Sharpening with grinder, new questions

[Ben from Vic.]

I'm considering using a bench grinder to do the majoity of the sharpening work for me (plane blades, chisels, etc). Followed by the Veritas green honing compound I already use for honing.

My questions are this....

Just how much of a hollow grind does an 8 inch wheel give?

The Abot and Ashby (8 inch) is the fav' so far (sold by H'n'F), do many of you have experiance with this model?
I know al least on BB member has one. ;)

A few of you appear to have the ~$39 jig, sold by almost everyone, for resting your tools on whilst sharpening, is this a good unit?

Is the step from the Bluemax wheel (56 grit) I intend to get from CWS (http://au.store.yahoo.com/cws-store/grindingwheels.html) to the green crayon to big?

Is the Blue max wheel that much better than the white wheel?


Er, thats about it for now. :o ;)

Thanks all. :)


Ben.

[Termite]

Is the step from the Bluemax wheel (56 grit) I intend to get from CWS (http://au.store.yahoo.com/cws-store/grindingwheels.html) to the green crayon to big?
Not if you consider the distance from Sydney to Melbourne just a short walk :D

[Ben from Vic.]

;) :D

Hey Termite, how'd you manage to get such a big avitar?? :eek:

[craigb]

Oh no. Another sharpening thread. :eek:

Run away! Run away! :D

[Termite]

;) :D

Hey Termite, how'd you manage to get such a big avitar?? :eek:
Plenty of use. ;)

[Ben from Vic.]

I know, I know, I tried not to, really. ;) :D

I did search first, and it was helpfull in building an overall picture, thats why my questions are fairly specific.


Termite, I knew that question was going to get me in trouble, I just couldn't think of a better way to word it. :rolleyes:


Ben.

[derekcohen]

Ben

A few rules for grinding blades:

(1) The smaller the diameter of the wheel the better! Don't go thinking "bigger is better" (OK, down guys!). What you want is a deep, but small hollow grind. A big wheel will not do this. So get a 6" wheel instead.

(2) The good news is that these 6" machines are cheaper. I hear good things about A & A, but a grinder is such a basic machine that you really can get a cheapie - the provisor is that the wheel turns smoothly and concentrically.

(3) The important parts of the set up are (a) the wheel type, (b) grit level, and (c) the blade support system.

(a) and (b) The rule for the wheel is that you want the coarsest possible grit, say 60. Why? Because these machines turn far too fast and a smooth wheel will generate too much heat and burn the blade. You could probably keep the grey wheel if it is a very coarse example. I have a white one. Others swear by the pink.

(c) a decent support is made by Veritas. A cheaper - very acceptable - version of this is sold by Carba-tec under their house brand.

(4) Keep in mind that the point of hollow grinding is to reduce the amount of metal to sharpen. It is NOT a sharpening method on its own. You do not want to grind to the blade's edge. This will not only just weaken the edge, but it will very likely burn it too. My plan is to flat grind/sharpen the blade to the bevel angle I want, then hollow grind inside the bevel, leaving about a 2-3mm edge.

(5) Don't hollow grind laminated blades (such as Japanese blades).

Regards from Perth

Derek

[goodwoody]

6" is better than 8" for grinding purposes? A smaller wheel produces a deeper hollow therefore removing more material in turn producing a weaker edge, no?

P.S. I prefer to have 8".

[derekcohen]

Krenov recommends a 5" or 6" diameter wheel. He argues that "the larger wheels produce very little hollow grinding" (from The Fine Art of Cabinetmaking).

Regards from Perth

Derek