Grinding Wheels

Hummm define Low Cost.

Most surface grinder wheels are available in that diameter and that thickness from your local machine tool supply company. They will have a 1.25 dia hole, but a bushing may be made easily.

Ebay is a good source for such if you are too far away from a supply house. MSC, Travers etc are good sources for catalog sales.

As for the safety...hummmm your on your own here. The grinding media may not be good for your motor, if it is open caged.

Gunner

"Gun Control, the theory that a 110lb grandmother should fist fight a 250lb 19yr old criminal"

Do you have a video camera? The tape might help pay medical bills.

MSC has some (

Eide

Ever hear the comment, "Don't try this at home"? Have you ever seen a wheel come apart?

mj

ROTFLMAO

greatest line yet. When I am setting up one of my "don't ever let me see you doing this" stunts, one of my co workers usually says, let me go dial 9, 1; so all we need to do is dial that last 1.

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Keep the whole world singing. . . . DanG

bills.

grinding wheels,

this thin so

groove into

tablesaw. Sort of

wheel and

appreciate any

I have yet to actually see one come apart. It happens so fast all you see is the resulting damage and carnage after the dust clears.

Les

Well I walked into a neighbors shop as a kid and found the owner on the floor with a hole in his head and brain matter on the floor from a grinding wheel that exploded during use, but it was from grinding aluminum on it. I would think this idea of using a grinding wheel on a table saw would be relatively safe as there would not be any side loads or abuse applied to a wheel as there is when its on a bench grinder. Bench grinder wheels are notoroious for being abused by most folks. I would not think it would be any worse than using and abusing a carbide tipped saw. Those aluminum guards do little for a tooth that comes loose during use. I had a DeWalt RAS one time that had a carbide tooth come off during use and it went through the steel siding and

Provided the wheels used are rated sufficiently high enough for the saws rpm, and considering that lots of bench grinders run at 3600 rpm, why would it be any more dangerous to turn it on a table saw? Depth of grind is being controlled a lot more uniformily than with a bench grinder, no side loads are applied. May not be good for the saws motor, so why would this idea be any worse? I'm not saying its a great idea but no reasons other than don't try it at home have been given to justify the answers given. basically just like a surface grinder, and if you keep out of direct path of wheel, just like when using a bench grinder or other equipment with rotaing wheels and blades should be no more dangerous IMHO.

This idea gives me an idea to utilize my old RAS frame, and a motor I have...........

Of course this is just my take on it, and I ama not an "expert" by any means. Don;t know how accurate it will turn out using a saw for a surface grinder, but yo should be able to get a pretty uniform and decent finish on an item.

Visit my website:

At times I wonder.

Like the man said, run the video. It may help with the medical costs. Cheap wheels in an unguarded machine ... You may get away with it for years. May not get away with it the first time.

Personally, I would never use a grinding wheel at more than its rated speed. Never.

I am curious though why grinding wheels explode.

What are the typical reasons for a wheel going (assuming it is not being spun faster than it was meant to) ?

One fellow mentioned grinding aluminum. What happened there?

What is the best way to get a wheel to go?

I would imagine that it is not a common occurance when the wheel is not abused otherwise we'd hear about it more.

I recently picked up a 3/4 HP Baldor pedastal grinder at Boeing Surplus that looked like a wheel blew up. The cast iron side guard is in 2 pieces and the wheel was fragmented when I got it. From what I've read, a good way to fix the side guard (cast iron?) would be with nickel rod--any comments?

Jeff Dantzler Seattle, WA

It's down to the stress patern, the stress is greatest at the inside, so the crack starts there and grows outward.... when the crack reaches the outside........

-- Jonathan

Barnes's theorem; for every foolproof device there is a fool greater than the proof.

To reply remove AT

Centrifugal force?

Grinding aluminum in and of itself will not cause a wheel to explode. I've ground aluminum in a centerless grinder, even with the wrong wheel selection (aluminum oxide when silicon carbide should have been used) for days on end and had no difficulties with the wheel aside from having to dress far more frequently due to wheel loading. My educated guess on a wheel that blows up from grinding aluminum is the higher forces applied to a wheel that didn't want to cut because of that condition. One might give a little consideration to the idea that the loading also behaves as a wedge and opens up a crack as the soft aluminum is driven deeper into the open structure of a wheel by the extra pressure applied by the operator in order to get the wheel to cut when it is fully loaded. . A harder, less friable wheel would likely reduce the chance of that happening. Regardless of the reason, grinding aluminum isn't a great idea, even with a silicon carbide wheel. Belt sanders are far more forgiving, likely because the belt won't permit deep loading.

Mounting one that is known to be cracked. The forces are extreme on wheels because of their preferred operating speeds. The slightest defect will give the wheel a good reason to let go. Always "ring" a wheel before mounting it, and never run one that doesn't have a distinct ring to it. Don't just set it aside, break it so someone else won't try to run it.

Never force a wheel on the arbor. If it won't go easily, look for the cause. In the old days of leaded bores, it was pretty easy to scrape the bore slightly until the wheel was an easy slip fit on the mounting arbor. You want it to be snug enough to locate, but not be forced in any way. That would be critical if the wheel tends to tip to a side and would be cracked when straightened. A sloppy bore would be far better.

Mounting a wheel without the blotters. Those pieces of paper attached to grinding wheels aren't there for advertising. Wheels that have minor variations in their thickness can be cracked by the flanges if there's not something to average out the clamping forces. Never run grinding wheels without using a blotter on both faces. Use a cereal or shoe box if nothing else. You might get away with it a thousand times, but it's asking for trouble, and is generally not forgiving when it occurs.

Always stand to the side of any grinding wheel when you first start it, allowing it to run for an honest minute before stepping in front of it. That's especially important with a new wheel that has not been run since being tested at the manufacturing facility.

Running wheels beyond their rated RPM is also a dumb trick, in spite of the fact that they are typically run at 150% of their rated speed in testing.

Side loading on a type 1 wheel can cause a wheel to come apart, and is likely the chief cause in many instances. If one is to do grinding that requires pressures in that direction, there are wheels designed for the load. A good example would be the steel backed type 6 found on carbide tool sharpening grinders.

If you consider the number of wheels in proper use, you're absolutely correct. However, it's like an airplane that goes down. Because it doesn't happen routinely, when it does happen it's big news, and is typically fatal to the operator. After all, in most instances the wheel is aimed at the operator. A centerless grinder is one exception, as is a normal reciprocating surface grinder.

Yes, a comment that in your instance the grinder was most likely tipped over or was otherwise struck with something. When a wheel lets go I would expect that you would find little of the wheel on the arbor, and the cast iron guard would likely be more like a do-it-yourself kit, certainly not just broken in half. I'll defer to those with welding expertise where it comes to fixing the guard.

Harold

Thanks for your informative post.

You're probably right about the tipped over pedastal grinder as the wheel wasn't in that many pieces.

Cheers--Jeff Dantzler

You're very welcome, Jeff.

Harold

I agree blotters a re important, and need to be used. Same for a ring test before a wheel is installed and always stand off to the side when its run or started initially, and even though I am the only one here that uses my grinders, I always let it run up to speed for awhile before I use it. The lousy minute or two spent waiting is better than any amount of time in the emergency room or worse yet a morgue.

From what I have heard and was told in tech school, the grey aluminum oxide wheel especially, as commonly found on most folks grinders can get loaded up with aluminum or even brass etc. This hyinders the abrasives cutting action, and increases heat generated during grinding. Same as any abrasive will get loaded up and cause heat buildup, but on a vitreous stone it expands in the pores between the abrasive particles and exerts pressure on the stone which can cause fracture of the wheel. This is still another reason to keep a grinding wheel dressed up, especially those cheap ones that are not as friable as the better grade of wheels. Cheap wheels are not as friable as a good wheel and are prone to loading and by not exposing clean sharp abrasive girt, more often than not they run hotter. Its hard to beat a good grinding stone. I learned that from my friend who is in the grinding business. I thought I had some great wheels until he gave me a few that he uses. World of difference in how they cut and the finish they leave. No more cheap wheels for me no matter what the cost is.

Visit my website:

To add to what Roy wrote,

What I usually saw was someone would load the wheel with aluminum, brass or rubber then turn around and grind iron.

Sparks carry heat from the wheel, if theres something in the wheel to hold the sparks the heat stays with the wheel. With something like aluminum or brass I think it would be friction causing heat buildup.

You mean blow up??

Drop a chisel between a badly adjusted tool rest and the wheel. Sudden stoppage will usually do it.

Another point that only use coolant on those rated for that - and only have it flow on to never sit into a pool. A stopped wheel will be heavy on one side if stopped in a pool. That will shift the balance out... Martin

Jeff Dantzler wrote:

The stop isn't a problem. The damage done to a wheel when the wedging action occurs certainly can be. I recall an incident many years ago in which we routinely ground a short piece of 3-1/2" diameter steel, three inches long, in a centerless (Cincinnati #2). Because the size was beyond the rated capacity of the grinder, even using our lowest height blade, the part rode too far above center, yielding an operation running on the edge where one shouldn't be running. The parts would traverse the blade with a rumbling sound, one that you knew was caused by the part starting to jump up, but always falling back in place, gradually running through the grinder. One fateful night that was not the case. I was, fortunately, not the guy running the job when it happened, it was on the opposite shift. One of the parts finally made the leap out of the machine, coming back down sideways. The grinding wheel, 6" wide and 20" diameter, driven with a 15 horse motor, was slammed to an immediate stop, wedging between the grinding and regulating wheel on top of the carbide blade, which was shattered. Messelman, the operator, was very pale, I was told. Go figure!

The grinding wheel had a divot removed, but after dressing to get down to a full wheel the wheel was used again. Stopping them fast doesn't do any damage. Apparently when they're well made, neither does wedging them!

Harold

Okay, I'll bite.

What are considered the "better grade" of wheels?

I picked up a Norton Alundum course wheel to fit on a recently acquired pedastal grinder. I've heard good things about them, but would like to know what wheels you folks consider good.

I usually run a course wheel and a wire wheel on my bench/pedastal grinders and grind exclusively mild steel. A machinist friend recently showed me how to dress a wheel and it definately made a difference on the grey wheel on my cheap, old, 6" Jet grinder. He is also turning some spacers and a 1" to 3/4" adaptor so I can get the pedastal grinder up and going.

I'm looking forward to turning the old Jet into a tungston grinder. I guess all I need at this point is a TIG setup--any one got a Miller Dynasty that's gathering dust at the back of the shop? :)

BTW one of my favorite abrasives is a good flap wheel (Pferd or Tiger) on an angle grinder. These can make a bead disappear quick if I'm so inclined (though I usually just leave them.)

Cheers--Jeff Dantzler

snip

I would assume what they mean by better grades of wheels are those normally sold by major companies with a brand name on them and not the el cheapo china import wheels. As good a grinder as Baldor makes, they still supply a pi$$ poor stone on them. Not even a manufacturers name on these wheels. I was really dissappointed in my 7" Baldors performance when I first got it, until I got rid of the no name wheels and put on some DoAll brand and Norton wheels.

The same is true with grinding wheels as everything else you buy. You get what you pay for 99% of the time. Visit my website: