Sweet dreams CNC - more than one step beyond...

[sweetdream]

Spindle cooling;
There's lots of ways to do this, here's my version.

Design spec was for a compact autonomous cooling system. I figured that when it was running, I'd have enough to worry about so anything that could be automated, I'd automate.

18DS20 sensors at the input to the spindle and output of the radiator send the temp data via a one wire system to the Arduino Mega that is looking after the cooling. That looks at the difference in temperature and either turns the radiator fans on or off and feeds the current status to a small LCD screen.



phone pic, sorry. :(
Pump on, fans on, temp in 18c temp out 17c. There's not a lot of heat generated by the spindle, haven't seen those numbers move much.

I had done a bench test with the radiator in free air and hot water in it, turn on the fans and watch the temperature drop over a set period of time. I then repeated the test but with the radiator bolted 5mm away from a sheet of 10mm alloy. The temperature of the alloy went up by one degree, but surprisingly there was not a difference that I could see over the average of 5 of each configuration in the speed the water was cooled. Reversing the direction of the airflow made no difference.

The radiator is bolted to the back of the Z axis with rubber spacers and the fans pull cool air through the 5mm gap and venting to the rear of the Z. Foam could be used as an air filter between the radiator and the back of the Z if required but there is, as yet, no sign of this being an issue despite routing some ply down from 22mm to 6mm.









image above is a the reverse of holder for a remote monitor and e-stop, allowing me to keep an eye on operations from the comfort of an easy chair. ;-)

The pump and reservoir are mounted above the Z axis, reinforced hose connects it all together.

The arduino also rotates the spindle work lights LED sequence (like a circular white cylon type pattern?) while the spindle and axis are still, so it can be seen at a glance that the pump is working ok. The work light is 3.3vdc, and minimal amps. I've got it through a relay but this will be revisited and modified at some point. My initial concerns that zeroing the tool on the workpiece without a stationary light were unfounded, its actually easier to see the tool tip with the light source rotating around the tool.

The cooling setup is a modified Thermaltake PC water-cooling unit, works really well.

The 3 fasteners above remind me that anywhere I had a horizontal fasteners I'd use 3 of them but vertical fasteners were used in 4's. The Z was fairly tight on space, as per the design spec, so this strategy kept them apart.

I'm posting this as I come across it but if theres' anything specific just ask. :-)