Sharpening planer blades

[MikeJhn]

I have never attempted to grind my planer blades, but use an Axminster diamond hone: http://www.axminster.co.uk/axminster-di ... one-510258 to keep them sharp, this has worked well, but there will come a time when I need to grind the faces and then lap them to a fine edge, to this end I found an interesting thread on here using a pillar drill: planer-knife-jig-t29969.html my thoughts are that my morticer has a sliding bed and could be utilised to carry the blade back and forth along the grinding wheel, the length of travel is OK, does anyone have any thoughts on this?

Mike

 

[Fitzroy]

I've tried to manually sharpen planer blades, freehand grinding to take out the chips and then sharpening with a jig on a flat surface. I managed to get back to a good straight edge but I ended up with the two knives begin a fractionally different weight and the machine vibrated terribly when I installed them. I can't remember how far out they were, i recall it was less than a gramme but it had a huge effect. If you do attempt this you need to check/ensure the knives are the same weight once you finish grinding/sharpening.

http://www.endmemo.com/bio/grpm.php shows the g-force generated at 6000rpm and a 5cm radius is c. 2000g. A 1g inbalance would equate to a 2kg out of balance force. Probably explains my vibration issue. And for a 25cmx2.5cmx0.3cm knife, 1g equates to .1mm more ground off of one knife compared to the other one, which I could easily have done.

Fitz.

 

[MikeJhn]

Thanks for that, I will use my cantilever balance that I bought to balance the rotor blades on my model helicopter, this was a internal combustion engine four rotor blade scale model of an Auguster 109A, so very accurate, blade to blade and checking of the C of G which on a rotating mass is equally important.

Mike