Diamond coated cutters/bits cutting steel

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MrAl
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Diamond coated cutters/bits cutting steel

Post by MrAl » Wed Apr 29, 2009 10:50 am

Hello there,


I read somewhere that carbon gets 'absorbed' into iron at the temperatures often
found when grinding steel, which seemed to imply that diamond isnt as good for
steel as it is for other metals like aluminum or say ceramics.
Anyone have any other info about this, pro's or con's or other?

Thanks...

I have tried diamond disks in hardened steel, like the kind used for those hard steel
screws used commonly for installing drywall. It seemed to cut just fine, making
a cut lengthwise through the screw which is a job for it to do (as if making one of
those self-tapping screws), and the cutter didnt seem to be bothered at all.
Maybe more cuts would damage it?
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Bob Scott
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Re: Diamond coated cutters/bits cutting steel

Post by Bob Scott » Wed Apr 29, 2009 4:49 pm

MrAl wrote:I read somewhere that carbon gets 'absorbed' into iron at the temperatures often
found when grinding steel, which seemed to imply that diamond isnt as good for
steel as it is for other metals like aluminum or say ceramics.
Anyone have any other info about this, pro's or con's or other?
Let us know what happens if you grind aluminum with the diamond blade. Every grinder I've seen gets clogged up with aluminum. I used the dremel's cutoff wheels to cut aluminum. Aluminum is brutal. You can see the grinding wheel get smaller and smaller in diameter right before your very eyes. I think what happens is the grinder grit gets stuck in the aluminum, breaks off and sticks in the aluminum. Then the rest of the grit on the wheel grinds on gritty aluminum, accelerating the wear drastically.
MrAl wrote:I have tried diamond disks in hardened steel, like the kind used for those hard steel
screws used commonly for installing drywall. It seemed to cut just fine, making
a cut lengthwise through the screw which is a job for it to do (as if making one of
those self-tapping screws), and the cutter didnt seem to be bothered at all.
Maybe more cuts would damage it?
I've had no problem with carbide tipped circular saw blades cutting nails. When I cut the bottom off my garage door, I managed to cut two nails in half lengthwise. Like a knife through butter. The saw didn't squawk or slow down. It cut and sounded normal as if the nails weren't there. Diamond is even harder and should cut steel effortlessly. I don't think brittleness is a problem.
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Re: Diamond coated cutters/bits cutting steel

Post by Dean Huster » Wed Apr 29, 2009 5:01 pm

I've used an older carbide tipped circular saw blade in my table saw to deliberately cut a 3/8"-thick aluminum extrusion. I'd never do this with my Freud blades, however. A carbide blade will cut through the nails, but you will have taken the razor-sharp edge off a new blade and you will notice a difference in cut quality when working with maple or oak.

I also use old carbide blades in my portable table saw to cut Hardibacker (cement board). It's much easier than using a circular saw for the same cuts, although you do have to have a long outfeed table or narrow cuts in thinner cement board will break off just from gravity.

I also would think that a diamond wheel would load up with aluminum. When I took shop class back around 1964, the teacher would kill us if we ever used a standard mill file on aluminum. I do all the time now, but also have to dig out the teeth afterward.

When tapping threads in thicker aluminum, you're better off using 2-flute taps in a drill press and hand-turning the chuck (don't use the drill press motor) -- use a product called Tap-ease for lubrication. It smells like cinnamon and works great. A 2-flute tap gets rid of the big, soft aluminum chips easier than 3- and 4-flute taps and doesn't bind up as readily. But they're difficult to use in a tap wrench by hand as the threads are difficult to keep concentric with the center line. You can end up with shallow threads on one side and deep threads on the other side of the hole or making the threaded hole non-parallel with the hole centerline.

Dean
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MrAl
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Re: Diamond coated cutters/bits cutting steel

Post by MrAl » Thu Apr 30, 2009 10:03 am

Hi again,


I havent actually tried a diamond cutter of any kind on aluminum yet, but maybe i will try
that soon just to see what happens. I need to cut aluminum angle from time to time
so this would be good if it worked.

As far as getting the aluminum particles stuck in the file, they do make a tool for that.
It looks like a wire brush but the difference is that the bristles are very very short. To
use it you press it against the file hard and pull it back toward you, and it removes the
debris that reside inside the file grooves. We used this tool way back some 40 years
ago when i briefly worked in a custom machine shop. Havent used one since though,
so i dont know where to get them anymore but i would bet the web has something.
I would bet that a good stiff wire brush would help too though, even with the longer
bristles. Whether or not this works with a diamond wheel cutter i dont know though
because i have never tried that (at least not yet).

The original problem i was asking about is where the diamond might wear and get
absorbed by the iron in the steel. I know they use these to sharpen carbide though
so i dont know what's up here yet. Perhaps that is what happens with the aluminum
too as it is ground. I used to know more about this kind of stuff but forgot a lot
of things over the years :smile:
I remember one thing though about aluminum, and that is when drilling it oil should
not be used for lubricant but something like mineral spirits instead.
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Re: Diamond coated cutters/bits cutting steel

Post by Dean Huster » Thu Apr 30, 2009 8:20 pm

Yep, Al, it's called a "file card" and the short, really springy bristles have a bend in them so that they point toward the flat handle. However, I find that it's nearly worthless for pulling imbedded aluminum out of a mill file. I end up having to do it using a really sharp awl, one file groove at a time.

Most diamond bits and cutters designed for a Dremel-type tool have really fine diamond bits and I'd assume that they'd load up with aluminum so fast that you'd never know what hit you. Tile saw blades have a larger diamond grit on them as do the dry diamond blades for a RotoZip. Still, I'd never try either of those on aluminum myself -- too cheap to risk ruining them!

If you insist on experimenting, it'll be interesting to note the outcome. Actually, I hope it works out well. The more tools that can be used to safely and cleanly cut aluminum, the better, right?

Dean
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Re: Diamond coated cutters/bits cutting steel

Post by EPA III » Fri May 01, 2009 12:02 am

Diamond wheels are not the first choice for sharpening steel tools or cutting steel parts because diamond is carbon and will be absorbed by the steel. The diamond wheels cost a lot more than a similar sized non-diamond wheel and most prefer to reserve the diamond wheels for things like tungsten carbide which will not sharpen or cut with other abrasives.

Having said that, diamond wheels or stones are used for hand sharpening tools. To get the carbon from the diamond to disolve in the steel, a high temperature is needed. When a wheel is spun fast as with common grinders, this happens. But when hand sharpening a tool, the speed is much lower and the diamond stone is not damaged. Also, some commercial sharpening machines that use diamond wheels run at relatively slow speeds (100 rpm) with a coolant (water or otherwise) and this also prevents high temperatures so the diamond wheel is not damaged.

Aluminum will clog almost any abrasive wheel. There are some that are made for aluminum, but you will need to dress them frequently. Diamond is way over kill for aluminum and other abrasive wheels WILL clog with it. Cut aluminum with a saw; even a wood saw will do. Clean up the cuts with a file. There are files made specifically for aluminum and they do not clog up as much, but ordinary files can be used. Either will need cleaning after some filing, but this is easy. If you must have an abrasive finish on aluminum, I would use sandpaper. Use a wet type and add some oil or cutting fluid for a better finish and to help keep the paper from clogging too quickly. Lay the paper on a flat surface (glass) and move the part over it.

On the file cleaning thing, I use a brass or steel toothbrush style brush to clean my files. Brush sideways, along the grooves. This has salvaged files that were clogged solid with years of accumulation and makes a new file cut with far less scratching of the surface. Files also benefit from a few drops of oil added to the brush while you clean them.
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Re: Diamond coated cutters/bits cutting steel

Post by MrAl » Fri May 01, 2009 11:33 am

Hi,


EPA, thanks for the nice reply with lots of info there! I'll have to look into this stuff more too.

Dean, i guess the 'file cards' i have used in the past were more ridged or something because i dont remember
them being too difficult to use.

Anyone:

I started looking up some info about grinding aluminum and found out some pretty interesting stuff,
including IMPORTANT NOTES about exploding grinding wheels due to a build up of aluminum in the
wheel and it being ignited and causing the wheel to explode and spew chunks of grinding wheel
all about!!
Anyone grinding aluminum should definitely take a look at this stuff. A simple search for
"Grinding Aluminum" turns up a lot of info on the safety issues that come up when grinding aluminum.

I did some quick tests with a diamond cutter and some angle aluminum, home repair grade, and
after cutting a piece i didnt see anything noticeable on the diamond wheel so i guess i'd have to
grind more of this metal for a while to see anything turn up. The wheel did not show any signs of
being smoother or holding any metal, even though i used the side as a sort of rotary 'sanding disk'
too just to see if that would accumulate some particles.
Could this be because i used a slower speed than most grinders?
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Re: Diamond coated cutters/bits cutting steel

Post by Robert Reed » Fri May 01, 2009 12:51 pm

MrAl
I think one clarification is in order here when we talk about "Aluminum". Like everything else in this high tech world, aluminum comes in many different grades and requires tooling appropiate to those gradws. On one end of the scale, I have worked with high grade aircraft aluminum and it machined like a dream with whatever - drill presses, milling machines or lathes and also in billet or sheet stock. On the other end of the scale, I have attempted to work with some low grade crap that I swear was an alloy of "Aluminum, rubber and butter " - absolutely horrible. Unfortionately, I have lost track of the grading system, but I do remember that the high grade stuff was VERY expensive and not very malleable but did make up beautiful front panels in sheet stock material.

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Re: Diamond coated cutters/bits cutting steel

Post by MrAl » Sat May 02, 2009 9:10 am

Hi Robert,


Yes, i believe there is a 'grain' size too, but the kind i am working with has to be the cheapest
kind you can get because it is sold by Home Depot and it is for general home repairs and
installs.

I took a look at one of my older grinding wheels (mini wheels) that is not diamond but is
some kind of stone, and i can see tiny metallic particles embedded in the surface. No doubt
that it grabbed some metal material at some point and held it in it's grains. Probably brass.
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Re: Diamond coated cutters/bits cutting steel

Post by Robert Reed » Sat May 02, 2009 12:50 pm

MrAl

Next time you are cruising for aluminum product, try punching up "Online Metal. com".
I have found them to be very knowledgeable and with competitve pricing too. They have a variety of metals (not just aluminum) and in a wide range of stock. Home Depot and most hardware outlets usually sell the kind of crap I was reffering to.

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Re: Diamond coated cutters/bits cutting steel

Post by MrAl » Sat May 02, 2009 1:40 pm

Hi Robert,


He he, as you probably guessed, i have a HD as close as 1 mile from here, hence the cheap angle
aluminum i have :smile: Also, we had some left over from a few home repairs too, that i have used
for electronic apps like heatsinks and mechanical apps like a 3 axis machine.

I'll have to check that link out, sounds very very interesting...thanks.
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Re: Diamond coated cutters/bits cutting steel

Post by Joseph » Sat May 02, 2009 5:12 pm

Hi Al. I cut some old bicycles frames with my diamond-impregnated concrete circular saw blade. The circumference of the blade seems to be brass studded with diamonds. It eroded away much of the cutting surface of the blade before I noticed the harm. I would have used a carbide blade if I had known better.

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Re: Diamond coated cutters/bits cutting steel

Post by MrAl » Sun May 03, 2009 8:43 am

Hi Joseph,

Interesting...so i'll have to remember that.
Do you know what speed you were using to do the bikes ?
Heat is the culprit here so i am thinking that slower speed might not be so bad.
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Re: Diamond coated cutters/bits cutting steel

Post by Bob Scott » Sun May 03, 2009 9:29 am

MrAl wrote:Heat is the culprit here so i am thinking that slower speed might not be so bad.
Or, keep a water hose drenching the diamond blade to keep it cool like the granite cutters do.
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Re: Diamond coated cutters/bits cutting steel

Post by MrAl » Sun May 03, 2009 12:13 pm

Hi Bob,

That's certainly a very good idea, but i would prefer to not have to use water like that
because i work mostly indoors and i wouldnt really want to have to hold it over
a sink or something while grinding. That would certainly keep it cool though.
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