Setting knives for a square cutterhead Yager
Modified on 2010/01/20 09:25 by BobHolcombe — Categorized as: Uncategorized
Early production of the Yager included a square cutterhead using 2 or 4 knives. Yager planers from serial number 1526 on had a round cutterhead using 3 knive to save costs. Although setting knives for the round cutterhead version is well documented, instructions for the square cutterhead model have yet to be found. Below is a method of setting 4 knives.
Setting knives for a square cutterhead Yager
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By Robert Fox
In trying to set the knives on this 4 knife cutterhead, I quickly realized that the standard method of raising a block into the cutterhead to lock it would not work very well on this planer.
With a knife edge at the top of the arc the block used at the bottom for a lock plate could damage the knives but more importantly was very hard to set because it kept rolling the knives a bit knocking the top knife away from the top of the arc. After looking at this set up for a couple of days a light bulb came on.
The cutterhead extends past the knives and there is space before you get to the bearings to put a lock device. This way I could still lock and have the knives set at the top of their arc. Seeing that these spaces were very narrow I thought an aluminum strap may work. So I cut a couple of short pieces of strap and tried to tape them in position for the table to raise up against. The tape idea did not work very well because the table is itself is only an inch or so wide at the point it is pressing against these straps. So I then cut a couple of short blocks of scrap wood and screwed the straps to the blocks. These were made short enough to allow no contact with the rollers so I would not have to depress them when raising the table to lock the cutterhead. The straps I used were aluminum 1/8 thick one inch high and two inches long. These were screwed to a block that is 1/2 high and 1 inch wide and just under 3 inches long ( this block is laying on its side). Be sure to make both the bottom of the strap and the bottom of the block in the same plane so that the top of the piece of 1/8” strap is the same on both. Now I had a reliable method to lock the cutterhead but how could I get some sort of registration method so each knife was locked at the same point in its arc. A second light bulb came on when I spotted the bearing retainer screw on the crank side of the side casting.
I pulled this screw out and found that the right size allen wrench would fit pretty tight in this hole and when sticking straight out would also lay in the slot in the cutterhead, So by slipping in the wrench, revolving the head till it was lined up with the wrench, it was then easy for me to set the knife and then go to the next one with the same results. Don’t forget to re install the bearing retainer screw
I set the knives with my dial indicator on the outfeed table and slid it along rubbing on the outfeed roller every time.
Tool used to raise knife by prying, leverage from roller. 90 degree bend makes knife raising tool. Small block of wood knocks knife down.