Friable grinding wheels
I’m new to bench grinding. My first power grinder is on its way (Rikon 80-808) but I’m unclear about the included wheels. They are white aluminum oxide in two different grits. I’ll be using this grinder to put a hollow ground bevel on chisels and plane irons. My understanding from Asa’s Bench Grinder Basics video is that a “friable” wheel is preferable. Neither Rikon’s online specs nor the downloadable user manual for this grinder specify whether the wheels are friable or not.
Anyone know if all aluminum oxide wheels are friable by nature, or do I need to find an aftermarket wheel that is friable to replace the stock ones on the Rikon?
I believe that the binder that holds the abrasive has all to do with how fast the wheel wears out. I have used white fiable wheels and they cut fast with minimum overheating, however they wear fast and do not keep a flat face very long. I then switched to Northon blue wheels advocated by wood turners and they will not wear as fast, cut well but will pack with steel requiring frequent dressing with a diamond tool, it is my go to wheel for general use. To get the final edge and maintain it, I use a CBN wheel grit 360, no wear, no dressing, no heat generation, razor sharp edges off the grinder.
The white Norton wheels work great. They are definitely friable. Stop overthinking it and get to work.
I'm looking for a grinder too. I felt thinking about what to buy and why was quite a good way to proceed. But now I'm wondering if I am "overthinking it" and what the penalties are for this. Does one's brain heat up and cause a blott? Will I have used up my quota of thinking before reaching GO and collecting my next 200 thinking points?
I'll risk it, the overthinking. After all, underthinking has seen many moments of "doh!" not to mention unnecessary financial leaks and depletions.
Anyroadup, I decided to avoid any of the very friable options for sharpening materials after having the Tormek experience for some years. Sharpening many shapes on that friable wheel could see me spending as much time getting the wheel surface flat & square again as sharpening things on it. Gouges and such played havoc with the flat!
But I feel this way about other friables, such as waterstones. In the various videos, the eager users seem to spend every other stroke flattening their waterstone (again) with an expensive diamond plate.
And all that watery mess.
CBN wheels looked interesting. But they're very expensive; and one poster here suggested that it only took one application of a too-soft metal to clog it forever.
So, I eventually decided on a Sorby Pro-edge belt sharpening machine. Reviews say there's far less heating of the blade than with a wheel grinder (especially the standard wheel grinders that rotate rather fast). The sharpening belts are very inexpensive yet seem to last well, especially the ceramic ones. The machine itself seems a properly made item rather than a crude thing tossed out of some Far East factory inclusive of burrs, wonky arbors and a seriously bad paint job.
And it comes with all the bits you need to sharpen things. No further £270 for proper CBN wheels and a tool rest or two that actually work as such, necessary if buying a-one of those wheel grinders, that seem not to have evolved for decades.
Just my threepence worth. :-)
Inclined to agree with Lataxe.
I use CBN for turning tools and a white wheel for everything else. Unless you do a ridiculous amount of woodwork then a single wheel will last ages.
Personally I prefer a crowned wheel for chisels and plane irons as it is somewhat easier to control the point of cut and reduces overheating.
This is not so good for drill bits (which I will probably move to doing on the CBN) as drill bits really need a flat surface.
White wheels are cheap - about 1/5 the price of CBN.
You can still get fair results with the crap wheels most grinders ship with, but it is a lot easier and more fun with better kit.
Sounds like you have a good grinder there. You will not regret the purchase. Chill and enjoy it.
I have never understood the amount of fear and hand wringing so many people have with grinders. Its just not that hard. I am a shop teacher and have taught innumerable students as young as 13, to grind chisels and plane irons. With anything from a high speed Baldor with old grey wheels to my standard medium speed 6" grinder with the original white wheel from the early 90s.
I grind and sharpen more tools in a month than most people will in years of work. The wheels last a long long time in a wood shop.
Any cheap grinder with a decent balanced wheel will work.
Please allow me to explain ....
Not everyone has the years of experience with grinding machines that you do. Naturally, we inexperienced fellows want to understand the things before plunging in with a fist full of dollars (or pounds). I suppose we should all be born with innate grinder knowledge; but we're not. :-)
The fact that you need to teach "innumerable students" must surely tell you something about varying states, amounts, degrees, quantities, depths and other parameters measuring knowledge about various things in various people's minds. Some of us are ignorant about, oh, all sorts. Well, I am. A good thing too or you'd be out of a job!
See this magazine and website here? That's for putting knowledge in so people can get it out. The forum is quite good for finding things out too. I pays my $99 and feel I got a bargain. Yes.
Now, what can you tell me and the rest of us about various grinding gubbins and the techniques for using them aright?
PS I can't afford "a class" as I am a just poor pensioner.
Its not hard. Any, any, any grinder will work to get started. Cheap ones are fine. Find what you can, where you are and just go practice. You're sharpening chisels/ planes not machining engine parts. Too much talking and questioning not enough practicing.
There are better machines and wheels than others. Do you need one. Maybe, maybe not. Grinders are generally pretty cheap. Get one. Grind, hone and get back to work.
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