I just got a shoe box freedom 8 4500psi I'm curious on how long it will take to top off a 66 cubic foot tank 6.8 liters from 3000psi to 4500psi I'm using a 4 scfm shop compressor on it at 90psi
Shoebox freedom 8 45 min scba tank fill times
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Well, it depends how you run it . . . the "8" in F8 indicates 8 cubic feet of compressed air in an hour, but you only get that much if it is fed 125 psi the whole run time, which is hard to do with many shop compressors.
My Max is modified to output air like an F8, but I only feed it air at a little over 100 psi - that used to the max I could get stably out of my old shop compressor, and even though I can do it higher with my new one I see no reason to do so.
At that input level, my 45 minute tank fills at a rate of just under 10 psi minute. If the input was 90 psi, I'd expect that to be a little under 9 psi per minute. That would put your fill at about 170 minutes, or just under three hours. If you could feed it at 125 psi it would take about 2 hours, but of course that is more load on the Shoebox too - it should be fine doing it, but the scarcity of parts is one of the reasons I have continue to take it easy on mine.
The CFM output of any shop compressor will be much higher than the Shoebox needs, so that is not a factor - note your unit puts our 4 CFM (per minute), when the Shoebox puts out 8 CF per hour, or about 0.13 CFM. It is all about the input pressure . . . .
It's great that you have this option! You will want to dry the air on the input to the Shoebox with a good sized desiccant filter (doing it after just makes your fill times even longer), and hopefully your unit has the auto lube kit installed - look for felt pads on the cylinders where the pistons enter it. If have the auto lube kit it can go about 10 hours between lubes, but if not you will need to manually lube it about every two hours or so with white lithium grease.
My Max is modified to output air like an F8, but I only feed it air at a little over 100 psi - that used to the max I could get stably out of my old shop compressor, and even though I can do it higher with my new one I see no reason to do so.
At that input level, my 45 minute tank fills at a rate of just under 10 psi minute. If the input was 90 psi, I'd expect that to be a little under 9 psi per minute. That would put your fill at about 170 minutes, or just under three hours. If you could feed it at 125 psi it would take about 2 hours, but of course that is more load on the Shoebox too - it should be fine doing it, but the scarcity of parts is one of the reasons I have continue to take it easy on mine.
The CFM output of any shop compressor will be much higher than the Shoebox needs, so that is not a factor - note your unit puts our 4 CFM (per minute), when the Shoebox puts out 8 CF per hour, or about 0.13 CFM. It is all about the input pressure . . . .
It's great that you have this option! You will want to dry the air on the input to the Shoebox with a good sized desiccant filter (doing it after just makes your fill times even longer), and hopefully your unit has the auto lube kit installed - look for felt pads on the cylinders where the pistons enter it. If have the auto lube kit it can go about 10 hours between lubes, but if not you will need to manually lube it about every two hours or so with white lithium grease.
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I might feed it 130psi what size is your shop compressor I was thinking it would take about a hour and half to top off
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Slow down . . . more pressure means more load, more wear, and possible damage - it's not just a number; it actually means something.
The Shoebox was originally designed to run on 90-100 psi input pressures, and when the F8 came out it was the first step in trying to actually bump up the speed of the compressor. The F8 had a smaller drive pulley that sped up the speed via faster RPMs on the cylinders, and Tom found that he could run it at up to 125 psi with no issues (with an added higher flow cooling fan too), so he rated it for that and changed the "marketing info" to support the higher fill rate and raised the price. It also was the first with the pressure shut off switch was rally was a nice upgrade - probably the most valuable part of the change (as the old mechanical system was very noisy).
Then the Yong Heng came out, and to compete better on speed - but still nowhere close - he dropped the pulley size again to create the F10, but the die was cast and it turned out the F10 would not be around much longer.
Bottom line, I think from all that I have read on the forums over the years indicate that the most durable of all the iterations was the Max and it's predecessors (many owners of the true "original" units had their boxes upgraded with belt drive (chain was used first - that was loud!) and hardened and polished pistons (longer o-ring life) that came on the Max, but those units ran forever. The F8s did well, but the F10 seemed to start to have more problems - and the difference is in the load on the compressor, as the drive and cyclinders is basically the same in all of them. Load wears things out - that is why I put an F8 drive pulley in my backup F10 - to slow it down and reduce the load.
There is no way around it - the Shoebox (and a booster pump too) is a slow and steady compressor - cut the time in half, and it is still slow. Trying to make it faster will almost certainly shorten it's life. Keep it slow and steady and all you need to do is lube it and replace o-rings every so often (likley every 150 hours, probably even longer). As an aspiring big bore shooter, you will be using your compressor a lot. If you want it to last, don't over drive it.
Do what most of us do - feed it air (dried of course) at a reasonable pressure, and if you want shorter fills then fill your tank at 3500 psi instead of 3000. It will take two hours to fill, and if you stay well within it's usage parameters the Shoebox can run as a "set it and forget it" unit - it can run while you watch a football game or do anything else you might do other than shooting with your tank. And if you really can't stand that, pick up a second used tank so you have one to shoot while the other fills.
Or run the crap out of it and be back here complaining about it in a short while asking what to buy next . . . .
The Shoebox was originally designed to run on 90-100 psi input pressures, and when the F8 came out it was the first step in trying to actually bump up the speed of the compressor. The F8 had a smaller drive pulley that sped up the speed via faster RPMs on the cylinders, and Tom found that he could run it at up to 125 psi with no issues (with an added higher flow cooling fan too), so he rated it for that and changed the "marketing info" to support the higher fill rate and raised the price. It also was the first with the pressure shut off switch was rally was a nice upgrade - probably the most valuable part of the change (as the old mechanical system was very noisy).
Then the Yong Heng came out, and to compete better on speed - but still nowhere close - he dropped the pulley size again to create the F10, but the die was cast and it turned out the F10 would not be around much longer.
Bottom line, I think from all that I have read on the forums over the years indicate that the most durable of all the iterations was the Max and it's predecessors (many owners of the true "original" units had their boxes upgraded with belt drive (chain was used first - that was loud!) and hardened and polished pistons (longer o-ring life) that came on the Max, but those units ran forever. The F8s did well, but the F10 seemed to start to have more problems - and the difference is in the load on the compressor, as the drive and cyclinders is basically the same in all of them. Load wears things out - that is why I put an F8 drive pulley in my backup F10 - to slow it down and reduce the load.
There is no way around it - the Shoebox (and a booster pump too) is a slow and steady compressor - cut the time in half, and it is still slow. Trying to make it faster will almost certainly shorten it's life. Keep it slow and steady and all you need to do is lube it and replace o-rings every so often (likley every 150 hours, probably even longer). As an aspiring big bore shooter, you will be using your compressor a lot. If you want it to last, don't over drive it.
Do what most of us do - feed it air (dried of course) at a reasonable pressure, and if you want shorter fills then fill your tank at 3500 psi instead of 3000. It will take two hours to fill, and if you stay well within it's usage parameters the Shoebox can run as a "set it and forget it" unit - it can run while you watch a football game or do anything else you might do other than shooting with your tank. And if you really can't stand that, pick up a second used tank so you have one to shoot while the other fills.
Or run the crap out of it and be back here complaining about it in a short while asking what to buy next . . . .
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"The F8 had a smaller drive pulley that sped up the speed via faster RPMs on the cylinders, and Tom found that he could run it at up to 125 psi with no issues (with an added higher flow cooling fan too), so he rated it for that and changed the "marketing info" to support the higher fill rate and raised the price. "
Alam McD is spot on. The only other thing that I might suggest (As Alan did) is to fill more often by not allowing your tank to run to a lower PSI/bar, and instead of filling to 4,500PSI, try filling to 4,300 PSI. It's easier on the Box and won't need to run as long.
Mike
Alam McD is spot on. The only other thing that I might suggest (As Alan did) is to fill more often by not allowing your tank to run to a lower PSI/bar, and instead of filling to 4,500PSI, try filling to 4,300 PSI. It's easier on the Box and won't need to run as long.
Mike
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I was topping-off my smaller 71cf tank when I replied to this thread earlier and the Box just stopped running from the shut-off limiter.
I have an hour meter on the Box, which only runs if the motor is running and from just under 4,100PSI to just over 4,350PSI it took .5 hours.
That's using the 21-groove motor pulley (faster), which the F-10 had (I had Tom upgrade my Box when they had it for an issue that I couldn't resolve, unusual).
I don't use mine unless the humidity is in the 30-40% range, it was 38% today, a bit high. I also monitor the temperature from start and end. Start was 82° inside the Box, 89° at end. The cylinder temperature at start was 82°, 100 at end.
I have a small aquarium pump that pumps ice cooled water/vinegar mix through a small 'radiator' mounted to the Box fan blowing cool air through the Box while running until cool.
I also have two tanks that split time in the field, so I always have a backup if the weather isn't cooperating with moisture in the air.
While Alan McD doesn't appear to have a high-pressure moisture filter, I do, and as he stated, it does take a little more time to fill my tank as air will not pass through the filter until pressure reaches about 1,800PSI. Not a deal breaker though.
I recently got a 15-groove motor pulley and once I receive the belt to match, I plan on replacing the faster 21-groove pulley to mitigate any fast-running issues that the F-10 seemed to suffer from.
Anyway, .5 hours to top-off a 71cf tank 250PSI, if that helps your inquiry at all.
Mike
I have an hour meter on the Box, which only runs if the motor is running and from just under 4,100PSI to just over 4,350PSI it took .5 hours.
That's using the 21-groove motor pulley (faster), which the F-10 had (I had Tom upgrade my Box when they had it for an issue that I couldn't resolve, unusual).
I don't use mine unless the humidity is in the 30-40% range, it was 38% today, a bit high. I also monitor the temperature from start and end. Start was 82° inside the Box, 89° at end. The cylinder temperature at start was 82°, 100 at end.
I have a small aquarium pump that pumps ice cooled water/vinegar mix through a small 'radiator' mounted to the Box fan blowing cool air through the Box while running until cool.
I also have two tanks that split time in the field, so I always have a backup if the weather isn't cooperating with moisture in the air.
While Alan McD doesn't appear to have a high-pressure moisture filter, I do, and as he stated, it does take a little more time to fill my tank as air will not pass through the filter until pressure reaches about 1,800PSI. Not a deal breaker though.
I recently got a 15-groove motor pulley and once I receive the belt to match, I plan on replacing the faster 21-groove pulley to mitigate any fast-running issues that the F-10 seemed to suffer from.
Anyway, .5 hours to top-off a 71cf tank 250PSI, if that helps your inquiry at all.
Mike
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Just be sure to dry your air with an appropriate desiccant filter - either on the input or the output side. Personally, I think with the Shoebox if you don't already have a filter the best way to go is to do it on the input side. I say this because the filters are less expensive (since they don't have to withstand 4500 psi, just ~150 psi), and adding the filter volume after compression will make the fill time take longer, as you are adding a good bit of volume that has to be filled to your ending pressure, only to be vented when done (so it takes longer and wastes run time on the Shoebox). But if you already have an output filter, it's obviously cheaper to just keep using it.
If you go with the input side, just make sure it is big enough to do the job - those little $15ish dollar ones are not big enough, unless you run several in series. I'd want one that holds a good bit of desiccant - this might be the smallest I'd recommend, but it would need changing often (bigger ones, or two in series would be better): https://www.amazon.com/NANPU-Desiccant-Compressed-Moisture-Separator/dp/B0B1YNJ2C4/ It holds about 50 grams of beads, which is not really much. The cheap ones hold less than half that.
The photo below is my set up. Left to right in the air path it has a ball valve to shut off the airflow (desiccant will pull moisture out of the air if not closed off, leading to have to recharge it sooner), a big Wilkerson silica bead dryer (holds 820 grams of desiccant and removes vapor to an ambient dew point of -45 F), then the blue one is the unit linked above filled with 4A Molecular sieve (removes most of what little vapor is left down to at least -80F dew point), a 0.1 micron filter (in case there is any desiccant dust in the air), and then a regulator to feed the Shoebox. I control my run times with electrical timers.
If you go with the input side, just make sure it is big enough to do the job - those little $15ish dollar ones are not big enough, unless you run several in series. I'd want one that holds a good bit of desiccant - this might be the smallest I'd recommend, but it would need changing often (bigger ones, or two in series would be better): https://www.amazon.com/NANPU-Desiccant-Compressed-Moisture-Separator/dp/B0B1YNJ2C4/ It holds about 50 grams of beads, which is not really much. The cheap ones hold less than half that.
The photo below is my set up. Left to right in the air path it has a ball valve to shut off the airflow (desiccant will pull moisture out of the air if not closed off, leading to have to recharge it sooner), a big Wilkerson silica bead dryer (holds 820 grams of desiccant and removes vapor to an ambient dew point of -45 F), then the blue one is the unit linked above filled with 4A Molecular sieve (removes most of what little vapor is left down to at least -80F dew point), a 0.1 micron filter (in case there is any desiccant dust in the air), and then a regulator to feed the Shoebox. I control my run times with electrical timers.
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I have a similar pre-filter station as well as the post Box moisture filter. I'm paranoid of moisture I guess LOL.
I went with a Milton set up that has a slightly smaller desiccant pot than Alan McD. I too have a ball valve before the pre-filter station.
My Craftsman 20-gallon oilless compressor normally kicks on once during a fill, but remember, I don't drain my tanks down too far so that the Box doesn't need to work hard to top-off....nor the shop compressor for that matter.
www.topgun-airguns.com
Mike
I went with a Milton set up that has a slightly smaller desiccant pot than Alan McD. I too have a ball valve before the pre-filter station.
My Craftsman 20-gallon oilless compressor normally kicks on once during a fill, but remember, I don't drain my tanks down too far so that the Box doesn't need to work hard to top-off....nor the shop compressor for that matter.
Pre-Order Alpha In-Line Moisture Filter – Sept 7, 2024
When Filling a PCP airgun or airtank from a Shoebox, Alpha, Omega (or similar inexpensive high pressure compressor without a true water separator filter), a quality in-line moisture filter should be used to remove all oil, water and particulates from the air. This is an absolute must to prevent...
www.topgun-airguns.com Mike
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Usually only once, and often not at all. But my compressor is a 26 gallon unit that fills to 175 psi (it starts when the pressure drops to about 135 and cuts out at 175). It is in my garage, and I keep it full and switched off.
I manually control when it runs as I use it for stuff, typically keeping it between about 120 and 150 on the tank (shutting it down before it gets full most times), but before I use the Shoebox I typically make sure the tank is full enough, and turn it on if needed - I then let it stop and cool down for a bit (having opened the valve to charge the manifold system before starting it up) before firing up the Shoebox in my basement workshop.
I do drain the shop compressor as needed, especially after long runs, but I want as a cool an air charge as possible to feed the Shoebox, and the long manifold helps with that. In the winter, the compressor being in the garage helps cool and "dry" the air even more . . .
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