Q about sharpening 3/4" tooth spacing with WM's CBN BMS250MU

[jimbarry]

I've got one of those automatic CBN machines from WM. Always sharpening 7/8" tooth space blades.  A fellow showed up today with blades from a small mill, it had 3/4" tooth spacing. He didn't know the degree blade he had. And the template I have is only good for determine 7/8" blades.

So my question is, can I use the CBN wheels that I use for 7/8" blades on a 3/4" blade?

[Southside]

Maybe.  First you will need a different cam for the shorter tooth spacing.  The factory one only goes down to 7/8", so you need to get the one for the shorter spacing, part number is in the book.  As to the wheel, you may end up re-profiling the tooth if the other band has a somewhat different shape, so plan on a couple of passes to get it done.

[jimbarry]

Maybe.  First you will need a different cam for the shorter tooth spacing.  The factory one only goes down to 7/8", ...

I just assumed shortening the push stroke on the tooth advancer would be enough. Also taking into consideration the different profile shape.

[Chuck White]

You might need a new grind wheel as well, using the one you have could actually change it's profile to the point where it isn't correct for your own blades!

If it were me, I'd check with Wood-Mizer!

[jimbarry]

You might need a new grind wheel as well, using the one you have could actually change it's profile to the point where it isn't correct for your own blades!

If it were me, I'd check with Wood-Mizer!

The 3/4" blades are for someone else's mill, not mine.   I already have an email sent to local distributor. Its the weekend of course, so I'll have to wait for their reply. Posted here just to see what other users have to say.

[terrifictimbersllc]

Wheel for 7/8 and 3/4 spacing won't be the same.  

Woodmizer CBN wheels are different for these two spacings.  The wheel conforms to the whole profile from tip to tip, either 7/8 or 3/4.

So if you used a 7/8 wheel to grind a 3/4 blade and had the flat left side of the wheel where it is supposed to be to grind the face of that tooth, it would take off the tip of the next tooth when it came down.

Or if you tried to grind a 7/8 pitch blade with a 3/4 wheel and the wheel was (correctly)adjusted so the flat side ground the face of that tooth, the wheel wouldn't reach the last 1/8" of the top side of that tooth. 

[Stephen1]

I have called WM about it, and the answer was buy the blades that match the wheel. I have had a few people show up with different types blades.  I tell them to buy a new set of WM blades and I can help them. I have been able to sharpen 10degree Norwoods so far, they were close enough. 

[jimbarry]

I carry WM cbn stones, as well as cbn stones for Ripper37 and Hakensson.  Most customers coming in have one of these three types. In this particular case its a Ripper blade based on what the customer is telling me, but its 3/4" spacing.