Harbor freight tools

I bought a "Clark" brand on clearance at a wood tool show... Likely a demo (or maybe return?). Lots of torque! But after about

60 seconds, the speed starts to drop, and I suspect that if there are ball instead of sleeve bearings, it might last a few weeks rather than a few hours.... The accessories are NOT BALANCED, and at top speed, will further destroy the integrity of whatever bearings are present. Best to true any stones up at moderate speed.... / mark

jim wrote:

I bought several packages of their diamond cutoff wheels, they last a while as long as they are not overheated. Bought two or three blister cards of 5 over a year ago when they were on sale, I am only on my second disc (light use only or where I need the thinnest kerf possible, otherwise I use a bigger tool). I killed the edge of first disc working too hard at cutting a hardened parting tool. For the price, I am impressed.

I have my doubts about the other ones, several of the diamond sets I have inspected had visibly eccentric tips or were worm shaped.

StaticsJason

Diamond tools run at elevated speeds should not be used on anything containing iron. You'll find that these tools will hold up quite well cutting things like rock, but not well at all on steel of pretty much any kind. Reason? Diamonds are, of course, carbon, and iron has an affinity for carbon, so at elevated temperatures the diamonds tend to dissolve into the steel you're trying to cut. That dulls the diamonds rapidly, leading to higher temperatures, and, of course, faster dissolution of the diamond.

Harold

Actually, diamond tools work quite well against steel if run slowly! quite handy for honing tools with.

Regards Mark Rand RTFM

Most of what you said as an explanation is not true. I have no idea what a dissolute diamond is but many dissolute people seem to be attracted to diamonds.

My limited experience with diamond tools is that the cheap ones are nearly worthless. The problem is that the diamonds are bonded in a single layer to a core. If this bond is easily broken, you soon have a "dissolute" core, without enough diamonds to do much cutting.

Perhpas you can tell all of us what is true, then!

I have

With that, I would likely agree.

Likely I have egg on my face regards a word chosen to describe a diamond being dissolved into steel (my mom told me I should have gone to college), but the principle is one well known by anyone that works with diamond grinding wheels. The information is well documented by the grinding industry. Diamonds are not recommended for use in grinding steels, and for the exact reason mentioned. The dulling of the diamonds lead to other problems as well, they are not limited to just further dulling. Pulling the dull diamond from the bonding matrix is one more of the problems. Diamond wheels experience very short life spans when used improperly.

It's the same with silicon carbide grinding wheels on steel, which, like diamond, dissolves into the steel being ground. If you've ever run any kind or grinder and had poor results, you'll now understand why an aluminum oxide wheel, in spite of being a lot softer (the abrasive, not the bond) than a silicon carbide wheel, cuts steel exceedingly well, while the silicon wheel dulls up instantly and creates lots of heat but does little grinding. That characteristic is very obvious on a surface grinder, where the wheel behaves as if it's loaded shortly after being dressed.

Did I use a selection of words that please you this time? If not, learn something from the message, and replace the improper words with those of your choosing.

Harold

I've been wondering about this; I guess,as long as I don't eat too many wheaties, I should be OK Gerry :-)} London, Canada

Not my job to tell you what is true, but diamonds don't dissolve and they certainly don't dissolve into steel. The diamonds in a wheel can shatter (break), they can be pulled out of the wheel matrix, and they can be smeared with either the wheel matrix or the material being ground. The latter is what happens when you say it loads up. Loading depends on a lot of things but highly important are the coarseness of the abrasive, the bond of the abrasive, and the speed of the wheel.

If silicon carbide is so bad on steel, how come most small bench grinders come with silicon carbide wheels? Granted that not every abrasive is suitable for every material. However, you can cut and polish just about everything with the correct grades of diamond. As another person stated, diamonds work quite well on steel.

Diamonds don't work well at the high speeds used in many industrial tools and they certainly won't last long without a cooling/lubricating fluid. However, speed is often much more important that cost, but that's no reason to not understand the physical process. Let me say one last time, there is no dissolving of diamonds or silicon carbide in the grinding process.

Maybe you can sell your diatribe to Norton, then, because their literature seems to think there is. But then, what the hell would the leading manufacturer of grinding wheels know about that?

Harold

You need to look at some very basic chemisty behind the diamond. Diamonds are the hardest material known for some very basic reasons. It's foundation is based on how the material is put together and what holds it together. Carbon atoms in a diamond are held together with covalent bonds. This would make them very difficult if not next to impossible to simply dissolve into another material, even at temperatures experienced in grinding. See web site listed for a quick and simplistic overview of the two basic forces that hold atoms together.

There are plendy of applications where diamond wheels are indeed used to remove steel. I have a drill doctor that uses a diamon wheel to sharpen drills made of HSS to Carbide. Tool grinders used diamond wheels to sharpen carbide tools. I have some DMT and cheap HF diamond whetstones that seem to continue to cut steel knife blades. These aren't tools that hog material but they do cut very hard steels and contiue to do so. Due to their fine abrasive nature, attempt to cut soft material can easily lead to loading or contamination issues. This will hinder the ability of the cutting portion of the wheel to actually contact and remove material from the work intended.

On a side note. Materials that are known to conduct electricity better, are also known to conduct heat better. There is on exception. An exremely good electrical insulator is diamond. This again has to do with covalent bonds and no free or shared electrons able to flow about. Strangely enough diamonds are exceptional thermal conductors.

Hey this is REC. It isn't your job to post here. It is just done for fun and helping people.

That said, I disagree with both of you. I do agree with Halold on Diamonds. That is why Borazon is used on Steel. Diamonds don't last and it does have to do with the fact they are carbon and I think it is because the steel reacts with the carbon.

But I disagree with what was said about silicon Carbide. Silicon Carbide is harder than aluminum oxide, but is not as strong. So it works great on lower strength materials as cast iron and very hard material as carbide. But it does not work well on steel. Does it gum up the wheels or just wear more rapidly. I am not sure. And most small bench grinders come with Aluminum oxide wheels. At least I have never seen a small bench grinder for sale with Silicon Carbide wheels. Angle grinders come with Aluminum Oxide wheels, but you can get Silicon Carbide wheels. They are labled as Masonry wheels.

Dan

Diatribe? now you are getting nasty. I don't have a clue who or what Norton is or says, but if they say diamond dissolves in iron or steel, then they don't know squat about physics or chemistry. Any first year (well, maybe 2nd year) chemistry student should be able to tell you that diamond won't dissolve in steel. Maybe you and Norton (if they said that) don't know what the word "dissolve" means?

You might try reading some lapidary sources, to get a more accurate idea of cutting and polishing with diamonds. But enough of this, as I said I'm not getting paid to educate you. My comment was just meant as a caution to the spead of misinformation. I've accomplished that, so I need say no more.

"Why can't you machine ferrous metals with diamond?

Diamond is unaffected by almost every other chemical or compound in nature. One exception is hot iron. The carbon atoms in diamond will dissolve into the iron, quickly eroding the diamond surface. Iron wheels are used for polishing natural diamond."

"Why is the hardest material, diamond, not good for machining ferrous metals at high cutting speed? Diamond readily dissolves into ferrous metals at high temperatures."

There are tons of other references online.

Hell, it should be obvious to anyone that carbon dissolves just fine in hot iron. That's basically what steel is, after all!

What reason do you have to believe they do? In almost all instances (tungsten carbide sharpening grinders excepted, those come with green wheels or diamond), they do NOT! Do you have any idea what constitutes a silicon carbide wheel? Can you identify one at a glance?

Harold

No, I'm not getting nasty, I'm simply stating that you come across as if you know something when you don't. Had you provided something of substance to substantiate your claim, perhaps I would have had a different response to your post. The information I provided is well known by any of us that have worked in the grinding trade, especially the one about silicon carbide dissolving it steel. That is well documented by the grinding industry, as is the fact that aluminum oxide does the same thing when grinding glass products. That's why rock people use silicon carbide grinding wheels (when not using diamond), which are far better suited to the application.

I have in my possession published documentation to back my claims, and it appears "Niccolo Vecchio" has provided enough information on the diamond discussion to remove doubts from your mind.

Harold

I don't have a clue

Neither of those sites provide anything more than a statement. I could probably find several site where Elvis was just sighted. Besides we already know that steel can be tooled and is tooled with diamonds. And, just as aside, you might want to check a lapidary equipment catalog to see what is used to facet gems including diamonds.

"We" know no such thing. In fact valenite specifically recommends against using their PCD inserts on ferrous materials.

You can still back out of this gracefully.

Jim

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