This article is from the newsletter 8th September 2026
ANOTHER BEARING CAUSING PROBLEMS.
This time last year we had just replaced the toe bearing on the main shaft (see article on the website for more details), this year in August the bearing at the bottom of the stone shaft of the French Burr stones we use for white flour production, suddenly started making that high whining sound and started running hot.
Each set of stones has its own drive shaft and so there is a bearing at the bottom of each shaft where it sits on the bridge tree. We have two different types of bearing on the stone shafts in the mill. The one causing the problem is the same design as the main shaft toe bearing. The end of the shaft sits in a bearing cup which is itself held in a casing which is mounted on the bridge tree. The two oat processing stones have the same design as the bearing causing problems.
A plan was formulated. We need to keep the millstones working whilst a new bearing was made. We decided that we if we removed the bearing from the oat milling stones we could use that whilst a new bearing was made. This sounds a simple process, first it was necessary to remove the stone furniture from the stones. Then we had to raise the runner stone off the spindle
These stones were not refurbished when the mill was renovated and it soon became obvious that the rynd was firmly fixed to the mace on the top of the spindle. However, this meant that as we raised the stone the spindle went with it, lifting it out of the bearing cup so it could be removed.
THE SPINDLE AND BEARING CUP ON THE OAT STONES.
One of the unfortunate outcomes of this was the discovery that the runner stone on the oat stones has a crack in it. This was across half the stone and the full thickness. This means we will never be able to use these stones. However, this was a very aspirational wish and was a plan for the distant future.
THE OAT STONE SHOWING CRACK (Starts just above the yellow marker.)
Back to the bearing. The cup from the oat stone was not in the best of condition. So we put the stone back (a piece of hard wood was placed under the spindle and the casing was placed back on.
Attention was turned to the problem bearing. We have raised these stones numerous times, so the rind came of the mace immediately. This caused a problem in that the spindle didn’t come out of the bearing cup. To lift the spindle a volunteer fabricated a frame that fitted under the lip on the bottom of the spindle and we then used two jacks to raise the spindle to allow the cup to be removed.
THE FRENCH BURR STONE SPINDLE JACKED UP TO ALLOW BEARING CUP TO BE REMOVED.
Examination of the spindle and the bearing cup showed some rough areas and abnormal wear. The cup was in better condition than the one removed from the oat stones. We decided to smooth the roughness and abnormal wear off both the spindle and cup and then to replace the cup.
Initially the bearing still ran warm after a few hours milling, but this has now settled down. We still have the block and cup from the oat stones out and so if necessary in the future we could have a new bearing cup made to replace the worn one.
If you would like to keep up to date with happenings at the mill sign up to the newsletter on this website.
