Hi everyone,

Looking for some clarity on the correct / optimum cutting speeds for Aluminium Oxide Mount Point Stones, like these ones for Cast Iron Cylinder heads.

The reason I ask is that I have been reading David Vizard's Cylinder Head Modification book, which is clearly quite old now (1973). In the first chapter it discusses tooling.

On pg 12 he mentions two types of commonly used stones "Aluminium Oxide" (The ones I have) and "Silicone Carbide".

He also suggests that Aluminium Oxide stones are usually blue, blue/grey or white, whereas the Silicone Carbide are usually green.

He goes on to say that, for cast iron, Silicone Carbide are the ones for the job, on the basis that if you use Aluminium Oxide at the correct speed on cast iron it will glaze up, reducing its cutting capacity by 95% and that continued use can damage the cylinder head!!

He then states that there is an exception to this by using small wheels under thier correct grinding speeds. He then says that to answer the dillema use a blue grit (Aluminium Oxide) wheel below it's grinding speed, to prevent glazing up.

In summary he suggests for grinding speeds between 10-15000 RPM a blue grit wheel (Alumium Oxide) can be used as long as the diameter is less than 5/8" / 16mm. He also suggests that where RPM is appreciably below 10,000RPM then best results can be had with a blue grit (Aluminium Oxide) for all sizes up to 1" / 25.4mm.

I have a Clarke X-Pro Professional Air Die Grinder which apparently has 4 speed settings 8300 – 25000RPM.

Obviously this will depend upon air delivery.

Question

So if I use Aluminium Oxide mount points up to 1" diameter and set the grinder to the lowest setting on the tool I should be good?

Associated Question

I have a diamond dresser which I bought for a bench grinder. Can I use this on circular mount point wheels?

If not which dressing tools do I need?

Many thanks

You may

That's the name of the tool, I never said anything about Machine Mart being professional