grinding wheel clogged with aluminum

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
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Let me know what you find out, mine is clogged with aluminum, copper and silver.
i
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Ignoramus16071 wrote:

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
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Grant, thank you, I will definitely try.
i
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On Tue, 16 Jan 2007 11:24:55 -0600, Ignoramus16071

==========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).
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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
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message

although
leaves
imbedded
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
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Harold, what kind of dressing stick would you recommend, I have a 80 grit wheel that is very clogged.
i
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That is not an acceptable choice. The stick should be VERY coarse----16 to 24 grit, vitrified silicon carbide.
Harold
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I use a norbide stick.
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snip-

Excellent choice when it has a sharp corner. They're made of boron carbide, and far harder than silicon carbide. Problem is, just like a diamond, as they wear, they quit cutting the wheel and start glazing it. As long as you can keep a sharp cutting edge---they're very good.
Harold
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On Tue, 16 Jan 2007 19:17:47 GMT, "Harold and Susan Vordos"

I must chime in here once again and recommend my personal favorite dresser.
http://www1.mscdirect.com/CGI/NNSRIT?PMPXNO16520&PMT4NO534908
It works in a combination of the method that the star wheel and dressing stick does. It leaves a very sharp, and smooth surface on the grinding wheel. I've used nearly every other type of dressing method and this one leaves the best surface for free hand grinding bar none.
The only drawback is the price. I must admit that the price is steep (the only reason I've not got one at the moment). But I used one at my former employers and will get one if I ever manage to have the extra cash for it on a order.
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snip---

I have serious doubts that it works as a star dresser. Indication are it is nothing more than a revolving vitrified dressing stick, likely silicon carbide. Star dressers work by hammering----they otherwise would be quickly wasted. I have no quarrel with your statement about the results of the device in question, but it's a high price to pay when a dressing stick does the same thing.
Please correct me if I don't understand the nature of the dressing device you suggested.
Harold
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On Wed, 17 Jan 2007 01:45:40 GMT, "Harold and Susan Vordos"

The wheel on the dresser normally runs at a slight angle. This provides the sliding motion of the dressing stick. But the rotary motion of the wheel pressing against grinding wheel causes a crushing action similar to but much more controlled when compared to a star dresser. For times when the grinding wheel is just dull and doesn't need any real dressing you can turn it to run straight on with the grinding wheel. This caused the crushing action which sharpens the grinding wheel without taking off any more than is needed. I can say from experience a wheel dressed this way will cut 5x faster (or more) than one dressed with a stick but still be as smooth and easy to control as a stick dressed wheel. My experience is that the surface left cuts better than any other method of dressing, diamond included.
Now for my big rough welding grinder I routinely use a star dresser. In fact I've got the largest size they sell which is so much better made and so massive that it does a pretty good job of smoothly dressing a wheel. I routinely sharpen my largest drill bits on that grinder after freshly dressing it flat with my star dresser (when sharpening a 2 1/4" drill bit it helps to have a grinding wheel wider than 1").
To give you a idea of how much I like the results of this type of dresser I'll say that I was very seriously considering making one for a while. At that time nobody I could find was selling them. MSC didn't have them for a number of years. Now as you know I've got a working shop and the time needed to make one would cost several times what they sell for. But I wish for one so often (like today when I was sharpening a HSS tool) that I had it on my list of things to build till I found them in the catalog. I currently use a dressing stick on my tool sharpening grinder and I'm definitely not satisfied with the performance of the wheel when I use it.
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snip----

So far it sounds very good. The sliding motion you speak of helps eliminate any grooves or high spots in the wheel, but can also be the source of grain dulling. That approaches the performance level of a stick.
You likely know that crush rolling is one of the accepted methods of dressing profiles on grinding wheels, but it's usually accomplished at slow speed, powering the crush form, so the grinding wheel doesn't abrade the roll form, and the roll form doesn't dull the grain of the wheel. This tool is a serious compromise on that method, and likely still dulls the grain ever so slightly. Like a stick! <g>
How much difficulty can you recall in getting a wheel rounded up when it's bouncing? Seems to me that applied pressure, if the tool works as you suggest, would make that task difficult. That's one of the complaints I've always had with a star type dresser, In order for it to function, it has to be loaded. If it's loaded on a bouncing wheel, it's a slow process getting the high out of the wheel because it's lowering the low side at almost the same rate as it's removing the high side. That's not true with a diamond or a stick.
>I can say

I'll take you at your word, Wayne. I've never even seen one of the devices, and would hesitate to rush to judgment.

No need to rush to judgment here. This one is a no-brainer. A diamond dressed wheel is about the most useless wheel there is if you're offhand grinding. I've used more than enough diamond dressed wheels for just about any occasion you might imagine, from internal grinding to centerless grinding. There's nothing that equals such a wheel, but ONLY if it's run under power conditions, and generous flood coolant. For offhand grinding, they cut hot and poorly. A diamond dressed surface is just too smooth to be effective for hand work.

Didn't realize the size of work you did, but I fully agree here. The only reservation I'd have is that the wheel, unless well undersized, is very poorly matched to the work at hand. Doesn't mean it wouldn't work, just means it's too hard for good grinding of HSS

I can't help but think that part of your less than equal satisfaction is how you're using the stick, Wayne. I've been using one for well over 40 years, and I can get any wheel to cut well (I admit I don't have one of those trick dressing tools so I can compare), but I've used a star dresser and can come very close to the same performance they yield. Difference is that the stick always dulls the grain ever so slightly---but if you present sharp edges, that's almost not detectable.
One thing you have to learn to avoid is letting a flat side of a stick to rub on a wheel in the hopes of achieving a flat surface. If you're doing that, I have no doubt, you're not going to like the wheel when you're finished. That's not an acceptable technique----it dulls the wheel too much.
Thanks for the great report. Always a pleasure to read your posts.
Harold
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OK but... wont the dressing stick quickly wear out the sharp corner? You say that a stick will last a hobbyist a lifetime. How do we get a sharp corner to last?
I do not have one of those $2.90 sticks, was too dumb to pay $10 for a diamond but I am going to get one as soon as figure how to use it properly.
Thanks Mauro
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snip---->

The stick does slowly degrade, but keep in mind it's a vitrified product, so it not only wears, it also allows dull particles to dislodge. That exposes new, sharp grain, just like a grinding wheel. Understand that you won't have a *sharp* corner in the sense of a new stick, but you have projections that are not large in area, and act effectively on the wheel, very unlike a broad, flat surface. They work, and very well, but you have to develop the technique. That includes choosing the right places on the stick to apply to the wheel. It makes a lot of sense when you use it---but it may not sound logical unless you've "been there, done that".

Same way you keep a diamond sharp. Diamonds that aren't mounted in an offset holder, and are used only in one position, or are used free hand, eventually are dulled to the point they are useless. By mounting in an offset holder, as the diamond establishes a flat, you rotate it slightly, presenting the edge of the flat. Think like that when you use the stick. You're constantly creating new edges, the just aren't 90, but they don't have to be.

properly.
To be best served, you should have a diamond and a dressing stick, and know when to use each one. That comes into focus quite readily when you start using them. Dressing stick is almost impossible to not have------particularly for those of us that have a background in grinding.
Harold
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On Wed, 17 Jan 2007 05:25:01 GMT, "Harold and Susan Vordos"

The angle is slight so the sliding is minimized.

I'm sure it does compared to a full fledged crush rolling.

It's the best method I've used bar using a guided diamond (one that's on a slide). I know what you're talking about on the star dresser. With the average star dresser it's hard to impossible to get a wheel really round. I have pretty good luck with my large one (which by the way would cost as much as the Crackerjack if bought new, mine came from a auction in like new condition for cheap). I've used star dressers that where so worn that it was totally impossible to really true a wheel.
Of course I'm sure you know that the proper use of a star dresser calls for the backing away of the rest and hooking the bottom of the dresser on the rest so you can lever it into the wheel. Not that I do it that way myself (to much time involved). I do set the dresser on top of the rest and press down pretty hard to prevent the jumping of the dresser .
When I first started using grinding wheels I was pretty young. I started working my dads old barn when I was around 8. My dad didn't have much of a shop out there. I was forced to gather up what tools I used. My first grinders where all just surplus motors with grinding arbors installed. The motors where invariably 1750 so where way to slow for proper wheel speed. My rests where always cobbled (when there was one). That was where I learned to grind with a wheel that was to soft and not get the wheel out of round (it's definitely a skill). I slowly improved my grinding setup through my teen years but never did have a really good setup till after I got out of the military and started my own shop. Even then in the early years the grinder I had didn't have as good a motor as it should have (It was a belt drive that I welded up and was a decent grinder if I'd put a better motor on it).
My current grinding setup is far superior. I've got a really old very well built 10" grinder that runs on 3 phase. It will coast for 15 minutes after turning it off (to give a idea of how smooth it runs). That is what I use for tool sharpening. I've also got a home made heavy duty grinder that came from my former employer. It's really old and heavy built. It can take up to a 16" grinding wheel but only at 1 1/2" wide which is nearly impossible to find now days so 14" wheels is what gets used on it.
There's also a really really old 18" flat face grinder. It's totally impossible to get wheels for it and the one that's on it is way to soft. I don't use it much but it's pretty handy for flat surfaces. I plan to one day make a platen to go on it so that I can use 20" sanding discs on it.
For a pic with the above in the background see here.
http://www.metalworking.com/DropBox/_2002_retired_files/Frame_Extension10.jpg
Then there's the 1" wide belt sander (really handy for deburring) and the Baldor tool grinder with the diamond wheel for my carbide lathe tools.

They seem to work similar to a brake controlled dresser like used on surface grinders (but I've never used one of those so can't say for sure).

Agreed. I have a hand held diamond dresser which I used for shaping grinding wheels when I was sharpening saw blades. It has it's uses but is dismal for bench grinder. It does do a decent job of truing a out of round wheel up but you'd better have something else to finish the job.

I know what you're saying but the wheels I have currently are really to soft for most of my work. But they where cheap so I'm using them up. I'm not real fond of a super hard wheel for large stock removal anyway. I do use a rest for this type work and years of off hand grinding experience allows me to keep a wheel running reasonably true. I do have problems when some of my help uses it though.

Based on what you've wrote in other posts I feel that I'm using the stick in the manner you describe. I figured out early on that presenting the flat surface to the wheel doesn't cut it. My original dressing stick that I got with my saw sharpening setup 20 years ago disappeared a while back and I got another which performs in the same way so I don't think it's the stick itself.

Agreed.

Thanks. I've not had much free time in the last year to do much posting.
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wrote:

have,
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
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