Spindle heating a problem?

[WoodMarvels.com]

Hi guys, now that the garage is above 0C, I've noticed after an hour or two (depending on load) that the spindle on my ShopBot Desktop gets so hot I can't even touch it. Is this something that I should be concerned about?

Cooling the garage isn't an option (it wasn't heated in the winter) so what else do you guys do to keep your spindles cool?

It's only 10-20C nowadays in Canada, so things will get warmer faster over the summer. Also planning to move to Australia where it will be in the upper 20s consistently year round.

Thanks,
Jon

[Brady Watson]

First...make sure that cooling fan is on, running and moving air through the body extrusion & exiting near the dust foot.

When doing production, especially @ high RPM, your spindle is going to get hot. Sometimes the cast iron bearing lands can get hot enough to zing whatever skin touches it. Your spindle has a built-in thermister that will shut it down if it gets too hot. This will throw an error code up on the VFD that reads something to the effect of 'OT' (Over Temp) etc. It would not hurt to add supplimental air cooling via another fan blowing on the body, but I think this is probably not needed. It might cool your worries down a little... :)

There is also such a thing as duty cycle. These spindles are made for production, but they also have a duty cycle to them. It is hard to determine actual duty because you would have to calculate how much load is actually on the spindle by monitoring how many amps you are pulling over a given time frame.

It is good to be concerned...but there is some protection built into your spindle cooling system.

-B

[WoodMarvels.com]

Thanks Brady, what I have been doing is letting the machine "rest" for 20-30 minutes with the enclosure open to let it cool a bit. Spindle needs a liquid cooling system like they have for CPUs!

Jon

[Brady Watson]

...with the enclosure open to let it cool a bit.

What enclosure? Do you mean the control box where all of your ShopBot electronics live? Or??? If you mean the SB control box, you can close it up...there is nothing in there for your spindle aside from power in & out to your VFD and a 24v power supply for the cooling fan on your spindle if you have an HSD. If you mean to cool the electronics - this is rarely necessary. There are cooling fins on the back side of Alpha control boxes - blow a fan on that...if anything. It was designed to be sealed and dust-proof.


-B

[zeykr]

He has a desktop. My guess was he meant the plexi cover/dust shield around the spindle on the desktop.

[WoodMarvels.com]

Hi Ken, you are right.

Jon

[Brady Watson]

He has a desktop. My guess was he meant the plexi cover/dust shield around the spindle on the desktop.

OK....got it now! Forgot about those little guys!

-B

[zeykr]

Jon,

I've not see the desktop with the cover in person. There is airflow through it isn't there? If not, I'd sure vent it somehow and use a filter if needed. You certainly need airflow through the spindle body.

[WoodMarvels.com]

Hi Ken, there doesn't seem to be any airflow other than the vacuum at the bottom sucking-up the saw dust. Maybe once I get set-up on a more permanent basis I'll drill a hole in the top of the enclosure and stick the other end of the shopvac in the hole... so air is pushing down from the top and being sucked-up from the bottom - I'm sure that would make a HUGE difference.

http://youtu.be/zf7QO9O2kVs

This link will bring you to me cutting one of my models so you can see the set-up I use.

Jon

[adrianm]

My first CNC was a machine I built myself roughly the same dimensions as the SB Desktop.

I put that in an enclosure with a large square mouth extractor duct leading to a normal 4" pipe extractor.

It didn't work at all. The dust just settled everywhere.

Eventually (the mind is a bit slow these days!) I realised I needed airflow so I drilled a square pattern of holes in the opposite end. The dust and chips took off from the surface of the table then!