A few months ago when I was young and ignorant I ground some aluminum on my 6" bench grinder. The grinding wheel is a course gray aluminum oxide one that came stock on the unit (Ryobi). It's clogged up pretty well.
Is there a way, perhaps using the various wheel dressers available, to clean the wheel or is it time to chuck the wheel a buy a new one? Would perhaps an old star wheel dresser knock out the aluminum?
--zeb
Let me know what you find out, mine is clogged with aluminum, copper and silver.
i
You can surely clean a loaded grinding wheel with a star dresser, although Harold hates 'em. You could also try a dressing stone. Use whatever you have, but don't expect the glazing to come off just by grinding.
GWE
If you're only using the wheel on a bench grinder, and you're reasonably careful, you can properly re-dress that stone with a starwheel tool.
LLoyd
Grant, thank you, I will definitely try.
i
I've only used star wheel dressers on my bench grinder. Very fast and leaves nice coarse finish for rapid cool grinding. I'm sure removing that imbedded metal will be no problem.
What problem does Harold have with them?
Karl
most grinding wheels are sintered tho some are resin bonded. the former can be cleaned of metal with either as you say, a star dessing wheel, but in the absence of one of those to hand, I use another old grinding wheel preferably the white ali oxide type. this will cut down the surface of the clogged wheel and expose a new clean surface. It will work much better if you can do it wet ie have a little tricke of water to aid the clogged wheel breakdown. Grinding the softer metals works better if you use water as an anti clogging agent on the rotating stone. BUT this is mainly done on grinding machines designed for wet use. Id have doubts about doing this on a small bench grinder. Finally, there are differnt grades of bond hardness in grinding wheels. the softer onesare designed to break up quicker. these clog much less. Hope this helps.
=========== Something to remember when using a star dresser is to be sure you have a solid support. If you attempt to do this freehand you will tend to jab into the wheel and generate a "square" rock where you want a round one.
A star dresser is good for removing a large amonunt of material, for example when you have a lot of loading (or a squarte rock). Invest in a diamond dresser [c. 5-10$] to touch up the wheel.
Unka' George [George McDuffee] ............................... On Theory: Delight at having understood a very abstract and obscure system leads most people to believe in the truth of what it demonstrates.
G. C. Lichtenberg (1742-99), German physicist, philosopher. Aphorisms "Notebook J," aph. 77 (written 1765-99; tr. by R. J. Hollingdale, 1990).
Grant's pretty much dead on. I don't like star dressers, but not because they don't do the job. Star dressing tools are difficult to use for the untrained hand, and wasteful of the wheel, but there is no better way to prepare a wheel for grinding. A dressing stick, which has always been my choice, is a close second. It might have a little trouble with a wheel loaded with aluminum, depending on how badly the wheel is loaded. A stick works by different principles than does a star dresser, which is an impact tool.
In this case, it would be the best choice. There is no need to replace the wheel if it's been serving with satisfaction. Such grinders are generally provided with a wheel that is good for general purpose grinding (although not suited for grinding non-ferrous materials and/or HSS), and can easily be restored to useful life by dressing.
Harold
Depending on how one uses a grinding wheel, a star dresser can be a real PITA. There is no better way to prepare a wheel for heavy grinding, but that's not the only way a wheel can be used.
I grind my HSS bits freehand, no work rest----and I don't like wasting a grinding wheel. We all know that the best part of of a wheel's life comes from the outer portion, where surface speed is proper. As a wheel diminishes in size, the drop in surface speed causes the wheel to change grinding characteristics, resulting in what appears to be a wheel that is too soft. I see no good reason to accelerate that process. Even if I used a work rest, I know all too well how hard it is to get a wheel running dead true with a star dresser, especially a worn one. Chatter of the stars tends to allow an irregular hammering process that keeps the wheel ever so slightly out of round. My grinding method suffers when the wheel isn't dead true. You can waste a considerable amount of the wheel trying to get it running well. Been there, done that.
For the record, I am first to agree that a star dresser is the best way to prepare a wheel for grinding. The mechanism by which it dresses does nothing to dull the grain, nor does it leave the wheel too smooth for offhand grinding, unlike a diamond. However, when you compare the ease by which a wheel can be dressed with a dressing stick, taking into consideration the slightly reduced grinding capacity of a wheel so dressed, a result of rubbing the wheel with something that tends to dull the grain to some degree, it is, by far, a better choice. Even free hand, a wheel can be brought true almost instantly, with no excessive loss of media, prolonging the useful life of the wheel and yielding what is a better running surface, with rare exception.
One of the nice advantages of a dressing stick is they are very inexpensive, and should last a person a life time.
Bear in mind, I have background in precision grinding on a commercial level, and am a retired machinist/toolmaker, so I've had more than enough experience in these matters to have an informed opinion.
Harold
Harold, what kind of dressing stick would you recommend, I have a 80 grit wheel that is very clogged.
i"ted frater" wrote: Grinding the softer metals works better if you use water as an anti clogging agent on the rotating stone. (clip) ^^^^^^^^^^^^^^^^ I seem to recall that if you "preload" the wheel with chalk, it will delay the loading with the softer metal. So you would have to re-do it frequently. I wonder if wax or soap would do any good.
What kind of wheel would be best for grinding HSS on a bench grinder?
Thanks,
Wes S
The harder the material, the softer the wheel. I used a pink aluminum oxide wheel in A hardness, about 80 grit, for a long time. They are surface grinder wheels, of course, so you'll have to bush the 1-1/4" hole down to your grinder's shaft diameter.
GWE
That is not an acceptable choice. The stick should be VERY coarse----16 to 24 grit, vitrified silicon carbide.
Harold
I was told (could be an old wives' tale) that loading up a grinding wheel with soft metal is the second best method for turning it into a bomb! First best method? - overspeeding.
I use a norbide stick.
You don't really have many choices. Rule of thumb with grinding is a hard wheel for soft material, and a soft wheel for hard material. That way the wheel is regenerated at the rate that's in keeping with the task at hand. You also must balance the abrasive type with the task at hand. Silicon carbide is much harder than aluminum oxide, but because it is soluble in steel, it is not acceptable when used at high speed, where the elevated temperature causes dissolution of the wheel. Slow speed application, such as honing or lapping, it works fine. Aluminum oxide is not soluble in steel, so, in spite of the fact that it is far softer than silicon carbide, it performs better than silicon carbide when operated at acceptable surface speed, which is near 6,000 fps.
Back to your question, I highly recommend a wheel that would meet the designation of a Norton wheel (it need not be Norton, just share the characteristics), which would be an aluminum oxide wheel, generally a 46 or
60 grit wheel (I prefer the 60 grit, but I don't use two wheels. I rough and finish with the same wheel), a hardness between H and J, vitrified bond. The designation might read like this: 38A60H8VBE.The second 8 in the designation is the density of wheel, and is important to a wheel's ability to deal with the swarf. You'd be well served with an 8, but avoid going much lower. As the number decreases, the wheel becomes more dense.
Hardness of grinding wheels has nothing to do with the media---it's a function of the amount of bonding agent. Hard and soft wheels share the same media.
Hope this helps.
Harold
============ Take the easy way out if you do soft material grinding/shaping and buy a 4 X 36 belt sander with a 6 inch disk. Easy to switch belts/disks and you can use a thing that looks like a big gum rubber / india eraser to keep the belts clean.
A belt/disk sander will even work with wood, but keep the sawdust swept up unless you don't mind a fire or two when your grind metal and make sparks. Even when grinding tools I find it is a big help to "hog" the metal off. An extra fine disk will let you put a literal mirror finish on your tool bit if thats hat you want.
for dressing sticks see
I have never worn one out, but have dropped several. You can use the pieces.
Unka' George [George McDuffee] ............................... On Theory: Delight at having understood a very abstract and obscure system leads most people to believe in the truth of what it demonstrates.
G. C. Lichtenberg (1742-99), German physicist, philosopher. Aphorisms "Notebook J," aph. 77 (written 1765-99; tr. by R. J. Hollingdale, 1990).
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