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.