[jkittleson]

Hey guys. Purchased a new 1100 around 60 days ago. Now it seems to be self destructing. Anything besides a VERY light cut results in the sound in the video, or worse.

I've pulled the fan off the motor no change. I've also pulled the belt off and ran the motor and spun the spindle by hand, and it feels smooth.

Not sure what to do next besides pulling the spindle bearings apart, then check the motor. Any ideas would be appreciated.


http://youtu.be/2CmxECXeEkc

[mrquacker]

That video sounds like chip re-cutting to me.

[Wog]

That video sounds like chip re-cutting to me.

Agree.
If that is a through-hole, might want to drill about a .5" hole first then mill the finish cut. That will allow a lot of the chips to fall through the hole.

[jkittleson]

It just started doing this and does it on all operations. Changed to new end mills to see if that was the issue, but still sounds like popcorn/marbles.

Here is a 3/8" 2-flute end mill, 24 IPM, .100 DOC, 50% step. Noise still sounds like it's coming from up top....

http://youtu.be/q7QSgMuYeIA

Any other ideas?

[tbaker2500]

Maybe because of the limits of video, it sounds just like chip-recutting to me. On the profile pass it's significantly less than the pocket.
I can only assume that you've done these cuts before, never with this sound?
If so, was there any change in your coolant pressure/angle/etc?

[GJeff]

The operations you're showing in your videos are also very prone to chip recutting. Does it happen when you do profiling?

[mike sr1]

It does sound like chip recutting only mine isnt as loud as that, try directing coolant on the back side of the cutter as it comes off the part to wash the chips out so that they dont carry around in the flutes and get recut.
Also increase the coolant stream to see if it makes a difference.

[twocik]

Try blasting your coolant, really sounds like chips being recut. Post a pic of your parts finish

[MichaelHenry]

Here is a 3/8" 2-flute end mill, 24 IPM, .100 DOC, 50% step. Noise still sounds like it's coming from up top....

Any other ideas?

You might also try more or less stepover - 50% is kind of a problem zone.

Mike

[TurboStep]

It would be interesting if you could try the profile pass again but using climb milling. The chips should fly off better behind the cut. They may also be less likely to get pushed back to the start of the cut by the coolant.
Step

[howecnc]

I haven't listened to the video but I added weather stripping to all my doors to keep them from vibrating.

[philbur]

Did you check your spindle bearing preload?

Phil

[nitewatchman]

After replacing my spindle bearing a couple of weeks ago, I went through a similar issue with surface finish and vibration. The original bearings had run at high speed with some heavy cuts for much of the 18 months that I have had the machine and I think that they delivered a reasonable life.

In hindsight, I think that the original bearings were a little light on preload and in a new machine assembly situation it is probably better to err on the light side than setting the preload too high. I have taken up preload on my bearing two times since installing and the cut, surface finish, and vibration are at least as good and perhaps better than the new machine.

When new, the machine ran with no detectable increase in spindle temperature. Now the spindle runs consistantly at about 95F. Last weekend the machine ran more or less constantly at 5140RPMs for about 30 hours and the temperature rose to 95F and stayed there. Tormach caution about going above 150F-160F (don't remember the exact number).

I believe that temperature is a good indicator of bearing preload in the absence of any other way to accurately set it. At least this seems to work for me, your mileage may vary.

Only time will tell if this is a good way to go. Running light preload on bearing can be as bad as excessive preload along with decreasing rigidity and increasing deflections.

Our big mills at my day job, which have 100HP and #60 tapers, run very high preload on the spindle bearings that is set hydraulically by extending the spindle. These spindles, although low speed are water cooled with a refrigeration unit to control bearing heat when thay are running.

At $175 a set the bearing aren't a cheap item but they also won't break the bank if they do fail.

nitewatchman


nitewatchman

[philbur]

It seems that the OP has left the building. Another incomplete story! Don't you just hate it when the last page in the book is missing, did the butler do it, or was it the gardener, we may never know? These kind of threads are only of general use to other members if they run to a conclusion.

Phil

[jkittleson]

Hey guys, sorry for the not replying sooner.

I ended up setting the spindle bearing preload a little tighter and it seemed to help, but the noise was still there. I called Tormach and let them watch the videos posted. They promptly sent another spindle. I haven't had a chance to cut any aluminum this week, just wood prototyping a new part. I can tell you that the spindle is running warmer than it did before. I appreciate they replies and suggestions posted. This forum has been a great wealth of information for a beginning machinist. And Tormach support has been awesome so far.

I'll post another video this weekend showing the result. I suspect that the issue is resolved with the new bearings and tighter preload.

JK

[tbaker2500]

It WAS the butler!