Renewing the Grinder Bit

When to replace the grinding head?

An obvious time is when the grinding becomes much slower than previously.  Adjusting the bit up or down to expose a new diamond grinding surface is the obvious first step.  When there is no more adjustment available it is time to replace the whole bit.

Another time to replace the bit is when a bare spot appears.  

One style of wear on these bits is not just the general, even wear all the way around the bit, but where all the diamonds are lost, and the metal is exposed.   

This bare spot can be observed upon inspection.  But most of us do not regularly inspect the bit before turning the grinder on.  There is another way to tell something is amiss.  What you may notice is an unexpected vibration during grinding.  When you experience this vibration, it is time to inspect the bit.  You will most likely find a patch of bare metal.

You do not have to throw the bit out.  If there is space above or below the bare spot that will provide a grinding surface for the thickness of glass you are grinding, you can do something to extend the life of the bit.

Simply raise or lower the bit until the bare spot is below the surface of the grinder grid, or in the case of this illustration, raise it sufficiently high to be above the thickness of the glass you are grinding.

Why do the bare spots appear?

It may be due to manufacture. The bonding of the diamonds may not have been completely even.  But it can also be due to grinding while there is little water – when a paste appears.  This leads to heating of the grinding bit as much or more than the glass.  A hot grinding head, especially those which are resin bonded, can lead to loss of diamonds either in one spot or generally around the bit.