Water cooled Chinese Spindle - air leak

[analogman]

Got my 2.2kW spindle all plumbed in and wired up. She works just great. The only think that baffles me is an air leak at the spindle. No matter how much I bleed it (did it 5 times), as soon as the pump is turned off, up come the bubbles.

Get this - it does not leak any fluid when the pump is on.

Anyone have this problem?

[palenn]

I can't answer your question but I have a question for you. Do you run any kind of corrosion inhibitor such as anti-freeze in your cooling water?

[csrc]

I am considering buying one of these spindles and would be interested in your experience. What are you cutting with it and is it truly significantly quieter.
Thank you!

[analogman]

Hey guys, I would be happy to answer your questions in another thread. I am pretty keen on getting this air leak problem solved and would like to keep this on topic.

[palenn]

Can you elaborate on exactly where the bubbles are showing up?

[ger21]

Is the air trapped in the spindle perhaps?

[analogman]

Is the air trapped in the spindle perhaps?

Quite possible, I was thinking the same, so I put the spindle down low and all the gear up high to get any air out. Then I would move the spindle in other various positions to see if I could get an trapped air out. Unfortuneatley it does not list inlet our outlet.

I will say, that it is keeping cool, not warming up at all, so something is working...

[analogman]

Well I simplified the whole setup and rebuilt it. Now the system is simply a 5 gal pail of coolant, submersible pump and the hoses running to the spindle. As per a suggestion I turned down the flow through the spindle. I bleed the spindle by rolling it around the table when the pump was on, that seemed to help quite a bit.

[palenn]

Are you not concerned that the spindle bearings have become contaminated with coolant? I may be a little confused about "air leak at the spindle". Where were you seeing the bubbles? In the coolant tank or at the spindle nose?

[analogman]

No, I am not concerned about coolant contaminating the bearings. What else would you put in there?

"air leak at the spindle" - air bubbles at the spindle inlet line.

Mute point, all is fine now.

[palenn]

Sorry, I thought maybe you were seeing bubbles at the spindle nose. That might have indicated some porosity in the housing casting letting coolant get thru the water jacket and into the bearings. That would not be a good thing

[stevespo]

When I first installed my spindle, I overtightened the compression fittings and would see some air bubbles entering the tubing near the inlet/outlet - but no leaking at all. When I replaced the tubing, I didn't torque things quite as tight and I'm not seeing the bubbles the way I used to.

Steve