View Full Version : Problem Spindle Vibration from 2.2kw Spindle whats the deal

09-02-2017, 07:09 PM
Ive been trying to figure out the cause of vibration on my Omni CNC router with 2.2kw Water Cooled Spindle. I have included video showing the spindle running without a bit as well as with bits. It seems that I am getting vibration at various locations and rpm. Is this just a frequency thing where I shouldn't run certain bits at certain rpm because of the vibration coming from the spindle or could there be another culprit? The vibration seems to happen at mid range rpm around 16000 - 18000 but runs clean above and below these rpm. I also changed the hight of where the spindle is mounted and it has seemed to help, is there a particular height that I should be mounting the spindle at other than high /low enough to cut through required material? What could be causing this?

09-02-2017, 10:33 PM
1st run it without the collet & nut, if it still vibrates the spindle is probably bent and you'll need a new spindle!
2nd put a long steel dowel pin in a collet, if the pin wobbles the collet and nut could be bad!
I have seen collet nuts without the little holes drilled in them to balance them, they are the cheaper ones!
Cheaper collets are made so poorly, that the center bore is NOT concentric with it's outer diameters!

09-02-2017, 11:07 PM
I did just that, the video shows the spindle running with no bit collet or nut, then with a 1/4 inch shank and 1/2 inch shank. problem occurs with 1/2 inch shank at different rpm. The collet and nut are brand new from Amana.

09-02-2017, 11:14 PM
Is it an actual vibration, or just a noise?

09-02-2017, 11:30 PM
The buzzing can be heard at around 55 seconds into the video when moving the x axis, it seems to be generated by the spindle. If I leave the spindle stationary it happens between 16-18000 rpm.

09-03-2017, 09:11 PM
Begin by describing the shielding and cables you have in your machine, do you have "Ferrite Cores" clamped on the ends of your spindle control cable as well as all the drive motors?
All the shielded cables must be grounded on ONE end only, then the shielding acts as an antenna and sends all noise to ground!
Also, never run an AC cable next to the motion cables or spindle cables, as AC emits too much noise!

09-04-2017, 04:35 PM
I don't know this information I did not build the CNC myself it is an omni-1212, Im beginning to wonder if the spindle itself is bad or on its way out. I can only seem to use a bit up to a half inch in diameter with no problem. I tried using a 1 3/4 inch surfacing bit and can't seem to run it at any rpm without it making the whole machine buzz. With the smaller bits it seems to have little to no vibration dependent on bit and rpm. How can I tell if the spindle Is bad? Would tramming it maybe make a difference? I used to run these larger bits without the buzzing from what I remember, Its difficult to believe that I wouldn't have noticed the buzzing before now.

09-04-2017, 05:34 PM
So this is a recent occurrence, and it was fine before?

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Did you snap the collet into the nut, before putting the nut on the spindle?

09-04-2017, 06:20 PM
https://youtu.be/I8YRH5f9-cQ Yes I snapped the collet in, Yes seems to be recent I can't remember it buzzing this bad over the past 4 years. But I have an update, So I unmounted the spindle with a larger bit in it to see if I had the same amount of vibration while unmounted. Found that the larger bit runs nice and quiet while unmounted, I am assuming that I might be over tightening the mount causing the spindle to vibrate more than it should? Here is the video of the spindle unmounted with a larger bit in it, you can hear it running nice and clean I even pick the spindle up and it gets even quieter. I think I'm getting close. Thanks for all the help by the way.

09-04-2017, 08:59 PM
Just because you bought a nice looking & sharp bit doesn't mean it was properly made and balanced! Try one of the older bits that you know ran quietly!

I have bought several 1 1/2" diam 90-deg bits on Amazon, and had to return them because they were so poorly made! The points were NOT concentric to the shank, and the carbide was different thicknesses!

If you put a bad bit in the spindle, run it at high speed for a while, it WILL damage the spindle bearings!
Also, as you increase the bit diameter, you should decrease RPM and feed rates proportionately!