Burr Alignment - Static and Moving Burrs

I have a question about burr alignment (in my case EK43, but would apply to most grinders I’m sure).

First burr to align is the static burr. After employing the marker pen/shimming technique, we get to a point where the marker pen is wiped clean across the whole face of the static burr.

Now, we move onto the moving burr. How is it possible for the moving burr not to be parallel with the static burr if it has wiped off marker pen from the whole of the static burr? If it was at a slight angle (i.e. not aligned), then it would only meet the static burr at a certain point and the marker pen would not have been fully wiped off.

The curious thing is that the moving burr does indeed appear to be not yet aligned, i.e. when employing the same marker pen technique it appears to require shimming.

I just cannot work out why or how this is possible!

Hi there,

When shimming the burrs, we are not changing the orientation of the angle of rotation of the shaft, but the orientation of the face of the burrs attached to the shaft.

If you imagine the end of the rotating shaft not being flat but cut away at an angle may be helpful, so it is like we are taking a file and smoothing the end of the shaft back to 90 degrees to the angle of rotation when aligning.

I hope that makes sense!!

TLDR: you are aligning the face of the shaft not the rotation.

EDIT: another way to explain would be if you had two pencils :pencil2::pencil2:️ . You align the pencils back to back with the erasers facing each other. You rotate one of the pencils between your fingers and they stay in contact. Now, wear one eraser down at an angle. Now when you put both pencils back-to-back there is a gap and the eraser faces do not meet flush together. When you rotate the pencil between your fingers you simulate how the burrs act when they are out of alignment.


That makes perfect sense, and is quite obvious now that you’ve pointed it out. Thank you :slight_smile: