[Cknoble1]

I got an alarm when I tried to home out the machine this morning. the machines a vf4. It is a

"120 Low Air Pressure"-- (Air dropped below 80 psi for a period defined by parameter 76. The low AIR PR alarm will appear on the screen as soon as the pressure has gets low and this alarm appears after some time has elapsed)

I have my compressor set at 100 psi and reads 100 psi
The regulator to the machine is also set to 85 psi and reads 85 psi.
The air is going to the machine, because I clear the alarm and hit tool release and it releases the air. So it must be a problem with the regulator itself.
Can I just change parameter 76? how can I get around this until I get a new sensor? Any help would be greatly appreciated.
P.s this is the first time it has happened.

[Matt@RFR]

You might try squirting some air tool oil in the air line going to the machine, then cycle the drawbar a bunch of times and see if that helps anything.

[Maintexpert]

You could change Parameter 76 to all 9 and it will run as normal.
sounds like you just have a pressure switch going out.

[Wizzard of H]

If you can clear the Low Air alarm, then it was only a short period of time when pressure was low. You need to find out why and when pressure is going low enough to trigger the alarm. If the alarm is still on the screen, it does not mean the pressure is still low. It could have happened long before. Don't start changing parts until you know more answers.

[BigNizzy]

Make sure the air hose to the machine is bigger than that in the machine, failing that replace the small diameter hose there are some that are stupidly small with bigger diameters. we found that you have small diameter pipes feeding larger diameter pipes causing a drop in pressure, especially when using the air hose on the machine.

[mactec54]

Cknoble1

You need the air pressure set at 100psi minimum up to the machine regulator, check the spec on the machine requirement
85psi is to low

[haastec]

Make sure the air hose to the machine is bigger than that in the machine, failing that replace the small diameter hose there are some that are stupidly small with bigger diameters. we found that you have small diameter pipes feeding larger diameter pipes causing a drop in pressure, especially when using the air hose on the machine.

Yes, make sure that you are supplying enough air volume to the machine. 85 PSI at the machine is correct.

Do not bypass the system by setting the parameter to all nine's without knowing what the issue is as you may run the risk of damaging something.

Find out when and why the low air problem is occuring and fix it.

Post more details if you still need help.

Good luck.

[mactec54]

haastec
Quote
Yes, make sure that you are supplying enough air volume to the machine. 85 PSI at the machine is correct.


The Haas spec is for a minimum of 100 PSI at the machine regulator on the back of the machine, Not 85 PSI being the supply to the back of the machine 85 PSI is way to low, the alarm comes on at 80 PSI

[Machineit]

You must remember that as soon as the valve is opened and air flows, there will be a drop in pressure.

The last shop I worked at plumbed the shop with plastic tubing that was approximately 5/16 ID. That was fine for all of those using an air nozzle to blow something off, but every time the newly installed Haas mills would change tools, we would get low air pressure alarms. Believe it or not it took me about 2 months to get them to change.

Air flowing through lines is just like any gas or liquid, there is friction to the flow and if you have 100 PSI at the compressor and run it through 100 feet of line, you will only get maybe 80 PSI out of the end of it at best.

Supply more and let the regulator control it. Use large lines whenever possible. I always plumb my shops with PVC of 1/2 inch or better.

Think of it like your water hose at your house. When you first open the spray nozzle it has a little bit more force than a split second or so later. That is friction at work. If you ran that same water through a hose that was 1000 feet long, you would get very little flow out of it at the end.

Cheers---Mike

[Geof]

...... I always plumb my shops with PVC of 1/2 inch or better......Cheers---Mike

I think you will find few people who think that is a good idea; the material choice, not the size.

[haastec]

haastec
Quote
Yes, make sure that you are supplying enough air volume to the machine. 85 PSI at the machine is correct.


The Haas spec is for a minimum of 100 PSI at the machine regulator on the back of the machine, Not 85 PSI being the supply to the back of the machine 85 PSI is way to low, the alarm comes on at 80 PSI

I think we are both correct but interpreting the OP a little differently from each other. Yes, 100 PSI of air supply to the machine. Machine regulator set to 85 PSI per manufacture spec. The alarm does come on at 80 PSI which is why air volume is just as important.

Some older machines can get by with 1/4" ID air line, some need 3/8", and others require 1/2" ID air line minimum to work properly.

[Machineit]

I think you will find few people who think that is a good idea; the material choice, not the size.

In case I was not clear, I don't run PVC to the machine itself. I run my main lines around the shop with it, with regular hose to the machines. It handles the volume of air needed.

Only been doing it that way for 20 years without an issue.

Cheers---Mike

[JohnJW]

I relocated last year and had to install the compressed air line and pretty much everything else from scratch. From what I read, if pvc piping fails under pressure, it shatters and shoots the pvc shrapnel out.

I ended up with 3/4" copper piping from home depot. Currently the air compressor is about 50' away but once I move the air compressor outside, the total length of the air line will be around 110'. If I encounter too much pressure drop due to the long run, I have a small ~35 gallon tank from a dead air compressor I am thinking of installing just before all the cnc machines to act as a reservoir.

Looking back, soldering the copper piping wasn't that bad and the piping held pressure for at least a couple days. Too bad, the rest of the system is not as leak proof.

[Geof]

.....length of the air line will be around 110'. If I encounter too much pressure drop due to the long run, I have a small ~35 gallon tank from a dead air compressor I am thinking of installing just before all the cnc machines to act as a reservoir....

This is a good idea and because the air cools as it travels down the long pipe it also acts as a water trap. Just make sure you have the air inlet and outlet at the top and have a drain valve at the bottom.

[Path]

Since we are talking about air ....

I just bought a Haas TM 2p during the HaasTec 2011 open house last week :banana:
Schedule to receive it in late April :wave:

Okay on to the question ...

I understand that I need to supply "Dry air" to the mill.

What are you guys using as a dryer??


Thanks,


Pat H

[JohnJW]

I use a refrigerated dryer couple to a screw compressor. I didn't install the dryer until half a year ago. I noticed dry air help reduce the loud pop during tool change, especially after running at high rpm for a while.

Congratulations on the TM2P

[Path]

Thanks John for your reply, I will look into a refrigerated dryer. Although I was hoping a Desiccant Cartridge Filter would work.

Anyone else willing to share!

Counting down the days until the arrival:wee:

Pat H

[hercules]

I use a desiccant cartridge filter and so far (3 years) it has worked just fine. I see no evidence of moisture in the drop just before the my mill, and have never found any in the regulator/coalescer that came mounted to the machine. In my case (prototyping) I only need to regenerate the desiccant about once every 2-3 months. The one I have is a CamAir CT30, it holds a 10 lbs desiccant cartridge. I searched around and found it new for about $200. Replacement cartridges are around $50 but so far I have been able to just regenerate mine.

[Cal West]

I read this whole thread and don't want to start a new one, I don't know if this issue was ever resolved as the original post is over a year old and the thread kind of went off side ways into air lines, pipes, air dryers and such.

I am having the same problem as the original poster, machine is a 2004 VF5/50, Low Air Pressure Alarm 120 pops up at any toolchange. No change to the airlines or air pressure (100psi), everything is the same as it was yesterday and the day before that. The machine has been running everyday, 2 other HAAS Macines are working fine, so it's not contagious...

Everything else works, tools can be removed, from the spindle, spindle runs fine, no other problems and the alarm can be reset but it keeps coming back at any tool change.

Any help would be appreciated...

[Al_The_Man]

I would say it is either a short bump or drop in the pressure and/or a very sensitive P.S. that is right on the edge.
If you locate the pressure sensor, just try jumpering the switch to see if the problem disappears.
Al.