Spindle heat and CPU heatsinks

[andyb]

I thought I had seen this somewhere before but I can't find it now. Has anyone tried to use a heatsink like is used on a computers CPU to disperse the heat on their spindle, with or without the fan? My spindle really got hot tonight cutting some 3D files. Don't have a thermometer yet but going to pick one up. I know that a heatsink on a CPU can cool the CPU by several degrees. How would it work by placing one on each side of the spindle? I know it won't cool the bearing directly but it may help pull some of the heat away.

Andy

[les_linton]

Andy,

I'm was thinking along the same lines as you are and am curious about this also. Mine does not get so hot that you can't touch it, but I am concerned with the length of time it takes for some of these files that over time it will cause a problem.

I do think that you would need some air movement across the fins for them to be effective.

Any thoughts anyone?

[gerald_d]

Step 1 is to ensure that the cooling and temperature monitoring system of the spindle, as designed by its manufacturer, is all connected and in good working condition. (Their warranty would also require it).

Does your spindle have a fan? Is it working? Is your spindle designed for compressed air cooling? Is it designed for water cooling?

Does your spindle have a temperature sensor built into it? Thermistor or thermoswitch? What is it connected to? Is it meant to be connected to the fan? Or is it supposed to shut down the spindle drive? Link (http://www.talkshopbot.com/forum/messages/7/13585.html)

Some folk swear by measuring only the outer bearing housing temperature, but that is an "after-market" approach. First you need to look at the basics as the spindle designer intended.

[bcammack]

Harbor Freight has a nice, laser-sighted non-contact thermometer for $40 right now.

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=91778

All Electronics has a lot of interesting surplus heatsinks and fans. If you want to get real trick, they even have some hefty Peltier junctions for about $40.


www.allelectronics.com (http://www.allelectronics.com)

They also carry an excellent assortment of magnets, switches, and relays.

[patricktoomey]

Andy,

What brand and model of spindle do you have? If it's a 5hp Colombo with the constant speed electric fan on top (it always runs if the spindle is turning or not) then you may have a bad fan. I just got bit by this and hopefully caught it before the spindle overheated. I was cutting a job and noticed that the fan didn't seem to be spinning at full speed. I felt the spindle housing and it was way warmer than usual. As soon as the bit came up out of the material, the fan spun up to full speed. When it started cutting again, the fan almost stopped. As it turns out, the Papst fans come in ball bearing and sleeve bearing versions. The sleeve bearing version appears to be vulnerable to failure where it stops spinning when the spindle is experiencing cutter vibration. As soon as the vibration goes away the fan comes back up to speed. It can be deceiving because it may just slow down and if you check it when it's not cutting it appears to be fine. I got a new fan from Colombo and it works fine now. They only had the sleeve versions and they swear they're fine but I'm not convinced so I ordered another ball bearing version from Mouser Electronics. They're on back order but when it comes in I'm swapping it for the sleeve version and I'll keep that one as a spare.

I would be very cautious about adding other cooling elements, especially active cooling of any sort. I would worry that if you cool one particular area of the housing more than another that you could induce thermal stress or draw the internal lubricants from one area to another due to thermal differentials. The manufacturer has designed it the way it is and as Gerald said, they designed it this way for a reason. If it's overheating some component must not be working as it should.

[andyb]

Les,
The heatsink should cool effectively without a fan. The fan just helps them cool faster.

Gerald,
I been reading the thread. I downloaded the manual and have been reading over it. The heat is not so hot as you can't put you hand on it for several seconds, it's just hotter than it's felt before.

Brett,
Thanks. I'll try to pick one up the weekend.

Patrick,
My spindle is a Columbo 5HP. The fan seems to be working fine. There is no variation in the speed of the fan during cut. How can you tell what fan you have?

Andy B.

[watswood]

Andy,
When I first got my 5hp Columbo I ran it through the warm up period then ran it at 18k RPM and just let it spin without cutting for about an hour(I was enjoying the peace after running a porter cable for 5 years). I happened to touch the outer casing and was very surprised it was at 145 deg.(my shop was at 85 deg. and that did not help). I sent it back to PDS and they tested it on their bench and it checked out fine. During their tests the spindle settled out at 132deg. F at 18k RPM (3 amp no load output current)in their 70 deg. F controlled clean room(clean power too!). When I asked what is going to happen when I start drawing current closer to the full load name plate of 15amps(which to this day I haven't done), they said "It's a 60% duty cycle spindle". This is something ALL of us Columbo fan cooled spindle owners need to keep in mind. So what does that 'phrase' mean? On for 6 min. off for 4 min., or on for 60 min. and off for 40 min. Or does it relate to power draw where we can draw full power for 60% of the time. In any case it's a phrase that lends itself to interpretation and simply means that the spindle is not designed for continuous use. The positive of this is that it will reach the required 98 deg f bearing housing temp. faster and the low(in my opinion) CFM fan runs extremely quiet. My guess is that they do not want us running these things cold.

Take a look at a temperature reading multimeter. You can velcro the meter to your z and tape the probe to the bearing housing. They can be cheaper than IR and just as, if not more, accurate that the IR's. I just saw this in MSC's sale flyer:
http://www1.mscdirect.com/CGI/NNPAGE?PMPAGE=specials/brochures.html&catalog_name=juness2006&rfx_page=1
or
look up part number fp83308981.

[elcruisr]

I've posted this before but I'll throw it out again in one place. The max operating temps (from PDS) are 145 F no load and 165 F under cutting load. We have run our spindle on cutting jobs as long as 16 hours a day. Duty cycle is just that, a percentage of time, figure it by the hour, quarter hour or whatever.

We routinely run single pass jobs in 3/4 ply that are 20 min. long with only a sheet change in between. Never had an over heated spindle except when we had a sleeve bearing fan or the spindle bearings wore out. We were the fortunate souls who found out the same fan could be had with ball bearings for only a few bucks more. Worth every penny! Check the model number. I think the sleeve bearing fan is a #3650. Just take the shroud off and you will see the model # on the back of the fan.

If you start monitoring your bearing temps you will notice one big thing that does effect temp is dull tools! Especially on long runs. Stay sharp and life will never be dull!!!

The places to check the temp are the bottom of the case, the bottom of the nose and the top of the case side about 1 1/2 inches down. The bearings at the bottom of the case are usually the hottest and the ones to watch the most. If they start pusing the limits all the time it's time for a rebuild.

Eric

[bcammack]

Anyone played with the "magnetic levitation bearing" fans?

http://www.buyextras.com/su50malefan1.html

[andyb]

Thanks all for the replies. Borrowed a IR thermometer until I could get one and the temp is around 145 cutting 3D files. Life is great.

Andy B.