Bending tubing, water fill prevents kinks.

Discussion in 'Off-Topic' started by #12, Feb 9, 2014.

  1. #12

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    Just a note to let you see that the method works. 1/2 inch copper tubing wound around a propane tank. Less than 4 inches I.D. No kinks.
     
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  2. Kermit2

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    Feb 5, 2010
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    the one time I needed to coil copper tubing; sand fill with solder plugs to hold it in worked for me, and I was able to anneal it and melt out the solder plugs at the same time when finished.

    It was not for electronics ;)

    I've also read that some folks use water and freeze it before bending.
     
  3. spinnaker

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    This is the method I have always heard of. Funny I thought filling tubing to prevent kinks in bending was a well known method.
     
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  4. inwo

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    Good idea.
    I've heard of using sand in larger tubing.
     
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  5. bertus

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  6. Sparky49

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    I had heard of sand, but not water.

    Couldn't find any sand so I played the part of a sucker and bought a bending spring.
     
  7. #12

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    Florida is made of sand, but it's dirty and messy and polluted with organic material. I assumed that any amount of sand would have air spaces in it, so I would have to add water. I just skipped the sand part and filled it with water. I could wish I knew about freezing the water, but the deed is done and it's good enough for a shock absorber between an air compressor head and an air tank.

    I'll just pull the loops apart until I get it 10 inches tall and silver solder some nice, round copper tubing on the ends to make it fit the connections on the machinery. The compressor can shake for a long time before it work hardens the copper and fractures it.
     
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  8. MaxHeadRoom

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    Freeze the water and the pipe splits, ask me how I know!!
    Max.
     
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  9. tcmtech

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    Nov 4, 2013
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    Hydroforming tubing or complex shapes is not a new process. Many of the body panels for vehicles are made that way now.

    The advantage of using a fluid instead of a granulated solid is that the internal pressures are equal throughout the whole inside of the part.

    Ideally you want to have the fluid under a fair amount of pressure when you make the bend. I think something on the order of 10 - 20% of the burst pressure with some sort pressure relief in place to keep the pressure from going too high as the tubing or part is being shaped.
     
  10. shortbus

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    The water and then freezing is one of the ways they do musical instruments, like a trumpet. Another way is they fill it with tar/bitumen and then melt it back out after bending.
     
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  11. Brownout

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    Jan 10, 2012
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    We know what you're really gonna do with that. But don't worrk, we won't tell :)
     
  12. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    I generally use sand.

    I bent some gentle bends in larger diameter handlebar tubing, and used a long stack of Australian $1 coins wrapped in electrical tape. It worked well but took a bit of poking to get out.
     
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  13. #12

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    It doesn't look so cost free now. I'm going to have to work to get this thing right. Most of the threaded connections leak. I can fix that. What has me stumped is, "How does this thing breathe?"

    I found what I'd call a transfer block, and that would make this a 2 stage compressor, but I can't see where the first stage inhales. Missing parts? Operator error? Where's the intake filter on this thing?
     
  14. #12

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    I have neighbors that talk like you. I set up a camera tripod during a rocket launch and they say, "window peeping". I make a flex tube for a compressor and they say, "illegal still". I just don't seem to fit in around here.:(
     
    Last edited: Feb 10, 2014
  15. inwo

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    Are you sure it's two stage? It looks pretty symmetrical.

    Is there another output port from the other cylinder? Below your copper connection in picture? If not the head chambers may connect internally.

    Then "transfer block" is the intake. With threaded filter/muffler port. Are they "reed valves" shown down hole? All the same direction?
     
  16. shortbus

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    Looks like a single stage to me. A two stage will have the second stage much smaller diameter than the first stage. A two stage has to be that way because the first stage compresses the air to a smaller, high pressure volume. If both cylinders were the same size, the air would just expand again in the second stage. And that would make the pressure the same as the first stage.:)

    A lot of those older type compressors have the intake reeds mounted in the piston tops and the exhaust reeds in the head. They are like a two stroke engine, but with a reed or ball type check valve in the exhaust.

    Why do you think you need that many coils in the line to the tank? A single loop will work better. Less weight to cause less vibration stress.

    For the threaded connections, I used a sweat/soldered connection on the pump end and a soldered union on the pump. This is on a 5HP, 80Gal tank. Been in use over 30 years now with no leaks.
     
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  17. #12

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    Answering questions: There is exactly one exit for the air as I found it at 15 or 20 years old. It's pretty obvious where the original air exit is. Follow the shiny, new tube. There is a similarly placed hole above the other piston, but it has a threaded plug in it.
    Yes, it has reed valves. Two per side as you can see in the photo. I haven't touched them with my fingers.
    You're right, two stage sounds wrong because both cylinders seem the same size...which leads to the original question: Why are they connected together at the top and where is the intake???

    Why do I think I need that many coils? What? You think I know how many coils a discharge pipe has? I can't even find the intake filter!

    Nobody asked this, but...I'm thinking there is a check valve where the copper tubing goes into the big tank because it has a 1/4 inch bleed line connected to that pipe fitting. If there is no valve on the tank side of that fitting, the head pressure release on the pressure switch will just empty the whole tank. But then, it might have spent it's whole life trying to keep filling a tank with a leak in it. I actually don't know.

    I kind of expect TCM to know about this.
    I'm beginning to suspect it only has one cylinder connected!
     
    Last edited: Feb 10, 2014
  18. tcmtech

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    The intake is where the white plug is screwed into the cast iron block you have that covers the intake valves.

    Put the cover assy back on and take that plug out. I bet when you crank it over it suck air in through the hole.
     
  19. #12

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    I suspected that, too. I was careful not to get my finger too close so it didn't get sucked in. I'm going to have to find or make an intake filter.

    Do you have any idea that one of the cylinders is not connected to anything?
     
  20. #12

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    I just went to Jim's house because he is an OCD with a 30 year old compressor. Confirming the (2) intake ports on top are supposed to be connected and I am short a filter. There is only one exhaust tube from his compressor head, so the 2 cylinders probably meet under that flat plate that says, "Caution, HOT". His compressor has the head pressure relief tube connected to one of the port holes in the head. I can use that if I need to.

    OK. Just about got this figured out. Some Teflon tape, some elbow grease, a new filter, and a new power cord will have it running safely.

    Remember boys and girls, you must always treat an air compressor as if it was a bomb that can kill you, because it IS!
     
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