Novice needs Jointer Help

[Andy Sowers]

I've had the Rigid 6 1/8" jointer for about a year now, and a few months ago I noticed that there were ridges produced, esp when face jointing. So, I figured that at some point the knives had gotten nicked and it was time to get the knives sharpened. While I figured out where to get the knives sharpened locally I decided to buy a set of spare knives from Global Tool Supply since they were pretty cheap...

Well the knives arrived a few weeks ago, and I figured this weekend was the time to replace them. I've never had the "pleasure" of aligning the knives, and I've been agonizing over how painful this was going to be.

My first attempt met with dismal failure. I tried using my Lee Valley precision straightedge to align the tops of the knives with the outfeed table by rotating the knives and adjusting until they just "kissed" the straight edge. But after cinching everything up, the resulting "quality of cut" was horrible. There was a more "chatter" while running a sample board through, and when I was done, there were several grooves running lengthwise along the board... worse than it was before I had even started. This brings me to question #1...

1) Do these replacement knives need to be sharpened first before use? I didn't think these were like hand plane or chisel edges which need to be sharpened before use... was I wrong?

Figuring that I must have done something wrong I went back to check the height of each of the knives again. Gasp... a least one of them was much higher than the other two... I know I must have checked each a hundred times before tightening the locking screws down. After loosening everything up, I confirmed that yes, each of the knives was set properly, but that the act of tightening up the four locking screws was causing the knives to go out slightly as I tightened them up. This brings me to question #2...

2) Just how does one go about tightening the locking screws without throwing the knives out of alignment. I tried tightening them slowly alternating between the four, but that met with only partial success... it took several tries to get it tightened up... I may be tightening these too tight?

My final pass after reworking the height of the knives was much better. The "chatter" was gone and things seemed to be much as they were before. However, I can still see a tell-tale set of grooves in the face of the board... you can't really feel them if you run your fingernail across the width of the board, but you can see them... I checked the new knives (after installation) to see whether I could see any nicks in them but they still look good to me. (but as an aside, the old knives I took out also didn't show any signs of nicks, just overall wear). This brings to me my final question...

3) Any ideas why grooves are still present?

Thanks

Andy

[Brian Keith]

Go to Fine Woodworking and type this in the search-Jointer Knife-Setting Jig. I made this last month and installation was a snap. Give it a try. Good luck. Brian

[glenn bradley]

Brian has you on the right track. I have also seen folks glue rare earth magnets to the back of a piece of 1/4" flaot glass to hold the knives whilst tightening. Is it any wonder folks love carbide insert heads?

Bob Vaughn makes it look easy in this video:

http://video.google.com/videoplay?docid=2983839096587014177&hl=en

[John Downey]

On the grooves, perhaps there is something on the outfeed side which causes "scratching". If the grooves are in the same place as before it can't be the knives, unless they're hitting one of the tables and getting knicked or something (hard to imagine such a poor design, but I have seen it on a Bridgewood planer).

As to setting the knives, its good to develop a light touch. Snug down a screw near each end of the knife, just tight enough to prevent movement. Then check the blade height again. Next snug down the other screws, check height, and tighten all the screws completely. You don't need to use a huge wrench, tight with a little 3" wrench is all thats needed. Another trick for final checking is to mark the knife edges with a sharpie and then plane a board. Look for uneven wear of the ink after one pass.

For setting I've got two pieces of hardwood planed straight with magnets recessed into them (as Glenn mentioned). The magnets hold the wood down to the outfeed table and also hold the blade up if needed, though my jointer has springs under the blade so I don't really need the blade held up.

[Andy Sowers]

Thanks All

That video was fantastic. Robert clearly covers the issue of the knives getting taller as you tighten the locking screws. I dont think I had enough pressure on the knives while I was adjusting the height. Plus, I didn't even consider using something to pound the knives down like he did. I was probably also tightening them more than required...

I do have a dial indicator that I could try, except I'd need to make a little jig to hold it (or buy one of the magnetic bases for it). So with this method did I understand that the knives should be within .001 from the height of the outfeed table?

Per John's suggestion, I also checked my outfeed table for anything that could be causing the grooves... I didn't find anything compelling.

Thanks again... looks like I might just need to tinker with this thing a little more.

Andy

[Peter Quinn]

Sounds like you are in the middle of enjoying the wonderful world of straight knife setting. It is a great exercise that you can master, you are already mostly there, and it will make all of your other machine set ups profoundly easier once you understand it. I advise you master this aspect of wood working before running to the safe refuge of a shelix head. My first attempt took several weeks, I can now do it reasonably well in 30 minutes if I'm moving slow. I am very much ready for a shelix head in my life.

Relative to the grooves in your boards after setting the new knives, are these grooves roughly the width of the straight edge you used to 'kiss' the knives? Straight edges tend to be made of steel much harder than HSS knives, and too much 'kiss'. I have found out the hard way, can literally make a lasting impression. They are generally a bit wider and more subtle than the lines left by nicks caused by rocks and ferrous material. ALWAYS turn the head backwards, gently, into the straight edge on the out feed table when using this method to preserve the knifes edge. It is also possible that your knives were sent poorly sharpened, though I have never experienced this. Every new set of jointer knives I have every bought or installed at work has arrived ready to use.

On the bright side the grooves created by kissing the knives too much with a straight edge can typically be sanded out with a few quick strokes of sandpaper, and are so slight that they should not interfere with planning accuracy in any event.

Relative to jigs, dial indicators and such, all of these techniques count on being able to find TDC (top dead center), which can be as elusive as sighting a rare bird. You will have to do it three times at least per knife change. I took classes at a school that had found TDC, then scribed it into the jointer fence with a machinists scratch awl to facilitate knife setting. It may be painful to set one visible perfect scratch in your otherwise pristine jointer fence, but it is worth it.

Good luck in your endeavors.

[Pete Bradley]

I use the straightedge method also. As you've found, the biggest challenge is keeping the knives in place while you tighten the screws. I use a block of hardwood and I push down *hard* on the edge of the knife directly above one of the jackscrews as I'm tightening.

Pete