Thread: Planer Knive Bevel Angle

Robland X31 Planer Knives, bevel angle?.

I have a Sherwood flat grinder, and want to re grind my planer knives on the Robland X31 combination machine.



They need regrinding because I ran white 16mm HMR over them and where the hard melamine coat is on each side of the board, the knives now have little 'nicks' every 16mm! (Ahh but for a scribe saw) .

So,

I removed the blades and set my sliding bevel to the existing bevel angle. Drew lines on paper from that with a very sharp pencil and measured the existing angle with a protractor @ 41 degrees.

I am looking to mostly plane hardwoods (Jarrah) etc and most literature I can find (mainly US) suggests up to 35 degrees for hardwoods like mahogany with some suggesting up to 4o degrees for harder woods.

It's a 3 knife head.

I'm not looking to back bevel them...

Should I just stick with the 41 degrees they currently are ground at?...

Just not sure what angle they come beveled at originally from factory....or what angle others have found most useful for our hardwoods?.

In the past I had 2 knife head jointer & 3 knife head thicky & just sent the knives to the saw doctor along with everything else (saw blades etc) so never really paid any attention to the bevel angles on them.

Now that I wish to do them myself - I can't seem to find anything "definitive"...about the bevel angle.

The steeper the angle, the closer to a scraping cut and the less tear out etc and surface better finish, BUT it's very important that the angles not so steep that the back edge of the bevel hits the timber surface as it draws out the temper in the blade... in very little time.

Anyone?

Thanks in advance.