cbn on scheppach?

[Faulko]

Hi all. Have been sharpening on the big diameter scheppach wet grinder. Pretty happy, but cheap stone starting to become a pain. Considering getting a cbn to fit on scheppach. Any reason wht this may not be a good option....pros and cons? Grit recommendations etc. Thanks

[BobL]

If your grinder is a ~90 rpm that is too slow for CBN.
All you will end up doing is wearing away the CBN and not removing anywhere near enough metal.

Recommended RPMs for an 8" CBN wheel (Dry) is between 1440 and 2880 RPM and 2880 and 3600 RPM (wet)
see http://www.graffdiamond.com/upload/file/speed_chart_and_sfpm_recommendations.pdf

[mick59wests]

had the same issue as my scheppach wheel started diminishing in size. After a reasonable amount of research (and some recommendations from those I respected) I bought a CBN from Jim Carroll (Carrolls Woodcraft supplies). I got the highest grit I could (240 from memory). I have not used it extensively but am so far very happy with the results. It needs a much lighter touch than the S. grinding wheel.
I was informed that the S. motor might labour under the heavier CBN grinding wheel, but so far, so good - I have probably completed around 30 sharpenings.
cheers
Mick

[Faulko]

Thanks mick....so you run it dry on the scheppach?

[Faulko]

Cheers Bob...Toying with option of vicmarc slow speed wirh cbn....

[mick59wests]

Thanks mick....so you run it dry on the scheppach?
I run it wet
cheers
Mick

[rtyuiop]

Cheers Bob...Toying with option of vicmarc slow speed wirh cbn....

I made this exact switch, from a scheppach to the slow vicmarc and CBN wheels - it's a giant improvement (note I've never tried the scheppach with a CBN wheel). Biggest difference to me is not having to muck about with water, so I am much more likely to sharpen when I should, as opposed to whether I can be bothered! I've got it set up next to the lathe on a nice high stand, so I can take two steps over and do a quick sharpen before an important cut... It's made the biggest improvement to my turning of any piece of equipment, I think.

Also much easier to reshape - I have an 80 grit and a 240 grit CBN on the grinder, but I think even the 240 is much faster than the scheppach for reshaping.

[NeilS]

To my way of thinking, slow grinders of one sort and another are about preventing high carbon steel from over heating and losing its temper.

As most of us woodturners use HSS tools of one variety or another, you are extremely unlikely to de-temper them at the temperatures we grind at, so the faster you can grind HSS the better. Well, that is, if you prefer to be turning than grinding!

And, if you are using cool grinding CBN or diamond wheels you are never going to touch the temper in HSS.

Putting a CBN wheel on a Scheppach or Torment seems to me akin to harnessing up Dobbin to pull a Formula One around the race track.

If you are going to go to the expense of buying a CBN wheel and don't already have a bench grinder, then try to go the extra bit and buy one; I expect you won't regret it.

PS - the above comments are not a reflection on Scheppachs or Torments, per se, just the use of CBN (or diamond) wheels on them.