Observations of a new owner of a used Shoebox

[lloyd-ss]

I bought a used early model Shoebox from a guy to help him buy a new Freedom 8 Shoebox.  Nice of me, LOL.
He told me that it only pumped to 2200 and needed a rebuild and supplied me with a rebuild kit and a new hardened piston kit.  Cool. Reputable guy, and I wanted to see what made them tick anyway.
I watched the rebuild videos that are on the Shoebox site and was impressed with the simple elegance of the design, and the re-buildability.  My hat is off to Tom Kaye. He filled a serious void in the paintball and airgun world.

Took it apart.  Cool.... the main dynamic sealing o-ring on the high pressure piston came out in 2 pieces.  The obvious cause of the 2200 psi limit.  I think that means that the low pressure piston can build up to 2200 psi if needed and the second stage does the rest. There was a bunch of gray grease residue inside the passages and the check valves.  The lithium grease is white, so what was with all the gray?

While I had the cylinders out I machined some cooling grooves .06 wide x .06 deep spaced .10 apart at the hot end of the cylinders (poor-man's freedom 8, ha, ha).  When cutting the grooves I realized that the cylinders are probably made with a special alloy with high silicon (sand) content (maybe ??) for wear resistance.  They cut kind of "crunchy" rather than gummy.  Anybody old enough to remember the Chevy Vega with the  aluminum block without cast iron sleeves?

I took my time and did everything as I was supposed to and put it all back together.  Hooked it all up, connected to a small scuba tank.  Turned it on (wow, noisy!) , dead headed against the tank yoke pressure gauge. Drat!! Nothing!! Not even a needle pulse on the gauge.  Now, I am a pretty handy guy and ought to be able to handle this, but it was getting very late and I figured "What did I miss?"  Turned it off.  Hmmmm.... what's that hiss.  OK, duh.  The bleed valve closes when screwed out, not in.  Voila!  It works. Time for bed.

Next morning.  Hooked it up again and working like a charm.  But the little oil-less pancake compressor said on the label 150 psi and it was pumping to that, but it's reg would only take the output to about 100 psi.  So what does any PCP person do with a low regulator? Yup, a couple of washers under the spring got the output to the advertised 150 psi.  Seriously, though, don't touch that unless you are aware of the safety ramifications. Boosting the input for the Shoebox to 150 psi made a noticeable decrease in the time it took in "minutes per 100 psi." I also aimed a small blower at the hot end of the cylinders and honestly, they never got too hot to touch.

One other thing I noticed was that in operation, the top cylinder was sliding back and forth in the manifold block by a tiny amount with each stroke.  Hmmm.  the source of all the gray in the grease?  I removed the snap ring that secured the cylinder, and made a couple of shims from a soda can (.007 thick) to take up the slack, and now have zero movement in the top cylinder. 

I have already topped off three tanks, one to 4500 (carbon fiber) and two to 3500 (steel). Other than the noise, I love this thing.  But I do have to say that after the pancake compressor cuts off, the Shoebox seems really quiet, LOL.
So thanks to everyone who has said they love their Shoebox.  You made me take the plunge.  The only problem is that I really like the guys (and girls!) at the dive shop where I got my refills.  Now what?
Lloyd-ss
PS, Desiccant filters on the input? What do you use? The air is dry now, but our summers are really humid. Thanks!

[rsterne]

You should find that increasing the input pressure to 150 psi should make the ShoeBox shut off before 4500 psi, as the opposite occurs.... If you run one without a shop compressor, they can (supposedly, according to Tom) build all the way to ~6500 psi.... It's because of the geometry of the off switch springing, apparently.... Did you change the spring on the switch to get the full 4500, or was there enough adjustment?....

I run 25' of coiled air hose (for cooling/condensing) between my shop compressor and a water/oil trap and then a 1 gallon tank (running at the recommended 85 psi) that I can drain (never had a drop of liquid water in either the trap or tank)....  I then have two (recently added the second) silica-gel dessicant filters between the pony tank and the ShoeBox.... When I was running only one, if the gel was pink, I would get a fine mist from the bleed screw on the ShoeBox (which is at the bottom of the tank block, and I think acts as a bit of a moisture trap).... If the gel was blue, I never saw that....

I was baking the gel to reactiviate it, and what used to be 2-3 fills gradually got down to one, and even at that the gel was turning pink near the end of the fill, with the accompanying blast of mist from the bleeder.... so I guess it has a "life" or rather loses some ability to be dried over time... That is why I added the second dessicant filter, to catch anything that makes it through the first one....

The first rebuild at 75 hours was just the inner (high pressure side) 1/8" ID white O-ring on the small cylinder, and all I did was swap it with the outer ("low" pressure side) white O-ring.... At 150 hours I replaced both the white O-rings on the small cylinder.... I'm now at about 230 hours and it's still ticking right along....

Bob

[YoteMaster]

Good posts!

I love my guys at the dive shop too, but being self-reliant with your own little compressor is appealing.

YM

[lloyd-ss]

Bob,
Thanks for the thoughts on the desiccant and dryer.  I will do something, for sure.

I still haven't wrapped my head around how the high pressure shut-off gizmo works.  The previous owner might have tweaked it cause he is a hands-on guy.
Lloyd-ss

[Norm_m]

On the Shoebox Compressor website in the FAQ area Tom says not to go over 100 PSI on the shop compressor. I asked Tom about that and he said going above 100 PSI would do exactly as Bob said that it would lower the shutoff set point.

I plan on posting some pictures of the updates I have done to my Shoebox and now it runs like a charm and it is now very quiet. Removed the original shutoff unit and installed an electric pressure switch, which is adjustable to any set point you want and removing the machanical shutoff did away with the major noise of the shutoff arm hitting the spring extension on the toggle switch.

BTW Lloyd glad to hear that someone else learned the same lesson about the bleed valve being wide open when screwed in. LOL

Norm

[lloyd-ss]

So all that clakity-clackity arm does is turn the machine off at max pressure?
And the only problem with running too much input pressure is that it lowers the max pressure cutoff point?

Seeing that I am using the compressor to fill tanks, and with most of them I can't go to 4500 anyway, is there any reason for me not to run the higher input air pressure?  (I guess what I really should do is check out the info on the Shoebox compressor site.)

Thanks for the feedback.
Lloyd-ss

[rsterne]

If you are achieving 4500 psi fills, I can see no reason to back down the input pressure.... and yes, the clackity-clack arm changes angle as the pressure builds and eventually shuts off the manual switch.... For some reason, the input pressure is part of the equation....

Bob

[canyonbiker]

I bought a used early model Shoebox from a guy to help him buy a new Freedom 8 Shoebox.  Nice of me, LOL.
He told me that it only pumped to 2200 and needed a rebuild and supplied me with a rebuild kit and a new hardened piston kit.  Cool. Reputable guy, and I wanted to see what made them tick anyway.
I watched the rebuild videos that are on the Shoebox site and was impressed with the simple elegance of the design, and the re-buildability.  My hat is off to Tom Kaye. He filled a serious void in the paintball and airgun world.

Took it apart.  Cool.... the main dynamic sealing o-ring on the high pressure piston came out in 2 pieces.  The obvious cause of the 2200 psi limit.  I think that means that the low pressure piston can build up to 2200 psi if needed and the second stage does the rest. There was a bunch of gray grease residue inside the passages and the check valves.  The lithium grease is white, so what was with all the gray?

While I had the cylinders out I machined some cooling grooves .06 wide x .06 deep spaced .10 apart at the hot end of the cylinders (poor-man's freedom 8, ha, ha).  When cutting the grooves I realized that the cylinders are probably made with a special alloy with high silicon (sand) content (maybe ??) for wear resistance.  They cut kind of "crunchy" rather than gummy.  Anybody old enough to remember the Chevy Vega with the  aluminum block without cast iron sleeves?

I took my time and did everything as I was supposed to and put it all back together.  Hooked it all up, connected to a small scuba tank.  Turned it on (wow, noisy!) , dead headed against the tank yoke pressure gauge. Drat!! Nothing!! Not even a needle pulse on the gauge.  Now, I am a pretty handy guy and ought to be able to handle this, but it was getting very late and I figured "What did I miss?"  Turned it off.  Hmmmm.... what's that hiss.  OK, duh.  The bleed valve closes when screwed out, not in.  Voila!  It works. Time for bed.

Next morning.  Hooked it up again and working like a charm.  But the little oil-less pancake compressor said on the label 150 psi and it was pumping to that, but it's reg would only take the output to about 100 psi.  So what does any PCP person do with a low regulator? Yup, a couple of washers under the spring got the output to the advertised 150 psi.  Seriously, though, don't touch that unless you are aware of the safety ramifications. Boosting the input for the Shoebox to 150 psi made a noticeable decrease in the time it took in "minutes per 100 psi." I also aimed a small blower at the hot end of the cylinders and honestly, they never got too hot to touch.

One other thing I noticed was that in operation, the top cylinder was sliding back and forth in the manifold block by a tiny amount with each stroke.  Hmmm.  the source of all the gray in the grease?  I removed the snap ring that secured the cylinder, and made a couple of shims from a soda can (.007 thick) to take up the slack, and now have zero movement in the top cylinder. 

I have already topped off three tanks, one to 4500 (carbon fiber) and two to 3500 (steel). Other than the noise, I love this thing.  But I do have to say that after the pancake compressor cuts off, the Shoebox seems really quiet, LOL.
So thanks to everyone who has said they love their Shoebox.  You made me take the plunge.  The only problem is that I really like the guys (and girls!) at the dive shop where I got my refills.  Now what?
Lloyd-ss
PS, Desiccant filters on the input? What do you use? The air is dry now, but our summers are really humid. Thanks!

Lloyd I fly electric model airplanes as well as shoot pcp rifles and I used a heat sink made for a 25mm electric motor to slide over the cylinders to help with the cooling. I had to resize them a little (squeeze them down to a smaller internal size ) to get them to fit tight to the cylinders and they work great!! I am sending a picture so that you can see them.

[lloyd-ss]

Nice idea with the heat sinks!  Getting rid of some heat has to be a good thing.

[bnowlin]

I found out through Tom's help that it is a good idea to use the hose bleeder instead of the shoebox bleeder, becaise behind the shoeboxbleeder in the block is a very small spring ballbearing and orings that can get a piece of trash or other debris behind it.  Then you have to tack the block completely out to clean it in most cases.  I was able at Tom's suggestion blow air back through the out put to close it.  Anyway that is a PITA and Tom said to just use the bleeder on the hose if you have one.  I finally had to replace the block.  I now have the F8 and I haven't touched the bleeder valve on the SB except for installing it.

Just my two cents and IMHO I think a very good idea.
Bob

[badredbird]

that shoe box is something else  , i just run mine at 90 psi have about 260 hours on it  and it runs fine , have the hardened steel   rods   , am very good about lubing it, was told never to use the green lithium causes probs , probably will wait till something happens like it doesnt fill to rebuild, i do have a question tho for some of the guys more knowledgeable than me, i have tanks but i never fill them   i always direct fill the gun , i do use a fan and a dessicant and water trap in lines the questionis this am i putting more stress on the shoebox compressor by direct filling gun s  or less another words should i be direct filling guns or would it be better on machine to fill my tanks   any opinions on this``````````````````/

[rsterne]

I don't know if the ShoeBox will care, but filling a tank and then filling your gun from that should result in drier air going into the gun.... with the chance of moisture collecting in the tank, of course.... The drier the air going into the ShoeBox the better, but boosting 90 psi air to 3000 will still change 3% relative humidity into 100%.... On the other hand, expanding the air from the tank into the gun will effectively lower the dew point, insuring no liquid water in the gun....

Bob

[badredbird]

thanks   hadnt thought about that angle

[lloyd-ss]

I was looking around online and you can buy desiccant beads in bulk...... a gallon of beads for $25 to $75 ....... Could you take the valve out of your regular airgun-only scuba tank and fill it a quarter to a third full with the desiccant beads, and then just use it that way?
I wonder if there is a down side to that?

Of course you would have to empty the beads out the next time you took the tank in for its annual visual inspection.
Lloyd-ss

[rsterne]

I don't know how that would work, probably fine.... You would want to make sure the beads didn't become saturated, I can envision them trapping moisture against the tank wall and causing more corrosion?....

Bob

[SciGuy]

I'm in Bama and have been running a SB for 2 years now.  I fill a Guppy tank and use that to fill my guns.  Last week I completely stripped my AR2079a HPA down to do a little valve tweaking and relube everything with Krytox.  I have never used desiccant with the SB.  I fill in my air conditioned house, but in the summer even in AC the air is pretty humid.  After 2 years of filling my rifle from the tank there was not a hint of corrosion.  None!!!!  Everything was in perfect condition. 

After seeing this I no longer have any concern about not using a desiccant with my SB. 

[lloyd-ss]

I'm in Bama and have been running a SB for 2 years now.  I fill a Guppy tank and use that to fill my guns.  Last week I completely stripped my AR2079a HPA down to do a little valve tweaking and relube everything with Krytox.  I have never used desiccant with the SB.  I fill in my air conditioned house, but in the summer even in AC the air is pretty humid.  After 2 years of filling my rifle from the tank there was not a hint of corrosion.  None!!!!  Everything was in perfect condition. 

After seeing this I no longer have any concern about not using a desiccant with my SB. 

Mike,
Have you by any chance removed the valve from your guppy tank and seen if any moisture is in there?
Thanks,
Lloyd-ss

[Rdsail]

Hi Lloys, this is off topic. I was reading you poster and noticed at the bottom Central, VA. I'm in Richmond and have not found man AGer in the area. Started with AG about 5 month ago and have a Xs46u ram from mike and a Disco.

Just figure I say hello.
daniel

[SciGuy]

Mike,
Have you by any chance removed the valve from your guppy tank and seen if any moisture is in there?
Thanks,
Lloyd-ss

I'm due for a visual inspection this month.  I'll try to remember to post what I find out then.  I expect that there is some moisture in the Guppy, but NONE of that appears to make it to the rifle.

[FNG54]

I am asking this because I don't have a clue.

If a tank were inverted and left it overnight and in the morning open the valve a little would any accumulated moisture blow out?

I don't have a shoebox and get refills at the fire dept. I am just curious. 



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