Mechanical vs Tool Problems, or Both?

Last night while milling on a piece of fir the x axis on my SO3 went inop. After sending in an email to tech assist I was able to get it operational again (eccentric nuts and tension strap adjustments). Or so I thought…the initializing checked good, but then when I went back to milling the bit is bogging down in the wood. I played around with the eccentric nuts and tension strap again thinking there was still some slop in it - still no luck.

Decided to swap out the .25 ball mill which I had been using with the 201 to see how it would perform - like butter.

There does not appear to be any damage to the ball mill and it has less than 3-4 hours of usage, but now I’m wondering if the cutting edge is dull (though I should be having those thoughts years from now)

I was having no problems stepping down .125 with the ball mill but I’m leaning towards my issues in the last 24 hours being two fold: mechanical and a bad bit.


Endmills are consumables — better to replace (or send out to have sharpened, or set aside for later sharpening) earlier rather than later — inspect the edge w/ a loupe?

Looks like lost steps — please check the machine mechanically.

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In the instruction manual it states the belt should be tight enough to snap against the x-rail when gently lifted.

I’ve searched this subject on the forum and one of the major contributors states if you can fit your pinky under the belt it’s too loose. Well I can probably fit two.

I’ll tighten this up tomorrow and see if this doesn’t correct the problem.

The instruction manual could probably benefit from a more helpful explanation…as even with my pinky+ I can Still snap the belt.

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Do tighten those belts, but my bet for your specific issue in that last pic would be on loose or incorrectly positioned setscrews on the X motor pulley (they must be tight, and one of the two must be positioned against the motor shaft’s flat). Even if they do seem tight, do the marker test to be really really sure the pulley is not slipping on the shaft:

With a marker, draw a line across the pulley and shaft,


run the job, and if the drifting issue is there, check whether the pulley and shaft are still aligned. If not…setscrew problem.
EDIT: pic is not the right one, do that on the X motor/pulley, but you get the point.


Gents, thank you for the tips. I’ve gone through and tightened the belts as well as tightening down the set screw on the pulley that “was not” properly aligned. No time to run it this evening, but I’m hopeful this will resolve my problems when I run the job tomorrow.

Grateful for your assistance.


Julien / William

Thank you again for the assist. Everything is running smoothly again. Definitely was the set screw on the X pulley.


Great, thanks for reporting back. It’s easy to miss.

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