Abraisve cutoff wheels: ferrous, non-ferrous, masonry

[Existential Angst]

Awl --

What's the real diff?

Can one wheel do all, to some degree? For cutting, not grinding. I"m
mainly concerned with ferrous, non-ferrous cutoff wheels, but just curious
as to how the masonry fits in.

If there really is a big diff between the ferrous, non-ferrous, I'd like to
get a second cheap chop saw from Sears, have them separately set up -- since
my 4x6 bandsaws look like they won't ever function properly again.... :(
AND since it looks like I'll never find a decent blade welder.... :( :(

Oh, along these lines, I use my RAS to cut alum bar, extensively -- carbide
blade.
Can I also cut brass/bronze this way? As efficiently? Abrasive better?
--
EA

[Home Guy]

Existential Angst wrote:

> What's the real diff?
>

> I"m mainly concerned with ferrous, non-ferrous cutoff wheels, but
> just curious as to how the masonry fits in.

All I can say is that in my experience, the metal-cutting disks do very
poorly at cutting concrete.

Don't know why that is...

[DanG]

Metal cutting blades and wheels use aluminum oxide as their primary
grain. Masonry and stone materials use silicon carbide. Non ferrous
materials, especially aluminum, will gum up and gall on blades, files,
and cutters.

According to my dad (92 year old retired tool and die maker) never use
the same files or cutting tools on ferrous and non. He always contended
that the use on one ruined its ability to work well on the other. I
don't know that I have been that much of a purist.


--


___________________________________

Keep the whole world singing . . .
Dan G
remove the seven

[Jon Danniken]

On 01/26/2013 06:42 AM, DanG wrote:
>
> Metal cutting blades and wheels use aluminum oxide as their primary
> grain. Masonry and stone materials use silicon carbide. Non ferrous
> materials, especially aluminum, will gum up and gall on blades, files,
> and cutters.
>
> According to my dad (92 year old retired tool and die maker) never use
> the same files or cutting tools on ferrous and non. He always contended
> that the use on one ruined its ability to work well on the other. I
> don't know that I have been that much of a purist.

After I go through a file used to sharpen a chainsaw chain, I still find
it is useful for many other things, even softer ferrous materials, but
you need a *new* one to sharpen a chain.

Jon

[SMS]

On 1/26/2013 4:55 AM, Existential Angst wrote:
> Awl --
>
> What's the real diff?
>
> Can one wheel do all, to some degree? For cutting, not grinding. I"m
> mainly concerned with ferrous, non-ferrous cutoff wheels, but just curious
> as to how the masonry fits in.
>
> If there really is a big diff between the ferrous, non-ferrous, I'd like to
> get a second cheap chop saw from Sears, have them separately set up -- since
> my 4x6 bandsaws look like they won't ever function properly again.... :(
> AND since it looks like I'll never find a decent blade welder.... :( :(

I recently put in a fake wood floor in a rental unit and I was trying to
undercut about 1" of the concrete under the fireplace brick with a
masonry cut off wheel. It really did nothing other than make a mess. I
ended up using a chisel which was very time consuming.

I wonder what the proper power tool would have been to do this.

[Vic Smith]

On Sat, 26 Jan 2013 08:50:15 -0800, SMS <scharf...@geemail.com>
wrote:

Probably an angle grinder with a diamond blade. I used a fibre
abrasive blade in a circ saw to cut some pavers. Tremendous amount of
dust in the air. Went through a couple blades, but they're cheap.
A good diamond blade is probably 30 bucks.
Even with a diamond blade, unless you can wet the cut somehow, you
need to tent the work off and use a good respirator.
Concrete varies in hardness too, so some will cut easier, some harder.

[DanG]

Dry diamond wheel on circular saw (might be hard to get the 1") or dry
diamond on small off set grinder. There will be a lot of dust which can
be minimized with water, but the resultant slurry might be worse.

[nestork]

Aluminum Oxide is most commonly used for grinding and cutting ferrous
metals.

Silicone carbide is most commonly used for grinding and cutting
non-ferrous metals.

I was told by one guy at Norton Abrasives that he was once told that the
reason for that was because when you're grinding ferrous metals, the
carbon in silicone carbide can be absorbed into the iron, increasing
it's carbon content, and thereby making the iron near the cut harder and
more difficult to machine. So, when grinding iron or steel, he was told
they used aluminum oxide to avoid that problem.

But, it turns out that he was misled. Apparantly, the absorbtion of
carbon from silicone carbide abrasives has nothing to do with it. But,
even though the reason given was wrong, he found that to be a good way
to decide what abrasives to use on what.

So, when in doubt, think about the carbon in the silicone carbide, and
know that the only difference between iron, steel and cast iron is the
amount of carbon in the metal, and so you don't want to change the
machining characteristics of your iron based metal by using silicone
carbide on it.

That is, wrong reason, but it still gives the right answer when it comes
to choosing grinding wheels.




--
nestork

[home...@home.com]

I have used masonry blades to cut steel when I didn't have a proper
blade. It worked, but I was not machining it after, just cutting some
angle iron for welding or something like that. I never did the
opposite.

[Home Guy]

nestork wrote:

> I was told by one guy at Norton Abrasives ...
>
> But, it turns out that he was misled. Apparantly...
>
> So, when in doubt, think about the carbon in the silicone carbide...

So how does all that relate to masonry disks - and what makes them good
for masonry?

[nestork]

Home Guy;3003979 Wrote:
> nestork wrote:
> -

> I was told by one guy at Norton Abrasives ...
>
> But, it turns out that he was misled. Apparantly...
>

> So, when in doubt, think about the carbon in the silicone carbide...-

>
> So how does all that relate to masonry disks - and what makes them good
> for masonry?

It doesn't address the issue of cutting or grinding masonary. It just
deals with what to use for cutting and grinding ferrous and non ferrous
metals.

A partial answer is better than no answer at all.

Really, the way to decide what abrasive to use on a particular material
doesn't have a straight forward answer. There are different grits in
different sizes that break with different characteristics, and all of
those factors affect cutting performance. Similarily there are
different "bonds" which are the glues used to hold those abrasive
particles together, and the bond the wheel uses makes a difference too.

So, deciding on the right disk to use in particular application is like
deciding on what grease to use in a particular application; you
generally need to get a recommendation from a company sales rep or tech
support person that's been trained in that technology as a starting
point, and then working with that expert to overcome any problems you
encounter. But, when you have nothing else to go by, aluminum oxide,
which is the abrasive best described as being "the most widely used
general purpose abrasive" is the default choice.

'GRINDING WHEEL and ABRASIVES BASICS'
(http://www.georgiagrindingwheel.com/grindingwheels_basics.htm)




--
nestork