Thread: Bench grinder advice

Originally Posted by sacc51

I have a gray coloured wheel I bought 20 odd years ago for sharpening some bits I had, it's an extremely course grit, would that be silicon carbide?

Very Unlikely.

I think grey would be aluminium oxide.

Phil

No it's not ally, touch it with HSS and it disintegrates, Wish I could remember what tool bits I was using at the time, all I remember is an ally wheel just wouldn't touch it. I'll get a picture...

This is it!

Aluminium Oxide (Grey Marked A) wheels are used for grinding mild steel, low carbon steels, it's a lot softer than anything else. Silicon Carbide (White Marked C) is what is required for tool steel. Green Silicon Carbide (Green Marked GC) is used for the Carbide tipped tools.
A good book to get, is Tool and Cutter Sharpening by Harold Hall. Workshop Practice Series number 38. It shows how to adapt a standard bench grinder, to be able to sharpen lathe tools, drills and milling cutters, by making reasonably simple tools to go on the grinder. Priced from Minitech in Qld $18. 00 plus Grab Snatch and Take, and postage. No connection with the business, just a happy customer. Well worth the money though
Kryn

Originally Posted by sacc51

This is it!

It looks like a grey Aluminium oxide wheel to me.

It could be a coarse, weakly bonded Al Oxide used to sharpen tool steel. They deliberately fray or disintegrate to keep the grinding a bit cooler than usual.

Just placed an order for this http://www.machineryhouse.com.au/G155

Seemed to have more features and more power then the abbot and ashby. Now to get some green wheels for it. Can green wheels be used on hss?

No it's not ally oxide, I specifically bought this wheel to sharpen some bits I bought for a project. HSS wouldn't cut the material and ally oxide wheels wouldn't touch the bits so I sent off for this wheel. I only remember these details because I was living in Katherine at the time, if memory serves, I bought the wheel from Herless before they disapeared, the same mob I bought my lathe from around the same time. No internet in those days, I used to get catalogues from Herless and Hafco, lathes and accessories weren't cheap back then and that wheel cost a bomb.

Originally Posted by sacc51

No it's not ally oxide, I specifically bought this wheel to sharpen some bits I bought for a project..

It looks to be a grinding wheel for carbide tools.

Norton make this style of stone with an open/coarse composition.

I have the exact same stone configuration, plus a regular fine green stone on my carbide tool sharpener.

I think Norton class it as an "A" type = not sure.

It's very aggressive, but still capable of a fine finish.

Goes through carbide like nothing else.

Cheers Rob

Originally Posted by brendanh

Just placed an order for this http://www.machineryhouse.com.au/G155
Seemed to have more features and more power then the abbot and ashby. Now to get some green wheels for it. Can green wheels be used on hss?

Power ratings on stand alone electric motors seem to be actual true output powers at the stated currents and voltages. Well at they have least for the 20 or so motors I have tested.
However, some bench top grinder power ratings seem to be based on input powers (Applied V x current draw).
Of the 6 grinders with integrated motors I have tested only the Abbot and Ashby and the GMF grinders 3 Phase had power ratings based on outputs.

Anyway it looks like a good grinder.
If you want a really good wheel I'd be looking at a CBN.

Alas, I'm too late to chime in with the suggestion of going and perusing old abandoned salt mines, as that's where I rescued my mighty little 150mm grinder from, solid, unsightly exterior with untouched insides, perfect balance, even had a wire wheel (rusted beyond use) and a coarse grey wheel.
Pretty lucky really, considering that everything else about that mine looked fairly well trashed from years of local louts visiting and vandalising

Also too late!! but fully agree with Bob L as regard the older grinders having a bit of life left in them.
I procrastinated for a while but on good advice from Anorak Bob decided to go back and purchase a nice 8" 3 phase pedestal grinder which I doubt I will ever regret.

Originally Posted by TomW

Also too late!! but fully agree with Bob L as regard the older grinders having a bit of life left in them.
I procrastinated for a while but on good advice from Anorak Bob decided to go back and purchase a nice 8" 3 phase pedestal grinder which I doubt I will ever regret.

By no means essential but that looks like a prime candidate for a VFD!