# G0704 Heat Issue Resolved



## cg 2005 (Jul 15, 2012)

Prior to today my G0704 motor would heat up to 140F after running a few minutes at say 1800 RPM in 90F Florida temperatures.

Took care of that with a couple of heat sinks I machined yesterday and a 56 cfm 120 volt pancake.  The fan is drawing off the hot air and pulling air through the mill motor.  Today the mill has been running nearly continuously for 6 hours in 90F heat.  The highest temperature I noted exiting the motor was 102F.  I will probably add an additional 4 more sinks for motor next week.


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## 8ntsane (Jul 15, 2012)

Nice Job
Thats is a major heat reduction, and your motor will thank you for it with much longer service life. The heat sinks you made look great too.

Im sure there is more than a few members here with hot running motors that could use this very same treatment. Thanks for sharing this.


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## Rbeckett (Jul 15, 2012)

That's just about slick as glass.  I think ya done great on that one.  Getting the motor down to 102 in Fl heat is a major feat in itself and will definately repay you in longer life and more available torque at the motor.  Hot motors seem to lose power as they heat up so this will add some giddy up to the machine probably too.  You could mill out a bunch of em and sell them among us with a few zip ties to offset some of your materials costs.  I for one would be willing to pay a fair price for a couple of sets for my lathe and mills.  Great project and great upgrade to an existing tool with a recognized issue.
Bob


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## Tony Wells (Jul 15, 2012)

In general, thinner fins will radiate a little better. Did you use any thermal paste? Hi temp silicone grease will do nicely. Don't wast money on the fancy CPU stuff like Arctic Silver, but it would benefit from some transfer compound.


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## cg 2005 (Jul 16, 2012)

Tony Wells said:


> In general, thinner fins will radiate a little better. Did you use any thermal paste? Hi temp silicone grease will do nicely. Don't wast money on the fancy CPU stuff like Arctic Silver, but it would benefit from some transfer compound.



Yes, I understand the thinner fin issue.  This was a quickie project to see if I could get any reasonable disapation of the heat with a minimal amount of effort.  It worked better than I thought.  If I get more ambitious I will mod the fins of the present heat sinks and include a transfer medium.  However with the response I am seeing now that is unlikely to happen.  I seem to be able to maintain a few degrees above ambient so I am pleased with the result.

I do need some help to solve the spindle heat build up.  I am presently using a 15:1 water to oil emulsion for most cutting.  However the spindle is still almost too hot to touch.  I think that is excessive but I am not sure how to resolve the issue.


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## kd4gij (Jul 16, 2012)

Your spindle should nor be getting that hot mine doesn't. Is the spindle stiff the it in nutruel. Eather the bearings are to tight or thay don't have grease in them.


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## cg 2005 (Jul 16, 2012)

I am not sure how stiff is stiff.  But assuming there is a bearing issue what is the remedy short of removing the motor and gears?  The bearings are sealed, correct?


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## kd4gij (Jul 16, 2012)

It has tapered roller bearings. First I would call grizzly and complain about the heat. Try to get them to send you a new spindle. Check the preload on the bearings. Check out this sight lot of info on the G0704. http://www.g0704.com/ Hoss has alot of vidios on this mill.


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## george wilson (Jul 16, 2012)

I think something is wrong with that motor. Can you put it back like it was before you return it? You may be cooling the outside,but how hot is it way down on the insides? Probably should get the motor exchanged while YOU STILL CAN get warranty work. They won't mess with you if they know you modified the product.


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## jgedde (Jul 16, 2012)

I'd venture to say that the heat issue has less to do with bearings than the fact that the motor probably doesn't have world class efficiency.  If it were stiff bearings, they too would be taking energy and warming up.

On the other hand, 50 degF (27 degC) really isn't all that bad of a temperature rise for a motor...

John


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## Wade8A (Jul 16, 2012)

I agree with George - there are issues with that motor.  I would guess bearings - especially if they are the cheap Chinese ones.  Cooling off the outside of the motor will not solve a bad bearing problem nor will it solve an internal motor wiring problem. 

Since you also have problems with the spindle overheating, I would undo the mods to the motor and send the whole machine back.  You are just asking for trouble down the road if you continue to run it the way it is.

Greg


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## cg 2005 (Jul 16, 2012)

george wilson said:


> I think something is wrong with that motor. Can you put it back like it was before you return it? You may be cooling the outside,but how hot is it way down on the insides? Probably should get the motor exchanged while YOU STILL CAN get warranty work. They won't mess with you if they know you modified the product.



Yes, nothing is permanent and can be easily removed.


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## cg 2005 (Jul 16, 2012)

Wade8A said:


> Cooling off the outside of the motor will not solve a bad bearing problem nor will it solve an internal motor wiring problem.



I checked te internal temperature and it matches the external.  so the cooling seems to be acroos the board, primarily I think do to the pancake fan.


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## george wilson (Jul 16, 2012)

A very poor motor,if it CANNOT be used full speed for more than a short time!! That really is a poor excuse for a motor on Grizzly's part. Never heard of such a thing on a machine. Have seen motors on other devices that can't be run full speed for long. But,those devices are things you would not run for long anyway,unlike a machine tool.


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## 8ntsane (Jul 17, 2012)

Interesting
I would be inclined to remove the belt assuming it has one, and run this motor without load. Your saying the spindle is very tight, and It could be tight enough that is what is causing the motor to run so hot.

You have managed to get the motor to run at cooler temps, I would get looking at the tight spindle, and get to the root of the problem. The motor usually is easy to replace if it craps out, but having the spindle take a dump, would really suck.


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## cg 2005 (Jul 17, 2012)

No belts, full gear head.


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