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thatmandan
04-13-2011, 11:50 PM
if you purchase the 4500psi compressor one but only want to fill your tank to 3000psi, though it is a 4500, can you shut the machine off before it completes its process or do you have to wait until the 4500 fill is complete?

Gabby
04-14-2011, 03:13 AM
Yes you can. Thats what I have been doing Since I got mine a couple of weeks ago. I haven't had any trouble at all with mine. I make sure to keep it lubed and I also keep a small fan running on the cylinders and they only get slightly warm to the touch. It has ran close to 5 hours now mainly just topping of my scuba tank about an hour at a time.Just make sure and don't overpressure your tank!!! I am waiting on a Guppy 2 CF tank from Joe Brancato to give the SB the real test. So far it is a great little machine.Very happy with it. No more driving 80 miles to fill my tank!

SiliconOrb
04-15-2011, 04:06 AM
if you purchase the 4500psi compressor one but only want to fill your tank to 3000psi, though it is a 4500, can you shut the machine off before it completes its process or do you have to wait until the 4500 fill is complete?

For safety (and legal) reasons, the Shoebox folks are never going to advocate doing this, and with good reason. If you forget that it's running on a 3000psi tank and go to bed, something is probably going to go *boom*.

I have both a 3000psi SCUBA tank and a 4500psi Paintball tank, so I bought a 4500psi model. My first fill was the SCUBA tank, and it was pretty easy to keep track of, as a tank that large builds pressure very slowly with a Shoebox. Even so, there is a pretty easy way to modify a Shoebox to be switchable between the two pressure levels, but it will add some cost to the unit. How much cost depends on how fortunate you are in finding the proper parts. But what you need is a toggle switch, a 3000psi DPST sensor switch and a relay. I won't go into too much detail, because if you don't know what you are doing with this kind of stuff, you should definitely not attempt mods of any sort. But if you do, its a fairly straightforward matter of wiring the pressure sensor / relay combo into the circuit between the main power switch and the motor. When the sensor sees less than 3000psi, the system would run normally and could still be switched off and on with the power switch. This would effectively turn your unit into a pretty accurate 3000psi machine. So the next step is how to get use of the current 4500(ish) psi shutoff, and that's where the toggle switch comes in. The toggle switch is wired in as a bypass to the 3000psi pressure switch. When the 3000psi pressure switch is bypassed, the normal mechanical shutoff is used, as though the pressure sensor was not even there. This makes the toggle act as a 3000psi or 4500psi setting.

Important caveat: If you use the pressure switch and relay to shut off the Shoebox when the 3000psi pressure is reached, you would physically need to turn off the power switch before disconnecting tanks, bleeding lines, etc. Once the pressure dropped, it would start the Shoebox up again, and if you have the cover off and your fingers were someplace they weren't supposed to be, your new nickname might be "Stumpy". There is a more advanced way to wire the relay into a "one shot" mode that would prevent this, but then you need momentary start and stop buttons and so on.

I plan to do this with my unit, and was fortunate enough to find sensors on ebay for $12 each plus shipping. I plan to use a 25amp solid state relay (and a wall wart for the signal voltage...just about any DC wall wart will work). Straight from China for less than $10 delivered.

Again, not something for the novice. Don't hurt yourself.

JSB
04-15-2011, 06:52 AM
But what you need is a toggle switch, a 3000psi DPST sensor switch and a relay.
What about using a latching relay/ reset button to help overcome your important caveat?

JSB

SiliconOrb
04-15-2011, 08:03 AM
What about using a latching relay/ reset button to help overcome your important caveat?


Absolutely. I mentioned that in the caveat ;) "One shot" mode, means it operates for one cycle, thus the need for two more momentary buttons which act as "start" and "stop" buttons. The "start" button energizes the coil, which closes the contacts, which powers the load and also keeps the coil energized. The only way to shut it off is to interrupt the power going to the coil, and that's where the NC "stop" button comes in, or the completion of the pump cycle.

Or you could just remember to keep your fingers out of the machine and use the power switch ;)

overfiendx
08-26-2011, 05:01 AM
I plan to do this with my unit, and was fortunate enough to find sensors on ebay for $12 each plus shipping.

Any chance at a link?:D