Large burrs and alignment. - Page 3
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- Posts: 2973
- Joined: 10 years ago
If you have a manual conical grinder such as the Lido or Pharos then radial alignment is easy to check. Axial alignment is not really adjustable in any meaningful amount. Motor drive is going to be design unique and may or may not be easy to do or stable after adjustment.
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- Posts: 220
- Joined: 14 years ago
Hello again,
There is a simple power off test that you can do. Clean out the grinder first. Manually spin the grinder and tighten down the adjustor until you feel the rotating burr rubbing the upper stationary. Note the orientation of the lower. Turn the lower burr 180 degrees. Now tighten the adjustor till you get the rubbing again. Note what portion of a revolution you moved the adjustor. The so many degrees x/360 will give you a number to multiply times the adjustors thread pitch. The one that is stuck in my head is the LaMarzocco Swift. It has a 1mm pitch so that's .0394" per revolution. If you turned the adjustor 90 degrees you would have a total of about .010" error between the rotating and the adjustor. If you only get about 10 degrees (which is more reasonable) you would have 10/360 * .0394 =0.0011" total error in your grind system. Now my thumb nail is about .015" so 1/15th of a thumbnail ain't too bad. Don't forget to add in the bouncing up and down of the armature. You didn't think that the axially loaded deep groove ball bearings were going to keep the rotating burr from jumping up and down did you? I'll say this once. "All coffee grinders have the wrong kind of bearings installed for the application. Inherent design flaw." Spend some time talking to the SKF engineers...
jpboyt
There is a simple power off test that you can do. Clean out the grinder first. Manually spin the grinder and tighten down the adjustor until you feel the rotating burr rubbing the upper stationary. Note the orientation of the lower. Turn the lower burr 180 degrees. Now tighten the adjustor till you get the rubbing again. Note what portion of a revolution you moved the adjustor. The so many degrees x/360 will give you a number to multiply times the adjustors thread pitch. The one that is stuck in my head is the LaMarzocco Swift. It has a 1mm pitch so that's .0394" per revolution. If you turned the adjustor 90 degrees you would have a total of about .010" error between the rotating and the adjustor. If you only get about 10 degrees (which is more reasonable) you would have 10/360 * .0394 =0.0011" total error in your grind system. Now my thumb nail is about .015" so 1/15th of a thumbnail ain't too bad. Don't forget to add in the bouncing up and down of the armature. You didn't think that the axially loaded deep groove ball bearings were going to keep the rotating burr from jumping up and down did you? I'll say this once. "All coffee grinders have the wrong kind of bearings installed for the application. Inherent design flaw." Spend some time talking to the SKF engineers...
jpboyt