What grit to use for jointer blades?

[David Romano]

How fine of a grit should I use when sharpening my jointer blades? Is 4000 grit fine enough? 8000 grit seems like overkill for this application.

thanks,

David

[Warren E. Johnson]

I don't have an answer to your question but I am intrigued by your question. What method of sharpening jointer blades are you using? Are you referring to the grit of a grinding wheel or some other abrasive?

I would like to determine if there is a way to sharpen jointer knives that does not involve $300 to $400 investment (I know - send them out).

[David Romano]

I don't have an answer to your question but I am intrigued by your question. What method of sharpening jointer blades are you using? Are you referring to the grit of a grinding wheel or some other abrasive?

I would like to determine if there is a way to sharpen jointer knives that does not involve $300 to $400 investment (I know - send them out).


I own the Veritas jointer blade sharpening jig. I first grind out the chips by attaching this jig to another jig that I made. This assembly fits in the slot of my Veritas bench grinder tool rest. This allows me to slide the knife back and forth across the 60 grit wheel very evenly. A bit more gets taken off from the ends, but I'm working on a solution for that.

After this step, I hone using 320 git sandpaper mounted to a granite surface plate with spray adhesive. Then I switch to 3M scary sharp paper 15 um, and 5um (1000 grit and about 4000 grit, respectively) mounted to another granite surface plate. The reason for the granite plates is that they are flat to only a few tenths of a mil. Super flat.

The PITA with jointer blades is that you can't just hone them, because they always get chips in them and shift a blade or two sideways in the cutterhead doesn't always solve the problem.

David

[Wilbur Pan]

My feeling is that your method is probably good enough. If it's sharp enough to give you a tear out free surface, then it's sharp enough.

In my case, I'm going to be reworking the surface from a jointer with a hand plane anyway, so the absolute sharpness isn't critical.

[Cliff Rohrabacher]

If it's sharp enough to give you a tear out free surface, then it's sharp enough.

Bingo~!! ...

[Jim Nardi]

400 grit seems to be the magic number for me.

[David Romano]

400 grit seems to be the magic number for me.

Do you mean 4000?

[Jim Nardi]

Do you mean 4000?

After you run 10' thru your jointer have a look at the edge with a 10X jewlers loop.