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Just the facts...about plasma cutters

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  • Rvannatta
    replied
    Originally posted by flukecej View Post
    Now this is where it gets really interesting. We found out the Powermax 380 is being phased out in favor of the Powermax 30 because they have the same cut capacity and the Powermax 30 is portable just like the Miller 375 X-treme. Since we ruled out the Powermax 30/380 which are on close out as low as $875.00, that was a non issue. The price we were quoted for the Powermax 600 was $1642.00, more than my dad was really wanting to spend but would be alright. When we got to Airgas, they had a suprise for us. The 600, which the computer said was in stock actually was out of stock and would be next week before getting one in. They offered us a Powermax 1000 for just over cost, $1710.00, since they didn't have the machine we wanted. We looked at the demo unit on display by the front counter, looked at the already prepared invioce and said, "OK, we'll take it!"

    Tomorrow, I have to make a home for the new unit. Fab a running gear for it and wire in the Nema 14-50Amp 4 prong plug and recepticle for the unit. Our Bobcat 225NT already has the 4 prong 50 Amp plug but I don't have one in the barn, its Nema 6-30Amp 3 Prong. After we both watch the setup DVD and read the book some, I will get the machine fired up and do some test cuts. I'll let you know how things go.

    Hopefully you got the model that works on single phase. You will need to upgrade your barn wiring a bit. My impression is tha tthe Bobcat should run it, but not quite at full output. let us know how it works out. I"ve certainly enjoyed the big plasma I've got.

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  • harcosparky
    replied
    Originally posted by vtwin4life View Post
    I guess I'm still confused. Bottom line question I have is this: My motorgaurd, compressor, and the plasma cutter itself all have 1/4" NPT fittings. I can't change this. So, will upgrading the hose from 3/8" to 1/2" work?
    Answer: YES

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  • flukecej
    replied
    Update Bump to Top

    Well, my dad got us a plasma torch for the shop. He looked at Miller and Hypertherm and had settled on the 375 Xtreme by Miller or the Powermax 30 by Hypertherm. Then he called Airgas. The guy at Airgas told him, that for the price difference of the Powermax 30 and Powermax 600 he would be happier with the 600 because of the extra capacity and duty cycle as well as the life of the consumables. The price difference would be eat up quickly trying to cut 1/2" plate with the smaller unit. So me and my dad talked about it and looked at the literature somemore. When we got ready to leave for Lubbock, he called Airgas and told them to have the Powermax 600 ready to pick up.

    Now this is where it gets really interesting. We found out the Powermax 380 is being phased out in favor of the Powermax 30 because they have the same cut capacity and the Powermax 30 is portable just like the Miller 375 X-treme. Since we ruled out the Powermax 30/380 which are on close out as low as $875.00, that was a non issue. The price we were quoted for the Powermax 600 was $1642.00, more than my dad was really wanting to spend but would be alright. When we got to Airgas, they had a suprise for us. The 600, which the computer said was in stock actually was out of stock and would be next week before getting one in. They offered us a Powermax 1000 for just over cost, $1710.00, since they didn't have the machine we wanted. We looked at the demo unit on display by the front counter, looked at the already prepared invioce and said, "OK, we'll take it!"

    Tomorrow, I have to make a home for the new unit. Fab a running gear for it and wire in the Nema 14-50Amp 4 prong plug and recepticle for the unit. Our Bobcat 225NT already has the 4 prong 50 Amp plug but I don't have one in the barn, its Nema 6-30Amp 3 Prong. After we both watch the setup DVD and read the book some, I will get the machine fired up and do some test cuts. I'll let you know how things go.

    Leave a comment:


  • harcosparky
    replied
    OK ... I have on my setup some 3/8" line ( about 24 inches of it ) back of cuttter to motor guard. From motor guard to compressor is 25 feet of 1/2".

    No putting 1/2" on with a couple of adapters will not defeat the purpose.

    What needs to be understood is volume of air available to the cutter.

    It should be obvious that a 1/2" line will allow more air to get to the cutter in a shorter period of time than 3/8", especially when there is substantial length.

    We set out compressor to 100 PSI output, so that the input to the cutter is 100 PSI. The internal regulator is then set to 60+, the plus being we set it to 60 with air flowing, when the flow is stopped the pressure goes up a bit.

    I am going to get a tank of nitrogen to try and see what difference that makes as well ( but this is not a priority so it will be a while )

    Leave a comment:


  • Scotth
    replied
    Vtwin4life (Tim), let me go over this again with you. The air pressure going into the back of the 375 should be 90-120 psi. The regulator setting on the front of the machine should be set at 60 psi with the air flowing (gas air set mode). All of the machines we send out are cut tested before they are shipped out, and our final test station would not pass a unit that couldn't cut 3/8 mild steel. I personally have cut 3/4 with my 375, albeit not pretty.

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  • drewworm
    replied
    Took me some time to get used to it. Try the airline. Don't expect to cut too thick with the 375.

    Leave a comment:


  • vtwin4life
    replied
    Originally posted by drewworm View Post
    Man, I always forget something. I wanted to mention that 5.5 cfm is by no means a lot of air. That is more air than you have now, but a good air compressor puts out 15 or 16 CFM. My plasma cutter (Miller 2050) requires 6.0 CFM according to the manual. The manual also states to set my pressure on the compressor at 90 to 150. I have it set at its max - 120 psi.
    Good luck.
    I agree, however I am out of 220 power. I can't go to a bigger unit. This is my last ditch effort. The machine says it needs 4.6cfm @ 60psi. I will be able to push 5.5cfm @ 90psi, which would be 7.Xcfm @ 60psi.

    If this combined with 1/2" hose doesn't fix the problem, I will be selling the Spectrum 375. From everything that I have read here, I think Miller should revise their specs.

    Leave a comment:


  • drewworm
    replied
    Man, I always forget something. I wanted to mention that 5.5 cfm is by no means a lot of air. That is more air than you have now, but a good air compressor puts out 15 or 16 CFM. My plasma cutter (Miller 2050) requires 6.0 CFM according to the manual. The manual also states to set my pressure on the compressor at 90 to 150. I have it set at its max - 120 psi.
    Good luck.

    Leave a comment:


  • drewworm
    replied
    My stuff has all the same 1/4 fittings that you have. I feel that the hose made a difference for me, but I had the hose sitting there and didn't have to buy one.

    Leave a comment:


  • vtwin4life
    replied
    I guess I'm still confused. Bottom line question I have is this: My motorgaurd, compressor, and the plasma cutter itself all have 1/4" NPT fittings. I can't change this. So, will upgrading the hose from 3/8" to 1/2" work?

    Leave a comment:


  • drewworm
    replied
    Just to clarify. I don't have any degree in fluid, mechanics, or hydraulics. Just the experience I have earned and learned. The real deal may tell you his opinion and say I'm blowing smoke.

    Leave a comment:


  • drewworm
    replied
    Ultimately, it would be best if you could put EVERY fitting at 1/2 i.d. A person versed in hydraulics, or fluid mechanics could give you the best answer with regard to frictional losses. There are things we don't think about that make a difference. The number of 3/8 fittings in your line makes a difference. If you have 10 instead of 3, you will notice a reduction. Think of your 3/8 hose as an ifinite number of 3/8 fittings the air has to pass through. The number of bends in your line makes a difference. This won't apply so much to your compressor as most, if not all, of your fittings are straight, not "elbows" or other angles. The number of elbows would affect you if you were running sprinker pipe, for instance. The larger 1/2 line also has a reservoir type of effect. I don't know how to explain it and it may be different with regard to air being forced THROUGH the line vs. air PULLED through the line. The example I'm thinking of where I went from a 1/2 fuel line on my drag car to a 3/4 fuel line. The motor is using all the fuel "emptying" the line. The bigger fuel line doesn't empty as fast - at least my pump can keep up more effectively. The car ran better. I can measure this in the 1/4 mile and it is definite. Lastly, I love to make a point by exaggering things. Lets say you went the other way and put a 1/8 air compressor hose - what do you think would be the result at the end of the line? Even if you put 1/2 fittings on that 1/8 line, I bet you would have just a wisper of air coming out. The longer your 1/8 hose, the worse it would be.
    Now go air up!

    Leave a comment:


  • vtwin4life
    replied
    Originally posted by harcosparky View Post
    I vote for " operator performance ".

    I recall a thread where a use was complainging his plasma cutter was not working, he took it in had it checked out and it was replaced. The new machine was not doing much better. To cut this short he was using an insufficient compressor ( low CFM ) and to add to that NO DRIERS inline. Now tack on his lack of experience and you have the recipe for dissapointment.
    That complaining user was me. I installed a motorgaurd drier but that had no effect. I'm now upgrading my compressor to a unit which is rated 5.5cfm @90 which is well above the 4.6cfm (can't remember the exact figure) @60psi. I'm now looking at upgrading from 3/8 hose to 1/2. However this is where more confusion comes in. I ordered 1/2 hose, and it has 3/8" NPT fittings. The plasma cutter, the motorgaurd, and the compressors I have seen have 1/4" NPT fittings. So how in the heck can I go to 3/8" NPT for 1/2" hose? If I use adapters, that still means the air is going through 1/4" NPT on all ends, which would seem to me would defeat the purpose of going to 1/2" hose.

    Leave a comment:


  • drewworm
    replied
    I might be buying the cheap ones, but I don't remember seeing brass with regard to the male part of the quick disconnect. All my female connectors (brass) look good, but the male zinc plated parts have corrosion inside the airway only. I haven't always had an operational water separator nor have I allowed the tank to bleed dry through the valve on the bottom so I'm sure I am to blame. In any event, that's why I have the Motorguard brand filter at my plasma machine. The filter resembles a tightly wound roll of gauze. Actually, it looks like a tightly wound toilet paper roll. I don't even know how the air gets through it although I guess it has something to do with my compressor pressure regulator being set at 120psi.

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  • harcosparky
    replied
    Originally posted by drewworm View Post
    The 3/8 line I swapped out was 25', the 1/2 I replaced it with is 100' (it was all I had). I did see an improvement. Don't know if a shorter line will make it even better. With my crappy Sears compressor, the 1/2 line acts as an extra reservoir.

    WOW .. you went from 3/8"@25' to 1/2"@100' and saw an improvement.

    That's good to know, I don't think my shortening the 1/2" hose from 25 to 10 would make a difference. I do know in my 3/8" install I had several downsizing adapters to go from compressor output to the 3/8" line, by going to 1/2" I got rid of all that crap.

    As to fittings, I had a 1/2" Quick Disconnect ( silver colored ) fitting fail on me, the spring mechanism siezed up and I had to use Vice Grips to disconnect it. Cut it open and found corrosion internal to the disconnect but NOT inside the air path. I am guessing that at some time in its life one end of that hose had hit water outside and I was not aware. Switched all connector out and got BRASS ones instead. Will have to remind myself to check them from time to time. Hopefully switching out to brass will help out a bit.

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