what knives I should get to fit my Sunhill 6" jointer

[capncarl]

Are the horizontal slots necessary? Looks like the upper slots would weaken the knife.

[LCHIEN]

Are the horizontal slots necessary? Looks like the upper slots would weaken the knife.

the slots are for the jackscrew fine blade height adjustment. Screws in the four vertical slots are mounting bolts, loosened to let the jack screws adjust the height, and after adjustment, to tighten and fix the blade in place once jacked to the adjusted position. The horizontal slots don't see any force more than the weight of the knife while doing the jacking. The mounting bolts take all the operating force while planing.

[dbhost]

Are the horizontal slots necessary? Looks like the upper slots would weaken the knife.

Yes, they are for the jack screws that adjust the knife height.

[dbhost]

Looking at reviews in our articles section Bill in Buena Park says he asked Sunhill way back then, and the said knives for the Craftsman 21788 work as well.

The difference between the "Official knives" for the 21788 and the ones I got, is the extra set of jack screw slots. IF I were to guess, the jack screws probably have enough throw to them to make either set work, but I will be winding in quite a ways to get the inner set of slots to work...

Looks like the 21788 knives are about 2 bucks cheaper...