head temp after 3000rmp motor

[powerr]

what are you guys with 3450 rpm motors seeing on your head temprature after running for a hour? mine are range about 130 to 150.

thanks Rob

[BrendaEM]

I would wait for official word, but if that's Fahrenheit, I would think that that's not bad. The people at IH seem to push their own mills pretty hard. I've seen one IH mill almost touching the ceiling. That would make the motor, which looks like a TEFC motor, starved for air, and then the heat would be transfered to the head.

[I guess if you were really really worried, and were running the mill 24-7, you could plumb an auto oil cooler, cooled by some 120mm computer fans. You would need a little pump, perhaps for an electric external dry sump oil pump for a high perfomance car, and probably a 12 volt power supply. Stainless braided lines would look neat, but a spin-on oil filter, or at least an inline screen filter would be a neat touch if the recommended lubricant isn't too thick. Making sure there are no chips in the oil during the process would be important, also most important is to find a way to get the oil in and out of the case without weakening it. If only there were something in the spindle case that pushes oil around, you could eliminate the pump, the most expensive part.

Another option would be adding large heatsinks and fans to the sides of the spindle head. On the IHs here seems to be nice large flat areas. For that to work, the oil level inside would have to be in the area that the heatsinks are attached to outside, which seems to be so. The paint would also have to be removed from the case in the areas of contact, so heatsink grease applied between, and then the heatsinks and fans be fastened to the spindle head, somehow, also without weakening the case. The heat would (hopefully) be transfered from the case--to the heatsink--which is cooled by the fans, which could be powered by a big wall wart, like a 1 amp one. The heatsinks could be bought from a surplus place, or perhaps be found in an aluminum pile in a metal yard. I guess you could make them too. Grills would keep your fingers out of fans while you are feeling around for things. I've seen epoxies made with metal filler, perhaps heatsinks could actually be bonded to the case with thermally conductive epoxy. I would put a tape over a corner to create a parting line, so they can be chiseled off with a putty knife if you don't like them. The heatsinks would probably need to be at least the size of the fans (120mm each) to make a difference.

Both of these would probably void your warante.]

[BobWarfield]

The most important question is whether that's a stable temperature or not. The last thing you want to deal with is thermal runaway where things are too tight, so they get hot, so they expand, which makes them tighter, which generates more heat, more expansion, yada, yada.

If you can really run it for an hour and it is stable, that may be a tolerable temperature. I have seen data, which I document on my spindle web page:

http://www.cnccookbook.com/CCMillBeltDrive.html

that indicates 100-140 Fahrenheit is the design temperature range for a lot of spindles. If you run less, you can add preload to tighten things up. 150 is past that threshold, and again it becomes an issue of whether you are courting thermal runaway.

I have seen cases where folks put LCD thermometers on their spindles so they can tell at a glance whether things are getting out of hand.

Consider too the viscosity of the oil you are running in the head. Industrial Hobbies specifies lower viscosities for higher rpms on their web site. That only makes sense. Make sure you're running their recommended oil or something equivalent at these higher rpms. If you do that, you shouldn't need additional cooling.

Ultimately, with enough rpms and enough horsepower, you will have to modify the mechanical design of the head. Just running a 3450 rpm motor of say 3HP or less shouldn't require that.

Best,

BW

[powerr]

i'm using the Mobil Velocite Oil #10 recomended in IH site. the highest temp has been 150F after about 4 hours of running with a few tool changes and material changes.
i have had my mill for about 4 years and just added the 3450 rpm motor a few weeks ago. the case gets to 150 but the spindle was only around 120.

thanks for your input
Rob

[Cruiser]

Rob, First look to exactly where your heat is building the most ! The motor can make its own heat but not too much. the the bearings in the gear box can get hot but being in an oil bath will keep them flush'd. the most troublesome area for heat generation would be in the spindle itself. The bearings are Grease lubed and if clean and set proper on preload, should run warm or quite warm. I have had my spindle get down right hot and start screeming, so i dismantled it too find that the grease was vaporized ! and the bearings were ready to self-destruct. I also found much cast iron fine all through it in the burnt grease. A good cleaning, fresh bearings, and better grease, with a three step pre-load adjustment. and it now runs cool and quiet. I say 3 steps to adj because i wasn't sure how much was needed so i enitially set it at zero. but the spindle still had some wiggle to it. so i took up the adj nut 1 more notch till it was sollid. Altho i have some backup bearings they have not been needed yet. I did use angular contact, Toyo, 7207bgc3 bottom & 7206bgc3 top. I don't recall the price but they were quite reasonable, not the high end spendy bearings, yet very much a good purchase for the machine.
(edited) = I forgot to mention that the reason for my belt upgrade and spindle rebuild ultimately came from cast iron contamination that ate all the bearings in the gear box and made it unservisable in my opinion. I did do a magnet sweep inside the gearbox before i ran it but there was yet a lot of cast fine hiding where the magnet would not get too. When i knew i had a problem and drained the box and cleaned up the spindle there had to be several T-spoons full of cast fine in the bottom of my cleaning pan, talk about panning for gold !
In conclusion i'll say that if the bearings are producing high heat at contact it'll quckly vaporize the grease till the bearing is running DRY ! and a little bit of cast iron contamination will cause exactly THAT !
Mistakes are made and we learn from them over & over & over & OVER . . . .