Norton 3X Grinding Wheels

gidon · 6 Jun 2008

Andy
If you're using the Tormek mainly for grinding make sure you run the diamond truing tool over it. If you move it quickly over the stone (30s) it leaves a very rough surface which grinds quickly. You also need to exert a lot of force on the wheel - not the light tough of a dry grinder.
For regrinding bevels and removing nicks I can do this quicker on the Tormek than on the Norton 3x wheel. Not sure why you are finding it so messy? At least all the metal filings are contained in the water (and attach themselves a rare earth magnet if you use that trick).
Cheers
Gidon

ivan · 6 Jun 2008

I can see why Tormek et al. supply a ~250 grit wheel, it's a feature of the turning/carving heritage, where chisels and plane blades come a poor second. Curvy cutting edges have limited wheel contact, so the fine wheel is needed to keep cutting at a rate slow enough to allow careful shaping.

Wide plane blades especially have a wheel contact measured in sq cm, so need very heavy pressure. If used, this can move the (not really stong enough, 12mm) rest, upsetting the carefully trued rest/wheel relationship, and giving you an unwanted slightly skewed grind. The once popular Viceroy (10 &12" horizontal + cutting oil pump) had a 60 grit wheel, if I remember right - so perhaps this is what we need?

Even light pressure of the diamond truing device can move the toolrest, so the wheel surface ends up almost but not quite // to the rest. This means even blades of 2" need moving side to side on the 2" wheel, so half the blade leaves the stone, along with streams of water that pool on the top, or miss the trough. 2 3/8 and wider blades even worse. The water problem is surmountable with some 3mm PVC sheet cut to redirect the run off, but should not be necessary if the machine was properly designed for wide blades.

Wet grinding may be worth persevering with, as (so we are told, anyway) high speed grinding can cause micro fractures* close to the cutting edge resulting in faster edge breakdown. Even HSS planer blades are professionally wet ground, albeit at fairly high speed. Microfracturing may be controlled by never regrinding too close to the cutting edge - but how close is too close?

Maybe time to re read Kirby's sharpening book and buy a 1425rpm grinder? But what about the American non non standard imperial bores?

* v small v short cracks caused by differential heating at cutting point, visible only under microscope

gidon · 6 Jun 2008

Ivan
The new diamond truing tool with the T7 (the TT-50) is set using the microadjuster and fed using two wheels and a threaded rod. No manual pressure on the tool rest required. The wheel comes out exactly parallel to the wheel. Unfortunately don't think it'll work with your Scheppach

.
You could always try a coarse wheel from Peter Childfor faster grinding. But try a fast true with the diamond truing tool first - it really does create a far more aggresive cut - at least on the Tormek wheel.
Cheers
Gidon

ivan · 7 Jun 2008

Thanks for the link, Gidon, interesting stuff! Peter Childs says the Tormek has

" very soft wheels, designed for plane irons and other wide blades, which rapidly go out of shape when sharpening HSS gouges etc. You need a harder tougher, faster cutting wheel for woodturning tools.."

The Sheppach 10" wheel is hardly soft, though! I have bookmarked the page against current wheel wearing out, although I'd need new flange washers to grip a 1 1/4" bore + bush wheel.

I have a Tormek diamond tool which fits the Sheppach, (alas not the latest one with a leadscrew) If the Tormek wheel really is that much softer, maybe less pressure is needed all round?

woden · 7 Jun 2008

gidon":1jwmv145 said:
Looks to me as though 3X is just marketing speak for wheels that use this "SG grain"? But I could be wrong!

Yes, you'd think that. However, that website was offering two distinct 'blue' Norton stones - the 3X and the SG. This and the price difference would suggest that the manufacturer must be claiming - even if it's only marketing lies - that there's a difference in them.
What that difference is I don't know but maybe as they've put SG in the name of the latter suggests that its seeded gel is even better than that used in the 3X. :roll: Or maybe you pay the considerable extra for the SG wheel because its colour is so much bluer! :shock:

Aled Dafis · 10 Jul 2008

Sorry to drag this thread up again, but I've just fitted one of these wheels to my cheapo machine mart grinder, and the difference is mindblowing! :shock: !

As Philly said at the start of this thread, this is how grinding should be - Quick (in fact VERY quick) with very little heat build up - probably no more than around 10 degrees, so no danger of ruining the temper of your prized irons.

Is there a list of (very) satisfied customers? I wouldn't mind seeing my name in with the likes of Philly, Konrad Sauer and Bill Carter.

Regards

Aled