

I too am ready to upgrade to a real vacuum system. I even have a great Hi-Vac Pump. I too am having issues with what tank to use. I have a 15 gallon, and over on the RPF a year or so back it was said that you could get away with that small of a tank IF everything worked perfectly. My bare minum is a 25 gallon tank. And the ideal is a "narrow' model 30 gallon hot water tank from Lowes. Less than $200. I keep trying to find a used water heater, the right size at a second hand appliance store for about $75. So far no luck.

One thing that is also holding me back, the 'controls' for the vacuum system seem much more conplicated. Gotta have a valve at the tank. Gotta have a valve at the pump, and all the elbows, T jonts and etc. to get the 'dump' valve handy when forming. Then I need guages to tell me when the tank is empty. yada, yada, yada.

Right now, my shop vac is one switch on, and then off when the thing is done.

But, I can get better pulls, pull thicker material, and pull ABS with a hi-vac system.

The other challenge is to pace the evacuation of air from the tank faster than it takes to heat the plastic!

Ah, what fun this hobby is.

[crashmann]

I've been digging like crazy to find a suitable, economical (read cheap ) vacuum tank, and I've come up with a couple of options:

I called Sears 800 - 4MY - HOME
Part number 919.184191 60 gallon Air Compressor - or -
Part number 919.167342 33 Gallon Air Compressor
"Hmm, that's wierd... It says non-servicable part. Can not be ordered. Try going to the Sears Service Center." I drove there and they shook their head and said the same thing. So, if you buy a compressor from Sears, and the tank rusts out, too bad. You've got to buy a whole new unit!

http://www.kegs.com/155gal3.html
Sabco is the leader in selling refurbished beer kegs, and they can even add an adapter to give you a threaded connector to the keg (like a 3/4" pipe) Daisy chain three kegs together with T connectors and the associated plumbing, and you've got 45 gallons of vacuum tank! However, I think there's a concern about draining out the condesation inside the tanks to prevent corrosion. Since kegs only have one opening, you'd have to remove the keg from the system and turn it upside down to drain the water. Too much work! Also, I think they're not interested in a tiny order like mine, since they haven't returned my calls (although their website claims to cater to home brewers...) Also, the shipping will probably be cost prohibitive.

Lowes.com Manchester 100 pound propane tank
Only $79.97!!! I haven't seen this thing in person, but from the picture, I'd figure it's 4' tall, and 18" in diameter. It should be around 30 gallons in volume, if not more. Compare it to the 60 gallon air compressor tanks, and I think it should be the same size. Did I mention it's cheap?!? I had trouble finding a Lowes that has these tanks in stock, and you can not order online. Also, being a propane tank, it's probably got a special fitting at the top, and no drain plug at the bottom. Since this is significantly bigger than a beer keg, you're not going to turn this upside down to drain it! Perhaps you could weld a fitting on the bottom?

GE 38 gallon water tank (no heating element - part of the instant hot water system, where the heater element is right under your sink)
It's pricey at $199.99 at Home Depot, but it's got the exact capacity that I need, 38 gallons! Also, it's not too big at 24" diameter and 40" tall. It's got two connections at the top for input and output of water, and a drain at the bottom. Everything you need! But, will it withstand 28" of mercury?

I called a bunch of air supply companies (oxygen suppliers, air compressor tool resellers, etc...) and they all thought I was crazy. Sure, everyone's got air compressor tanks, but you want a vacuum tank? And how big?!? I would figure that if the tank can stay together with up to 150 pounds of pressure, then it should be able to withstand 28" of vacuum. Maybe those companies are afraid of liability lawsuits from improper application...

So, I finally broke down and went to http://www.gastmfg.com, home of the Gast 1065 vacuum pump. Clicked on Sales and Distribution and called the first dealer closest to Maryland. What do you know? The guy said "Sure, we can sell you a vacuum tank!" Finally! Now, he hasn't gotten back to me with a price, and after my euphoria wore off, I realized I need some extra stuff. But like Monty Python and the Holy Grail "Our quest is at an end!"

I'm working on a Visio drawing detailing the parts needed for the vac plumbing. I've got a vacuum gauge from an auto parts store, and will probably buy a couple more (one at the tank, one at the pump, and another right at the forming platen). I'll also need a check valve at the exhaust port of the pump. When you turn it off, the vacuum draws the air right back in - doh! I'd like to use rubber hose from the table to the pump, and from the pump to the tank. This would allow me to leave the vac system inside, but move the table outside.

Then I'll get pricing for convenience items: Pressure cut-off switch (so I don't have to watch the gauge and manually turn off the pump). Electronic valve to open the vacuum chamber as the plastic clamping frame lands on the forming platen.

I'll report back on pricing information next week (after the snow storm )

Charlie
TI-386

[mpmurray]

It sounds like you found a tank. I just want to say - in case anyone is looking for a hot water tank - I just got a used hot water tank. Owners frequently replace these with new ones because their life (thermostat) is less than 10 years. I got mine from a landlord. However, other sources such as refuse stations, installers, and scrap metal dealers may have. I saved my landlord $40 salvage fee by taking it. The only catch is taking it apart. This consists of removing the metal sheath, then the foam insulation. But it's cheap and salvaging is an environmentally appropriate way to get a tank! One can also try the www.freecycle.org. Just follow links to your local area and post a WANTED for free tanks.

[crashmann]

Well, the guy from the Vacuum supply company called me back and said I would be better off going with McMaster Carr and searching for part number 4376K11
60 gallon vertical pressure tank. Then I looked at the price... $397.72 before shipping!!!

Hmm, that propane tank is looking better

I've done a little Freecycling in the past, so I decided to give that a shot. I got three replies, and there's a plumbing company that has a yard full of old water heaters. I picked up a very classic (rusty) 52 gallon water heater


After extracting the actual tank from the metal sheath and fiberglass insulation, I finally got to the the tank.


A little grinding and sanding, and it appears to be in decent condition, and the plate says it (was) rated for 300 PSI.


Throw on an Imperial cog, and she'll be ready for action!


But if this tank implodes, I've got another Freecycler lined up to take it's place. This other tank shouldn't be nearly so crusty...

I'm off to Homie Depot tomorrow for some fittings and ball valves, then we'll see if I can get it all connected together

Thanks for the Freecycle suggestion Michael!

Charlie
TI-386

[mpmurray]

Charlie,

Nice going with getting a tank so quickly! Since my first reply, I've discovered some junk inside my tank (pvc pipe, broken element, and calcium chunks). I'll be getting all that out somehow and hopefully won't regret getting the tank (so far I'm still happy). Another challenge has been completely removing the spray-on foam. I've used a metal scraper, hatchet, and wire brush, but there's still a little residue in spots.

Your tank looks really clean. Did it come with spray foam or just fiberglass insulation.

If foam, ror the benefit of me and perhaps others, how did you get the foam off?

I'll be very interested in hearing how you plumb, and of course, how it works out for you! I'm still making a table and platen. Good Luck

michael

[jegner]

WOW! That cleaned up nice! I thought I had a good 30 gallon, but it turned out to be rusted all the way through on the bottom. Totally useless. If I can get a sales coupon or some sort of discount, I might just spring for a new one from Lowes.

60 gallon. Man, thats big. You should have no trouble getting lots of pull time.

Yes, please keep us updated on your plumbing progress, etc.

[crashmann]

I got lucky with the classic tank, it had regular fiberglass mat insulation (although it was nasty from soaking up water when their basement flooded ) Oh, and the tank makes lots of crunchy noises as you move it around. There's lots more than just rust inside there! But since it is all sitting at the bottom, and the connectors are at the top, there shouldn't be a problem with the debris fouling the system. There is a pretty good filter before you get to the pump as well.

You might hit the foamy residue with an orbital sander (and wear a dust mask).

I followed up on the second water tank offer, and it came from a nice lady with too much money. The water heater was installed in her garage by the original home owners, and she wanted it in her basement. So rather than move it, she bought a new one. The heater had only been in service for 6 years, and it's in better shape than the one I've got in my house! I'm going to swap them out, and then take apart my old one. It is MUCH lighter than old crusty, so I'm wondering what the tank is made from. The labels state they were tested at a maximum pressure of 300 PSI, so they should be able to hold vacuum.

I highly recommend posting to Freecycle.org if it's in your area.

I also created a diagram laying out all of my connections for the table and the pump, then picked all of the plumbing parts. I had a very hard time finding the flexible hose. Plenty of 3/8" 300 PSI compressor hoses, but I'm afraid that would constrict the airflow. I really wanted 1/2" In the plumbing section I found 5/8" high pressure washer hose for $0.99 per foot. It passed the pinch test between my thumb and fingers. We'll see how it does under vacuum

I'll post my plumbing diagram and pictures after I get it all together.

Charlie
TI-386

[Blaxmyth]

Not sure about you guys in the States, but here in New Zealand there are scrap yards full of old, condemned LPG and CNG (compressed natural gas) cylinders that were used during the 80's and 90's as alternative fuels.

They range from 50 to 90 litres, and are 3/8" steel - very heavy, capable of holding any vacuum anywhere. The good thing is that they're cheap, and you can connect them in series for more volume.

Might not be of use, but some of those other options sound very pricey.

Phil

[jegner]

Looks like my 40 gallon hot H2O tank is failing. About 10 years is all one is to get out of these things. I guess I'll try to salvage my current tank, and replace it with a 50 gallon for the house.

49 gallon is a bit more than what I was looking for, so the evac time will be longer. Maybe the old 40 gallon will do for my vac table needs.

Wish me luck!

[crashmann]

It is alive!!!

I can't believe it actually works! The Gast pump does an amazing job taking the vacuum down to 20" of mercury in one minute. Anything further, and the pump starts making some grumpy noises. I'm not quite done with it yet (one of the glass filter jars needs a new gasket - currently bleeds air back into the system...) And I still have to put together a diagram with pictures of my ridiculously over-engineered plumbing

But first, enormous video of the table in action (16MB!!!)


First I had to make a cap to seal off the old shop vac connector. So I put a hose coupler in the middle of the platen (along with some 2" PVC rings for thermal detonator end caps) then pulled .090 HIPS over it. I cut out the cap and it fit perfectly under the table

The next two pulls are using the Gast 1065 vac pump connected to a 52 gallon water heater tank. The plastic doesn't suck down as fast as with the shop vac, but it does pull to 10" of mercury (as opposed to 4" with the vac).

Cool stuff!

[jegner]

Lovely!

Thanks for sharing! Great job!

My guess, is, if you can get the vac down to 26-27, you will see a more rapid evac.

Great stuff!

[jegner]

Crashman!

Watching you video for the umpthteen time, and noticed how the table seems to wobble a but . Add some 45 degree support boards will help. I had the same wobble, and with the support boards, MAN did that firm up the table.

Great job! any pics of the plumbing?

[crashmann]

Hi Jim,

But the real question is... Do you have the Inspector Gadget song stuck in your head?

The first challenge was what to do about the original vac hose connection. As the first pull in the video showed, I made a cap from .090 HIPS. Then I decided to make two new openings on either side for the hi-vac connections. I drilled 3 1/2" holes, and mounted 3/4" floor flanges with E6000 glue and screws.

Added 1" nipple pipes, 3/4" 90' street elbows, and connected them to 3/4" Tees

I put a 3/4" cap at one end, and added 2x 3/4" pipes (12" and 8")

2x 3/4" 90' street elbows connect to the ball valve

2" nipple then goes into a 3/4" coupler, a 10" pipe, then a 3/4" reduction Tee connected with a 1/2 street elbow

Then a 1/2" to 3/8" bushing connects to a 3/8" barb, then the hose leads to the vacuum gauge

The other end of the Tee fitting connects to the 3/4" to 5/8" barb connected to the black hose which runs to the water tank

Here's a view of the plumbing underneath:









The vacuum gauge is mounted between the hinge points on the table




Here's the Gast 1065 pump. The top left hose comes from the water tank and connects to a 3/4" to 1/2" reducing elbow. All of the pump plumbing is 1/2" There's a pressure relief valve and a big filter (which I need to replace the gasket for the glass jar). You hit the pump, then a ball valve to ensure no air can leak back in after I cut off the pump. Then a 1/2" to 3/4" garden hose adapter, garden hose check valve, 3/4" garden hose to 1/2" adapter, filter, and finally the exhaust muffler.




I still haven't worked up a Visio drawing, but I've got notes and shopping lists on 5" x 7" cards

And yes, the table wobbles a whole bunch. I reinforced with steel brackets, but the 1 1/2" studs are too flexible. Adding the 45 degree braces would definitely stabilize the table, but I also like to have room to roll the shop vac in and out from underneath. Thanks for the recommendation, and I'll definitely add them!

Charlie
VAC-386

[thebluecanary]

I think you need to scuff it up a bit. Looks too clean. It is a very good looking setup tho.