Denford Software & Machines

Hi.
When I run my spindle at 2200 rpm the whole motormount and spindle bearinghouse (the big z-block going up and down, solid casting metal), gets warm. So warm that when I put my hand on it i get a bruning sensation (not for real though..). I guess around 50 deg Cel. This is with spindle just truning, not milling anyghing but air.
Is this normal? I will try to put some more grease in there but it seams plenty at the moment.
I also get fluctuations in rpm with no particular reason, say -50 rpm just like that, then up again. When i stop the spindle and listen if I can hear som if there is dirt or chips in the bearings it sounds normal, but like a bearing that is just a little too tight fit.. This might be from the design of the spindle, i dont know (only one bearing plane, then might need a higher preassure on the bearings to keep zero lash..?).

Per

If you can spin the spindle by hand, and it feels smooth - then the fluctuating speed is probably down to the tacho feedback - check that out for dirt etc...

Won't putting more grease in, cause increased temperature ???

There is also some info here about the bearings:
viewtopic.php?t=745

So, the preload is taken up by ground spacers

Don't worry, this seems to be normal with these machines. Our Triac's head also gets really warm from just running - I suspect there's a lot of preload on the bearings to stiffen up the spindle. Seems to be common with Orac's as well - we joke at work that those canny Yorkshiremen built a rather convenient hotplate into the headstock to keep your cup of tea warm!!!

Alastair

Aye Up, Us Yorkshiremen always like to oblige

I suppose if the temperature goes up and then remains constant, its not a problem - increasing temperature is another thing.
I always been told that if you can touch a bearing casting without pulling your hand off, then its not too hot.

Hi, Missed this one earlier

Mine also gets quite warm, so not uncommon, I think Clarke has it about right. The Bearings are quite close together on the Triac, so there is a fair bit of preload to keep everything running true.

Make sure the bearings are well greased, but be careful not to over do it.

Roy

Cheers for the replies.
I got some fancy hi qual. SKF bearing grease that should be good for high speeds and high loads. Seams to remedy the problem a bit and the noise is now "smoother". Feels better in my gut to know that there is at least a good grease in the bearings.
Been running several hours at 2300 rpm and the bearing head gets real warm but not increasing so I figure that it´s fine the way it is.

Per