Hone jointer knives in the head...While running

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Forum topic by SirIrb posted 02-13-2015 10:51 PM 2407 views 0 times favorited 19 replies Add to Favorites Watch
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1239 posts in 1432 days

02-13-2015 10:51 PM

Do i start this by saying “talk me off the ledge”?

To begin, big thanks to all who commented on the jack screw issue I was having, issue being that they were missing.

Now the jack leg I bought the jointer from also prided himself as a professional knife sharpener. I think he placed them in a vice and ran a belt sander over them. Yes, many hours and many grits later much of his damage is gone.

As I was setting the knives I got to thinking that, similar to those old powermatic planer attachments that move a stone over the knives I could have the knives high by a thou or two and stone them even…While running [he takes his bow and exits stage left with all then digits and both hands].

Someone who does this all the time, give me a shout out and let me know that, “sure, we always do that.”

I take full responsibility for all my actions. Please don’t start a safety thread. I know, it’s more dangerous than petting kittens.

Thanks jocks.

-- Don't blame me, I voted for no one.

19 replies so far

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3261 posts in 2876 days

#1 posted 02-13-2015 11:07 PM

I used to have an old hard back book on shop tools. It recommended this practice. I have done it a couple of times but it does change the angle on he sharp edge. The procedure is like this. Remove the fence and clamp a straight edge across the in feed table. This can be a 1×2 or 1×4. start the jointer with the knife edge 2 or 3 thousandths above the out feed table. wrap a sheet of notebook paper around the stone you choose to ruin. It will cut a groove in your stone. At least it did in my stone. Now slowly feed the stone over the running cutter head while keeping your hands and fingers on the out feed table. The straight edge will be large enough to stop the stone from feeding across the head. This will cut the knives the thickness of the paper above the out feed table. The stone should be gently slid right to left and back across the knife while doing this. This procedure takes a little convincing at first but it works well. You knives are perfectly parallel to the table when finished. You might have to talk to yourself to decide you can and want to do this the first time.

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169 posts in 2411 days

#2 posted 02-13-2015 11:19 PM

You are clearly aware of the hazards, so I’ll leave the safety be… but here are some technical thoughts from someone who doesn’t know a whole lot about sharpening.

‘While running’ will result in a curve bevel. Consider a hand plane and the bevel. My understanding is that you should set the bevel angle such that when in the plane the bevel is not parallel to the face of the plane. If it were parallel then it would continuously rub resulting in friction etc. Probably has some negative effect at the cutting edge as well. This is equivalent to the round bevel you would get by sharpening while the jointer is running.

‘Not running’ (aka, unplugged) stands a chance, I would think. Set the blades close then lower the in-feed table and work from it. Find a way to lock the drum the blades are in (I’m sure there is a name but I don’t know it) with one blade at the right angle for whatever bevel is considered correct. Set something between your stone and the in-feed to avoid scratching the table and adjust the infeed height until you get a little bit of contact with the stone. go for it. After you do this to all blades you would have to reset the height of the outfeed table to the new blade height.

Remember this is based purely on thoughts, not any useful experience sharpening. Also, I am not suggesting I think this is better than any other approaches that I’m sure have been discussed by much more knowledgeable people than me many times over. But, perhaps it helps you think through your options.

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7046 posts in 2400 days

#3 posted 02-13-2015 11:44 PM

While I’ve never done it before, and I’m not sure if I would even want to, the manual for my old Boice Crane jointer described the procedure as follows:

1. Lay a fine carborundum stone on the front table so that one end of the stone projects slightly beyond the top dead center of the cutterhead. Note how much of the stone comes in contact with the surface of the front table and wrap this part of stone tightly in paper to prevent scratching the table.

2. Turn the cutterhead by hand until the bevel on one of the knives lies directly underneath the carborundum stone. Then lower the front table until the stone is resting flat on the bevel.

3. With one hand, keep the cutterhead from revolving and with the other hand whet down the bevel of the knife by sliding the stone back and forth laterally across the knife. Repeat this operation on each knife, doing the same amount of whetting on each knife bevel.

4. Sharpen the knife edges (be sure to whet the bevels first) now. Use the same carborundum stone and place it on the rear table. Lower the rear table until the stone just touches the cutting edge.

5. Pull the stone back away from the cutterhead and turn the jointer on. Now slide the stone forward until it is over the knives and move it back and forth across the entire length of the cutting knives. Be sure the stone is kept flat on the rear table at all times. If the stone does not touch the knives at all points, stop the jointer, lower the rear table a very slight amount (not over two thousandths of an inch at a time) and repeat until the knives are sharp along the entire edge.

6. If the sharpening process has been done with care, the cutter knives will again cut very smoothly.

7. In the event that the knives can no longer be sharpened by the procedure just described, a new bevel edge will have to be ground or the blades replaced. If a new bevel is desired, remove the knives and regrind them or have them reground at a local saw and knife grinding shop or machine shop.

I just find it easier to take them to my local place and let them do it right :)


-- Brad in FL - In Dog I trust... everything else is questionable

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1239 posts in 1432 days

#4 posted 02-14-2015 12:36 AM

Real good comments so far and none by screen name “Lefty”, which makes me feel much better. The 1×4 across the infeed table makes much sense. Thank you, im all over that one. And the above from the owners manual is the stuff I wanted. Those two together and I will knock this out tomorrow.

It has been said that there are no atheist in foxholes; I say there are no atheists who hone jointer knives while it’s running. Billy Graham said that. Ok, he may have said that. Well, probably not but he should have.

-- Don't blame me, I voted for no one.

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2113 posts in 2839 days

#5 posted 02-14-2015 01:07 AM

You SirIrb, are a nervy guy!

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1239 posts in 1432 days

#6 posted 02-14-2015 01:22 AM

I’ll tell you where I get it from. As I would guess most of us do I owe my trial and error approach to life to dad. Withost pontificating grandly I’ll just share what he and I did when I was 13. We had a Bush hog that needed to be rebuilt. Fully rebuilt. Only thing we could salvage was the stumpjumper, blades and differential. The rest of the Bush hog was just to pull tape on for dims.

Well we get close to done and dad pulls out the smoke wrench and proceeds to cut a foot off the back of the Bush he so “we can back into them trees we can’t run over and take them down”. Then he puts the back tire on a hinge so it can be chained up. That was one bad bush hog.

You SirIrb, are a nervy guy!

- Ocelot

-- Don't blame me, I voted for no one.

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10732 posts in 1687 days

#7 posted 02-14-2015 01:37 AM

I discovered Lansky diamond knife sharpening kit works well on jointer knives.

-- Shooting down the walls of heartache. Bang bang. I am. The warrior.

View wheelerspop's profile


9 posts in 1722 days

#8 posted 02-14-2015 05:03 PM

“Lansky diamond knife sharpening kit”
I have that set myself, and wondered if anyone had tried them on shop tools. I didn’t see why it won’t sharpen cutting tools.

View SirIrb's profile


1239 posts in 1432 days

#9 posted 02-14-2015 05:21 PM

I searched this sharpening kit. What am I missing? Looks like either Arkansas stones and diamond stones. Good prices, though. Just getting the coarse and fine in one kit and using that on the knives?

I got to tell yall, my thumbs hurt this morning from sharpening that hss. It isn’t known for taking an edge. If the sharpening kit cuts that time down I’ll buy it. I worked the knives down from a coarse stone to fine to paper and up to 600 grit. Too much time but better finish than a surface grinder.

-- Don't blame me, I voted for no one.

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1317 posts in 2136 days

#10 posted 02-14-2015 06:28 PM

Fridge- That’s brilliant. I have a lanksy and never even thought of that. I’m giving that a shot!

-- The Wood Is Your Oyster

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1239 posts in 1432 days

#11 posted 02-17-2015 12:02 AM

Fellow jocks, I thought I would post the follow up. I am now 3 less digits due to sharpening my jointer this way…ok, I’m good, no damage done.

I made the tables coplanar, C clamped a board across the infeed table where it would give me about 2 inches of table visible before I hit the board. I taped a sheet of paper to one of my stones and oiled it. Then prayed, prayed, turned the machine on, prayed, held the stone firm in my left and, as though it were hinged, lowered it , grabbed the top of the stone in my right, prayed, and finally pushed down hard with my left and guided it side to side with the board and my right. I was very cautious. This is not for the faint of heart. Seems like it works well.

Let me know if you have done this. I’m open to fine tuning.

-- Don't blame me, I voted for no one.

View gfadvm's profile


14940 posts in 2891 days

#12 posted 02-17-2015 01:41 AM

Wow! You are one brave guy! Let us know if it cuts well, please.

-- " I'll try to be nicer, if you'll try to be smarter" gfadvm

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1239 posts in 1432 days

#13 posted 02-17-2015 01:47 AM

That’s really the money question, right? Well per a previous comment about this forming a micro bevel that is at such an angle that it won’t cut the wood being fed in well. I didn’t notice that. The cut looks very good. To me if the old powermatic planer honing jig is good this has to be. It’s the same principal minus all the cast iron jigs and engineering. Honestly I am going to move the board back and go one more honing to make sure it didn’t just divet the stone and that the honing went all the way across. Yall should try it, all the cool kids are doing it.

-- Don't blame me, I voted for no one.

View Joe McDonald's profile

Joe McDonald

11 posts in 1437 days

#14 posted 02-18-2015 05:23 AM

My old jointer manual says to sharpen the knives just as you are asking, i have not tried it bc i have a byrd head but i sure wanted to at least once!

View Aj2's profile


1878 posts in 1999 days

#15 posted 02-18-2015 06:15 AM

I’ve done something similar on my oliver jointer,What I did was to glue some 600grit wet dry paper to a precision granite plate that covers the whole head at one time.Then I lowerd the outfeed table till it barely touch the highest knive.Then rotated the head buy hand.
I didn’t care too much for the cut its a really steep bevel.And I felt like the heel of the bevel was pounding the wood that’s not good for glueing edges.I shapen my jointer knives and have found the best angle for my work is 42.And when the angle starts getting past 45 the heel of the bevel can make contact.
Someday I might visit the idea again esp if I need my finger nails trimmed up to my knuckles.Aj

-- Aj

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