Joinet knives , need your help setting

[Darren Graham]

I cannot get the jointer knives set. I think I have tried every method/tip in the world.

Here is the scenario:

Jointer is a jet 6" that is 8 months old. It only has springs to adjust knives. (no jackscrews)

I cannot get the knives installed without them creeping out of place. I have tried using the jointer-pal, a staight edge, a piece of glass to keep them in place, smoothing the knife gib bolt heads to help eliminate creep and also tried some light oil on parts to help keep them from moving.

Lastly, I spent alot of coin on the dispoz-a-blade system. For my jointer the knife and holder is supposed to sit flat into the pocket of the cutterhead. (it does not use the posi-set or self-set) Just bottom it out into the knife pocket and tighten the gib bolts and guess what...it creeps and moves as you tigthen the bolts just like all of the other times with normal knives.

I have tried to tighten the bolts starting from the center and then alternate outwards to others until snug and every other possible combination and it does not help.

One possible cause??:: When I had to remove the factory installed blades it seems like the gib bolts were VERY tight. In the pocket of the cutter head where the bolt heads tighten against the wall there are slight indentations where you can see where each bolt has been tightened. Is this normal??

[Byron Trantham]

I cannot get the jointer knives set. I think I have tried every method/tip in the world.

Here is the scenario:

Jointer is a jet 6" that is 8 months old. It only has springs to adjust knives. (no jackscrews)

I cannot get the knives installed without them creeping out of place. I have tried using the jointer-pal, a staight edge, a piece of glass to keep them in place, smoothing the knife gib bolt heads to help eliminate creep and also tried some light oil on parts to help keep them from moving.

Lastly, I spent alot of coin on the dispoz-a-blade system. For my jointer the knife and holder is supposed to sit flat into the pocket of the cutterhead. (it does not use the posi-set or self-set) Just bottom it out into the knife pocket and tighten the gib bolts and guess what...it creeps and moves as you tigthen the bolts just like all of the other times with normal knives.

I have tried to tighten the bolts starting from the center and then alternate outwards to others until snug and every other possible combination and it does not help.

One possible cause??:: When I had to remove the factory installed blades it seems like the gib bolts were VERY tight. In the pocket of the cutter head where the bolt heads tighten against the wall there are slight indentations where you can see where each bolt has been tightened. Is this normal??

I wouldn't think this normal. Since it is only eight months old you should call Jet. They might replace the cutter head. I can see that if the head has "a hole" to fall into it would be very difficult to keep the blade setting.

[Tom Veatch]

My Jet 6" jointer's cutterhead also shows the "tooling marks" where the gib bolts bear against the cutter head. Don't know that I'd call them "indentations", but there are definite and obvious contact marks. Mine is a few years old and has jackscrews so I can't offer much help with dealing with the springs.

[David Keller NC]

Darren - A couple of things to try. Both are free, one takes little work. The first thing to try is to put a drop of machine oil on the bearing surfaces of the gib screws. Sometimes this helps, though not always. One possible explanation is that the slot is not milled parallel. If this is the case, one would expect creep as the gib crews are tightened.

The second option is a little more drastic, and depends on how much creep you're talking about. If it's a couple of thousandths, this method's guaranteed to work. If more, it's a lot of work.

Align the knives, and set them as best you can. Place a piece of paper on the outfeed table of your jointer directly adjacent to the cutterhead opening. Move each knife to the top dead center position and wedge the head in place to keep it from moving. Use a flat oilstone, medium grit, to lap across the knife edge using the outfeed table as the reference surface (hanging just enough of the oilstone over the edge to contact the knife). Do this to all of the knives.

When done, raise the outfeed table the thickness of the paper (typically 3 or 4 thousandths).

While I don't have difficulty setting the knives on my Delta DJ-20, I still do this. It absolutely ensures that the knives are in the same plane and get more or less equal wear. Moreover, unless one of the knives is chipped, this is a 5 minute procedure that makes a world of difference in the jointer's performance (with freshly honed knives), and it's a lot less work than the hour or so it takes to remove the knives, hone them on the bench, and re-install them.

[John Baranowski]

If you are at TDC, I would think you would dull the knives with this approach. How does this not happen?

[Wilbur Pan]

When your knives creep out of place, are they creeping up, or down?

If they are creeping up, I would set them so that they are a little low, then see how much they creep up as you tighten the bolts. Then when your bolts are just about finger tight, put a block of wood on the knives so that the edge of the knives are going into end grain, and use a hammer to lower it by banging. Don't worry about dulling the blade by doing this -- during normal use, the blade will be impacting wood with far greater force than this maneuver.

[Tom Esh]

Been there. Try playing with the tightening sequence of the bolts. The trick is to find two on each knife that don't creep (as much) and start with those.
All else fails, put a 2x4 on the outfeed table and borrow a neighborhood kid to stand on it while you tighten the bolts.;)

[M Toupin]

Creep is normal, just adjust a bit and then tighten the gibs.

With a little practice it's really not that hard to change knifes. The most important part is to have the head TDC when adjusting the knife. Like anything, the first few times will be slow as you figure it out. I do my 8" in about 10 min. Here's a good "how to".

http://video.google.com/videoplay?docid=-572604587960322121

Mike

[Chip Lindley]

Darren, you say you are using the dispoz-a-blade system which requires you to bottom out the blade/holder at the bottom of the cutter head slot.

What is the problem then????? Press down on the knife with a block of wood while you tighten the gib screws. IF all knives/holders are of the same height, all should remain at the same height when you tighten the gibs. This all seems too simple!!! Am I missing something?

[Darren Graham]

Well, thanks all for the good suggestions. I actually have been on the phone with both jet and esta (dispoz-a-blade).

Jet could not help me out much other than to suggest to tighten the gibs by first lightly tighten the two center then go out to the two end screws then back to the centers then back out to the ends etc. etc.

When on the phone with esta we hopefully resolved my knife creeping problem and the new problem that I noticed after posting the original question. When I dropped the esta knife into the cutter head I noticed the knife holder bevel was going BELOW the outside diameter of the cutter. Which puts the knife at the wrong height and also forms a gap for wood chips to collect. They are sending a replacement set that should take care of that.

They are sending the self-set holders. They say you can use more downward force on these when tightening the gibs screws to help eliminate the creep. Who knows??

Their other suggestion (if I still have problems) was to try a product called Tri-Flow which makes lubricating oils. However, they specifically said to use the dry lubricant that they make. Using it where the knife and lock bar meet together will help REDUCE the creep.

So we will see how it goes

[David Keller NC]

"
If you are at TDC, I would think you would dull the knives with this approach. How does this not happen?"

That's TDC for the knife edge, not the knife itself. If you look at your jointer with the knife edge at TDC, there will still be a significant cant to the back of the blade in relation to the wood. When you hone knives in this manner, you are slightly increasing the bevel by putting a steeper "micro bevel" on it, but there's still plenty of cutting action to take off wood. Even without a physical explanation, though, I can say from my own experience that it works, and it works extremely well.