Air Compressors for Newbies- by Forrest Addy - Page 3
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  1. #41
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    The reed valves many times break and fall down in the cylinders.I have dug many out,sounds like a rod is going out but only the piston pounding the reed against the head.many compressor builders spin the pumps so fast that they are on the edge of the valves floating.And what happens is this,as rpm increases so does A.C.F.M. to a certain point.when the limit is reached and exceeded in pump rpm.the valves float,the amp draw increases and the A.C.F.M. goes down.
    If of intrest i have written many times about the 6.5 hp sears sweepers.in the rotary converter section.premium motors ? they are hard to come by nowdays and are not all created equal.even some of the big players have cut corrners.The general rot,more copper,more steel,better motor,better phase converter.
    Nowdays on motors and pumps its more like let the buyers beware.imho,the best bang for the buck nowdays in 5 h.p. 2 stage is the saylor-beal,low rpm,disc valves,oil sight gauge,cast iron block.15,000 hours between tune ups as rot.

    Scott

  2. #42
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    I just talked to somone this morning that had a sch 40 line blow,he said he had used it for 6 years,when it blew,it sunk some plastic into a plywood covered wall as well as blowing rusty water all over.black pipe sch 40 is the way to go at 140 psi

    Maybe I just have good luck because I've had my schedule 60 plastic system on line for 8 years now and I've never had a problem, especially with rust and scale. Of course I don't run my system at 175 psi, rather I have my limit backed down to 140 which is plenty for even my 3/4" IR impact and I have plenty of CFM at all times.

  3. #43
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    The lower you can run the PSI,The better.The higher the psi,= lower cfm,= higher amp draw to boot.

  4. #44
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    It all depends on where tested and how,also relationship to sea-level.

    And ambient air temp tested at.


    Scott

  5. #45
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    Had Another C/H drop its self tappers that hold the reeds in come in the door,there stuck in top of a alm piston,not a good design

    Scott

  6. #46
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    R.P.C. MAN, have you ever seen anybody use a car to power an air compressor? Henry Ford made his Model T power all sorts of farm stuff but I thought that a car has plenty of power to do big jobs like sand blasting and big air tools but never seen it done. I thought auto ramps you drive the car onto with rollers driven by the wheels could be connected to a compressor. Crazy idea or possible? Big air compressors are beyond the pocket book of people like me.

    Steve

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    I have seen v-8 engines coverted 4 gas,4 air many times.they work great.What size compressor are you needing? CFM ? PSI ?

    Scott

  8. #48
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    Good question, my needs have been for sand blasting rust off of car parts. What do you recommend?

    Steve

  9. #49
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    If you eiether built up,or bought a small pressure pot,you could run a 1/8" id ceramic tip.This would require 15 CFM @ 100 Psi.And give you a pattern the size of a quarter. A 5 hp Single stage would be best with a max rating of 125 Psi. You could also run a 2 stage and lower its shut of pressure.I see no problem with the roller ramp idea do to the very low hp requirement. appox pulley size on the ramp would be 5" to 8" depending on what pump you select.
    A simple set up would be base plate mount the pump,belt drive of course,go from the pump to a discharge unloader/this will not only bypass air to atmoshere at max psi,but will act as a check valve as well,the a small air reciever with a saftey valve.

  10. #50
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    I have a 60 gallon 6.5 hp craftsman oiless compressor and a 60 gallon 6.5 hp cast iron campbell hausfeld t'd together with a single output. The craftsman compressor came with my house and I already had a compressor so I figured by plumbing them together I would double the CFM rating at 90psi. They each have a rating of about 10.5 cfm at 90psi. Apparently this theory of mine does not work. When sandblasting (the reason for the greater air consumption) both pumps run constantly and are only able to maintain 75psi. Has any one tried to plumb 2 compressor systems together? Is there a formula for calculating the new rating?

    On another note, I aquired a very nice single stage IR v-twin vacuum pump from work. It looks just like an air compressor. Can I just switch the input(filter) and output to convert this into a compressor?

  11. #51
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    Displacement C.F.M. Is bore X stroke X R.P.M.

    A.C.F.M Is Delivered At a PSIG.

    Yes you can tie them together,just use one switch so they start in tandem

    [ 06-04-2007, 07:34 PM: Message edited by: R.P.C.MAN ]

  12. #52
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    Let me add now,i could not edit my post,1 pressure switch,2 magnetic starters,1 control circut,pipe together with schedule 40 black pipe/your in

  13. #53
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    "Yes you can tie them together, just use one switch so they start in tandem"

    I'm sure the Crapsman® compressors are not designed this way as I used to have one, and I now own a C-H stationary, vertical model (a cast iron one ... a good value for the money), and it starts the same way ... an "off-the-line" pressure switch starter, no magnetic motor starter.

    Now, if you had an I-R or other really good compressor, and you needed to double (or to triple, etcetera) your CFM, you would wire the two (or more) magnetic motor starters to start at the same time, or, even better, for one starter to start when the low-pressure trip point was reached, and then a time delay would be used for the second (or subsequent) starters.

    It should be possible, for at least two compressors, to alternate which one is started first, thereby implementing "work sharing", whereby both compressors would have about the same duration on-time, over the long haul.

    Of course, the "memory" as to which compressor was to start first, etcetera, would be lost should all power be lost to the system, whether intentionally, by operator action, or by loss of utility power.

    Especially if on a single-phase system, I would consider implementing a time delay feature, as described, above.

  14. #54
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    Jigwelder, if you hook 2 compressors together FAD rated at the same pressure the FAD ratings add up like you would expect. Dont believe the makers FAD or HP. Your compressors are too small for the sandblaster. To measure the FAD, measure the tank volume. Start the compressor and when it is 15psi from shutoff time how long it takes to get that last 15psi. divide 60 x the number of seconds and multiply by the tank size in cubic feet to get the FAD at your working pressure

    FWIW I have a 10hp compressor which never uses full motor power and it has a measured FAD of 35 Cfm @ 110 psi. As for the electrics why start them in tandem use 2 pressure switches and contactors (magnetic starters) set one switch with say 110 start 125 stop and the other 100 start 115 stop, One compressor will do most of the work but you can swap settings once a year or so. Peters timer suggestion is good for the initial start, I set my air dryer for a 1 minute delay on the initial start and have never had the circuit breaker trip.

    The IR vac pump might not be up to the heat and pressure of compressing to 100 or so psi, they are usually built with light pistons, old IR stuff is way over built so you may be lucky

  15. #55
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    How long has the Ingersoll Rand T-10 compressor been out of production and is it built any better than the current offerings from IR? I've tried searching here and elsewhere on the web but can't find much info on this model.

    Is it a reasonable choice for light duty in a home shop? What's a reasonable price range for one in good condition?

    Mike

  16. #56
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    Mike for a home shop that does not need a high and constant volume of air. You can go to sears and pick up a compressor with a pressure gauge and a big air tank. After it get up to presure just shut it off untill it out of air.You don't have a toolchanger and if your just running a spaymist and an airgun a tank of air will last a while.Then you don't have a big old compresure running all the time pissing off the wife.If you ever are going to get a high speed air spindle for the tormach your going to need a clean air soucres and the old ingersol maynot be thhe best down the road. So this is more a starting point for you .I also don't mind spending a little bite of cash for something a little better for my home shop.As I have to live with it and don't ever what to hear why did you buy that thing. So something with nice paint and clean is worth the cash to me

  17. #57
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    Boston,

    Thanks - the seller wanted $500 for the T-10. It appeared to be in essentially new condition despite being 9 years old and he claimed it had less than 100 hours on it. He didn't have 220 VAC run to the garage, though, so it couldn't be run. A new IR compressor with similar specs runs $580 from Northern Tool with free shipping.

    Unless the T-10 is somehow substantially better than the current IR compressor, $500 for a used T-10 doesn't seem like much of a bargain, especially since there is no guarantee that the it actually works. I've searched the web and this forum without finding any significant info on IR T-10 compressors so am assuming it's no better than the current offerings from IR and probably most other $600-800 new compressors. The seller was not too impressed with my offer of $300, claiming he paid nearly $1k for it.

    I'd use the compressor to supply air for an air bearing on T&C grinder plus other modest uses, but would eventually like to use it for a small sand blaster which I'll buy some time in the future. I've got way too many tools that need a "bit of work" so whatever compressor I buy will have to be ready to use when it gets installed.

    Mike

  18. #58
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    I'm looking at spending a little more myself. Where as it in the basement it got to be quite. So when I was at Easttec I saw the Kaeses both http://www.kaeser.com/
    they have a nice small unit it about $2500 so I'm not running right out and getting it right away

  19. #59
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    I've never heard of Kaeser but they look interesting. They have several oil-free compressors and I've always thought oil-free was a bad thing for a compressor used in more than very light duty, but maybe German engineering has come up with some way to eliminate the need for lubricant.

    Mike

  20. #60
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    What I'm looking at doing is adding an air spindle http://www.airturbinetools.com/ to Tormach (they have one on a 3/4 shaft). It will need a clean air supply


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