500W 12000RPM spindle not enough?

Hi everyone,

I made a trial milling with 500W air cooled spindle (12000RPM). Did a roughing first with ok result. Then installed ball end bit (R=1mm, short one). feed rate was 1500mm/min on oak (also tried on pine). Z is lowered 100mm below the most upper state. Please check attachment for details of hardware.

The vibrations were awful, like I needed to hold the bottom of router with hand, otherwise during passage the bit could do a 1mm circle movement due to kind of resonance vibration. Vibration seemingly comes from the bit interaction with material. Bit itself is centered well and it’s spinning perfectly on no load.

On youtube I saw so smooth operation where bit is going easily along the material but here it’s absolutely not like not like that. I am even afraid to run one more time to take video for you to avoid possible damabe to bit or machine.

So, is it not enough wattage on spindle? Not enough RPM?

Thanks for possible suggestions.

1500 is too much. Use fswizard calculator

I typically use 900mm/minute (15 mm/second) for milling. Depending on the wood, it may get adjusted down. Also, don’t forget a finishing pass as deep as your bit or workpiece supports and relatively slowly, like 450mm/minute

By finishing pass you mean making 3D milling again? Like a third pass after roughing and 3D?

BTW, I changed feed rate to 860mm/min. Have a look at this. Pease pay attention to timeline 00:03, 00:16, 00:43, 00:57 - this is nowhere near to acceptable operation… Of course, all blame is on me but so far I don’t have a clue where I messed up.


file not found

My mpcnc is a 500w spindle, works just fine. Throw some pictures up of your build.


Agree with Barry, some pictures would help. The video you linked above gave me a file not found error.

  1. Well, Barry, I must say that your machine is moving damn fast. Looks like a lot faster than 1500mm/min. Is it 12000 RPM? What kind of bit?

I cannot imagine how would that be possible on my setup.

  1. Please check the video of resonance here (timeline 00:03, 00:16, 00:43, 00:57):


Machine dimensions 1300*750, During operation Z axis is lowered 110mm down.

  1. Here is a short video to show you my setup overall:


50mm/s, 1mm depth of cut with the 1/8" 2 flute ball endmill Ryan sells in the shop. I have no idea how fast it’s spinning, I manually turn it up or down so it doesn’t chatter much and let it go. You’ll always get some chatter cutting wood(with these spindles), just depends on the direction of the cut.

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Hi Barry, what about fine cutting with ball-end bit, also going smooth in your case?

Yep, no issues that weren’t self inflicted.

This is a 1/16" ball.

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Looks like you don’t have problems that I do… I gotta investigate what can be done. I’ll report if I find.

Hey. Just thought of something. Look at this image, is your spindle sticking way down, or is the collet up close to the Z assembly like mine? I had issues before moving it up. Too much sticking out with no support before.

In your video it looks like it only does it when it comes to a vertical wall cut. I cant tell for sure but is the bit plunged in past its cutting length? It looks good otherwise.

Actually yes, it was below the cutting allowance. You are totally right. However, resonance also happened in places where plunge depth was less than that.

I will make sure that plunge is not more than allowance. Also will:

  • lower machine
  • install triangle supports to avoid X-Y vibration of frame
  • install middle supports for long rails
Will report when done


So I did it. It took so long because I fell with machine in hands and broke half of fittings so needed to reprint )

Ok I did the following:

  • designed and installed additional legs in corners and they are tilted at 45 degrees so that they're forming triangle with main legs of machine. This way I avoid X-Y vibration of frame
  • installed vertical supports for long rails that ire advised in https://www.thingiverse.com/thing:1160962 (had to edit model though)
  • lowered machine and decreased Z axis traveling downwards to reach material.
I did not try it on ball-end fine milling yet. But even on roughing operation with flat 6mm bit I clearly see that now it is performing much better.


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Yep, I tried on ball-end bit and it’s a lot better this time.

I attach here pictures of upgrade.

PS. I also installed 1.5kW water cooled spindle and it cuts a lot better because it’s 24000RPM vs 12000RPM in 500W spindle. However, not sure yet if MPCNC will be able to drag this heavy head all over the work piece with affordable speed.

I have run into similar problems with a 500W DC spindle. I spent months trying to get it to work correctly (discussed here), but invariably would run into the same problems with chatter and violent shaking. After moving back to other spindle options (DW660 and Makita RT0701C) I am pretty certain that the MPCNC frame is not the weak link. I believe that it is either a problem with excessive runout (I really need to buy some dial indicators) or a thin shaft with junk bearings that allows the endmill to get pulled into the material while climbing. I don’t want to say that the 500W spindles are all bad, but I think that there are a portion (mine and it sounds like yours too) where the manufacturing quality is too poor to work under anything but the lightest of cutting loads.

Hi. I understand that DW660 and suchlike will work better just because they are higher in RPM with up to 30K. I would install such tool as well but since it’s a “collector type” I am afraid that it will run out it’s resource fast and I’ll need to buy new and so on.

500W are ok and I have ensured that by inserting long 100mm bit. When you touch material only with flutes (not deeper) - it works fine. Of course I suggest that if area of contact will be large at some moment then problems may occur due to inability of spindle to push through so much of material effortlessly.

It is. I have ensured that when I saw difference “before” and “after” installation of supports.

Same, since it’s 500W and 12000RPM only, it may not have enough power at a moment to push through the material and therefore can not get in time with scheduled movement of gantry.

You built a very very tall machine, most of us do not have room on the leg for supports. 3" of Z is a lot, looks like you have 6+"?

Hi, yes I had.

I reduced and now middle junction’s lower point is 5.9’’ above the bed. Z path can be up to 3’’ now.

However, machine is still tall right now because of long bit (3.93’’) and thick material (1.85’’).