Just making up my mind about a water cooled spindle.
When thinking about risks / possible fails I came also to leaking water hoses and connectors.
Pushing the coolant into the system will spill all of coolant somewhere until the reservoir is empty.
Sucking it through the system will pull air into the hoses but probably no or little coolant will be spilled.
So, sucking seems to be the better option to me.
Any opinions on that.
My set up is a push system I have a submersible pump in my coolant tank.
The coolant keeps the pump cool and does a lot to deaden the noise of it, it intakes via a mesh grill in the pump body and discharges through the coolant pipe via a flow indicator mounted near to the Onefinity screen, then to the spindle return pipe follows same route back to tank with no flow indicator and discharges via a pipe that is secured into the tank below the surface level of the coolant.
I use a mix of deionised water and high quality vehicle coolant that colours the liquid. Flows and pressures are all fairly low, I have no issues with spindle/coolant temp and no leaks yet.
I did use high quality pipe and fittings and always inspect them at the same time that I do a clean and oil on the Onefinity
I wouldn’t take any hose connections at all where I have to worry about something like that. As far as I’ve heard, there are problems only with the hose connectors on those cheap Chinese spindles or people clamping their spindle to death in the spindle mount until the spindle housing cracks and the water leaks out.
My spindle has the Festo QS8 tool-less hose connectors and Festo hoses, so I sleep easy.
I have no experience with the no-spill quick disconnect fittings Daniel @PwnCNC offers, maybe someone has?
The pump will pump liquid into the hose as long as there is liquid in the tank.
If you have a cooling station with flow sensor and the flow collapses, it can send the VFD an alarm signal which will stop the spindle (and the g-code program if wired to CNC controller correctly)
Push. Most of the small pond type pumps aren’t high efficiency pumps. They are designed to sit in the reservoir. they count on both atmospheric pressure and the weight of the water above the pump inlet to push water into the pump. If sucking you will need to prime the pump and even then it could cavitate or possibly collapse a vinyl hose cutting off flow. Pushing water is almost always the easier way.
I would opt to push based on prior experience, less priming issues. If you’re doing a closed loop system then you could go either way…
Thank you so much for all of your answers - that was really helpful.
Special thanks for pointing me to FESTO connectors and cooling stations.
Doing a little bit of searching and mathematics, I found a cooling station for under EURO 200,- with flow and temperature alarm.
BTW: While searching through all of this material, I found that purified water is the best coolant when freezing and corosing protection is not needed. (OK - no colored liquid in the pipes…)