[reflexx]

Please help!

I've had a Cincinnatti Arrow 500 (1997) for a few years and it's always been a huge air user. I have an 80 gallon compressor, with another 30 gallon tank next to the machine, and it cycles every 4 minutes!!!

It seems excessive for a machine that only uses air for spindle oil mist and tool change. The factory cannot give me a clear answer and I've checked the oiler system. I'm afraid to turn down the air supply to the spindle (they're a bit EXPENSIVE if I fry it).

Any suggestions? Other users?

thanks,

REFLEXX

[reflexx]

ANYONE???

Problem still exists. Fellow Arrow CNC users, what do you think?

[Geof]

Your compressor could be cycling frequently because it is too small for the machine consumption. You have a total of 110 gallons of tank capacity but the important thing is the cfm output of the compressor. If the compressor cfm output is correctly matched to the machine consumption another reason it can cycle very often is because the cut out and cut in pressures are too close. For a piston compressor it is not unusual for the two pressures to be different by up to 20 psi; cut out at 115 psi and cut in at 95 psi if the machine regulates the pressure down to about 85 psi. The further apart the two pressures are the less often the compressor cycles and the longer it runs in a cycle.

[reflexx]

Thanks, Geof!

I thought about that, but this machine clearly uses a very large amount of air in the spindle "misting" system.

I feel air blowing past the spindle like an air gun set on half open. I realize that it is to keep the coolant and contamination out, but it seems a lot more than necessary. It's the only use of air in the machine besides the tool magazine, and that certainly doens't cycle that often.

I'm just hoping to find someone that has the same machine to confirm.

Is there a gauge that measures CFM that I can put in-line.

[Geof]

Is there a gauge that measures CFM that I can put in-line.

I googled and yes sure there is and they all look like many $$$$$.

If you can feel the air blowing I suggest trying to find what psi the spindle misting is supposed to operate at. I don't have the same make of machine but I know my systems run on 18 psi and it is not possible to feel any air escaping.

[Verfur]

reflex the blow down through the spidle should only happen at tool change. If seting idle with no tool in spindle there should be no air leak exept for the positive pressure for the spindle bearings/lube and I do actualy arrow 750, and 1250 machines.

The only machine I have with coolant through spindle is the 1250 (not a mist) flood coolant.

I suspect you have a valve stuck.

Can you feel the air come out of the inside the spindle with no tool in the spindle??

John

[reflexx]

Verfur,

I do not have blow down thru spindle (to clean the taper). There's no air coming thru the center of the spindle. I feel air coming between the part of the spindle that rotates and the stationary metal at the bottom of the head.

Imagine you wanted to spin the spindle by hand (no tool in the spindle), where you grasp it to spin it is where I feel air blowing on my thumb and pointer finger. Does that description make sense? do you feel the same on yours?

I'm certain that it is the spindle bearing misting/lube and postitive air pressure system, but it seems to be overkill.

[Verfur]

I do not feel any air comming out of the spindle bearing area, I can how ever hear it slight hiss and a pulsed his when you spin the spindle I will look and see what the press. is set at in the morning and post the readings. if memory is right there are two regulators on the back one main and then one for the spindle.

John

[Verfur]

Ok,

Here is the setting I am running on my machines main press. at 80psi and second reg set at 20psi and spindle lube set to 2bar (VIP2) is the type of lube control on my 750.

2bar = Aprox. 29 psi

hope this helps
John

[reflexx]

John,

What's the brand name of the mist/lube system on the back of your machine? Mine says "DROPSA" a box with a yellow/orange cafe with LEDs.

There's a pressure gauge to the right of it (black face) reads 4 BAR and there's one directly above it (small, white face) only goes off when he luber cycles.

The machine is set at 80psi. Is this what you have also???

thanks again,

gene s.

[Verfur]

reflexx,

DROPSA is the brand and it is a VIP2 its a little blue box with two LCD displays.

As far as the gauges go there is a little whit face gauge above the Box and I belive you are right it only moves when the lube cycles.

I belive the reson mine has the extra regulators is because it has the glass scales on X and Y.

hum 4Bar = 58. psi

again my machines sound about as loud as a crummy air hose quick connect SSSSSSSS. you have to have you head in the machine to even hear it above the spindle cooling fan.

What RPM spindle do you have?

The one on the VMC 750 has a 8000rpm cat 40 spindle. and the 1250c has a 10,000 rpm cat 40 spindle.

John

[sarms]

My Arrow does the same thing. I just put up with it. It air supply is a 200 gallon twin piston. Under opperation the compressor runs every 12 minutes. I'm a 90 psi.

[cncwork]

Hello,

I have two of these arrow 500 and interrested if these should using air (a lot of air)
while sitting not even running? If not how do I fix this? Did you find a solution?

CNC Programming, Inc.
Matt Murray

[reflexx]

Wow! talk about reviving a post from the past.

in short, NO. I have not figured out or heard a good answer as to how to minimize the spindle air use.

The air is mixed with oil and sprayed /misted onto the spindle bearings. this process uses a ****load of air. Makes my 60 gallon air compressor go off every 5 minutes.

I have not lowered the air pressure because of fears of burning out the $10 spindle! I've just lived with the noise (and the extra cost of electricity).

If you do figure it out, I'd love to know what to do!!!

gene s.

[cncwork]

Hi Gene,

I have begin lowering the air pressure and monitoring temp.
My suspicion is that when the machines were new less air escaped and over time they allow to much air pass do to wear.
I have installed new machines (different make) with same type of positive air pressure bearings and they do not require this amount of air!! Its crazy!! You cool the bearings with the oil in the air line not the air itself the air is more to introduce the oil then cooling.
I do not recommend you follow my lead. But I have been testing one of my two arrow 500 mills and will let you know the results. It is either that or Buy A Huge Compressor and run it nonstop to cool two small bearings.

I'm either briliant or an idiot! Time will tell- I've been wacthing the temp close but It's quieter then lisening to the commpressor.

Great talking with you STAY TUNED!

CNC PRogramming, Inc.
Matt

[cncwork]

Hi Gene,

During testing and further investigation. I have discovered the air supplied to the spindle is not a cooling device at all. The purpose of this air is to keep chips from entering spindle bearings (air knife) actually an option not installed on standard machines. Customers running short holder with high pressure coolant (flood, air mist) or nonmetallic dusty airborne materials (Wood, Foam) would request this option to protect material from getting into the bearings. The bearings are factory lubed and sealed. On page 4.1.1 of the service manual you will notice some machines are equipeted with a spindle labyrinth seal that requires you the regressed it every 6 months. Note: on bottom of page describes our circumstance with 3mm drain hole in rear spindle with no labyrinth seal. But rather than just allowing this cavity to drain air has been installed to keep a positive pressure to keep materials out.

In my case doing mostly MR&D work and running all makes of materials I will make my own labyrinth seal positioned just outside the spindle nose and will not be using air at the spindle. Once again I do not recommend you follow my lead just keeping you aware of what I have learned and will keep you up to date as I move forward.
Until I have time to make the labyrinth I will be applying 3 psi for safe measures.
Good to be able to keep the compressor from running every 10 min. I feel kind of unintelligent for not figuring this out sooner and running my compressor so much thinking I was in cooling the bearings.
Oh well as lease everyone on the internet will have written record of my mistake and hopefully learn from it. Like you I was concerned about protecting the spindle motor and willing to put up with massive use of air to assure it.
Hope this helps.
Matt