I never had issue with diamond cutting disks before. I got cheap-ish
ones, and they just worked.
However, yesterday I had about 80 facing brick cross-cuts to make
(cutting tapered headers etc), using 230mm disks in angle grinder
stand. The first disk was a cheapy "titan" (20 quid) that I had been
using for a few months cutting bricks now and then. This was worn
quite low and it suddenly stopped cutting, the brick vitrifying as if
if there were no diamond left. Off to screwfix to get another titan,
since the last had quite a good life. This disk got through 60 cuts
OK, and suddenly stopped cutting like the last, although there was
loads of the cutting band left, and diamonds could be seen on the
sides, but the bottom almost looked "polished" and rounded off.
Long story short, another "clarke" disk from nearby machinemart (20
quid) did not appear to even start cutting. I put that down to
learning experience (it will cut aircrete !!!). Finally, screwfix, got
the Edge GP turbo or something, that took a short while to get going,
but then was pretty good (although no better than the titan, although
it may last longer).
I later read something in the leaftlet that came with the apparently
hopeless clarke disk, saying if the disk stops cutting you may need to
cut some abrasive material to expose some diamonds. So perhaps this is
the problem with all the disks.
If so, whats the best mateial to cut to expose some more diamonds ?
All the disks were general purpose medium/hard versions.
I would probably have been better off getting an expensive disk for
hard material including engineering bricks at the start of my building
work, but there you are.
However, I seem to be lacking some knowledge about the use of there
disks.
Any tips ?
Simon.

HI Simon

sm_jamieson wrote:
I never had issue with diamond cutting disks before. I got cheap-ish
ones, and they just worked.
However, yesterday I had about 80 facing brick cross-cuts to make
(cutting tapered headers etc), using 230mm disks in angle grinder
stand. The first disk was a cheapy "titan" (20 quid) that I had been
using for a few months cutting bricks now and then. This was worn
quite low and it suddenly stopped cutting, the brick vitrifying as if
if there were no diamond left. Off to screwfix to get another titan,
since the last had quite a good life. This disk got through 60 cuts
OK, and suddenly stopped cutting like the last, although there was
loads of the cutting band left, and diamonds could be seen on the
sides, but the bottom almost looked "polished" and rounded off.
Long story short, another "clarke" disk from nearby machinemart (20
quid) did not appear to even start cutting. I put that down to
learning experience (it will cut aircrete !!!). Finally, screwfix, got
the Edge GP turbo or something, that took a short while to get going,
but then was pretty good (although no better than the titan, although
it may last longer).
I later read something in the leaftlet that came with the apparently
hopeless clarke disk, saying if the disk stops cutting you may need to
cut some abrasive material to expose some diamonds. So perhaps this is
the problem with all the disks.
If so, whats the best mateial to cut to expose some more diamonds ?
All the disks were general purpose medium/hard versions.
I would probably have been better off getting an expensive disk for
hard material including engineering bricks at the start of my building
work, but there you are.
However, I seem to be lacking some knowledge about the use of there
disks.
Any tips ?
Simon.

In the lapidary (gemstone cutting) business, the advice for rejuvenating
a glazed-over diamond saw used to be to make a couple of cuts with the
blade into a discarded grinding wheel. The idea was to wear away the
edge of the sawblade to reveal a new diamond cutting surface.

I seem to recall that the better blades have a thicker layer of diamonds
(which this technique relies upon) - whereas cheaper blades may only
have a very thin 'surface layer'of diamonds - and when they're gone
you're stuck !

Hope this helps

Adrian

On 25 June, 09:42, sm_jamieson wrote:

I later read something in the leaftlet that came with the apparently
hopeless clarke disk, saying if the disk stops cutting you may need to
cut some abrasive material to expose some diamonds.

This is usual for bulk abrasive disks (vitirified or sintered), but
not for diamonds.

Bulk abrasive disks can "glaze" on the surface, especially with soft
metals and some clays (hard facing or blue bricks). The trick is
usually to dress the wheel directly with a diamond or hard steel.
Grinding something moderately abrasive (hunk of hard sandstone) can
also help.

Diamond disks are differerent - they've only ever had a thin layer of
diamonds plated into the nickel surface. If you dig through this, then
you've removed the whole diamond layer. The usual failure here is
that you've worn the diamonds out, because they're cheap
polycrystalline diamonds rather than the natural or high-end synthetic
monocrystalline, and you actually broken them in half.

You _might_ still have a problem with glazing the diamonds and
occluding them. So it's back to the sandstone lump for a scrub up.
Worth trying.

I use Aldi's disks. As good as any other cheap diamond disk (inc
Titan), and a lot cheaper.

On 25 June, 10:18, Andy Dingley wrote:
On 25 June, 09:42, sm_jamieson wrote:

I later read something in the leaftlet that came with the apparently
hopeless clarke disk, saying if the disk stops cutting you may need to
cut some abrasive material to expose some diamonds.

This is usual for bulk abrasive disks (vitirified or sintered), but
not for diamonds.

Bulk abrasive disks can "glaze" on the surface, especially with soft
metals and some clays (hard facing or blue bricks). The trick is
usually to dress the wheel directly with a diamond or hard steel.
Grinding something moderately abrasive (hunk of hard sandstone) can
also help.

Diamond disks are differerent - they've only ever had a thin layer of
diamonds plated into the nickel surface. If you dig through this, then
you've removed the whole diamond layer. *The usual failure here is
that you've worn the diamonds out, because they're cheap
polycrystalline diamonds rather than the natural or high-end synthetic
monocrystalline, and you actually broken them in half.

You _might_ still have a problem with glazing the diamonds and
occluding them. So it's back to the sandstone lump for a scrub up.
Worth trying.

I use Aldi's disks. As good as any other cheap diamond disk (inc
Titan), and a lot cheaper.

So a lump of sandstone would be good to try and deglaze ?
Any material more readily to hand ? ;-)

Do Aldi do 230mm disks ? I think I've only seen the smaller ones in
there.
Simon.

"Andy Dingley" wrote in message
...
On 25 June, 09:42, sm_jamieson wrote:

I later read something in the leaftlet that came with the apparently
hopeless clarke disk, saying if the disk stops cutting you may need to
cut some abrasive material to expose some diamonds.

This is usual for bulk abrasive disks (vitirified or sintered), but
not for diamonds.

Bulk abrasive disks can "glaze" on the surface, especially with soft
metals and some clays (hard facing or blue bricks). The trick is
usually to dress the wheel directly with a diamond or hard steel.
Grinding something moderately abrasive (hunk of hard sandstone) can
also help.

Diamond disks are differerent - they've only ever had a thin layer of
diamonds plated into the nickel surface.


Are you sure?
The ones I have from lidl appear to have sintered metal "teeth" with
diamonds throughout.
You get new diamonds as you wear the teeth away.
I can't imagine a diamond blade lasting long if it only has a surface
coating.

"sm_jamieson" wrote in message
...
I never had issue with diamond cutting disks before. I got cheap-ish
ones, and they just worked.
However, yesterday I had about 80 facing brick cross-cuts to make
(cutting tapered headers etc), using 230mm disks in angle grinder
stand. The first disk was a cheapy "titan" (20 quid) that I had been
using for a few months cutting bricks now and then. This was worn
quite low and it suddenly stopped cutting, the brick vitrifying as if
if there were no diamond left. Off to screwfix to get another titan,
since the last had quite a good life. This disk got through 60 cuts
OK, and suddenly stopped cutting like the last, although there was
loads of the cutting band left, and diamonds could be seen on the
sides, but the bottom almost looked "polished" and rounded off.
Long story short, another "clarke" disk from nearby machinemart (20
quid) did not appear to even start cutting. I put that down to
learning experience (it will cut aircrete !!!). Finally, screwfix, got
the Edge GP turbo or something, that took a short while to get going,
but then was pretty good (although no better than the titan, although
it may last longer).
I later read something in the leaftlet that came with the apparently
hopeless clarke disk, saying if the disk stops cutting you may need to
cut some abrasive material to expose some diamonds. So perhaps this is
the problem with all the disks.
If so, whats the best mateial to cut to expose some more diamonds ?
All the disks were general purpose medium/hard versions.
I would probably have been better off getting an expensive disk for
hard material including engineering bricks at the start of my building
work, but there you are.
However, I seem to be lacking some knowledge about the use of there
disks.
Any tips ?
Simon.

There is a faq on diamond cutting here
http://www.encoreproducts.co.uk/advice.shtml

Peter K

On 25 June, 10:58, "dennis@home"
wrote:
"Andy Dingley" wrote in message

...



On 25 June, 09:42, sm_jamieson wrote:

I later read something in the leaftlet that came with the apparently
hopeless clarke disk, saying if the disk stops cutting you may need to
cut some abrasive material to expose some diamonds.

This is usual for bulk abrasive disks (vitirified or sintered), but
not for diamonds.

Bulk abrasive disks can "glaze" on the surface, especially with soft
metals and some clays (hard facing or blue bricks). The trick is
usually to dress the wheel directly with a diamond or hard steel.
Grinding something moderately abrasive (hunk of hard sandstone) can
also help.

Diamond disks are differerent - they've only ever had a thin layer of
diamonds plated into the nickel surface.

The ones I have from lidl appear to have sintered metal "teeth" with
diamonds throughout.

They're not sintered, they're electroplated nickel onto a steel core,
with diamond dust captured in the nickel layer.

Sintering is a hot-press process that works for metallic compounds,
including metal carbides, that can be persuaded to weld themselves by
diffusion bonding. This is the process used for the "knobbly", often
gold-coloured, carbide mortar-rake bits.

You get new diamonds as you wear the teeth away.
I can't imagine a diamond blade lasting long if it only has a surface
coating.

It is however cheaper to make them that way. Spending more gets you
better diamonds (monocrystalline) and in thicker layers. Where I'm
buying hand sharpening stones I'll pay good money to get these. When
I'm buying angle-grinder disks the quality seems to hold up more than
the price drops, so I buy the cheapies. Both Aldi and Lidl have had
9" disks at a smidgen under a fiver.

On 25 June, 10:27, Simon wrote:

So a lump of sandstone would be good to try and deglaze ?
Any material more readily to hand ? ;-)

Any moderately hard grit in a non-clay binder that doesn't try and
vitrify itself. You could probably use limestone, if you're
Northerly, just avoid a matrix that's going to gum up faster than it
cleans (so no bricks).

In article
,
Simon wrote:
Do Aldi do 230mm disks ? I think I've only seen the smaller ones in
there.

Lidl had them the other week.

--
*Learn from your parents' mistakes - use birth control

Dave Plowman London SW
To e-mail, change noise into sound.

On 25 June, 11:34, Andy Dingley wrote:
On 25 June, 10:58, "dennis@home"
wrote:



"Andy Dingley" wrote in message

...

On 25 June, 09:42, sm_jamieson wrote:

I later read something in the leaftlet that came with the apparently
hopeless clarke disk, saying if the disk stops cutting you may need to
cut some abrasive material to expose some diamonds.

This is usual for bulk abrasive disks (vitirified or sintered), but
not for diamonds.

Bulk abrasive disks can "glaze" on the surface, especially with soft
metals and some clays (hard facing or blue bricks). The trick is
usually to dress the wheel directly with a diamond or hard steel.
Grinding something moderately abrasive (hunk of hard sandstone) can
also help.

Diamond disks are differerent - they've only ever had a thin layer of
diamonds plated into the nickel surface.

The ones I have from lidl appear to have sintered metal "teeth" with
diamonds throughout.

They're not sintered, they're electroplated nickel onto a steel core,
with diamond dust captured in the nickel layer.

They are all described as one of two options, sintered or laser
welded.
The laser welded ones are the more expensive.
But all certainly have more diamonds appearing as the disk wears down.
Simon.

On 25 June, 11:59, Simon wrote:

They are all described as one of two options, sintered or laser
welded.

Are those 9" or 12"?

You can't sinter diamonds, but you can mix them with powdered metals
and sinter the lot. This is how "diamond disks" have been made for a
long time, before the electroplating process became cheap and popular
a decade or two back. It's still around, but tends to be for the tiny
stuff, or the big and expensive 12"+ stone-cutters. As you suspect,
there's diamonds all the way through.

Can't make a whole disk like this, so the segments are made separately
and attached. Most are brazed, better ones are laser or e-beam welded.
Less heat dumped into the disk means less distortion, so they run
truer. You can also "spring" the separate disk blanks (as is done for
cicrcular saws) by roller tensioning them, so they stay flatter at
speed or when hot. As you are heating things up though, you can't make
a solid disk with them and so all of these are segmented (not all
segmented disks are attached segments though).

These are all expensive though - they're not in Aldi. Nor are they the
usual sort for "angle grinder" use, they're generally either bigger or
smaller (you can get them Dremel-sized too, and those frequently are
solid unsgemented disks, as they're smaller).

On 25 June, 14:22, Andy Dingley wrote:
On 25 June, 11:59, Simon wrote:

They are all described as one of two options, sintered or laser
welded.

Are those 9" or 12"?

You can't sinter diamonds, but you can mix them with powdered metals
and sinter the lot. This is how "diamond disks" have been made for a
long time, before the electroplating process became cheap and popular
a decade or two back. It's still around, but tends to be for the tiny
stuff, or the big and expensive 12"+ stone-cutters. *As you suspect,
there's diamonds all the way through.

Can't make a whole disk like this, so the segments are made separately
and attached. Most are brazed, better ones are laser or e-beam welded.
Less heat dumped into the disk means less distortion, so they run
truer. *You can also "spring" the separate disk blanks (as is done for
cicrcular saws) by roller tensioning them, so they stay flatter at
speed or when hot. As you are heating things up though, you can't make
a solid disk with them and so all of these are segmented (not all
segmented disks are attached segments though).

These are all expensive though - they're not in Aldi. Nor are they the
usual sort for "angle grinder" use, they're generally either bigger or
smaller (you can get them Dremel-sized too, and those frequently are
solid unsgemented disks, as they're smaller).

http://www.screwfix.com/prods/21955

Simon.

On Thu, 25 Jun 2009 02:18:57 -0700 (PDT), Andy Dingley
wrote:

On 25 June, 09:42, sm_jamieson wrote:

I later read something in the leaftlet that came with the apparently
hopeless clarke disk, saying if the disk stops cutting you may need to
cut some abrasive material to expose some diamonds.

This is usual for bulk abrasive disks (vitirified or sintered), but
not for diamonds.

Bulk abrasive disks can "glaze" on the surface, especially with soft
metals and some clays (hard facing or blue bricks). The trick is
usually to dress the wheel directly with a diamond or hard steel.
Grinding something moderately abrasive (hunk of hard sandstone) can
also help.

Diamond disks are differerent - they've only ever had a thin layer of
diamonds plated into the nickel surface. If you dig through this, then
you've removed the whole diamond layer. The usual failure here is
that you've worn the diamonds out, because they're cheap
polycrystalline diamonds rather than the natural or high-end synthetic
monocrystalline, and you actually broken them in half.

You _might_ still have a problem with glazing the diamonds and
occluding them. So it's back to the sandstone lump for a scrub up.
Worth trying.

I use Aldi's disks. As good as any other cheap diamond disk (inc
Titan), and a lot cheaper.


What some of the concrete drilling guys I have seen working do to
recover their drilling barrels on site is to lightly dress the
segments with a small angle grinder fitted with a cutting or grinding
disc intended for steel. This is ok with slow running core barrels,
but with a high rev. disc it would be better to lightly cut into a
worn out disc.
May be worth a try.
Regards,
Ian....

remove NOSPAM_ from address

There is a faq on diamond cutting here
http://www.encoreproducts.co.uk/advice.shtml

Peter K
As an old fart who goes back to the times when diamond was only an option if
you had NASA-type budgets, the performance of even cheapie disks is
astonishing compared with traditional abrasives. The FAQ is right in saying
that water is a GOOD THING for tile cutting machines, but in my experience
the 300 mm disks in a hand-held grinder will just power through limestone or
paving slabs without any water, as long as you have a sense of touch that
recognises when you are starting to bind because you have gone off-line. At
the smaller scale, the cheap dremel disks have diamond in a chrome? electro
plate layer which is very easy to destroy. The screwfix and aldi/lidl disks
for 115 and 300 mm grinders are *much* more robust; so far, I havn't
actually managed to wear one out (I have to admit that I don't use them all
that much, but I sliced up half a dozen 24 inch slabs last week with a 300
mm disk that I bought a couple of years ago, and I think I'm still on my
first 115 mm disk after several years too).