Aluminium Oxide Mount Point Grinding Tools

[William Harvey 1Participant @williamharvey1]

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

[William Harvey 1Participant @williamharvey1]

[Michael GilliganParticipant @michaelgilligan61133]

[ Pedant Alert ]

May I just mention that the material is Silicon Carbide, not Silicone Carbide

MichaelG.

[Tony Pratt 1Participant @tonypratt1]

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?

Give it a go.

Associated Question

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

Yes.

If not which dressing tools do I need?

Tony

[noel shelleyParticipant @noelshelley55608]

Be VERY wary of using hand held die grinders ! If being used in a confined space the point may bounce round and shatter – peripheral speed may be in the region of 150mph ! You will need a large air compressor ! IF there is ANY measurable play in the die grinder bearings or the collet is not a good true fit on the point shaft I would think twice about using it. As for trueing a hand held tool with a hand held dresser, be VERY careful. Unless you have a large amount of metal to remove had you thought of using flap wheels ? Noel.

[Tony Pratt 1Participant @tonypratt1]

I would also suggest carbide burrs for good metal removal.

Tony

[Nick WheelerParticipant @nickwheeler]

I hope you have a powerful compressor with a big tank if you expect to port a head with an air die grinder.

And earplugs. And some nice thermal gloves.

[not done it yetParticipant @notdoneityet]

I might ask – do ‘machinemart’ and ‘professional’ really go together?

[Michael GilliganParticipant @michaelgilligan61133]

‘professional’ is one of the most abused and ambiguated words in the English language

… best summarised [in my opinion] as ‘does it for money’

MichaelG.

[noel shelleyParticipant @noelshelley55608]

Cheap tools and PRO – Yeh, hence my comment about bearings and collets ! Noel

[William Harvey 1Participant @williamharvey1]

Posted by Michael Gilligan on 26/09/2021 09:57:10:

[ Pedant Alert ]

May I just mention that the material is Silicon Carbide, not Silicone Carbide

MichaelG.

You may

[William Harvey 1Participant @williamharvey1]

Posted by Nicholas Wheeler 1 on 26/09/2021 12:27:39:

I hope you have a powerful compressor with a big tank if you expect to port a head with an air die grinder.

And earplugs. And some nice thermal gloves.

I have a Burisch (Air Wolf Copy) 14CFM, but only 90Litre. I ought to get another storage tank – someday.

Anyway I managed to do one test chamber no problems, sure the Compressor cycled a lot but hey it worked.

[William Harvey 1Participant @williamharvey1]

Posted by not done it yet on 26/09/2021 13:38:39:

I might ask – do ‘machinemart’ and ‘professional’ really go together?

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

[John ReeseParticipant @johnreese12848]

Be careful with long or heavy stones. If run above their critical speed the shank is likely to bend about 90 deg. just beyond the collet. I had it happen on a Dumore (37K rpm) and a Makita (24K rpm). Both had a toggle switch on the back end instead of a trigger. It took both hands to control the tool so I couldn't hit the switch. I had to walk away from the wall socket until the cord pulled out.

[John ReeseParticipant @johnreese12848]

If you are having difficulty finding silicon carbide mounted points try MSC Industrial. I believe they sell in the UK.

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