Hi Jon, the best advice I can give you is to consult the manufacturers guidance. However the the lifespan of grinding wheels is mostly down to the bonding of the grinding particles, vitrified bonded wheels usually last much longer then resin bonded wheels. If you have doubts at all about the safety of your wheels, it is best to replace them, especially given the age of them. As clogs has said, you should not stand in front of any grinding wheel during start up, as this is the time when the wheels are at their most stressful stage. Below is info on wheel classification.

Regards Nick.

Hi Jon, they look like vitrified wheels to me, but one way to find out is to take them off and see if there is a classification code on the blotting paper. The top picture looks as if the blotting paper is actually degrading, it is important that these should be sound. Mounting the Wheels info below.

Regards Nick.

Edited By Nicholas Farr on 01/09/2020 11:06:59

Hi Jon, the papers each side don't have to be bonded, but are normally stuck with relatively low strength adhesive as it makes it easier to mount the wheel as they don't have a small hole in the middle that will fit the shaft, but they do need to be a little compressive, like blotting paper is, as they act as a soft buffer between the wheel and the steel flanges and take up any small irregularities on the surface of the wheel side and of course gives the grip needed between the flanges and the wheel. Do not mount a wheel without one on each side. The scan below may be helpful to you.

Regards Nick.

P.S. I believe many people cut their blotters from cereal packets.

Edited By Nicholas Farr on 01/09/2020 12:15:16