Tons of dross with my new Spectrum 375

[harcosparky]

The manual on page 16 tells you to " lift " the knob to adjust.

In reality you pull it OUT from the panel to expose the colored band, turn to set the pressure and push it back in to lock it.

The AIR light being out indicates there is sufficient pressure on the supply side of the regulator in the 375. Now you need to readjust the regulator on the 375.

Another thing I saw the Miller guy do was, readjust the regulator on the 375 when the cutter was set to 27 amps and trigger pressed. This is to compensate from pressure drop when the cut begins

[Frank865]

What size & length hose are you using from your compressor to the 375?
It sounds like you've got pressure, but low volume.
There's not a table leg or a wheel on the hose, limiting flow is there?

[harcosparky]

What size & length hose are you using from your compressor to the 375?
It sounds like you've got pressure, but low volume.
There's not a table leg or a wheel on the hose, limiting flow is there?

I was thinking the same thing at first but was able to duplicate his problem with unimpeded flow by setting up the 375, making a cut, and then turning back the Regulator on the 375. If he has enough pressure in and cranks the regulator on the 375 up, the problem should go away. If not then it is a FLOW issue

Although I still think an increase in flow rate would be better. Sometimes just increasing the hose size is a help. I used to run skinny hose, now it is all the larger diameter and the air tools seem to operate better.

[vtwin4life]

Where should the pressure be on the 375? I have cranked it up way past the little green arrows that seem to indicate a desired pressure range. Even this has not helped. I'm really at a loss here. Cutting 1/8" to 3/16" should be child's play for this machine, but it is really doing a crappy job of it.

[Frank865]

Call Miller & ask them what you need to do...If it's the machine, they'll fix it.
If it's you...They'll do what they can to help fix that also!
They WANT you to be happy with your machine....Give them a call.
There should be a toll-free number in your manual....
HTH

[vtwin4life]

Call Miller & ask them what you need to do...If it's the machine, they'll fix it.
If it's you...They'll do what they can to help fix that also!
They WANT you to be happy with your machine....Give them a call.
There should be a toll-free number in your manual....
HTH

I gave them a call, and they are echoing you guys, saying it looks like an air problem. The only thing I can think of is maybe it's the air line. Like I said before, I'm putting 90psi into this thing. The tech again confirmed that even though my compressor is under powered cfm wise - it should be ok because I have 25 gallons in the tank. He just again stated that this would only effect me on long cuts. I'm going to try a few more air adjustments tonight after I finish my 14 hour day...

The other thing he noted, was that it sounded like I was moving too slow with the torch. Problem is, when I move faster with the torch, I don't cut through. Seems like I'm always getting sever cuts even on 1/8".

[harcosparky]

I gave them a call, and they are echoing you guys, saying it looks like an air problem. The only thing I can think of is maybe it's the air line. Like I said before, I'm putting 90psi into this thing. The tech again confirmed that even though my compressor is under powered cfm wise - it should be ok because I have 25 gallons in the tank. He just again stated that this would only effect me on long cuts. I'm going to try a few more air adjustments tonight after I finish my 14 hour day...

The other thing he noted, was that it sounded like I was moving too slow with the torch. Problem is, when I move faster with the torch, I don't cut through. Seems like I'm always getting sever cuts even on 1/8".

I would for the moment forget torch speed. Get the MASS of air flowing. Understand the situation is not a lack of PRESSURE ( PSI ) but a lack of MASS ( CFM ). Think of it like this .... your compressor can deliver 4.5 PINT jars of air at 60 PSI. The 375 requires 4.5 QUART jars at 60 PSI. The numbers are not actual, just used to show meaning.

Another " cheap trick " you might try, add capacity to your air system by adding in another air tank. Like on of those 'portable air tanks " they sell for about $30. The problem with this would be you now increase the demand on the compressor to supply the additional volume. But if you try this and it runs the 375 then you know for sure the problem is air volume.

I would try the largest diameter air hose you can find. This will add volume to the air feed. I had some air tools that seemed starve for power, they were at the end of 50 feet of hose. When I increased the hose from 3/8" to 1/2" it made a difference as it should as the size increase was a 33% volume increase.

[vtwin4life]

I would for the moment forget torch speed. Get the MASS of air flowing. Understand the situation is not a lack of PRESSURE ( PSI ) but a lack of MASS ( CFM ). Think of it like this .... your compressor can deliver 4.5 PINT jars of air at 60 PSI. The 375 requires 4.5 QUART jars at 60 PSI. The numbers are not actual, just used to show meaning.

Another " cheap trick " you might try, add capacity to your air system by adding in another air tank. Like on of those 'portable air tanks " they sell for about $30. The problem with this would be you now increase the demand on the compressor to supply the additional volume. But if you try this and it runs the 375 then you know for sure the problem is air volume.

I would try the largest diameter air hose you can find. This will add volume to the air feed. I had some air tools that seemed starve for power, they were at the end of 50 feet of hose. When I increased the hose from 3/8" to 1/2" it made a difference as it should as the size increase was a 33% volume increase.

Great advice. I did a search online the other day looking for a reserve tank but all I found were the tanks that have a little bicycle fill hose on them. Any good sites out there for these? Also - can I use the same 1/4 NPT fittings on a 1/2" hose? Or does that defeat the purpose?

Thanks again all for the great advice.

[harcosparky]

Great advice. I did a search online the other day looking for a reserve tank but all I found were the tanks that have a little bicycle fill hose on them. Any good sites out there for these? Also - can I use the same 1/4 NPT fittings on a 1/2" hose? Or does that defeat the purpose?

Thanks again all for the great advice.

I would look at those tanks, I realize they have a small Schrader valve on them, but you should be able to remove the valve assembly and install a fitting. What I did on my 1/2 hose was to get fitting on the tool end to make a downsize adapter. Also on your compressor you should be able to remove the fitting on there an install an adapter to upsize.

What I would do is go to a store like Home Depot or Lowes ... where they have the compressors displayed they should also have a large assorment of fittings in all size and configurations.

I opted for installing " quick disconnects " all around so that I could easily plumb air to where and what needed it.

Best way to do it is figure out how to hook the 1/2" hose to your compressor using the least number of parts possible. Then go to the end where the plasma will be connected and do the same.

If you can visualize this, I have 25 feet of 1/2" hose from the compressor out to the tool end. At the tool end I downsized the connector ro 3/8". At this point I will attach a short piece of 3/8 hose at the end of the 1/2" to the tool. I did this for hand air tools because the 3/8 is more flexible.

Hooking up to the 375 is a different matter, you might be able to plumb the 1/2" up to the back of the 375 but make sure the hose is supported to minimize stress on the connector back there. They should be able to withstand the stress, but why risk it.

That should be enough info to confuse you - hopefuly it is clear enough to avoid confusion.

[vtwin4life]

Well, I managed to fix my air problem. I got to the point where I can set the air pressure with the air/gas set knob and get the "machine gunning" to stop. I then set the pressure to the max of the range indicated on the 375 and...... STILL CRAPPY CUTS. Tons of dross, machine is struggling to get through 1/8" and below. I tried new tips/electrodes/etc.

At this point, I have a couple options.

1) Spend even MORE money and get a whole new compressor and see if this fixes the problem

2) Figure out a way to sell this thing and recoup as much money as possible and consider this another "screwed again" situation

3) Find my sledge hammer