Air Assist PSI Reduction Problem

[Dave Sheldrake]

Worn seals or cylinder bores usually

[Gary Hair]

So let's say the gauge is saying X PSI. It is now showing a lower Y PSI. What would cause that and how would I trouble shoot it?

The only things that would affect the indicated pressure would be:
1 - Compressor
2 - Air lines
3 - Gauge

Disconnect the air line from the compressor and hook up the gauge directly to the output of the compressor. If you get 30 psi then you have an air line problem. You can find an air leak by brushing on some liquid dish soap and watching for bubbles. If you don't get 30 psi then you either have a gauge problem or a compressor problem. Buy a quality gauge and connect it to the compressor. If it indicates 30 psi then you have a gauge problem, if not, you have a compressor problem. Now you just have to decide how much money you want to spend on a compressor that will keep up with your needs. I burned through two of the HF airbrush compressors before I plumbed in a line from my 60 gal shop compressor. They both died after about an hour of continuous running while cutting acrylic.

[David Somers]

Ed...before you go ripping into equipment or buying something new something simple you can do to test the integrity of the hoses going from the compressor to the valve would be to use a brush and some soapy water? If you hit leaks in any hoses or fittings the soapy water will bubble. Fast check and no expense involved. Then dig into the more difficult things folks have been describing to you. Dont forget to check your gauge and valves. Everything between the compressor and the nipple feeding the air into the laser tube.


Dave

[Mark Sipes]

Well Ed you seem to be convinced that the air compressor is operating at a level to produce 30psi with the reduction valve wide open. If you plug the end of the hose l at the laser head and the pressure goes up to 30psi, then the advice given over the past 20 posts are spot on. The compressor is not keeping up with the size of the hose and setting of the reduction valve. If the gauge does not change then there are leaks in the system or the pump is not producing the psi you are expecting. Start at the exit to the gauge. Plug it there and see what happens. It should be a single hose to the gauge from the pump.

Get back... also ....Make sure the inlet fitting or filter at the pump is not clogged.......



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[Ed Maloney]

Epilog called and told me to reverse the solenoid which I did. With the laser idle the gauge on the compressor shows 30, when I engage the laser for a vector cut it drops to 10PSI. When I talked to Epilog they guess that somewhere in the hoses it was clogged up with something for the past 8 years. They suspect the clog is no long there and would account for the PSI drop.

I asked them for a recommendation for a compressor that would up the PSI. I did a search here and most of the air compressor posts are many years old. Interestingly enough, some replied they used the same compressor that I have.

[Dave Sheldrake]

With the laser idle the gauge on the compressor shows 30, when I engage the laser for a vector cut it drops to 10PSI.

Perfectly normal, if idle the system is closed and can build pressure, if the system is open is has to generate far far more air to keep up with the loss.

Look at it like filling a bucket with water, if the bucket is secure it will fill up, if it has a hole it will drain out nearly as fast as you are filling it.

[Mark Sipes]

Ed... What does the end of the air assist exit look like. Is it an open plastic tube, a metal tube??? Is it possible there was a tip in the tube at one point that directed the air flow . If this tip were present then the air flow speed would be increased, while the CFM was reduced thus increasing the PSI on the gauge.

Much like putting a Nozzle on a yard hose. with it attached you can shoot the water 20-30 feet. with out it attached 4-5 feet.... same water pressure at the source but the line pressure would increase with the nozzle on!!


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[Ed Maloney]

It is a metal tube Mark. It never had any type of attachment on it. Think it would be safe to cut 1/8" acrylic at 10PSI air assist?

[Bill George]

Update: I used my old compressor and I still have the same problem.

You have a air leak someplace like others have told you, that's unless the old compressor is also worn out. When compressors run, they wear out. If yours has ran daily for 5 years it needs rebuilt. Piston rings and / or valves need replaced. Unless you have an air leak.

I can just about bet a million pesos your air line is not metal all the way when the hose or vinyl line moves it will wear and leak someday.

[Kev Williams]

I like the 'there was a small clog and now it's gone' theory.

Me, the only reason I've found for air assist whatsoever is to keep the flares down. And I don't use a cone because I've found a noticeable difference in laser power (increase) when it's off. My air assist tube just hangs off a reshaped paperclip on top of my lens head. It's a blue hose with a 3" section of smaller hose, which normally goes into the fitting on the cone. When I'm cutting I just tape the hose to the side of the lens tube. Keeps the fires out...

However, one day I noticed the parts I was cutting weren't cutting correctly; starting and ending points not lining up, wobbly lines...

I finally figured out the problem: The air was pushing the pieces around! And these pieces were like 2 x 10" pieces of 1/8" thick Rowmark. --I sometimes wonder if this may be the source of other people's funky engraving problems...

My air pump is just one of those humming diaphragm things. With the bare hose the pressure isn't regulated so it does blow a lot of air, but the I've never considered it all that powerful. I can get more 'apparent' pressure from my LS900's air nozzle...

SO, I pulled the small hose out and just use the bigger house. And what comes out of the bigger hose is a nice VOLUME of LOW PRESSURE air- keeps the flames down, but doesn't push the work around on the table.

[Glen Monaghan]

A couple of years ago, I thought something was wrong with my air assist that was resulting in flare ups where they weren't a problem before. Turned out that I'd just recently cut a bunch of acrylic and the white, dusty looking crud that produced had managed to cling to, accumulate on, and clog the tip of the air assist tube. Perhaps your tube was similarly clogged and you unknowingly knocked the obstruction loose, or it just finally came off by itself.

[Ed Maloney]

OK folks - Time for me to get a new compressor. I did a search here and most of the air compressor posts are many years old and some of the recommended ones are no longer available. Would like to get one that has the gauge and a regulator. Recommendations for one that will do the job and not be an overkill?

[Dave Sheldrake]

Ghast? Rich Harman ?

[Tony Lenkic]

Ed,

Gast compressors are expensive when new but you can get the from ebay or Craigslist for very reasonable price.

See ebay listing for a sample of one...................222186474007

222186474007

222186474007

[Ed Maloney]

My problem is resolved. It was a faulty solenoid.