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jointer blade question

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Forum topic by D_Allen posted 06-22-2012 12:32 AM 1146 views 0 times favorited 4 replies Add to Favorites Watch
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D_Allen

495 posts in 2244 days


06-22-2012 12:32 AM

This is a closeup of one of the 3 blades on an old 4” jointer that I an restoring. The blades feel sharp to the touch but all 3 of them have this secondary bevel that is dead even all the way along the edge. These look like they are perhaps the original blades and it does not look like they have ever been sharpened across the full width of the wide bevel. The cross-hatch grinding marks leads me to think they are not resharpened. However, I cannot figure out if the small bevel at the edge would have been put there by the factory. Is this something that would have been done back in the day? I cannot image that they wore away that evenly.
This seems to be a 37-110 model made in the 1950s. I am going to try to sharpen them with sandpaper just to get a keen edge back on them and see how they cut.
Anyone ever see this before?

-- Website is finally up and running....www.woodandwrite.com


4 replies so far

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MonteCristo

2098 posts in 1649 days


#1 posted 06-22-2012 02:27 AM

Someone may have put what’s called a micro-bevel on them to make it easier to sharpen them.

I would be careful trying to sharpen them by hand with sandpaper. Unless they are evenly worked they may not all cut the same, not to mention that the edge on the blade(s) may not be straight. These things matter on a jointer.

-- Dwight - "Free legal advice available - contact Dewey, Cheetam & Howe""

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D_Allen

495 posts in 2244 days


#2 posted 06-23-2012 02:07 AM

All that is indeed true. I have determined that the major bevel is at 35 degrees so I will attempt a temporary tool to do 2 at a time and rotate them accordingly.
It should not take much to put the edge back on them.
I got new bearings and some matching paint. Now it will just take some hours of time.
I also have a new set of blades that I bought for my other 4” jointer that I never installed.

-- Website is finally up and running....www.woodandwrite.com

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Grandpa

3256 posts in 2136 days


#3 posted 06-23-2012 03:28 AM

There is a technique that is used by some people when they install blades in a jointer. They are set up as usual then stop is clamped to the infeed table. The motor is started and a whetstone is eased over to the stop. This will put an edge on like you have here and it will also perfectly align the knives or blades with the outfeed table. Can this be what you have here?

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D_Allen

495 posts in 2244 days


#4 posted 06-24-2012 01:56 PM

Grandpa, that could be the case. I have heard of that technique but I do not think it has any advantages. What that does is puts an arc sharpening profile on the blade. It would be like sharpening a drill but in a cone shape where there is no height difference on the leading edge. It would have an extremely shallow point in which to cut into the wood before the heal of the arc would bounce against the stock.

I have made a sharpening block from a piece of plastic modeling form. It was cut very square at the corners and has a good amount of weight. Using some spacers that fit beside the blade and keep it tight, I do 2 blades at a time on some 600 grit glued to a piece of tempered glass. I was fairly sure the large bevel was at 35 degrees so I cut these at 34 degrees. I guessed right because the short bevel is being sharpened. In the 2nd picture, the arrows are pointing out the sharpened small bevel that is reflecting like a mirror.

-- Website is finally up and running....www.woodandwrite.com

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