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Ed Maloney
07-11-2016, 2:45 PM
I have my compressor set at 30PSI but during vector cutting it's showing 10-20PSI. It's been fine for years up until a month or so ago. I removed the hose from the back of the laser and blocked it and the compressor shows 30PSI. Any suggestions how to troubleshoot or if anyone else ran into this?


Ed

Dave Sheldrake
07-11-2016, 2:47 PM
It means the compressor cannot keep up with the air requirement.

CFM is displacement FAD is air delivered.

Ed Maloney
07-11-2016, 4:06 PM
Thanks for the reply Dave. Don't know what it means though. If I disconnect the hose from the laser and cover the end with my finger, the compressor shows 30PSI. Connected to the laser it is lower.

Mike Lassiter
07-11-2016, 4:22 PM
Ed the compressor cannot maintain 30 psi with the volume of air being used. Putting your finger over it and blocking the opening lets it build up pressure due to zero flow. I would look at the filter on it if there is one to see perhaps it is time to clean or replace it. That could be limiting the air the compressor can pump. If no problems there or running it without the filter doesn't change the pressure I believe it is time to look for another compressor.

Ed Maloney
07-12-2016, 4:43 PM
Update: I used my old compressor and I still have the same problem.

Dave Sheldrake
07-12-2016, 5:34 PM
Pressure depends on nozzle size and displacement of the compressor. To get 30 psi through a 3mm hole you need 16CFM displacement or FAD of 9 CFM @ 60 psi

David Somers
07-12-2016, 6:16 PM
Ed....Any chance you have some leaks in the hose from the compressor to the air nozzle on the laser? That could reduce the PSI. And it could account for the fact that two compressors are showing the same problem. The hose would be the common element in that case.

I see the same thing in my vacuum pump on my wood lathe. Every few years I watch the vacuum gauge drop steadily and the cause is typically fittings that have loosened over time, or a hose that is aging and cracking enough to affect the vacuum. The vacuum pump itself chugs along reliably otherwise.

I did notice you are on the Jersey Shore? If you are near enough the ocean you may have some corrosion issues in some valves, or additional cracking in the hoses due to proximity to the ocean. I used to live in Hawaii. I was about 1.5 miles from the volcanic vent on Kilauea and we had some pretty interesting atmospheric gasses to deal with. Acid Rain, sulphur dioxide, etc. The amount of rust that caused in my garage and also exposed equipment was stunning. And rubber stuff died early and unhappy deaths.

Ed Maloney
07-13-2016, 11:32 AM
Checked the hoses and didn't see anything obvious. I contacted Epilog via email and am getting nowhere. Guess it's such a rare thing that they may not have any troubleshooting steps to reference.

Gary Hair
07-13-2016, 12:05 PM
What are the specs on your compressor(s)?
Tank size:
Motor H.P.:
Max PSI:
CFM:

Ed Maloney
07-13-2016, 12:35 PM
It's one of the HF ones that I have been using for years. This problem just started to come up a couple of months ago.

Tank size:
Motor H.P.: 1/5
Max PSI: 58
CFM: .5@20PSI

Ed Maloney
07-13-2016, 12:37 PM
Here's the reply from Epilog when I told them I checked all the hoses:

This is a really simply system. Pump, solenoid, air assist tube, brass elbow, air assist tube, brass elbow, air assist nozzle. If you find no fault in the pump itself , it has to be one of these other parts.

Gary Hair
07-13-2016, 1:13 PM
CFM: .5@20PSI

There is the problem. As was pointed out in a previous post, you would need 6 CFM at 30 psi with the size hose on you machine. With .5 cfm you'll never get anywhere near that pressure with such low volume. The "problem" has been there all along and you just noticed it - it is impossible for that compressor to have ever put out that pressure.

Ed Maloney
07-13-2016, 1:31 PM
There is the problem. As was pointed out in a previous post, you would need 6 CFM at 30 psi with the size hose on you machine. With .5 cfm you'll never get anywhere near that pressure with such low volume. The "problem" has been there all along and you just noticed it - it is impossible for that compressor to have ever put out that pressure.

Hey there Gary. I always glance at the gauge that is on the compressor, especially when cutting acrylic. So my observation is on the gauge showing a lower PSI now, which for the past 8 years has shown 30.

Dave Sheldrake
07-13-2016, 1:57 PM
0.5 CFM at 20psi is an airbrush compressor. The only way it could show 30PSI is if either 1: the gauge is faulty or 2: the System is closed (allowing pressure to build up) in an open flow system (air assist) you need at least 3HP+ and a CFM of 14 to get 30psi at the nozzle with a 2.5mm exit hole

Ed Maloney
07-13-2016, 2:23 PM
0.5 CFM at 20psi is an airbrush compressor. The only way it could show 30PSI is if either 1: the gauge is faulty or 2: the System is closed (allowing pressure to build up) in an open flow system (air assist) you need at least 3HP+ and a CFM of 14 to get 30psi at the nozzle with a 2.5mm exit hole

Let me first say that I appreciate all the technical details from everyone of what's going on and thanks for taking the time to respond. I purchased a new compressor back in February of this year and the gauge showed 30PSI until recently. My old compressor used to show 30PSI as well.

Let's assume both gauges are incorrect.

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?

I checked the air hoses and don't see anything obvious as far as holes go etc.

Dave Sheldrake
07-13-2016, 4:01 PM
Worn seals or cylinder bores usually

Gary Hair
07-13-2016, 4:36 PM
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
07-13-2016, 4:55 PM
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
07-13-2016, 7:51 PM
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.......



.

Ed Maloney
07-14-2016, 10:04 AM
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
07-14-2016, 10:20 AM
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
07-14-2016, 12:27 PM
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!!


.

Ed Maloney
07-14-2016, 12:33 PM
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
07-14-2016, 12:50 PM
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
07-14-2016, 2:09 PM
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
07-14-2016, 9:40 PM
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
07-15-2016, 7:49 AM
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
07-15-2016, 8:16 AM
Ghast? Rich Harman ?

Tony Lenkic
07-16-2016, 10:20 AM
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
07-19-2016, 8:19 PM
My problem is resolved. It was a faulty solenoid.