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Most users ever online was 66 on Sat May 28, 2011 5:55 pm


    Part 3: The Shoebox and preparing to work on it.

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    Abda
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    20110523

    Part 3: The Shoebox and preparing to work on it.

    Post by Abda

    Part 3: The Shoebox and preparing to work on it.


    I’m not a mechanic but I do know it’s my right thumb that gets smashed when I pick up a hammer---no, wait, that’s my other left . . . Laughing

    When it comes to mechanical things, such as cars, lawnmowers and weedeaters, I’m not bad at simple repairs or figuring out what’s wrong with them. But I always seem to have a screw left over. Don’t you just hate that? Some little bolt that turned up you just can’t place? Experience has taught me that those little guys are just as important as the next part in a machine with moving parts. Especially when you go to pull on the starting cord and the whole top of the lawn mower comes off with the first pull!

    The Shoebox isn’t any different in this respect. You need to know your left hand from your right, what counter clockwise is from clockwise and understand that each part has its function in the place you found it when you disassembled it---not where you can “remember” or “guess” it might go. Memory is good to have, but KNOWING without a doubt is even better.

    Just as with anything you find you haven’t worked with before, the placement of each screw, the mount it holds in place and or the tension it secures is extremely important to document: BEFORE you start disassembling. Personally, I do this by “marking” things. But we’ll get more into that later on in part 4.

    If you look at the Shoebox in the way you would, say, a ten speed bicycle, you’ll understand its simplicity. There’s really not much to it. And if you can work on a bicycle for your kids, I feel that you’d have no problems if you take things slow and deliberate with the Shoebox when and if you try to affect a repair or overhaul.

    And, yes, it’s going to need it. All machines do. It doesn’t matter if it is a $4,000.00 diver’s compressor or the Shoebox: it’s going to need help to stay running after so many hours of operation or have some misshape, by operator error or just plain happenstance or part failure. Except that with the Shoebox, you won’t have to be a certified mechanic with a degree in compressors to do this maintenance.

    There are, however, some key features about the Shoebox that are notable. It’s a very precise machine and not much room for error in certain things. Not to stress you out before you get started, but do be aware that any machine put back together wrong is liable to have undesirable consequences no matter be it the Shoebox or a bicycle.

    One thing to note is that the air block is precision mounted. Before you remove it, you must scribe around it with a marker. If you need to disassemble the gear assembly, mark the screws by drawing a line through the screw on to either side of it if so that the line goes from one side of the case to the other through the place of the screw you are removing. This will help you NOT need to try to do something that shouldn’t have to be done if you just take your time and do it right the first time. Remember, if you don’t have time to do it right the first time, how in the world are you going to find time to do it twice or again? This is not a place where saying you’re sorry is better than begging permission.

    Personally, I’m one of those guys that tends to take things apart and when you come back to see my progress some time later, you see this jumble of parts laying helter-skelter about the table or bench. It looks like a mess, yes, but I have laid everything out in a manner of beginning to end in the order I took it apart: The tools are harder for me to find that I’m using than the parts I’ working with. (Now, where did I put that wrench?) What I suggest to others is have a good clean area, preferably cloth covered in a color that will show up small parts and have this area large enough to have more than a couple of inches between the parts you are loading on the area that you place these parts orderly for later reassembly.

    Another trick I use is my handy little digital camera. I have a camera with a memory card I can load right into my computer straight from the camera. I take pictures of the machine before I do anything else. I take close ups of the areas I find to look complicated and I try to get every angle AFTER I have taken a marker and marked every little nut and bolt, gear, whatever, for an accurate record. Remember the saying? “One picture is worth a thousand words.”

    See, it’s more about preparation. With proper preparation, and let’s not forget the fact that I’m a certified idiot that you don’t have to be as covered in part two of this blog, you can eliminate a great deal of apprehension and KNOW what you are doing instead of relying on memory. Memory is faulty: Knowledge is forever. It also helps to read the manual and instructions---or so I’ve found out the hard way! Remember, I may be an idiot, but you don’t have to be.

    So, now that we have some basics lined out and in a real situation where I had to affect a repair, I’ll cover some of the ways I was successfully able to achieve said repair---and the mistakes you may not have to make by learning from mine.

    My Shoebox was probably about 50 to 70 hours old. And by this, I mean that I’d ran the machine for approximately that long on an average pumping up my Air Guns and Air Hog tank. Most of my hours were spent on the Air Hog tank. It’s great system to use it this way and I’ll be glad to share about that at another time.

    Regardless, one day I went to do my usual routine of getting everything just so ready to pump. Part of that process for me is that I keep my valve closed on the Air Hog tank so that it fills up the air line with an equal or more pressure that is in the Air Hog Tank before I open up the valve. I accomplish two things in this manner: I don’t LOOSE air into the air ling coming from the Shoebox to the Air Hog and while it is pumping up that air line, I get to see if it is pressurizing the line correctly and not loosing air. I’d do this with any highly complicated and expensive compressor as well so this isn’t something I do just for the Shoebox. It just makes sense to me to do it that way.

    As I was performing this operation I noticed that the air pressure was only building to 1,000 PSI (Pounds Per Square Inch). It would get to that point and stop even after I let it run more than what I had been accustomed to waiting for this process to complete. So, I turned off the Shoebox and shut the valve off from the Air Hog. This should have trapped air in the line between the two and kept a steady pressure: *if* there were no leaks.

    However, sure enough, the line pressure dissipated not at a rush, but a slow decline according to the gauge on the Air Hog. This I would call a high pressure leak. But at 1,000 PSI when you are talking pressures of *4,500* PSI as a target pressure, it’s not exactly HIGH pressure. But 1,000 PSI is not a fast deflating event either. It’s not something you’d find just by putting a little pressure on the lines like from a compressor that only does between, on average from your normal run of the mill air compressor that only does 110 to 150 PSI and sure enough, when it got down to about those pressures at 160 or so, the leak would stop and the gauge would maintain that level on the dial.

    This is where having never used up my reserve of HPA (High Pressure Air) within the Air Hog paid off. I had enough in it to keep testing the lines by opening up the Air Hog valve enough to pressurize the line and shut it off again while I poured over the machine to see if I could HEAR the leak---sometimes you can’t. But I got lucky. I COULD hear the leak with all quiet in the house. But I still couldn’t figure out where it was coming from: There are a lot of fittings in a very small space on the Shoebox and trying to tell where it was PROBABLY coming from, as I always suspect a fitting before a ruptured line, I first tried the wet fingers test.

    I wet my fingers and felt around the area I suspected by virtue of noise and waited for some part of wet on my fingers to get cold or cooler. I thought I found it but it didn’t make sense to me. There was a little bolt behind the air block toward the bottom. I took a flashlight and looked at it closely and found that there was this little hole through it. Next I went for some soapy water. WARNING: DO NOT USE WINDEX! WINDEX HAS AMONIA IN IT AND AMONIA WILL REACT WITH THE ALUMINUM AND CORRODE IT! (I made that mistake and was summarily corrected by the people of the Shoebox).

    Well, sure enough, I got the bubbles bubbling around the area of that little bolt. Having been the idiot more than once on this machine, I now directed my attention to the manual and blow up section of the shoebox at http://shoeboxcompressor.com/index.php?option=com_content&view=article&id=11&Itemid=4 . (One can download the PDF there via the link provided) I located the part picture and cross referenced it as the “Burst Disk” which is par number 33 and #271 for par ordering. Of course, I had no idea what a “Burst Disk” was so I had to look this up. Turns out it is part that is designed to fail should the max presser reach 7,500 PSI. As a matter of fact, straight out of the manual on page 6, it states the following:

    Burst Disk Overload Protection
    The ShoeBox Compressor is equipped with a burst disk
    that can be found behind the main air block. If the
    compressor sees pressures greater than approximately
    7500psi, the copper seal in this device will blow out and
    vent the system. This burst disk is industry standard and
    must be replaced after a venting incident. Use the same
    pressure rated burst disk for replacement. Replacements
    are available from Technicor Industries.
    Now see what READING can do for you? It cures a severe case of being an idiot! And I figured it out all by my lonesome! Wow! Imagine that!
    But this didn’t help me understand what I need to do to fix it or why it had failed in the first place. NOW I was prepared to ask for help. NOW I knew I’d done my part in helping myself before asking others to help me. It was time for a post on the forum as the support statement indicates where support questions should be directed since I KNEW my pressures never exceeded that 7,500 PSI cut off. (Support for the Shoebox is at http://www.shoeboxcompressor.com/index.php?option=com_content&view=article&id=11&Itemid=4 ) So I did contact the forum for support and I got a response immediately just like the Shoebox site says. That exchange can be found at http://www.shoeboxcompressor.com/forum/showthread.php?182-Burst-Disk-Iissue&highlight=Burst+Disk


    So I tightened the nut hoping to stop the leak. There wasn’t an “event” loss of air so I was inclined to believe too that it was something just loose from hours of operation. And I hadn’t ever had the unit that high in pressure to make it blow out. Now enter mistake number one: Know the difference between a compression fitting and a threaded seal fitting and how to properly seal each. You’d have to do this with an more expensive compressor as well and I’ll keep stressing this because it’s just a smaller scale on the smaller Shoebox than the big jobs---you can’t get out of it if you are going to be self reliant and that last, you just may not be able to do on your own with a more expensive compressor.

    On the Shoebox forum, I’ve noticed that I wasn’t the only one that made this misconception and others have tried fixing a compression fitting with Teflon Tape and to me, this is understandable from my dogged common sense way of looking at things. If you look at the Shoebox, at first glance, your eyes can’t help but detect that, along with the lower pressure fittings that one uses for regular low pressure compressors that reach pressures of around 110 to 150 PSI, you’ll see the Teflon Tape used to seal the threads so that an air tight fitting can be achieved like on the main feed to the Shoebox from the first stage compressor. This works for lower pressures. But for higher pressures, a compression fitting is used. This could be a bell and flare fitting or a compression fitting where the bottom of the surface of one is met precisely with the top of the other and held into place with torque. Remember, these are HIGH pressure fittings: Not something you encounter and extra “oomph” is needed to secure a seal. So enter mistake number one part A: You can’t use Teflon Tape to seal in a compression fitting. It won’t work. It just doesn’t work that way.

    So, my seeing the Teflon tape on some of the fittings common to normal air compressors you’d buy at Lowes or Home Depot, my great idea was to put Teflon Tape on the Burst Disk Threads as well and put it back in and torque it back down. It kept leaking and I kept tightening. Mistake number 1 part B: don’t use Teflon Tape to seal a compression fitting because the added torque you’ll get will fool you into getting it too tight.

    Teflon Tape will act like a lubricant. It will make the threads where they come into contact with each other “slipperier” for lack of a better term. It doesn’t just fill the voids between the threads as a lot of people may think. So, I tightened my Burst Disk Nut with added lubrication: Enter mistake number two: Know your strength, know you are dealing with a soft metal like aluminum.

    Now enter mistake 1, part A and B and add it to mistake number 2. The sum of this equation is some of the undesired results I spoke of earlier. Yea, I tightened it alright. It kept leaking and I kept tightening. You know where this is going, don’t you? Yep, I stripped out the threads. Don’t do this. I’d suspected I’d stripped it because I had to use some trickery by applying pressure to the underside of the nut to get it to back out to replace it with the new one when Technicor sent me the replacement. The old one seemed to be intact and shouldn’t have leaked but it did and to this day, I still don’t know why. And to me, it’s okay that I don’t. Sometimes parts fail and that’s all there is to it. Regardless, I am of the firm belief that by using the Teflon Tape in that place I shouldn’t have, I contributed to the ease of which I stripped out the threads---it acted like a lubricant.

    So, when I got the new one a few days later in the mail and tried to put it in, yep, it would get just so tight and then get easy to turn again. Sure sign that I’d stripped out the threads. What now?

    Well, I ended up buying a new Air Block at cost. But this meant that I’d have to replace the entire Air Block with the new one. I didn’t mind doing this. After all, it was *MY* mistakes that got me in the pickle I was in and I said as much to those that helped me at www.Shoeboxcompressor.com . I wasn’t even charged shipping for the part(s) and that is way beyond the call of duty for the establishment, don’t you think? But I suspect if I’d gone to management with a bad attitude and blaming everything and everybody but myself, I’d not had the good relationship and reactions I got from the makers of the Shoebox. It’s just the right way to do things.

    For a recap so far we have the following:

    1. Perpetration, preparation, preparation!

    2. All machines need maintenance and repair but it will be far less involved to do your own repair and much more economic to do so with the Shoebox than with something exceeding thousands of dollars such as a diver’s compressor.

    3. Document all parts and placement by dedicating them to memory and documentation. Take pictures if you need to *before* you pick up the first tool or have the first thought about repairs. KNOW what you are doing, don’t guess or “have a good idea”. MARK things that need marking.

    4. Read the instructions and understand what you need to know to be able to ask for help. I’m an idiot but you don’t have to be!

    5. Do NOT use Windex for a leak test! The ammonia in it will react with the aluminum and corrode it.

    6. Do NOT use Teflon Tape on Compression Fittings! Besides having undesired results, it won’t work! Compressors use a number of fittings: Know what they are and how you should make them seal.

    7. Do NOT over tighten nuts or bolts and DO understand that Aluminum is a softer metal that steel. If in doubt, STOP turning! You may end up with more of a problem for that one little nut than what you started off with if you go too far!

    8. Be willing to take responsibility for your mistakes: You’ll get a lot further with management than if you try to blame the machine that has no thinking parts. You have to take personal responsibility for your actions as in all things in life.

    Stay tuned for part 4 where I actually get into disassembling the Shoebox for repair.


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